During Caenorhabditis elegans development, the embryo acquires its vermiform shape due to changes in the shape of epithelial cells, a process that requires an apically localized actin cytoskeleton. We show that SMA-1, an ortholog of beta(H)-spectrin required for normal morphogenesis, localizes to the apical membrane of epithelial cells when these cells are rapidly elongating. In spc-1 alpha-spectrin mutants, SMA-1 localizes to the apical membrane but its organization is altered, consistent with the hypothesis these proteins act together to form an apically localized spectrin-based membrane skeleton (SBMS). SMA-1 is required to maintain the association between actin and the apical membrane; sma-1 mutant embryos fail to elongate because actin, which provides the driving force for cell shape change, dissociates from the apical membrane skeleton during morphogenesis. Analysis of sma-1 expression constructs and mutant strains indicates SMA-1 maintains the association between actin and the apical membrane via interactions at its N-terminus and this activity is independent of alpha-spectrin. SMA-1 also preserves dynamic changes in the organization of the apical membrane skeleton. Taken together, our results show the SMA-1 SBMS plays a dynamic role in converting changes in actin organization into changes in epithelial cell shape during C. elegans embryogenesis.

The gut mucosa is an important site of HIV immunopathogenesis, with severe depletion of CD4+ T cells occurring during acute infection. The effect of prolonged anti-retroviral therapy (ART) on cycling and restoration of T lymphocytes in the gut remains unclear. Colon and terminal ileal biopsies and peripheral blood samples were collected from viremic, untreated, HIV-infected participants, patients treated with prolonged ART (>5 years), and uninfected controls and analyzed by flow cytometry. In the gut, the proportion of cycling T cells decreased and the number of CD4+ T cells normalized in treated patients in parallel with β7 expression on CD4+ T cells in blood. Cycling of gut T cells in viremic patients was associated with increased plasma LPS levels, but not colonic HIV-RNA. These data suggest that gut T cell activation and microbial translocation may be interconnected while prolonged ART may decrease activation and restore gut CD4+ T cells.

During acute human immunodeficiency virus (HIV) infection, there is a massive depletion of CD4؉ T cells in the gut mucosa that can be reversed to various degrees with antiretroviral therapy. -infected individuals treated with prolonged antiretroviral therapy (ART) (VL [viral load]<50). We found that LTNPs have intact CD4؉ T cell populations, including Th17 and cycling subsets, in the gut mucosa and a preserved T cell population expressing gut homing molecules in the peripheral blood. In addition, we observed no evidence of higher monocyte activation in LTNPs than in HIV-infected (HIV ؊ ) controls. These data suggest that, similar to nonpathogenic simian immunodeficiency virus (SIV) infection, LTNPs preserve the balance of CD4 ؉ T cell populations in blood and gut mucosa, which may contribute to the lack of disease progression observed in these patients.

Translocation of microbial products has been described in chronic human immunodeficiency virus (HIV) infection and correlates with activation of the immune system. We investigated the potential translocation of microbial products in idiopathic CD4 lymphocytopenia (ICL), a rare disorder characterized by low CD4 T cell counts in the absence of HIV infection. Plasma lipopolysaccharide (LPS) levels and T cell activation were measured in a cross-sectional cohort study of patients with ICL and HIV infection and healthy control subjects. Increases in CD4 T cell proliferation but not CD8 T cell proliferation were observed in patients with ICL. LPS levels were significantly elevated both in patients with ICL and in patients with HIV infection, and they were strongly correlated with the proportion of proliferating CD4 T cells in the cohort of patients with ICL (r = 0.88; P = .003). The proportions of T helper (Th) 17 and Th1 CD4 cells in peripheral blood were similar between patients with ICL, patients with HIV infection, and control subjects. These findings suggest a potential association of translocation of microbial products with perturbed CD4 T cell homeostasis in individuals with CD4 lymphopenic states other than HIV infection.

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BackgroundDeath audits have been used to describe pediatric mortality in under-resourced settings, where record keeping is often a challenge. This information provides the cornerstone for the foundation of quality improvement initiatives. Malawi, located in sub-Saharan Africa, currently has an Under-5 mortality rate of 64/1000. Kamuzu Central Hospital, in the capital city Lilongwe, is a busy government referral hospital, which admits up to 3000 children per month. A study published in 2013 reported mortality rates as high as 9%. This is the first known audit of pediatric death files conducted at this hospital.MethodsA retrospective chart review on all pediatric deaths that occurred at Kamuzu Central Hospital (excluding deaths in the neonatal nursery) during a 13-month period was done using a standardized death audit form. A descriptive analysis was completed, including patient demographics, HIV and nutritional status, and cause of death. Modifiable factors were identified that may have contributed to mortality, including a lack of vital sign collection, poor documentation, and delays in the procurement or results of tests, studies, and specialist review.ResultsSeven hundred forty three total pediatric deaths were recorded and 700 deceased patient files were reviewed. The mortality rate by month ranged from a low of 2.2% to a high of 4.4%. Forty-four percent of deaths occurred within the first 24 h of admission, and 59% occurred within the first 48 h. The most common causes of death were malaria, malnutrition, HIV-related illnesses, and sepsis.ConclusionsThe mortality rate for this pediatric referral center has dramatically decreased in the 6 years since the last published mortality data, but remains high. Areas identified for continued development include improved record keeping, improved patient assessment and monitoring, and more timely and reliable provision of testing and treatment. This study demonstrates that in low-resource settings, where reliable record keeping is often difficult, death audits are useful tools to describe the sickest patient population and determine factors possibly contributing to mortality that may be amenable to quality improvement interventions.

BackgroundThe pathogenesis of immunodeficiency due to human immunodeficiency virus (HIV)-1 is incompletely understood, but immune activation is believed to play a central role. Immunomodulatory agents that decrease immune activation may be useful in the treatment of HIV-1 infection.MethodologyA randomized, double blind, placebo-controlled pilot study of leflunomide for 28 days was performed in participants with HIV-1 infection who were not receiving antiretroviral therapy. Participants randomized to leflunomide were subsequently treated with cholestyramine until leflunomide levels were below detection limit.FindingsTreatment with leflunomide was well tolerated with mostly low-grade adverse events. Leflunomide administration reduced cycling of CD4 T cells (by ex vivo bromodeoxyuridine uptake and Ki67 expression) and decreased expression of activation markers (HLA-DR/CD38 co-expression) on CD8 T cells in peripheral blood. In addition, decreased expression of HIV-1 co-receptors was observed in both CD4 and CD8 T cells in the leflunomide group. There were no significant changes in naïve and memory T cell subsets, apoptosis of T cells or markers of microbial translocation.ConclusionsLeflunomide was effective in reducing immune activation in the setting of chronic HIV-1 infection suggesting that targeting immune activation with immunomodulatory agents may be a feasible strategy.Trial RegistrationClinicalTrials.gov NCT00101374

The effect of SARS-CoV-2 seropositivity on the immune response to mRNA-based SARS-CoV-2 vaccines has not been well-described. Here we report longitudinal SARS-CoV-2-specific antibody responses pre- and post-vaccination among a cohort of healthcare personnel, with and without prior infection, from a large academic medical center. Our results provide preliminary evidence that prior SARS-CoV-2 infection may prime the response to the first mRNA-based SARS-CoV-2 vaccine dose. These findings could have significant impact on the allocation of mRNA-based vaccines and support the need for future research into the effect of prior infection on magnitude and durability of vaccination response.