Ahmed Alaswad

γδ T cells maintain intestinal immune homeostasis, but their contributions to human ulcerative colitis (UC) are poorly understood. We characterized γδ T cells in intestinal biopsies obtained from patients with UC and healthy donors using single-cell RNA sequencing, T cell receptor profiling, and mass cytometry. UC reduced CD103 ⁺ Vγ4Vδ1 ⁺ γδ intraepithelial lymphocytes (γδ IELs) and increased γδ T cell subsets with stemlike phenotypes expressing TCF-1 (T cell factor 1) and PD-1 (programmed cell death receptor 1) or effector-like phenotypes expressing granzyme B, perforin, and T-bet in the lamina propria. γδ T cell composition changes in UC correlated with decreased expression of epithelial BTNL3 and BTNL8 and increased BTN3A1 and BTN3A3 , suggesting altered recruitment and activation. Clinical improvement recovered γδ IELs and reduced inflammation-associated subsets. Inflammation-associated changes were observed in peripheral blood γδ T cells. Thus, distinct γδ T cell subsets in different niches exert protective or pathogenic functions in UC.

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by recurrent life-threatening infections and hyperinflammatory complications. It is caused by mutations in the reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex and the consequent loss of reactive oxygen species (ROS) production. Recombinant human interferon gamma (rIFN-γ) prophylaxis reduces the risk of severe infections, but the mechanisms behind its efficacy in CGD are still an open question, as it does not restore NADPH oxidase-dependent ROS production. Here, we demonstrate that the innate immune cells of patients with CGD are transcriptionally and functionally reprogrammed to a hyperactive inflammatory status, displaying an impaired in vitro induction of trained immunity. CGD monocytes have reduced intracellular amino acid concentrations and profound functional metabolic defects, both at the level of glycolysis and mitochondrial respiration. Ex vivo and in vivo treatments with IFN-γ restored these metabolic defects and reduced excessive interleukin 1β (IL-1β) and IL-6 production in response to fungal stimuli in CGD monocytes. These data suggest that prophylactic rIFN-γ modulates the metabolic status of innate immune cells in CGD. These data shed light on the effects of NADPH oxidase–derived ROS deficiency to the metabolic programs of immune cells and pose the basis for targeting this immunometabolic axis, potentially beyond CGD, with IFN-γ immunotherapy.

Vaccination-induced protection against influenza is greatly diminished and increasingly heterogeneous with age. We investigated longitudinally (up to five time points) a cohort of 234 vaccinated >65-year-old vaccinees with adjuvanted vaccine FluAd across two independent seasons. System-level analyses of multiomics datasets measuring six modalities and serological data revealed that poor responders lacked time-dependent changes in response to vaccination as observed in responders, suggestive of systemic dysregulation in poor responders. Multiomics integration revealed key molecules and their likely role in vaccination response. High prevaccination plasma interleukin-15 (IL-15) concentrations negatively associated with antibody production, further supported by experimental validation in mice revealing an IL-15–driven natural killer cell axis explaining the suppressive role in vaccine-induced antibody production as observed in poor responders. We propose a subset of long-chain fatty acids as modulators of persistent inflammation in poor responders. Our findings provide a potential link between low-grade chronic inflammation and poor vaccination response and open avenues for possible pharmacological interventions to enhance vaccine responses.

Background&Aims: The role of antibody-mediated rejection (ABMR) after liver transplantation (LT) remains controversial. Chronic ABMR (cABMR) is often subclinical and potentially missed without surveillance biopsies (svLbx). Transcriptome analysis previously characterized molecular changes in T cell-mediated rejection (TCMR) after solid organ transplantation. We aimed to identify molecular cABMR signatures after LT. Methods: Indication and svLbx from two prospective institutional biorepositories were screened. We performed RNA-sequencing on liver biopsies (discovery cohort: n=71; Hannover validation cohort: n=58; Barcelona validation cohort: n=29). Downstream analyses explored the molecular features of cABMR, clinical (clinTCMR), subclinical TCMR (subTCMR) and chronic ductopenic rejection compared to no histological rejection (NHR). Results: Nineteen percent of LT recipients with donor-specific antibodies had cABMR in the training cohort. Fifty seven percent of cABMR patients had normal/near normal liver enzymes, recognized only by svLbx. CABMR was associated with subsequent cirrhosis development in 40-50% and displayed differentially expressed genes (DEGs) uniquely enriched in fibrogenesis-, complement activation- and TNFα-signaling-related pathways. ClinTCMR showed no such recurrent cirrhosis and DEGs uniquely enriched in antigen presentation-, interferon-signaling-, and T cell receptor-signaling-related pathways. SubTCMR was molecularly almost indistinguishable from NHR. There was a high degree of correlation in the DEGs between the training and two independent validation cohorts. Conclusions: We report transcriptome features of cABMR that is a unique molecular identity associated with inflammation and fibrogenesis as described in other solid organ transplantations and being linked to a high rate of liver graft failure. Impact and Implications: - Chronic antibody-mediated rejection (ABMR) is a recognized relevant cause of graft injury and unfavorable patient outcomes after kidney, heart and lung transplantation but the role of chronic ABMR after liver transplantation (LT) remains controversial, despite a recurrent cirrhosis rate of 40-50% in the present study. Therefore, we aimed to characterize rejection phenotypes after LT on a molecular basis, as done in other solids organ transplants, to identify unique features of chronic ABMR. - Our findings highlight chronic ABMR to be a molecularly distinct clinical phenotype of rejection after LT that often presents with normal liver enzymes validated in three independent cohorts. - Therefore, our work emphasizes the usage of surveillance graft biopsies for the detection of a fibrosis associated phenotype of chronic ABMR. The molecular signature may be used in the future by researchers and clinicians to discriminate chronic ABMR from graft injury of other causes.