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Surgery of the tracheobronchial tree carries high morbidity, with over half of the complications occurring at the anastomosis. Although fibroblasts are crucial in airway wound healing, the underlying cellular and molecular mechanisms in airway reconstruction remain unknown. We hypothesized that airway reconstruction initiates a surgery-induced stress (SIS) response, altering fibroblast communication within airway tissues. Using single-cell RNAseq, we analyzed native and reconstructed airways and identified five fibroblast subpopulations, each with distinct spatial distributions across anastomotic, submucosal, perichondrial, and paratracheal areas. During homeostasis, Adventitial and Airway fibroblasts (Adventitial Fb and Airway Fb, respectively) maintained tissue structure and created cellular niches by regulating ECM turnover. Under SIS, Perichondrial fibroblasts (PC-Fb) exhibited chondroprogenitor-like gene signatures, and Immune-recruiting fibroblasts (IR-Fb) facilitated cell infiltration. Cthrc1 activated fibroblasts (Cthrc1+ Fb), mainly derived from Adventitial Fb, primarily contributed to fibrotic scar formation and collagen production, mediated by TGFβ. Furthermore, repeated SIS created an imbalance in fibroblast states favoring emergence of CTHRC1+ Fb and leading to impaired fibroblasts-basal cell crosstalk. Collectively, these data identify PC, IR, and Cthrc1+ Fb as a signaling hub, with SIS emerging as a mechanism initiating airway remodeling after reconstruction that, if not controlled, may lead to complications such as stenosis or anastomotic breakdown.

Chronic wounds have emerged as a tough clinical challenge. An improved understanding of wound healing mechanisms is paramount. Collagen XVII (COL17), a pivotal constituent of hemidesmosomes, holds considerable promise for regulating epidermal cell adhesion to the basement membrane, as well as for epidermal cell motility and self-renewal of epidermal stem cells. However, the precise role of COL17 in wound repair remains elusive, and the upstream regulatory mechanisms involved have not been fully elucidated. In this study, we delineated the temporal and spatial expression patterns of COL17 at the epidermal wound edge. Subsequently, we investigated the indispensable role of COL17 in keratinocyte activation and re-epithelialization during wound healing, demonstrating the restoration of the normal repair process by COL17 overexpression in diabetic wounds. Notably, we identified a key transcriptional signaling pathway for COL17, wherein PKM2 (Pyruvate kinase isozyme M2) promotes phosphorylation of STAT3, leading to its activation and subsequent induction of COL17 expression upon injury. Ultimately, by manipulating this pathway using the PKM2 nuclear translocator SAICAR, we revealed a promising therapeutic strategy for enhancing the healing of chronic wounds.

Aortic dissection or rupture is a major cause of mortality in vascular Ehlers-Danlos Syndrome (vEDS), a connective tissue disorder caused by heterozygous mutations in the COL3A1 gene. C57BL6/J (BL6) mice carrying the Col3a1 G938D/+ mutation recapitulate the vEDS vascular phenotype and die suddenly of aortic rupture/dissection. However, 129S6/SvEvTac (129) mice expressing the same Col3a1 G938D/+ mutation show near-complete life-long protection from vascular rupture. To identify genetic modifiers of vascular risk in vEDS, we performed genome-wide genotyping of intercrossed BL6/129 vEDS mice stratified by survival and identified a significant protective locus encompassing a variant in Map2k6, encoding Mitogen-Activated Protein Kinase Kinase 6 (M2K6), a p38-activating kinase. Genetic ablation of Map2k6 rendered previously protected 129 vEDS mice susceptible to aortic rupture, in association with reduced protein phosphatase 1 activity and increased PKC and ERK phosphorylation. Accelerated vascular rupture in vEDS mice treated with a pharmacological inhibitor of p38 was rescued by concomitant ERK antagonism, supporting an opposing role for ERK and p38 in the modification of aortic rupture risk in vEDS. These results suggest that pharmacologic strategies aimed at mimicking the effect of this natural protective pathway may improve prevention of aortic rupture risk in vEDS.

Endometriosis is a chronic gynecological disease that affects 1 in 10 reproductive-aged women. Most studies investigate established disease; however, the initiation and early events in endometriotic lesion development remain poorly understood. Our study used neutrophils from human menstrual effluent from subjects with and without endometriosis for immunophenotyping, and a mouse model of endometriosis and a mouse endometriosis cell line to determine the role of neutrophils in the initiating events of endometriosis, including attachment and survival of minced endometrial pieces. In menstrual effluent from women with endometriosis, the ratio of aged and pro-angiogenic neutrophils increased compared to controls, indicating a potentially permissive pro-inflammatory microenvironment. In our endometriosis mouse model, knocking-down neutrophil recruitment with α-CXCR2 into the peritoneum decreased endometrial tissue adhesion-supported by decreased levels of myeloperoxidase and neutrophil elastase in both developing lesions and peritoneal fluid. Fibrinogen was identified as the preferred substrate for endometrial cell adhesion in an in vitro adhesion assay and in developing lesions in vivo. Together, aged and pro-angiogenic neutrophils and their secretions likely promote attachment and formation of endometriotic lesions by releasing neutrophil extracellular traps and upregulating fibrinogen expression as a provisional matrix to establish attachment and survival in the development of endometriosis lesions.

The impact of remdesivir on SARS-CoV-2 diversity and evolution in vivo has remained unclear. In this single-center, retrospective cohort study, we assessed SARS-CoV-2 diversification and diversity over time in a cohort of hospitalized patients who did or did not receive remdesivir. Whole genome sequencing was performed on 98 paired specimens collected from 49 patients before and after remdesivir administration. Genetic divergence between paired specimens was not significantly different from what was observed in paired specimens from patients who did not receive the drug. However, when comparing minority variants, several positions showed preferential diversification after remdesivir treatment, several of which were associated with different variants of concern. Most notably, remdesivir administration resulted in strong selection for a nonsynonymous mutation in nsp12, G671S, previously associated with enhanced viral fitness. This same mutation was found enriched in a second cohort of 143 inpatients with specimens collected after remdesivir administration compared to controls. Only one other mutation previously implicated in remdesivir resistance (nsp12:V792I) was found to be preferentially selected for after remdesivir administration. These data suggest that SARS-CoV-2 variants with enhanced replicative fitness may be selected for in the presence of antiviral therapy as an indirect means to overcome this selective pressure.

Elevation of intraocular pressure (IOP) due to trabecular meshwork (TM) dysfunction, leading to neurodegeneration, is the pathological hallmark of primary open-angle glaucoma (POAG). Impaired axonal transport is an early and critical feature of glaucomatous neurodegeneration. However, a robust mouse model that accurately replicates these human POAG features has been lacking. We report the development and characterization of a novel Cre-inducible mouse model expressing a DsRed-tagged Y437H mutant of human myocilin (Tg.CreMYOCY437H). A single intravitreal injection of HAd5-Cre induced selective MYOC expression in the TM, causing TM dysfunction, reducing the outflow facility, and progressively elevating IOP in Tg.CreMYOCY437H mice. Sustained IOP elevation resulted in significant loss of retinal ganglion cells (RGCs) and progressive axonal degeneration in Cre-induced Tg.CreMYOCY437H mice. Notably, impaired anterograde axonal transport was observed at the optic nerve head before RGC degeneration, independent of age, indicating that impaired axonal transport contributes to RGC degeneration in Tg.CreMYOCY437H mice. In contrast, axonal transport remained intact in ocular hypertensive mice injected with microbeads, despite significant RGC loss. Our findings indicate that Cre-inducible Tg.CreMYOCY437H mice replicate all glaucoma phenotypes, providing an ideal model for studying early events of TM dysfunction and neuronal loss in POAG.

Thrombin promotes the proliferation and function of CD8+ T cells. To test if thrombin prevents exhaustion and sustains antiviral T cell activity during chronic viral infection, we depleted the thrombin-precursor prothrombin to 10% of normal levels in mice prior to infection with the clone 13 strain of lymphocytic choriomeningitis virus. Unexpectedly, prothrombin insufficiency resulted in 100% mortality after infection that was prevented by depletion of CD8+ T cells, suggesting that reduced availability of prothrombin enhances virus-induced immunopathology. Yet, the number, function, and apparent exhaustion of virus-specific T cells were measurably unaffected by prothrombin depletion. Histological analysis of the lung, heart, liver, kidney, spleen, intestine, and brain did not reveal any evidence of hemorrhage or increased tissue damage in low prothrombin mice that could explain mortality. Viral loads were also similar in infected mice regardless of prothrombin levels. Instead, infection of prothrombin-depleted mice resulted in a severe, T cell-dependent anemia associated with increased hemolysis. Thus, thrombin plays an unexpected protective role in preventing hemolytic anemia during virus infection, with potential implications for patients who are using direct thrombin inhibitors as an anticoagulant therapy.

Hereditary angioedema is an autosomal dominant disorder caused by defects in C1-esterase inhibitor (C1-INH), resulting in poorly controlled activation of the kallikrein-kinin system and bradykinin overproduction. C1-INH is a heavily glycosylated protein in the serine protease inhibitor (SERPIN) family, yet the role of these glycosylation sites remains unclear. To elucidate the functional impact of N-glycosylation in the SERPIN domain of C1-INH, we engineered four sets consisting of 26 variants at or near the N-linked sequon (NXS/T). Among these, six are reported in HAE patients and five are known C1-INH variants without accessible clinical histories. We systematically evaluated their expression, structure and functional activity with C1¯s, FXIIa and kallikrein. Our findings showed that of the eleven reported variants, seven are deleterious. Deleting N at the three naturally occurring N-linked sequons (N238, N253 and N352) results in pathologic consequences. Altering these sites by substituting N to A disrupts N-linked sugar attachment but preserves protein expression or function. Further, an additional N-linked sugar generated at N272 impairs C1-INH function. These findings highlight the importance of N-linked sequons in modulating the expression and function of C1-INH. Insights gained from identifying the pathological consequences of N-glycan variants should assist in defining more tailored therapy.

Spatial profiling of tissues promises to elucidate tumor-microenvironment interactions and generate prognostic and predictive biomarkers. We analyzed single-cell, spatial data from three multiplex imaging technologies: cyclic immunofluorescence (CycIF) data we generated from 102 breast cancer patients with clinical follow-up, and publicly available imaging mass cytometry and multiplex ion-beam imaging datasets. Similar single-cell phenotyping results across imaging platforms enabled combined analysis of epithelial phenotypes to delineate prognostic subtypes among estrogen-receptor positive (ER+) patients. We utilized discovery and validation cohorts to identify biomarkers with prognostic value. Increased lymphocyte infiltration was independently associated with longer survival in triple-negative (TN) and high-proliferation ER+ breast tumors. An assessment of ten spatial analysis methods revealed robust spatial biomarkers. In ER+ disease, quiescent stromal cells close to tumor were abundant in good prognosis tumors, while tumor cell neighborhoods containing mixed fibroblast phenotypes were enriched in poor prognosis tumors. In TN disease, macrophage/tumor and B/T lymphocyte neighbors were enriched and lymphocytes were dispersed in good prognosis tumors, while tumor cell neighborhoods containing vimentin-positive fibroblasts were enriched in poor prognosis tumors. In conclusion, we generated comparable single-cell spatial proteomic data from several clinical cohorts to enable prognostic spatial biomarker identification and validation.

Both CO2 retention, or hypercapnia, and skeletal muscle dysfunction predict higher mortality in critically ill patients. Mechanistically, muscle injury and reduced myogenesis contribute to critical illness myopathy, and while hypercapnia causes muscle wasting, no research has been conducted on hypercapnia-driven dysfunctional myogenesis in vivo. Autophagy flux regulates myogenesis by supporting skeletal muscle stem cell - satellite cell - activation, and previous data suggest that hypercapnia inhibits autophagy. We tested whether hypercapnia worsens satellite cell autophagy flux and myogenic potential and if autophagy induction reverses these deficits. Satellite cell transplantation and lineage-tracing experiments showed that hypercapnia undermined satellite cells' activation, replication, and myogenic capacity. Bulk and single-cell sequencing analyses indicated that hypercapnia disrupts autophagy, senescence, and other satellite cell programs. Autophagy activation was reduced in hypercapnic cultured myoblasts, and autophagy genetic knockdown phenocopied these changes in vitro. Rapamycin stimulation led to AMPK activation and downregulation of the mTOR pathway, which are both associated with accelerated autophagy flux and cell replication. Moreover, hypercapnic mice receiving rapamycin showed improved satellite cell autophagy flux, activation, replication rate, and posttransplantation myogenic capacity. In conclusion, we have shown that hypercapnia interferes with satellite cell activation, autophagy flux, and myogenesis, and systemic rapamycin administration improves these outcomes.