T-lymphocyte Tyrosine Hydroxylase Regulates TH17 T-lymphocytes during Repeated Social Defeat Stress Institutional Repository Document uri icon

abstract

  • AbstractPosttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder which results in deleterious changes to psychological and physical health. Patients with PTSD are especially susceptible to co-morbid inflammation-driven pathologies, such as autoimmunity, while also demonstrating increased T-helper 17 (TH17) lymphocyte-driven inflammation. While the exact mechanism of this increased inflammation is unknown, overactivity of the sympathetic nervous system is a hallmark of PTSD. Neurotransmitters of the sympathetic nervous system (i.e., catecholamines) can alter T-lymphocyte function, which we have previously demonstrated to be partially mitochondrial redox-mediated. Furthermore, we have previously elucidated that T-lymphocytes generate their own catecholamines, and strong associations exist between tyrosine hydroxylase (TH; the rate-limiting enzyme in the synthesis of catecholamines) and pro-inflammatory interleukin 17A (IL-17A) expression within purified T-lymphocytes in a preclinical rodent model of PTSD. Therefore, we hypothesized that T-lymphocyte-generated catecholamines drive TH17 T-lymphocyte polarization through a mitochondrial superoxide-dependent mechanism during psychological trauma. To test this, T-lymphocyte-specific TH knockout mice (THT-KO) were subjected to repeated social defeat stress (RSDS). RSDS characteristically increased tumor necrosis factor- (TNF), IL-6, IL-17A, and IL-22, however, IL-17A and IL-22 (TH17 produced cytokines) were selectively attenuated in circulation and in T-lymphocytes of THT-KO animals. When activated ex vivo, secretion of IL-17A and IL-22 by THT-KO T-lymphocytes was also found to be reduced, but could be partially rescued with supplementation of norepinephrine specifically. Interestingly, THT-KO T-lymphocytes were still able to polarize to TH17 under exogenous polarizing conditions. Last, contrary to our hypothesis, we found RSDS-exposed THT-KO T-lymphocytes still displayed elevated mitochondrial superoxide, suggesting increased mitochondrial superoxide is upstream of T-lymphocyte TH induction, activity, and TH17 regulation. Overall, these data demonstrate TH in T-lymphocytes plays a critical role in RSDS-induced TH17 T-lymphocytes and offer a previously undescribed regulator of inflammation in RSDS.

altmetric score

  • 3.6

author list (cited authors)

  • Elkhatib, S. K., Moshfegh, C. M., Watson, G. F., & Case, A. J.

citation count

  • 0

complete list of authors

  • Elkhatib, Safwan K||Moshfegh, Cassandra M||Watson, Gabrielle F||Case, Adam J

Book Title

  • bioRxiv

publication date

  • January 2022