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 (B
RM
) that are stably maintained in the lungs of mice after pulmonary influenza infection. Influenza
-
specific B
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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 B
RM
. We found that CCR6 facilitates increased recruitment and/or retention of B
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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 B
RM
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 B
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may constitute a discrete component of B cell immunity, positioned at the lung mucosa for rapid humoral response against respiratory viral infections.
Postinjury (primary) abdominal compartment syndrome (ACS) was described more than 15 years ago as severe abdominal distension with high peak airway pressures, CO(2) retention, and oliguria, which led to unplanned re-exploration after damage-control laparotomy. Later, a more elusive type of ACS was recognized, which develops without abdominal injuries (secondary ACS). Both syndromes were recently characterized, their independent predictors were identified, and preventive strategies were developed to reduce their incidence. Once viewed as a syndrome with almost uniform mortality, systematic preventative strategies and therapeutic efforts have reduced the prevalence, morbidity, and mortality of the syndrome. This review was designed to summarize the recent advances in the management of ACS, to classify the currently available evidence, and to identify future directions of research and clinical care.
Endemic human coronaviruses (hCoV) 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. We quantified CD4 T cell and antibody responses to hCoV spike antigens in 42 SARS-CoV-2 uninfected individuals. 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. 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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