The crosstalk between autophagic and endo-/exosomal pathways in antigen processing for MHC presentation in anticancer T cell immune responses
You et al. Journal of Hematology & Oncology
The crosstalk between autophagic and endo-/exosomal pathways in antigen processing for MHC presentation in anticancer T cell immune responses
Liangshun You 1 2 3
Liping Mao 1 2
Juying Wei 1 2 3
Shenhe Jin 1 2 3
Chunmei Yang 1 2
Hui Liu 1 2 3
Li Zhu 1 2 3
Wenbin Qian 1 2 3
0 Qingchun Road , Hangzhou 310003, Zhejiang , People's Republic of China
1 Institute of Hematology, The First Affiliated Hospital, College of Medicine, Zhejiang University , 79
2 Department of Hematology, The First Affiliated Hospital, College of Medicine, Zhejiang University , Hangzhou, Zhejiang 310003 , China
3 Malignant Lymphoma Diagnosis and Therapy Center, The First Affiliated Hospital, College of Medicine, Zhejiang University , Hangzhou, Zhejiang 310003 , China
4 Qingchun Road , Hangzhou 310003, Zhejiang , People's Republic of China
T cells recognize antigen fragments from proteolytic products that are presented to them in the form of peptides on major histocompatibility complex (MHC) molecules, which is crucial for the T cell to identify infected or transformed cells. Autophagy, a process that delivers cytoplasmic constituents for lysosomal degradation, has been observed to provide a substantial source of intra- and extracellular antigens for MHC presentation to T cells, which will impact the tumor-specific immune response. Meanwhile, extracellular components are transported to cytoplasm for the degradation/secretion process by the endo-/exosomal pathway and are thus involved in multiple physiological and pathological processes, including immune responses. Autophagy and endo-/exosomal pathways are intertwined in a highly intricate manner and both are closely involved in antigen processing for MHC presentation; thus, we propose that they may coordinate in antigen processing and presentation in anticancer T cell immune responses. In this article, we discuss the molecular and functional crosstalk between autophagy and endo-/exosomal pathways and their contributions to antigen processing for MHC presentation in anticancer T cell immune responses.
Autophagy; Endosome; Exosomes; Immune; MHC presentation; Cancer; Immunotherapeutic
In eukaryotic cells, MHC presentation monitors two
proteolytic routes: the ubiquitin-proteasome and the lysosomal
systems. Both of these systems are involved in the
degradation of endogenous and exogenous antigens. The
lysosomal system degrades and recycles long-lived proteins and
defective organelles [
], in which extracellular
components and plasma membrane receptors are transported to
the degradation/secretion pathway by the endo-/exosomal
pathway, whereas intracellular components are transported
to the lysosome by the autophagy process [
and endo-/exosomal processes differ mainly on the
molecular pathway by which the products (cargo) are delivered to
lysosomes for degradation but closely interact with each
other at multiple key checkpoints [
Macroautophagy (hereafter referred to as autophagy),
a cellular self-consumption process, is the main form of
autophagy. Basal autophagy enables cells to recycle
cytoplasmic constituents and restore metabolic
homeostasis, thereby maintaining cellular survival [
regulation of autophagy has been implicated in the
pathogenesis of diverse disease states, such as
neurodegenerative disorders [
], microbial infection [
endocrine diseases [
], myopathies [
], aging [
], and cancer [
]. Except for its
basal function, autophagy is readily induced in harsh
conditions, including nutrient deprivation, radiation,
metabolic stress, endoplasmic reticulum (ER) stress, and
chemotherapeutic agents [
]. The role of autophagy as
an alternate energy source, and thus as a cell survival
mechanism under stressful conditions, is well
recognized. Accumulating evidence has revealed that the
autophagy pathway and its interacting proteins
substantially impact several aspects of innate and adaptive
]. The immune system uses autophagy
to detect invading pathogens and monitor transformed
cells. The specific roles of autophagy in innate immunity,
which is regulated by pattern recognition receptor (PRR)
signaling, are regulating inflammation and eliminating
apoptotic corpses to prevent insufficient inflammatory
or excessive inflammatory responses [
]. In adaptive
immunity, the autophagy pathway is essential to antigen
presentation, thymus selection, lymphocyte
development, and immune homeostasis [
Autophagy has also been implicated in the exosome
secretory pathway [
]. An exosome is a kind of small
nanometric membrane vesicle that is released to the
extracellular environment by almost every cell type. As
important mediators in intercellular communications,
exosomes manage the exchange of proteins and genetic
material derived from parent cells. Evidence shows that
this kind of intercellular communication by exosomes is
involved in multiple physiological and pathological
processes, including immune responses [
particular, the communications between immune cells
and cancer cells via exosomes play dual roles in
modulating tumor immunity [
Recent studies suggest that autophagy and
endo-/exosomal pathways are closely involved in antigen
processing for MHC presentation, which results in the
activation of tumor-specific T cells. However, thoroughly
understanding the inter-regulations between autophagy
and endo-/exosomal pathways in antigen processing is
an interesting challenge. In this review, we focus on the
crosstalk between autophagy and endo-/exosomal
pathways and their contributions to antigen processing for
MHC presentation in cancer.
Overview of autophagy
More than 30 autophagy-related gene (ATG) proteins are
involved in the complex processes of autophagosome
formation, encapsulation of target cargoes, and subsequent fusion
with the lysosome for degradation [
formation is a multistep process involving at least three
]: initiation, nucleation, and expansion of the
isolation membrane (Fig. 1 (A)). The initiation begins with
the formation of the phagophore assembly site (PAS), the
origin of which is still unclear in mammals [
UNC51-like kinase (ULK) complex, consisting of ULK1 (or
ULK2), ATG13, ATG101, and focal adhesion kinase family
interacting protein of 200-kDa (FIP200), creates the PAS
]. When cells are stimulated by autophagy, type I
PI3KAKT-mTOR signaling is inhibited and type III PI3K
mammalian vps34/Beclin1 (ATG6) is activated. Inhibition of
mTOR re-associates dephosphorylated ATG13 with Atg1,
which induces redistribution of mAtg9 from trans-Golgi to
late endosome [
]. Simultaneously, the activation of vps34/
Beclin1 generates phosphatidylinositol 3-phosphate (PIP3)
on the endomembrane, resulting in the isolation and binding
of ATG5 and ATG16 to a small template membrane, which
is designated as the phagophore [
nucleation and recruitment of ATG5-ATG12-ATG16L to the
autophagosome membrane facilitates the conjugation of
phosphatidylethanolamine (PE) to microtubule-associated
protein 1 light chain 3 (MAP-LC3) [
MAP-LC3 is required for expansion of autophagosome
membranes, recognition of target cargo, and fusion of the
autophagosome with lysosomes [
]. The autophagosome
then fuses with endocytic and lysosomal compartments,
ultimately leading to formation of the autolysosome, where
engulfed components are eventually degraded [
The crosstalk between autophagy and exosomal pathways
Perpendicular to the autophagy process is the endosomal
pathway. Numerous studies have shown a close relationship
between the autophagy pathway and the biogenesis and
secretion of exosomes [
5, 20, 34, 35
must undergo a series of maturation steps, in part by fusing
with endocytic vesicles, including early and late endosomes
and multivesicular bodies (MVBs) [
26, 36, 37
maturation of the autophagosome requires an intact endocytic
trafficking pathway, components of the endosomal sorting
complex required for transport (ESCRT) pathway, and
components involved in endocytic vesicle fusion [
ESCRT mutants failed to complete autophagic maturation
due to the lack of autophagosome fusion with the
endolysosomal system and resulted in an increased number of
]. Remarkably, autophagy modulators
regulate MVB formation and exosome release (Fig. 1 (A)).
MVBs are derived from endosomes by inward budding of
their membrane to create intraluminal vesicles (ILVs) .
Once formed, MVBs can go through the secretory or
lysosomal pathway. In the secretory pathway, the MVB can fuse
with the plasma membrane to release its intraluminal vesicles
as exosomes directly into the extracellular space. In the
lysosomal pathway, the MVBs fuse with a lysosome, or
alternatively with the autophagosome, to become an amphisome
prior to fusion with a lysosome, ultimately leading to content
35, 43, 44
]. In autophagy induction, MVBs are
directed to the autophagic pathway with consequently greater
autophagic degradation and inhibition of exosome release.
Alternatively, in a blockage of autophagosome maturation or
fusion with a lysosome, the equilibrium would be shifted
toward the endo-/exosomal pathway through the fusion of
autophagosomes to MVBs and release in exosomes. This
dynamic interaction between these interconnected pathways
may be of great significance in the context of cellular stress
Phagocytosis (Fig. 1 (A)), a prominent endocytic pathway,
is regulated by ATG proteins . During this
LC3associated phagocytosis (LAP) process, MAP-LC3 seemed
to be transiently recruited to a subset of the phagosome
membrane, which is surrounded by pathogen-associated
molecular pattern (PAMP) receptors, thus enhancing
phagosome fusion with lysosomes [
]. The generation
of reactive oxygen species (ROS) produced by NADPH
oxidases-2 (NOX-2) at the phagosome was proposed to be
necessary in maintaining the conjugation of MAP-LC3 to
phagosomes in LAP . The fate of these phagosomes
depends on their cellular background. In plasmacytoid
dendritic cells (pDCs) and human macrophages, LAP
vesicles seem to be stabilized for fusion with toll-like
receptors (TLRs) that contain endosomes and postponed
the presentation of extracellular antigens for MHC class II
]. Thus, the autophagy machinery that mediates LAP
can affect the fate of phagosomes and the processing of
Autophagy and antigen presentation in cancer
Recent accumulating evidence has shown that the autophagy
pathway plays a crucial role in antigen processing (Fig. 1 (B)).
Cancer cells use autophagosome formation to fuse
endogenous and exogenous antigen processes with MHC I and II for
antigen presentation to T cells, which is of great significance
in antitumor immune response [
Autophagy can deliver cytoplasmic constituents for
lysosomal hydrolysis, which contributes to the
processing of endogenous antigens for presentation by MHC II
]. Some previous studies revealed that
antigens, including tumor antigens, can be presented on
MHC II molecules. For example, the agents specifically
blocking autophagy (3-MA and Wortmannin) were
shown to reduce the capacity of dendritic cells (DCs) to
present MHC II-restricted peptide derived from
endogenously synthesized mucin1 (MUC1), which is a
heterodimeric protein that is aberrantly expressed in
various cancer cells [
]. It is likely that some
anticancer drugs potentially act by triggering autophagy and,
by doing so, could cause an enhanced presentation of
intracellular CD4+ T cell epitopes in MHC II-expressing
tumor cells. These studies demonstrated that autophagy
facilitates MHC II presentation of peptides from
intracellular proteins in a general way and indicated that
autophagy might act as a potential mechanism for the
presentation of tumor antigen to MHC molecules.
Different from antigen processing for MHC II
presentation, the role of autophagy in antigen processing for
MHC I presentation is not well studied. However,
autophagy machinery has been implicated in the
presentation of exogenous, endocytosed antigens by MHC class
I molecules and is a pathway termed cross-presentation
that plays a critical role in cytotoxic T cell immunity
against tumors. Several studies reported the relationship
between MHC I-mediated autophagy and cancer
immune response. The direct evidence from Li et al.
] showed that in HEK 293 T cells expressing
ovalbumin (OVA) antigen treated with mTOR, inhibitor
rapamycin underwent autophagy and displayed elevation of
the MHC class I cross-presentation of OVA antigens by
DCs. A recent study discovered that TNF-α could
induce autophagy to enable the processing and
presentation of mitochondrial antigens at the cell surface by
MHC class I molecules [
]. Collectively, autophagy has
been suggested to contribute to the cross-presentation
of MHC I molecules, which plays a pivotal role in the
initiation and development of T cell immune responses
to tumor-associated antigens, including self or mutated
self-antigens derived from tumor cells.
Exosome-mediated activation of immune response via antigen presentation to T cells
Exosomes are a kind of nanometric (30–120 nm in
diameter) extracellular vesicles (EVs) formed in vesicular
bodies in the endosomal network and can be released by
almost all types of cells, including cancer cells. Exosomes
play an essential role in cell-to-cell communication, both
locally and systemically, by exchanging of their contents,
including a subset of proteins, lipids, and functional
genetic material derived from the parent cells [
Emerging evidence shows that intercellular communication
mediated by exosomes is involved in pathological processes
of many diseases, especially in cancers. Interestingly,
exosomes have been observed to play crucial roles in
carrying and presenting functional MHC-peptide complexes to
modulate antigen-specific T cell activation through direct
presentation and cross-presentation pathways [
this section, we focus on exosome-mediated activation of
anticancer immune response via MHC presentation to T cells.
Dendritic cell-derived exosome (DEX)-mediated antigen
Through intercellular communication, exosomes
stimulate the immune system to produce antitumor responses,
of which the key factor is the APCs, which present
MHC-peptide complexes to T cells. Initial studies of the
proteome of DEXs revealed a unique molecular
composition that endows them with strong immunostimulatory
properties in antigen processing and presentation .
In 1996, B cell-derived exosomes were first identified as
possessing antigen-presentation machinery on their
surface membranes and the ability to induce
antigenspecific MHC II-restricted T cell immune responses
]. Subsequently, this phenomenon was discovered to
be shared by DEXs, which carry surface MHC class I
and MHC class II molecules, and therefore can
potentially directly stimulate CD8+ and CD4+ T cells against
cancer cells, respectively [
]. Furthermore, DEXs
derived from tumor peptide-stimulated DCs could be
used to prime tumor-specific cytotoxic T lymphocyte
(CTL) responses that could control, or in some cases
eradicate, established murine tumors [
DEXs were shown to possess some kind of functional
molecular substance on its surface that may participate
in antigen presentation. CD86, a functional
costimulatory molecule, may contribute further toward aiding T
cell priming during antigen presentation [
shock protein 70 (Hsp70) family members, another DEX
component presented in endocytic compartments of
DCs, are in charge of a part of immunogenicity, given
their antigens’ chaperone and MHC-loading roles [
Two mechanisms have been proposed for how DEXs
present antigens via their MHC molecules to stimulate
T cell responses: direct and indirect pathways (Fig. 2). It
was shown that DEXs can directly stimulate T cells in
vitro, although it appears that this mechanism operates
much more efficiently in stimulating T cell lines,
including activated and memory T cells, compared with naive
T cells [
]. Direct DEX-to-T cell stimulation
appears to be more inefficient in priming naive T cells than
T cells of the parent APCs, but it can be improved if
DEXs are immobilized or their concentration is
increased in vitro .
Indirect DEX-to-T cell presentation following
interactions of DEXs and DCs is another pathway that
stimulates T cell responses and is likely to be the most
fundamental pathway in vivo (Fig. 2) [
63, 71, 75
particular note, DEX priming of naive T cells has been
shown to occur only if APCs are present [
presence of certain exosome surface membranes, such
as integrins and intercellular cell adhesion molecule-1
(iCAM1, also known as CD54), facilitates the uptake of
DEXs by APCs [
]. Indeed, the exosomes released
from mature DCs treated with lipopolysaccharide (LPS)
or IFN-γ possess more surface expression of MHC class
II, CD86, and iCAM1 molecules and exhibit a more
potent T cell stimulatory function than exosomes
secreted by immature DCs [
]. To date, two
possible mechanisms have been described for indirect
DEX-to-T cell stimulation via bystander DCs. One
indirect presentation mechanism, which has been proven and
approved, may temporarily be called “reprocessing.” In
this process, the DEX-MHC antigens are captured and
reprocessed by APCs and act as the APC-MHC antigens
]. In the other process, known as “cross-dressing,”
DEX peptide-MHC complexes attach to mature APC
surfaces, which provide the required costimulatory
molecules that are absent in the DEXs, and can thus be
recognized by T cells directly without the need of APC
]. However, the “cross-dressing”
process is still debated and must be further investigated.
Modified tumor-derived exosome (TEX)-mediated
tumorspecific antigen presentation and tumor vaccine
Different from DEXs, in terms of the immune system,
TEXs play dual roles in modulating tumor immunity:
immunosuppression and immune activation. TEX
properties are distinct from the properties of exosomes secreted
by normal cells, except TEXs are rich in various
immunosuppressive molecules. TEXs also carry tumor-associated
antigens (TAAs), a variety of co-stimulatory proteins and
MHC molecules, all of which enable them to stimulate
immune responses [
]. The “yin and yang” of TEXs
in the regulation of tumor immunity are summarized in a
review by Liu et al. [
]. In this section, we focus on
TEXmediated tumor-specific antigen presentation in the
antitumor immune response.
Early studies showed that TEXs containing native
tumor antigens can be efficiently transferred to DCs and
induce antigen-specific CD8+ T cell activation via the
reprocessing or cross-dressing process, which results in
tumor rejection in various prophylaxis and therapeutic
murine tumor xenograft models [
vaccination of mice with TEXs was shown to induce a
potent CD8+ T cell-mediated antitumor effect not only
on the autologous tumor, but also against other related
tumors expressing the same tumor-rejection antigens
. Another approach to exploit exosome-based cancer
immunotherapy is the application of DCs pulsed with
tumor peptides [
]. Both mouse and human
TAAloaded DCs can secrete exosomes that express
functional MHC class I, class II, and T cell co-stimulatory
molecules. These exosomes have been reported to
stimulate tumor-specific CD8+ T cells in vivo and inhibit
tumor growth in mice. On the basis of these clues, TEXs
have been developed as cancer-specific vaccines for
clinical application. In fact, TEX vaccines from patients with
metastatic melanoma, advanced colorectal cancer, and
non-small cell lung cancer have been tested in phase I
and/or phase II clinical trials [
However, the antitumor immune responses induced by
TEXs are mild, and thus, many strategies have been
adopted to develop modified TEXs to elicit a more
efficient antitumor immune response (Fig. 3). One of the
common strategies is to make genetic modifications to
the original cells to improve the immunogenicity of
exosomes, such as CD40L- or cytokine gene (IL-2 and
IL18)-modified cancer cells [
]. Other strategies involve
adding external stimulus, such as tumor-specific antigens
], to trigger tumor cells to release more effective
specific exosomes. Of particular note, combining treatment
involving TEXs and program death-1 (PD-1) or program
death ligand-1 (PD-L1) blockades could reduce
tumorinfiltrating lymphocyte (TIL) suppression and enhance T
cell priming [
]. Moreover, a recent study showed
that TEXs combined with chemotherapy agent
cyclophosphamide (CTX) significantly enhanced tumor
antigeninduced CD8+ T cell recall responses in vivo, leading to a
synergistic effect against pre-established tumors .
The notion that autophagy and endo-/exosomal pathways
are distinct should be reconsidered because they share
many components and are intertwined in a highly intricate
manner. In essence, autophagy can regulate endosomal
secretion to form extracellular vesicles, which can in turn
regulate autophagy in a paracrine manner. Recent studies
suggest that autophagy plays such a role in the context of
anticancer T cell immune responses, while exosomes have
been observed to play crucial roles in carrying and
presenting functional MHC-peptide complexes to modulate
tumor-specific T cell activation. Therefore, we predict that
antitumor immune responses could be regulated by
modulating the molecular interactions between the autophagy
and endo-/exosomal pathways according to the status of
cellular metabolism. Despite the major challenges that may
be encountered in further investigation of the precise
regulation of these two pathways to achieve the expected
effective anticancer immune response, the prospect of
autophagy- and exosome-associated immunotherapy as a
novel cancer treatment remains highly promising.
APCs: Antigen-presenting cells; ATG: Autophagy-related gene; CTL: Cytotoxic
T lymphocyte; CTX: Cyclophosphamide; DCs: Dendritic cells; DEXs: Dendritic
cell-derived exosomes; ER: Endoplasmic reticulum; ESCRT: Endosomal sorting
complex required for transport; EVs: Extracellular vesicles; FIP200: Focal
adhesion kinase family interacting protein of 200-kDa; Hsp70: Heat shock
protein; iCAM1: Intercellular cell adhesion molecule-1; IL: Interleukin;
ILVs: Intraluminal vesicles; LAP: LC3-associated phagocytosis;
LPS: Lipopolysaccharide; MAP-LC3: Microtubule-associated protein 1 light
chain 3; MHC: Major histocompatibility complex; mTORC1: Mammalian target
of rapamycin complex1; MUC1: Mucin1; MVBs: Multivesicular bodies;
NADPH: Nicotinamide adenine dinucleotide phosphate; NOX-2: NADPH
oxidases-2; PAMP: Pathogen-associated molecular pattern; PAS: Phagophore
assembly site; PD-1: Program death-1; pDCs: Plasmacytoid dendritic cells;
PDL1: Program death ligand-1; PE: Phosphatidylethanolamine;
PIP3: Phosphatidylinositol 3-phosphate; PRRs: Pattern recognition receptors;
ROS: Reactive oxygen species; TAAs: Tumor-associated antigens; TEXs:
Tumorderived exosomes; TIL: Tumor-infiltrating lymphocyte; TLR: Toll-like receptor;
ULK: UNC51-like kinase; vps34: Vacuolar protein sorting 34
This study was supported by the National Natural Science Foundation of
China (Nos. 81500110, 81370645, 81670178), the National Key Research and
Development Program of China (No. 2016YFC090150X), and the Research
Project for Practice Development of National TCM Clinical Research Bases
WBQ and LSY were responsible for the conception and design of the
manuscript. All authors participated in the drafting of the manuscript and
approved its final version.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
1. Varshavsky A. The ubiquitin system, autophagy, and regulated protein degradation . Annu Rev Biochem . 2017 ; 86 : 123 - 8 .
2. Mizushima N. Methods for monitoring autophagy . Int J Biochem Cell Biol . 2004 ; 6 ( 12 ): 2491 - 502 .
3. Ktistakis NT , Tooze SA . Digesting the expanding mechanisms of autophagy . Trends Cell Biol . 2016 ; 26 ( 8 ): 624 - 35 .
4. Levine B , Klionsky DJ . Development by self-digestion: molecular mechanisms and biological functions of autophagy . Dev Cell . 2004 ; 6 ( 4 ): 463 - 77 .
5. Baixauli F , Lopez-Otin C , Mittelbrunn M. Exosomes and autophagy: coordinated mechanisms for the maintenance of cellular fitness . Front Immunol . 2014 ; 5 : 403 .
6. Mizushima N , Levine B , Cuervo AM , Klionsky DJ . Autophagy fights disease through cellular self-digestion . Nature . 2008 ; 451 ( 7182 ): 1069 - 75 .
7. Wong YC , Holzbaur EL . Autophagosome dynamics in neurodegeneration at a glance . J Cell Sci . 2015 ; 128 ( 7 ): 1259 - 67 .
8. Orvedahl A , Levine B. Eating the enemy within: autophagy in infectious diseases . Cell Death Differ . 2009 ; 16 ( 1 ): 57 - 69 .
9. Demirtas L , Guclu A , Erdur FM , Akbas EM , Ozcicek A , Onk D , et al. Apoptosis, autophagy & endoplasmic reticulum stress in diabetes mellitus . Indian J Med Res . 2016 ; 44 ( 4 ): 515 - 24 .
10. Malicdan MC , Nishino I. Autophagy in lysosomal myopathies . Brain Pathol . 2012 ; 22 ( 1 ): 82 - 8 .
11. Zhang C , Syed TW , Liu R , Yu J . Role of endoplasmic reticulum stress, autophagy, and inflammation in cardiovascular disease . Front Cardiovasc Med . 2017 ; 12 : 4 - 29 .
12. Yen WL , Klionsky DJ . How to live long and prosper: autophagy, mitochondria, and aging . Physiology (Bethesda) . 2008 ; 23 : 248 - 62 .
13. Fulda S. Autophagy in cancer therapy . Front Oncol . 2017 ; 7 : 128 .
14. Yoshida GJ . Therapeutic strategies of drug repositioning targeting autophagy to induce cancer cell death: from pathophysiology to treatment . J Hematol Oncol . 2017 ; 10 : 67 .
15. Puleston DJ , Simon AK . Autophagy in the immune system . Immunology . 2014 ; 141 ( 1 ): 1 - 8 .
16. Shibutani ST , Saitoh T , Nowag H , Münz C , Yoshimori T. Autophagy and autophagyrelated proteins in the immune system . Nat Immunol . 2015 ; 16 ( 10 ): 1014 - 24 .
17. Pan H , Chen L , Xu Y , Han W , Lou F , Fei W , et al. Autophagy-associated immune responses and cancer immunotherapy . Oncotarget . 2016 ; 7 ( 16 ): 21235 - 46 .
18. You L , Jin S , Zhu L , Qian W . Autophagy, autophagy-associated adaptive immune responses and its role in hematologic malignancies . Oncotarget . 2017 ; 8 ( 7 ): 12374 - 88 .
19. Deretic V , Kimura T , Timmins G , Moseley P , Chauhan S , Mandell M. Immunologic manifestations of autophagy . J Clin Invest . 2015 ; 125 ( 1 ): 75 - 84 .
20. Papandreou ME , Tavernarakis N. Autophagy and the endo/exosomal pathways in health and disease . Biotechnol J . 2017 ; 12 ( 1 ): e00175 .
21. Liu Y , Gu Y , Cao X. The exosomes in tumor immunity . Oncoimmunology . 2015 ; 4 ( 9 ): e1027472 .
22. Wang J , Sun X , Zhao J , Yang Y , Cai X , Xu J , et al. Exosomes: a novel strategy for treatment and prevention of diseases . Front Pharmacol . 2017 ; 8 : 300 .
23. Kalluri R. The biology and function of exosomes in cancer . J Clin Invest . 2016 ; 126 ( 4 ): 1208 - 15 .
24. Klionsky DJ , Emr SD . Autophagy as a regulated pathway of cellular degradation . Science . 2000 ; 290 ( 5497 ): 1717 - 21 .
25. Eskelinen EL . Maturation of autophagic vacuoles in mammalian cells . Autophagy . 2005 ; 1 ( 1 ): 1 - 10 .
26. Lamb CA , Yoshimori T , Tooze SA . The autophagosome: origins unknown, biogenesis complex . Nat Rev Mol Cell Biol . 2013 ; 14 ( 12 ): 759 - 74 .
27. Alemu EA , Lamark T , Torgersen KM , Birgisdottir AB , Larsen KB , Jain A , et al. ATG8 family proteins act as scaffolds for assembly of the ULK complex: sequence requirements for LC3-interacting region (LIR) motifs . J Biol Chem . 2012 ; 287 ( 47 ): 39275 - 9 .
28. Young AR , Chan EY , Hu XW , Köchl R , Crawshaw SG , High S , et al. Starvation and ULK1-dependent cycling of mammalian Atg9 between the TGN and endosomes . J Cell Sci . 2006 ; 119 ( Pt18 ): 3888 - 9000 .
29. Axe EL , Walker SA , Manifava M , Chandra P , Roderick HL , Habermann A , et al. Autophagosome formation from membrane compartments enriched in phosphatidylinositol 3-phosphate and dynamically connected to the endoplasmic reticulum . J Cell Biol . 2008 ; 182 ( 4 ): 685 - 701 .
30. Yin Z , Pascual C , Klionsky DJ . Autophagy: machinery and regulation . Microbial Cell . 2016 ; 3 ( 12 ): 588 - 96 .
31. Maiuri MC , Zalckvar E , Kimchi A , Kroemer G . Self-eating and self-killing: crosstalk between autophagy and apoptosis . Nat Rev Mol Cell Biol . 2007 ; 8 ( 9 ): 741 - 52 .
32. Sou YS , Waguri S , Iwata J , Ueno T , Fujimura T , Hara T , et al. The Atg8 conjugation system is indispensable for proper development of autophagic isolation membranes in mice . Mol Biol Cell . 2008 ; 19 ( 11 ): 4762 - 75 .
33. Nakatogawa H , Suzuki K , Kamada Y , Ohsumi Y. Dynamics and diversity in autophagy mechanisms: lessons from yeast . Nat Rev Mol Cell Biol . 2009 ; 10 ( 7 ): 458 - 67 .
34. Nowag H , Munz C . Diverting autophagic membranes for exocytosis . Autophagy . 2015 ; 11 ( 2 ): 425 - 7 .
35. Ojha CR , Lapierre J , Rodriguez M , Dever SM , Zadeh MA , DeMarino C , et al. Interplay between autophagy, exosomes and HIV-1 associated neurological disorders: new insights for diagnosis and therapeutic applications . Viruses . 2017 ; 9 ( 7 ): 176 .
36. Griffiths RE , Kupzig S , Cogan N , Mankelow TJ , Betin VM , Trakarnsanga K , et al. Maturing reticulocytes internalize plasma membrane in glycophorin A-containing vesicles that fuse with autophagosomes before exocytosis . Autophagy . 2012 ; 119 ( 26 ): 6296 - 306 .
37. Lamb CA , Dooley HC , Tooze SA . Endocytosis and autophagy: shared machinery for degradation . BioEssays . 2013 ; 35 ( 1 ): 34 - 45 .
38. Murrow L , Malhotra R , Debnath J . ATG12 - ATG3 interacts with Alix to promote basal autophagic flux and late endosome function . Nat Cell Biol . 2015 ; 17 ( 3 ): 300 - 10 .
39. Lee JA , Gao FB . Roles of ESCRT in autophagy-associated neurodegeneration . Autophagy . 2014 ; 4 ( 2 ): 230 - 2 .
40. Xavier M , Renaud L . Autophagy in endosomal mutants: desperately seeking to survive . WormBook . 2012 ; 1 : 216 - 20 .
41. Lee J , Beigneux A , Ahmad ST , Gao FB . ESCRT-III dysfunction causes autophagosome accumulation and neurodegeneration . Current Biology Cb . 2007 ; 17 ( 4 ): 1561 - 7 .
42. Scott CC , Vacca F , Gruenberg J . Endosome maturation, transport and functions . Semin Cell Dev Biol . 2014 ; 31 ( 7 ): 2 - 10 .
43. Fader CM , Colombo MI . Autophagy and multivesicular bodies: two closely related partners . Cell Death Differ . 2009 ; 16 ( 1 ): 70 - 8 .
44. Fevrier B , Raposo G . Exosomes: endosomal-derived vesicles shipping extracellular messages . Curr Opin Cell Biol . 2004 ; 16 ( 4 ): 415 - 21 .
45. Fader C , Colombo MI. Multivesicular bodies and autophagy in erythrocyte maturation . Autophagy . 2006 ; 2 ( 2 ): 122 - 5 .
46. Munz C , Of LAP . CUPS, and DRibbles-unconventional use of autophagy proteins for MHC restricted antigen presentation . Front Immunol . 2015 ; 6 : 200 .
47. Bhattacharya A , Eissa NT . Autophagy as a stress response pathway in the immune system . Int Rev Immunol . 2015 ; 34 ( 5 ): 382 - 402 .
48. Romao S , Gasser N , Becker AC , Guhl B , Bajagic M , Vanoaica D , et al. Autophagy proteins stabilize pathogen-containing phagosomes for prolonged MHC II antigen processing . J Cell Biol . 2013 ; 203 ( 5 ): 757 - 66 .
49. Lee HK , Mattei LM , Steinberg BE , Alberts P , Lee YH , Chervonsky A , et al. In vivo requirement for Atg5 in antigen presentation by dendritic cells . Immunity . 2010 ; 32 ( 2 ): 227 - 39 .
50. Delamarre L , Pack M , Chang H , Mellman I , Trombetta ES . Differential lysosomal proteolysis in antigen-presenting cells determines antigen fate . Science . 2005 ; 307 ( 5715 ): 1630 - 4 .
51. Jin Y , Hong Y , Park CY , Hong Y. Molecular interactions of autophagy with the immune system and cancer . Int J Mol Sci . 2017 ; 18 : e1694 .
52. Schmid D , Pypaert M , Münz C . Antigen-loading compartments for major histocompatibility complex class II molecules continuously receive input from autophagosomes . Immunity . 2007 ; 26 ( 1 ): 79 - 92 .
53. Munz C . Antigen processing via autophagy-not only for MHC class II presentation anymore ? Curr Opin Immunol . 2010 ; 22 ( 1 ): 89 - 93 .
54. Dörfel D , Appel S , Grünebach F , Weck MM , Müller MR , Heine A , et al. Processing and presentation of HLA class I and II epitopes by dendritic cells after transfection with in vitro-transcribed MUC1 RNA . Blood. 2005 ; 105 ( 8 ): 3199 - 205 .
55. Brazil MI , Weiss S , Stockinger B . Excessive degradation of intracellular protein in macrophages prevents presentation in the context of major histocompatibility complex class II molecules . Eur J Immunol . 1997 ; 27 ( 6 ): 1506 - 14 .
56. Liu S , Yin L , Stroopinsky D , Rajabi H , Puissant A , Stegmaier K , et al. MUC1 -C oncoprotein promotes FLT3 receptor activation in acute myeloid leukemia cells . Blood . 2014 ; 123 ( 5 ): 734 - 42 .
57. Li Y , Wang LX , Yang G , Hao F , Urba WJ , Hu HM . Efficient cross-presentation depends on autophagy in tumor cells . Cancer Res . 2008 ; 68 ( 17 ): 6889 - 95 .
58. Bell C , English L , Boulais J , Chemali M , Caron-Lizotte O , Desjardins M , et al. Quantitative proteomics reveals the induction of mitophagy in tumor necrosis factor-α-activated (TNFα) macrophages . Mol Cell Proteomics . 2013 ; 12 ( 9 ): 2394 - 407 .
59. Li X , Wang S , Zhu R , Li H , Han Q , Zhao RC . Lung tumor exosomes induce a pro-inflammatory phenotype in mesenchymal stem cells via NFκB-TLR signaling pathway . J Hematol Oncol . 2016 ; 9 : 42 .
60. Thery C , Ostrowski M , Segura E. Membrane vesicles as conveyors of immune responses . Nat Rev Immunol . 2009 ; 9 ( 8 ): 581 - 93 .
61. Lou G , Song X , Yang F , Wu S , Wang J , Chen Z , Liu Y. Exosomes derived from miR-122-modified adipose tissue-derived MSCs increase chemosensitivity of hepatocellular carcinoma . J Hematol Oncol . 2015 ; 8 : 122 .
62. Soung YH , Ford S , Zhang V , Chung J . Exosomes in cancer diagnostics . Cancers (Basel) . 2017 ; 9 ( 1 ): e8 .
63. Greening DW , Gopal SK , Xu R , Simpson RJ , Chen W. Exosomes and their roles in immune regulation and cancer . Semin Cell Dev Biol . 2015 ; 40 : 72 - 81 .
64. Zhang X , Yuan X , Shi H , Wu L , Qian H , Xu W. Exosomes in cancer: small particle, big player . J Hematol Oncol . 2015 ; 8 : 83 .
65. Raposo G , Nijman HW , Stoorvogel W , Liejendekker R , Harding CV , Melief CJ , et al. B lymphocytes secrete antigen-presenting vesicles . J Exp Med . 1996 ; 183 ( 3 ): 1161 - 72 .
66. Zitvogel L , Regnault A , Lozier A , Wolfers J , Flament C , Tenza D , et al. Eradication of established murine tumors using a novel cell-free vaccine: dendritic cell derived exosomes . Nat Med . 1998 ; 4 ( 5 ): 594 - 600 .
67. Pitt JM , André F , Amigorena S , Soria JC , Eggermont A , Kroemer G , et al. Dendritic cell-derived exosomes for cancer therapy . J Clin Invest . 2016 ; 126 ( 4 ): 1224 - 32 .
68. Segura E , Nicco C , Lombard B , Véron P , Raposo G , Batteux F , et al. ICAM-1 on exosomes from mature dendritic cells is critical for efficient naive T-cell priming . Blood . 2005 ; 106 ( 1 ): 216 - 23 .
69. Clayton A , Court J , Navabi H , Adams M , Mason MD , Hobot JA , et al. Analysis of antigen presenting cell derived exosomes, based on immuno-magnetic isolation and flow cytometry . J Immunol Methods . 2001 ; 247 ( 1-2 ): 163 - 74 .
70. Théry C , Regnault A , Garin J , Wolfers J , Zitvogel L , Ricciardi-Castagnoli P , et al. Molecular characterization of dendritic cell-derived exosomes: selective accumulation of the heat shock protein hsc73 . J Cell Biol . 1999 ; 147 ( 3 ): 599 - 610 .
71. Robbins PD , Morelli AE . Regulation of immune responses by extracellular vesicles . Nat Rev Immunol . 2014 ; 14 ( 3 ): 195 - 208 .
72. Utsugi-Kobukai S , Fujimaki H , Hotta C , Nakazawa M , Minami M. MHC class I-mediated exogenous antigen presentation by exosomes secreted from immature and mature bone marrow derived dendritic cells . Immunol Lett . 2003 ; 89 ( 2 ): 125 - 31 .
73. Admyre C , Johansson SM , Paulie S , Gabrielsson S. Direct exosome stimulation of peripheral human T cells detected by ELISPOT . Eur J Immunol . 2006 ; 36 ( 7 ): 1772 - 81 .
74. Vincent-Schneider H , Stumptner-Cuvelette P , Lankar D , Pain S , Raposo G , Benaroch P , et al. Exosomes bearing HLA-DR1 molecules need dendritic cells to efficiently stimulate specific T cells . Int Immunol . 2002 ; 14 ( 7 ): 713 - 22 .
75. Kosaka N , Yoshioka Y , Fujita Y , Ochiya T. Versatile roles of extracellular vesicles in cancer . J Clin Invest . 2016 ; 126 ( 4 ): 1163 - 72 .
76. Théry C , Duban L , Segura E , Véron P , Lantz O , Amigorena S. Indirect activation of naive CD4+ T cells by dendritic cell-derived exosomes . Nat Immunol . 2002 ; 3 ( 12 ): 1156 - 62 .
77. Segura E , Guerin C , Hogg N , Amigorena S , Thery C. CD8+ dendritic cells use LFA-1 to capture MHC-peptide complexes from exosomes in vivo . J Immunol . 2007 ; 79 ( 3 ): 1489 - 96 .
78. Montecalvo A , Shufesky WJ , Stolz DB , Sullivan MG , Wang Z , Divito SJ , et al. Exosomes as a short-range mechanism to spread alloantigen between dendritic cells during T cell allorecognition . J Immunol . 2008 ; 180 ( 5 ): 3081 - 90 .
79. Viaud S , Ploix S , Lapierre V , Théry C , Commere PH , Tramalloni D , et al. Updated technology to produce highly immunogenic dendritic cell-derived exosomes of clinical grade: a critical role of interferon-γ . J Immunol . 2011 ; 34 ( 1 ): 65 - 75 .
80. Segura E , Amigorena SC . Mature dendritic cells secrete exosomes with strong ability to induce antigen-specific effector immune responses . Blood Cells Mol Dis . 2005 ; 35 ( 2 ): 89 - 93 .
81. Nakayama M. Antigen presentation by MHC-dressed cells . Front Immunol . 2014 ; 5 : 672 .
82. Andre F , Schartz NE , Chaput N , Flament C , Raposo G , Amigorena S , et al. Tumor-derived exosomes: a new source of tumor rejection antigens . Vaccine . 2002 ; 20 ( Suppl 4 ): A28 - 31 .
83. Wieckowski E , Whiteside TL . Human tumor-derived vs dendritic cell-derived exosomes have distinct biologic roles and molecular profiles . Immunol Res . 2006 ; 36 ( 1-3 ): 247 - 54 .
84. Ohno S , Drummen GP , Kuroda M. Focus on extracellular vesicles: development of extracellular vesicle-based therapeutic systems . Int J Mol Sci . 2016 ; 17 ( 2 ): 172 .
85. Yang C , Kim SH , Bianco NR , Robbins PD . Tumor-derived exosomes confer antigen-specific immunosuppression in a murine delayed-type hypersensitivity model . PLoS One . 2011 ; 6 ( 8 ): e22517 .
86. Yang C , Ruffner MA , Kim SH , Robbins PD . Plasma-derived MHCII+ exosomes from tumor-bearing mice suppress tumor antigen-specific immune responses . Eur J Immunol . 2012 ; 42 ( 7 ): 1778 - 84 .
87. Altieri SL , Khan AN , Tomasi TB . Exosomes from plasmacytoma cells as a tumor vaccine . J Immunother . 2004 ; 27 ( 4 ): 282 - 8 .
88. Mallegol J , Van NG , Lebreton C , Lepelletier Y , Candalh C , Dugave C , et al. T84 -intestinal epithelial exosomes bear MHC class II/peptide complexes potentiating antigen presentation by dendritic cells . Gastroenterology . 2007 ; 32 ( 5 ): 1866 - 76 .
89. Viaud S , Théry C , Ploix S , Tursz T , Lapierre V , Lantz O , et al. Dendritic cellderived exosomes for cancer immunotherapy: what's next? Cancer Res . 2010 ; 70 ( 4 ): 1281 - 5 .
90. Hsu DH , Paz P , Villaflor G , Rivas A , Mehta-Damani A , Angevin E , et al. Exosomes as a tumor vaccine: enhancing potency through direct loading of antigenic peptides . J Immunother . 2003 ; 26 ( 5 ): 440 - 5 .
91. Chaput N , Flament C , Viaud S , Taieb J , Roux S , Spatz A , et al. Dendritic cell derived-exosomes: biology and clinical implementations . J Leukoc Biol . 2006 ; 80 ( 3 ): 471 - 8 .
92. Escudier B , Dorval T , Chaput N , André F , Caby MP , Novault S , et al. Vaccination of metastatic melanoma patients with autologous dendritic cell (DC) derived-exosomes: results of the first phase I clinical trial . J Trans Med . 2005 ; 3 ( 1 ): 10 .
93. Morse MA , Garst J , Osada T , Khan S , Hobeika A , Clay TM , et al. A phase I study of dexosome immunotherapy in patients with advanced non-small cell lung cancer . J Transl Med . 2005 ; 3 ( 1 ): 9 .
94. Besse B , Charrier M , Lapierre V , Dansin E , Lantz O , Planchard D , et al. Dendritic cell-derived exosomes as maintenance immunotherapy after first line chemotherapy in NSCLC . Oncoimmunology. 2015 ; 5 ( 4 ): e1071008 .
95. Shao Y , Shen Y , Chen T , Xu F , Chen X , Zheng S. The functions and clinical applications of tumor-derived exosomes . Oncotarget . 2016 ; 7 ( 37 ): 60736 - 51 .
96. Dai S , Wei D , Wu Z , Zhou X , Wei X , Huang H , et al. Phase I clinical trial of autologous ascites-derived exosomes combined with GM-CSF for colorectal cancer . Mol Ther . 2008 ; 16 ( 4 ): 782 - 90 .
97. Tian H , Li W. Dendritic cell-derived exosomes for cancer immunotherapy: hope and challenges . Ann Transl Med . 2017 ; 5 ( 10 ): 221 .
98. Yang Y , Xiu F , Cai Z , Wang J , Wang Q , Fu Y , et al. Increased induction of antitumor response by exosomes derived from interleukin-2 gene-modified tumor cells . J Clin Oncol . 2007 ; 133 ( 6 ): 389 - 99 .
99. Wang J , Wang L , Lin Z , Tao L , Chen M. More efficient induction of antitumor T cell immunity by exosomes from CD40L gene-modified lung tumor cells . Mol Med Rep . 2014 ; 9 ( 1 ): 125 - 31 .
100. Chen W , Wang J , Shao C , Liu S , Yu Y , Wang Q , et al. Efficient induction of antitumor T cell immunity by exosomes derived from heat-shocked lymphoma cells . Eur J Immunol . 2010 ; 36 ( 6 ): 1598 - 607 .
101. Dai S , Zhou X , Wang B , Wang Q , Fu Y , Chen T , et al. Enhanced induction of dendritic cell maturation and HLA-A*0201-restricted CEA-specific CD8(+) CTL response by exosomes derived from IL-18 gene-modified CEA-positive tumor cells . J Mol Med . 2006 ; 84 ( 12 ): 1067 - 76 .
102. Chen T , Guo J , Yang M , Zhu X , Cao X . Chemokine-containing exosomes are released from heat-stressed tumor cells via lipid raft-dependent pathway and act as efficient tumor vaccine . J Immunol . 2011 ; 186 ( 4 ): 2219 - 28 .
103. Muller L , Muller-Haegele S , Mitsuhashi M , Gooding W , Okada H , Whiteside TL . Exosomes isolated from plasma of glioma patients enrolled in a vaccination trial reflect antitumor immune activity and might predict survival . Oncoimmunology . 2015 ; 4 ( 6 ): e1008347 .
104. Hu X , Huang W , Fan M. Emerging therapies for breast cancer . J Hematol Oncol . 2017 ; 10 ( 1 ): 98 .
105. Achkar T , Tarhini AA . The use of immunotherapy in the treatment of melanoma . J Hematol Oncol . 2017 ; 10 ( 1 ): 88 .
106. Guo F , Chang CK , Fan HH , Nie XX , Ren YN , Liu YY , et al. Anti-tumour effects of exosomes in combination with cyclophosphamide and polyinosinicpolycytidylic acid . J Int Med Res . 2008 ; 36 ( 6 ): 1342 - 53 .