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Hermansky-Pudlak syndrome (HPS), particularly in types 1 and 4, is characterized by progressive pulmonary fibrosis, a major cause of morbidity and mortality. However, the precise mechanisms driving pulmonary fibrosis in HPS are not fully elucidated. Our previous studies suggested that CHI3L1-driven fibroproliferation may be a notable factor in HPS-associated fibrosis. This study aimed to explore the role of CHI3L1-CRTH2 interaction on ILC2s and explored the potential contribution of ILC2-fibroblast crosstalk in the development of pulmonary fibrosis in HPS. We identified ILC2s in lung tissues from idiopathic pulmonary fibrosis (IPF) and HPS patients. Using bleomycin-challenged wild type (WT) and Hps1-/- mice we observed that ILC2s were recruited and appeared to contribute to fibrosis development in the Hps1-/- mice, with CRTH2 playing a notable role in ILC2 accumulation. We sorted ILC2s, profiled fibrosis-related genes and mediators, and conducted co-culture experiments with primary lung ILC2s and fibroblasts. Our findings suggest that ILC2s may directly stimulate the proliferation and differentiation of primary lung fibroblasts partially through Amphiregulin-EGFR-dependent mechanisms. Additionally, specific overexpression of CHI3L1 in the ILC2 population using the IL-7Rcre driver, which was associated with increased fibroproliferation, indicates that ILC2-mediated, CRTH2-dependent mechanisms might contribute to optimal CHI3L1-induced fibroproliferative repair in HPS-associated pulmonary fibrosis.

Widespread vaccination and natural infection have resulted in greatly decreased rates of severe disease, hospitalization and death after subsequent infection or reinfection with SARS-CoV-2. New vaccine formulations are based on circulating strains of virus, which have tended to evolve to more readily transmit human to human and to evade the neutralizing antibody response. An assumption of this approach is that ancestral strains of virus will not recur. Recurrence of these strains could be a problem for individuals not previously exposed to ancestral spike protein by vaccination or infection. Here, we addressed this question by infecting mice with recent SARS-CoV-2 variants and then challenging them with a highly pathogenic mouse-adapted virus closely related to the ancestral Wuhan-1 strain (SARS2-N501YMA30). We found that challenged mice were protected from death and substantial weight loss, even though they generally had low or no neutralizing antibody response to SARS2-N501YMA30 at the time of reinfection. T cell depletion from the previously infected mice did not diminish infection against clinical disease, although it did result in delayed kinetics of virus clearance in the nasal turbinate and in some cases, in the lungs. Levels of tissue resident memory T cells were significantly elevated in the nasal turbinate of previously infected mice compared to mice that had no previous exposure to SARS-CoV-2. However, this phenotype was not seen in lung tissues. Together, these results indicate that the immune response to newly circulating variants afforded protection against re-infection with the ancestral virus that was at least in part T cell based.

Left ventricular hypertrophy (LVH) and dyslipidemia are strong, independent predictors for cardiovascular disease, but their relationship is less well-studied. A longitudinal lipidomic profiling of left ventricular mass (LVM) and LVH is still lacking. Using LC-MS, we repeatedly measured 1,542 lipids from 1,755 unique American Indians attending two exams (mean~5-year apart). Cross-sectional associations of individual lipid species with LVM index (LVMI) were examined by generalized estimating equation (GEE), followed by replication in an independent bi-racial cohort (65% white, 35% black). Baseline plasma lipids associated with LVH risk beyond traditional risk factors were identified by Cox frailty model in American Indians. Longitudinal associations between changes in lipids and changes in LVMI were examined by GEE, adjusting for baseline lipids, baseline LVMI, and covariates. Multiple lipid species (e.g., glycerophospholipids, sphingomyelins, acylcarnitines) were significantly associated with LVMI or the risk of LVH in American Indians. Some lipids were confirmed in black and white individuals. Moreover, some LVH-related lipids were inversely associated with risk of coronary heart disease (CHD). Longitudinal changes in several lipid species (e.g., glycerophospholipids, sphingomyelins, cholesterol esters) were significantly associated with changes in LVMI. These findings provide insights into the role of lipid metabolism in LV remodeling and the risk of LVH or CHD.

Sepsis-induced acute lung injury (ALI) is prevalent in septic patients and has a high mortality rate. Peptidyl arginine deiminase (PADI) 2 and PADI4 play crucial roles in mediating the host's immune response in sepsis, but their specific functions remain unclear. Our study shows that Padi2-/-Padi4-/- double knockout (DKO) improved survival, reduced lung injury, decreased bacterial load in Pseudomonas aeruginosa (PA) pneumonia-induced sepsis mice. Using single-cell RNA sequencing (scRNA-seq), we found that the deletion of Padi2 and Padi4 reduced the Nlrp3+ pro-inflammatory macrophages and fostered Chil3+ myeloid cell differentiation into anti-inflammatory macrophages. Additionally, we observed the regulatory role of NLRP3-Ym1 axis upon DKO, confirmed by Chil3 knockdown and Nlrp3 KO experiments. Thus, eliminating Padi2 and Padi4 enhances the polarization of Ym1+ M2 macrophages by suppressing NLRP3, aiding in inflammation resolution and lung tissue repair. study unveils the PADI2/PADI4-NLRP3-Ym1 pathway as a potential target in treatment of sepsis-induced ALI.

Daptomycin is a last resort lipopeptide antibiotic that disrupts cell membrane (CM) and peptidoglycan homeostasis. Enterococcus faecalis has developed a sophisticated mechanism to avoid daptomycin killing by re-distributing CM anionic phospholipids away from the septum. The CM changes are orchestrated by a three-component regulatory system, designated LiaFSR, with a possible contribution of cardiolipin synthase (Cls). However, the mechanism by which LiaFSR controls the CM response and the role of Cls are unknown. Here, we show that cardiolipin synthase activity is essential for anionic phospholipid redistribution and daptomycin resistance since deletion of the two genes (cls1 and cls2) encoding Cls abolished CM remodeling. We identified LiaY, a transmembrane protein regulated by LiaFSR, and Cls1 as important mediators of CM remodeling required for re-distribution of anionic phospholipid microdomains. Together, our insights provide a mechanistic framework on the enterococcal response to cell envelope antibiotics that could be exploited therapeutically.

Human periosteal skeletal stem cells (P-SSCs) are critical for cortical bone maintenance and repair. However, their in vivo identity, molecular characteristics, and specific markers remain unknown. Here, single-cell sequencing revealed human periosteum contains SSC clusters expressing known SSC markers, PDPN and PDGFRA. Notably, human P-SSCs, but not bone marrow SSCs (BM-SSCs), selectively expressed newly identified markers, LRP1 and CD13. These LRP1+CD13+ human P-SSCs were perivascular cells with high osteochondrogenic but minimal adipogenic potential. Upon transplantation into bone injuries in mice, they preserved self-renewal capability in vivo. Single-cell analysis of mouse periosteum further supported the preferential expression of LRP1 and CD13 in Prx1+ P-SSCs. When Lrp1 was conditionally deleted in Prx1-lineage cells, it led to severe bone deformity, short statue, and periosteal defects. By contrast, local treatment with a LRP1 agonist at the injury sites induced early P-SSC proliferation and bone healing. Thus, human and mouse periosteum contains unique osteochondrogenic stem cell subsets, and these P-SSCs express specific markers, LRP1 and CD13, with regulatory mechanism through LRP1 that enhances P-SSC function and bone repair.

Mutations in the CLCNKB gene (1p36), encoding a basolateral chloride channel, ClC-Kb, cause type 3 Bartter's syndrome. We identified a family with a mixed Bartter's / Gitelman's phenotype and early-onset kidney failure and employing a candidate gene approach, discovered a homozygous mutation (CLCNKB c.499G>T [p.Gly167Cys]) in exon 6 of CLCNKB in the index patient. We then validated these results with Sanger and whole exome sequencing. Compared to wild-type ClC-Kb, the Gly167Cys mutant conducted less current and impaired, complex N-linked glycosylation in vitro. We demonstrated that loss of Gly-167, rather than gain of a mutant Cys, impairs complex glycosylation but that surface expression remains intact. Moreover, Asn364 was necessary for channel function and complex glycosylation. Morphologic evaluation of human kidney biopsies revealed typical basolateral localization of mutant Gly167Cys ClC-Kb in cortical distal tubular epithelia. However, we detected attenuated expression of distal sodium transport proteins, changes in abundance of distal tubule segments, and hypokalemia-associated intracellular condensates from the index patient compared to control nephrectomy specimens. The present data establish what we believe, are novel regulatory mechanisms of ClC-Kb activity and demonstrate nephron remodeling in man, caused by mutant ClC-Kb, with implications for renal electrolyte handling, blood pressure control, and kidney disease.

The earliest MD/PhD programs were small and enrolled mostly men. Here we show that since 2014 there has been a steady increase in the number of women in MD/PhD programs, reaching parity with men in 2023. This change was due to an increase in female applicants, a decrease in male applicants, and an increase in the acceptance rate for women, which had previously been lower than for men. Data from the National MD/PhD Program Outcomes Study show that training duration has been similar for men and women, as have most choices of medical specialties and workplaces. However, women were less likely to have full-time faculty appointments, fewer had NIH grants, and those in the most recent graduation cohort at the time of the survey reported spending less time on research than men. Previously-cited reasons for these differences include disproportionate childcare responsibilities, a paucity of role models, insufficient recognition, and gender bias. Institutions can and should address these obstacles, but training programs can help by preparing their graduates to succeed despite the systemic obstacles. The alternative is a persistent gender gap in the physician-scientist workforce, lost opportunities to benefit from diverse perspectives, and a diminished impact of valuable training resources.

Type 2 diabetes (T2D) arises when pancreatic β-cells fail to produce sufficient insulin to control blood glucose appropriately. Aberrant nutrient sensing by O-GlcNAcylation and mTORC1 is linked to T2D and the failure of insulin-producing β-cells. However, the nature of their crosstalk in β-cells remains unexplored. Recently, O-GlcNAcylation, a post-translation modification controlled by enzymes OGT/OGA, emerged as a pivotal regulator for β-cell health; deficiency in either enzyme causes β-cell failure. The present study investigates the previously unidentified connection between nutrient sensor OGT and mTORC1 crosstalk to regulate β-cell mass and function in vivo. We show reduced OGT and mTORC1 activity in islets of preclinical β-cell dysfunction model and obese human islets. Using loss or gain of function of OGT, we identified that O-GlcNAcylation positively regulates mTORC1 signaling in β-cells. O-GlcNAcylation negatively modulates autophagy, as the removal of OGT increases autophagy, while the deletion of OGA decreases it. Increasing mTORC1 signaling, via deletion of TSC2, alleviates the diabetic phenotypes by increasing β-cell mass but not β-cell function in OGT deficient mice. Downstream phospho-protein signaling analysis reveal diverging impact on MKK4 and calmodulin signaling between islets with OGT, TSC2, or combined deletion. These data provide new evidence of OGT's significance as an upstream regulator of mTORC1 and autophagy, crucial for the regulation of β-cell function and glucose homeostasis.

Sjögren's disease is a chronic autoimmune disease characterized by symptoms of oral and ocular dryness and extra-glandular manifestations. Mouth dryness is not only due to reduced saliva volume but also to alterations in the quality of salivary mucins in these patients. Mucins play a leading role in mucosa hydration and protection, where sulfated and sialylated oligosaccharides retain water molecules at the epithelial surface. The correct localization of glycosyltransferases and sulfotransferases within the Golgi apparatus determines adequate O-glycosylation and sulfation of mucins, which depends on specific golgins that tether enzyme-bearing vesicles. Here, we show that a golgin called Giantin is mislocalized in salivary glands from patients with Sjögren's disease and forms protein complexes with Gal3-O-sulfotransferases (Gal3STs), which change their localization in Giantin knockout and knockdown cells. Our results suggest that Giantin could tether Gal3ST-bearing vesicles and that its altered localization could affect Gal3ST activity, explaining the decreased sulfation of MUC5B observed in salivary glands from patients with Sjögren's disease.