Surgery (Austin & Northern Health) - Research Publications
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ItemLung-resident memory B cells established after pulmonary influenza infection display distinct transcriptional and phenotypic profiles(AMER ASSOC ADVANCEMENT SCIENCE, 2022-01)Recent studies have established that memory B cells, largely thought to be circulatory in the blood, can take up long-term residency in inflamed tissues, analogous to widely described tissue-resident T cells. The dynamics of recruitment and retention of memory B cells to tissues and their immunological purpose remains unclear. Here, we characterized tissue-resident memory B cells (BRM) that are stably maintained in the lungs of mice after pulmonary influenza infection. Influenza-specific BRM were localized within inducible bronchus-associated lymphoid tissues (iBALTs) and displayed transcriptional signatures distinct from classical memory B cells in the blood or spleen while showing partial overlap with memory B cells in lung-draining lymph nodes. We identified lung-resident markers, including elevated expression of CXCR3, CCR6, and CD69, on hemagglutinin (HA)- and nucleoprotein (NP)-specific lung BRM. We found that CCR6 facilitates increased recruitment and/or retention of BRM in lungs and differentiation into antibody-secreting cells upon recall. Although expression of CXCR3 and CCR6 was comparable in total and influenza-specific memory B cells isolated across tissues of human donors, CD69 expression was higher in memory B cells from lung and draining lymph nodes of human organ donors relative to splenic and PBMC-derived populations, indicating that mechanisms underpinning BRM localization may be evolutionarily conserved. Last, we demonstrate that human memory B cells in lungs are transcriptionally distinct to populations in lung-draining lymph nodes or PBMCs. These data suggest that BRM may constitute a discrete component of B cell immunity, positioned at the lung mucosa for rapid humoral response against respiratory viral infections.
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ItemAdaptive immunity to human coronaviruses is widespread but low in magnitude(WILEY, 2021)OBJECTIVES: Endemic human coronaviruses (hCoVs) circulate worldwide but cause minimal mortality. Although seroconversion to hCoV is near ubiquitous during childhood, little is known about hCoV-specific T-cell memory in adults. METHODS: We quantified CD4 T-cell and antibody responses to hCoV spike antigens in 42 SARS-CoV-2-uninfected individuals. Antigen-specific memory T cells and circulating T follicular helper (cTFH) cells were identified using an activation-induced marker assay and characterised for memory phenotype and chemokine receptor expression. RESULTS: T-cell responses were widespread within conventional memory and cTFH compartments but did not correlate with IgG titres. SARS-CoV-2 cross-reactive T cells were observed in 48% of participants and correlated with HKU1 memory. hCoV-specific T cells exhibited a CCR6+ central memory phenotype in the blood, but were enriched for frequency and CXCR3 expression in human lung-draining lymph nodes. CONCLUSION: Overall, hCoV-specific humoral and cellular memory are independently maintained, with a shared phenotype existing among coronavirus-specific CD4 T cells. This understanding of endemic coronavirus immunity provides insight into the homeostatic maintenance of immune responses that are likely to be critical components of protection against SARS-CoV-2.
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ItemThe use of organ donor blood in liver transplantation(WILEY, 2021-09)BACKGROUND: Blood removed from organs during deceased donor organ procurement is routinely discarded but is a potential resource for donor-specific transfusion (DST) in subsequent liver transplantation (LT). This study retrospectively analyses the impact of DST on intraoperative bank blood product usage, long-term graft, and patient survival, as well as frequency of rejection post-LT. METHODS: A total of 992 adult LT performed from 1993 to 2018 in a single quaternary center were included. Intraoperative blood product usage, patient, and graft survival, as well as acute and chronic rejection were assessed in patients who received blood retrieved from the organ donor, the "donor blood" (DB) group (n = 437) and patients who did not, the "no donor blood" (NDB) group (n = 555). RESULTS: Processing of DB ensured safe levels of potassium, magnesium, and insulin. There were fewer units of bank red blood cells transfusion required in the DB group compared to NDB group (2 vs. 4 units, P = .01). Graft survival was significantly superior in the DB group (10-year survival 75% vs. 69%, respectively, P = .04) but DST was not an independent predictor of graft survival. There was no significant difference in patient survival or rejection between the groups. There was no difference in treated, biopsy-proven rejection between the two groups. CONCLUSIONS: This is the first large-cohort study assessing long-term outcomes of intraoperative DST in LT. The collection of organ donor blood and subsequent use in LT recipients appeared feasible with appropriate quality checks ensuring safety. DST resulted in a reduction in the use of packed red blood cells. There was no difference in the rate of rejection or graft or patient survival.