Abstract Introduction Restimulation-Induced Cell Death (RICD) is a crucial self-regulatory apoptosis pathway that constrains effector T cell expansion during an adaptive immune response. Our lab and others have implicated multiple genes involved in regulating RICD sensitivity, but molecular mechanisms that explain highly hetergeneous RICD susceptibility across healthy human donors remain nebulous. We hypothesized that relative RICD sensitivity could be explained by specific gene expression programs that correspond to functional differentiation states of multiple, distinct effector T cell subsets. Methods We took an unbiased approach to this question by amassing extensive phenotypic data on T cells collected from >50 healthy human donors, employing spectral flow cytometry and scRNA-seq on effector T cells from the most highly resistant vs. sensitive individuals. Results Our results unveiled enrichment of CD8+ T cells expressing senescence (CD57, NKG2D) and exhaustion (TIGIT) markers in highly sensitive donors; indeed, FACS-based purification confirmed CD8+CD57+ T cells were markedly more susceptible to RICD compared to CD57- counterparts. Moreover, scRNA-seq revealed upregulation of PI-3K pathway genes in RICD sensitive donors, consistent with enhanced PI-3K signaling in senescent T cells. RICD sensitive donors also harbored more “aged” CD4+ T cells expressing ZEB2 and cytotoxicity genes (PRF1, GZMB/K, GNLY, NKG7). Conversely, RICD-resistant CD4+ and CD8+ effector T cells were enriched for genes/markers corresponding to more stem-like properties (IL7R, SELL, CD27, LRRN3, LEF1, BACH2). Indeed, more naïve/central memory T cells were observed in initial PBMC collected from RICD-resistant donors. Conclusion Collectively, our work provides the first “atlas” of human RICD variability that can be used to elucidate and predict relative RICD susceptibility across humans donors, informing new approaches for optimizing adoptive T cell immunotherapies and understanding capricious T cell responses to infection/immunization. Funding Source NIH R35GM139619 Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)
Abstract Introduction Lyssaviruses are the causative agent for rabies, a disease that is uniformly fatal in humans without post-exposure prophylaxis (PEP). Once infection reaches the central nervous system (CNS), PEP is no longer effective. Using a mouse model of lethal rabies disease, we previously demonstrated that peripheral administration of a single dose of neutralizing human monoclonal antibody (mAb), A6, which targets the viral glycoprotein, is highly effective at protecting against lethality. Notably, A6 is effective even when administered following robust replication of virus in the CNS. Moreover, A6 is effective at reducing or even fully reversing multiple signs of disease, including weight loss and limb paralysis. Methods Motor function analyses demonstrated improved motor function of infected A6-treated animals compared to infected untreated controls during the acute phase of disease, but significant impairment compared to uninfected control animals over the post-recovery phase, even months post-treatment. In this study, we perform immunohistochemistry on tissue samples collected at multiple time points post-infection to investigate the underlying mechanisms that may account for failure to completely recover motor function. Results Via stains for inflammatory markers of blood brain barrier (BBB) integrity, initial findings suggest diminished BBB function in both infected untreated animals and infected A6-treated animals. Conclusion These findings corroborate previous data that have suggested structural damage to the CNS, and further suggest that elements of this damage may be beyond repair, despite rescue from mortality and partial functional recovery. Funding Source NIH, DoD USUHS Topic Categories Vaccines and Immunotherapy (VAC)
Introduction: Fetal alcohol spectrum disorders (FASD) affect 1-5% of US children. Co-occurring neurodevelopmental disorders (NDD) can create diagnostic complexity that may lead to missed FASD diagnoses. Understanding NDD co-occurrence may help inform diagnosis and treatment. Materials and Methods: Using the Military Health System Data Repository (MDR) from fiscal years 2016-2023, we evaluated the prevalence of co-occurring NDDs in children with FASD. We further grouped NDD diagnoses into DSM-5-aligned categories: autism spectrum disorder (ASD), intellectual disorders (ID), communication disorders, attention deficit disorder with hyperactivity (ADHD), specific learning disorders, motor disorders, tic disorders, other NDDs, and delayed development. A Multivariable logistic regression identified demographic risk factors. Secondary analysis included the number of co-occurring NDD categories.Results: Among 1476 eligible children, 84.6% had ≥1 co-occurring NDD category; nearly half had ≥3. ADHD was the most common. Co-occurring NDDs was significantly associated with male sex (aOR 1.78; 95% CI 1.31-2.41), guardianship (aOR 3.65; 95% CI 1.57-8.48), and being a stepchild (aOR 2.94; 95% CI 1.13-7.66).Conclusions: Most military-connected children with FASD had at least one co-occurring NDD diagnosis. These findings highlight the importance of evaluating children with NDDs for FASD. Screening at the time of NDD diagnosis may help facilitate earlier identification, better target interventions, and improve overall healthcare delivery.
Decompression sickness (DCS) risk limits human undersea operations through tissue inert gas supersaturation and pathological bubble formation. Switching the inert breathing gas prior to decompression to a gas with lower diffusivity could allow faster and safer decompression. This principle was tested in 20 kg swine after a helium-oxygen (He/O2) dive using carbon tetrafluoride. Sedated swine breathed He/O2 79/21 at a pressure equivalent of 200 feet of seawater (714 kPa) in a hyperbaric chamber for 50 min until randomized to continuing He/O2 or switching to carbon tetrafluoride and oxygen (CF4/O2 79/21) for 10 min before decompression. The CF4/O2 group had reduced DCS with lower mortality, hypoxemia, pulmonary edema, venous gas emboli, gait disturbance, rash, and central nervous system hemorrhage. CF4/O2 has the potential to expand human exploration through enabling deeper dives, longer dives, and rapid decompression while maintaining safety.
Abstract Introduction Developing therapeutic countermeasures that can target pathogens within the central nervous system (CNS) remains a challenging task. Rabies virus and other lyssaviruses are well-known examples of neurotropic pathogens that can efficiently evade both the host immune response and current therapeutic strategies. Australian bat lyssavirus (ABLV) is a member of the lyssavirus genus and is known to causes disease that is indistinguishable from rabies. Rabies is uniformly fatal once the infection has entered the CNS, and there is currently no effective treatment post-CNS involvement. Previously, our group demonstrated that a single dose of monoclonal antibody (mAb) treatment can prevent mortality even in mice with established CNS infections, and mAb-mediated survival was CD4 T-cell dependent. To investigate the mechanism of enhancement of the host adaptive immune response, we have developed tools to assess the dynamics of virus-specific CD4 T-cells produced in ABLV-infected mice. Methods Using a novel anti-lyssavirus MHC II tetramer, we quantified virus-specific CD4 T-cell responses in the spleens and brains of infected mice that received mock- or mAb-treatment. Results We found evidence of anti-lyssavirus CD4 T-cells in the spleen as early as day 8 post-infection in infected animals, and this population increased until ≥28 days post-infection in infected mAb-treated mice. We also found a higher frequency of anti-lyssavirus CD4 T-cells in the brains of infected mAb-treated mice on day 14 post-infection, when compared to infected, mock-treated mice. Interestingly, although there were fewer ABLV-specific T-cells in the mock-treated animals, these T-cells produced much more IFN-γ than the T-cells isolated from mAb-treated mice. Conclusion Collectively, our data suggests that mAb treatment can alter the T-cell response by augmenting the generation of virus-specific CD4 T-cells and by modulating effector cytokine production by these T-cells. Funding Source U.S. Department of Defense Topic Categories Vaccines and Immunotherapy (VAC)
