Protective anti-chlamydial vaccine regimen-induced CD4+ T cell response mediates early inhibition of pathogenic CD8+ T cell response following genital challenge.

We have demonstrated previously that TNF-α-producing CD8+ T cells mediate chlamydial pathogenesis, likely in an antigen (Ag)-specific fashion. Here we hypothesize that inhibition of Ag-specific CD8+ T cell response after immunization and/or challenge would correlate with protection against oviduct pathology induced by a protective vaccine regimen. Intranasal (i.n.) live chlamydial elementary body (EB), intramuscular (i.m.) live EB, or i.n. irrelevant antigen, bovine serum albumin (BSA), immunized animals induced near-total protection, 50% protection, or no protection, respectively against oviduct pathology following i.vag. C. muridarum challenge. In these models, we evaluated Ag-specific CD8+ T cell cytokine response at various time-periods after immunization or challenge. The results show protective efficacy of vaccine regimens correlated with reduction of Ag-specific CD8+ T cell TNF-α responses following i.vag. chlamydial challenge, not after immunization. Depletion of CD4+ T cells abrogated, whereas adoptive transfer of Ag-specific CD4+ T cells induced the significant reduction of Ag-specific CD8+ T cell TNF-α response after chlamydial challenge. In conclusion, protective anti-chlamydial vaccine regimens induce Ag-specific CD4+ T cell response that mediate early inhibition of pathogenic CD8+ T cell response following challenge and may serve as a predictive biomarker of protection against Chlamydia -induced chronic pathologies.

Ischemic Stroke Secondary to Myocarditis in the Setting of COVID-19.

Coronavirus disease (COVID-19) is primarily a respiratory disease that has also been shown to be associated with neurological complications such as ischemic stroke, Guillain-Barré syndrome, and encephalitis. Ischemic stroke in patients with COVID-19 has mostly been observed in the elderly, those with significant comorbidities, and the critically ill. In this report, we discuss a case of ischemic stroke in an otherwise healthy young male patient who only had a mild case of COVID-19. It is likely that the patient suffered from an ischemic stroke secondary to cardiomyopathy that resulted from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The ischemic stroke was most likely a result of thromboembolism caused by stasis of blood from acute dilated cardiomyopathy and the hypercoagulable state of COVID-19 patients. It is important to maintain a high degree of clinical suspicion for thromboembolic events in COVID-19 patients.