Dysregulation in microRNA Expression Is Associated with Alterations in Immune Functions in Combat Veterans with Post-Traumatic Stress Disorder

et al. (2014) Dysregulation in microRNA Expression Is Associated with Alterations in Immune Functions in Combat Veterans with Post-Traumatic Stress Disorder. PLoS ONE 9(4): e94075. doi:10.1371/journal.pone.0094075 Dysregulation in microRNA Expression Is Associated with Alterations in Immune Functions in Combat Veterans with Post- Traumatic Stress Disorder Juhua Zhou 0 1 Prakash Nagarkatti 0 1 Yin Zhong 0 1 Jay P. Ginsberg 0 1 Narendra P. Singh 0 1 Jiajia Zhang 0 1 Mitzi Nagarkatti 0 1 Pedro Gonzalez, Duke University, United States of America 0 Current address: Institute for Tumor Immunology, Ludong University School of Life Sciences , Yantai, Shandong , PR China 1 1 Department of Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, South Carolina, United States of America, 2 William Jennings Bryan Dorn Veterans Medical Center , Columbia , South Carolina, United States of America, 3 Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina , Columbia, South Carolina , United States of America While the immunological dysfunction in combat Veterans with post-traumatic stress disorder (PTSD) has been well documented, the precise mechanisms remain unclear. The current study evaluated the role of microRNA (miR) in immunological dysfunction associated with PTSD. The presence of peripheral blood mononuclear cells (PBMC) and various lymphocyte subsets in blood collected from PTSD patients were analyzed. Our studies demonstrated that the numbers of both PBMC and various lymphocyte subsets increased significantly in PTSD patients. When T cells were further analyzed, the percentage of Th1 cells and Th17 cells increased, regulatory T cells(Tregs) decreased, while Th2 cells remained unaltered in PTSD patients. These data correlated with increased plasma levels of IFN-c and IL-17 while IL-4 showed no significant change. The increase in PBMC counts, Th1 and Th17 cells seen in PTSD patients correlated with the clinical scores. Highthroughput analysis of PBMCs for 1163 miRs showed that the expression of a significant number of miRs was altered in PTSD patients. Pathway analysis of dysregulated miRs seen in PTSD patients revealed relationship between selected miRNAs and genes that showed direct/indirect role in immunological signaling pathways consistent with the immunological changes seen in these patients. Of interest was the down-regulation of miR-125a in PTSD, which specifically targeted IFN-c production. Together, the current study demonstrates for the first time that PTSD was associated with significant alterations in miRNAs, which may promote pro-inflammatory cytokine profile. Such epigenetic events may provide useful tools to identify potential biomarkers for diagnosis, and facilitate therapy of PTSD. - Funding: This work was supported by National Institutes of Health (NIH) R01MH094755, P01AT003961, P20 GM103641, R01AT006888, R01ES019313, and VA Merit Award BX001357. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. Post-traumatic stress disorder (PTSD) is a psychiatric disorder. Exposure to life-threatening events such as war, earthquake, sexual assault or family violence usually lead to PTSD [1]. It is estimated that 3.6% of American adults aged 18 to 54 years have PTSD. PTSD is often a chronic disorder in the combat Veteran population. For instance, about 30% of Vietnam Veterans developed PTSD [2]. Also, it was detected among 8% of Gulf War Veterans [3] and up to 35% of the military personnel deployed to Iraq and Afghanistan [4]. Patients with PTSD may display not only interpersonal withdrawal but also progressive decrease in muscle mass, increased risk of osteoporosis and fractures, as well as dementia due to tissue damage [57]. In addition, patients with PTSD are six times more at risk of committing suicide and having marital problems, and the annual loss of productivity is estimated to be approximately $3 billion [8]. Currently, there is no cure for patients with PTSD, and available treatments often are not completely effective. Despite extensive research, the precise mechanisms of pathogenesis of PTSD are unclear. It has been reported that the biological dysfunction can result from immune alterations associated with PTSD [9]. There have been relatively few studies that have investigated immune functions in PTSD patients with contradictory findings. A recent review which analyzed published literature concluded that a majority of the reports indicated the presence of an excessive inflammatory state in PTSD, which may result from insufficient regulation by cortisol [10]. However, the role of immune system in the regulation or outcome of PTSD is still unclear [11]. Epigenetic regulation, involving the temporal and spatial control of gene activity without altering the basic structure of DNA, is getting increased attention in recent years. Epigenetic modifications can occur in response to environmental influences to alter the functional expression of genes [12]. Epigenetic regulation has been shown to play a major role in immune modulation and development and progression of diseases [13,14]. Because PTSD patients are exposed to trauma, it is likely that epigenetic modifications may play an important role in the disease development and prognosis. Epigenetic regulation includes DNA methylation, histone deacetylation, chromatin remodeling and expression of microRNAs (miRNAs). miRNAs are small noncoding RNAs that regulate gene expression by binding to complementary target mRNAs and thus inhibit their translation. miRNAs have been implicated in immune regulation [15,16]. There are no previous studies on epigenetic regulation of immune dysfunction by miRNA in PTSD. Elucidation of the role of miRNAs in PTSD may provide novel modalities for the effective care and treatment of PTSD patients and have great implications in understanding the pathogenesis of the disease. In the current study, we determined the peripheral lymphocyte subsets, cytokine dysregulation and miRNA expression in patients with PTSD. Our studies demonstrate for the first time that PTSD patients exhibit pro-inflammatory T cell and cytokine profile, which correlates with specific changes in miRNA expression. Cell population changes in the blood of PTSD patients We first investigated the number of PBMCs found in patients with PTSD when compared to the controls. Table 1 lists the demographics and clinical history of the PTSD patients. Our analysis demonstrated that PBMC counts showed a significant increase in patients with PTSD when compared to the controls (Figure 1A). Furthermore, the PBMC counts in PTSD patients correlated with anxiety score [17], inasmuch as, increasing score was proportional to the PBMC counts (Figure 1B). Moreover, there was significant c (...truncated)