BackgroundInflammation drives COPD development in people living with HIV (PLwHIV), and the HIV virus impairs T regulatory (Treg) cell responses that deter immune-mediated lung injury. This study sought to determine how cigarette smoke exposure alters lung Treg responses to increase COPD susceptibility in PLwHIV.MethodsLung lavage levels of the Treg chemoattractant CXCL11 were quantified in a cohort of 26 HIV-infected subjects and 34 age-matched controls. To ascertain how CXCL11 modifies lung Treg responses, analyses were then conducted using a chimeric HIV (EcoHIV) infection smoke exposure mouse model and elastase treatment of Treg depleted (DEREG) mice.ResultsCXCL11 lung lavage levels increased in HIV + subjects compared to controls. However, CXCL11 levels were significantly lower in those HIV + subjects with a reduced diffusing capacity for carbon monoxide compared to HIV + subjects with normal lung function. Cigarette smoke exposure reduced CXCL11 levels in HIV + current smokers and decreased lung Cxcl11 levels and Treg frequency in control and EcoHIV-infected mice. Cigarette smoke increased lung c-Src activity in mice and the c-Src inhibitor AZD0530 restored Cxcl11 expression in smoke exposed mice and alveolar macrophages. Direct administration of CXCL11 protein to the airways of EcoHIV infected or smoke exposed mice significantly enhanced lung Treg responses. Treg deficient DEREG mice exhibited increased airway resistance at baseline and had greater lung tissue destruction post elastase treatment.ConclusionsThese findings indicate that cigarette smoke activates c-Src to suppress CXCL11 levels thereby diminishing lung Treg responses that counter airways disease and lung tissue destruction in HIV-infected individuals.

The low-density lipoprotein receptor-related protein 1 (LRP1) performs multiple functions with cell-specific regulation. Genetic variants in LRP1 are associated with chronic obstructive pulmonary disease (COPD), but the underlying mechanisms are unknown. Alveolar type 2 cells (T2C) synthesize pulmonary surfactant lipids and are involved in the pathophysiology of COPD. To investigate LRP1 in T2C, we stably transfected a human T2C cell line with LRP1-shRNA (LRP1 knockdown, LRP1 KD) and generated tamoxifen-inducible T2C-specific LRP1 knockout mice (SPC-LRP1-/-). LRP1 KD cells showed decreased surfactant phospholipid secretion and increased neutral lipid accumulation, despite lower expression of lipid metabolic genes. T2C and alveolar surfactant isolated from SPC-LRP1-/- mice showed lower concentrations of phosphatidylcholine than those from Lrp1-floxed controls. At baseline, SPC-LRP1-/- mice had decreased lung compliance and forced vital capacity. After a cigarette smoke exposure challenge, SPC-LRP1-/- mice developed worse fibrotic remodeling than control mice. Both LRP1 KD cells and T2C isolated from SPC-LRP1-/- mice exhibited increased gene expression of detoxification and inflammatory pathways associated with COPD. Finally, the query of public human data showed that T2C from patients with COPD have lower expression of LRP1 and lipid metabolic genes. These data show that LRP1 is needed in T2C for surfactant lipid metabolism and pulmonary function, and suggest that reductions of LRP1 expression promote smoke-associated fibrosis.

Connexin 43 mediated gap junction signaling between ABCG2 hi endothelial progenitor cells and alveolar epithelium governs epithelial differentiation and injury response. Here, we identify a previously unrecognized endothelial - epithelial communication axis that regulates AT2-to-AT1 transition during fibrotic repair. Disruption of ABCG2 hi derived endothelial Cx43 impairs canonical regeneration but activates an alternative basal cell driven repair program. These findings reveal intercellular communication as a key determinant of lung repair trajectory.

Background, Introduction, or Rationale: The activity of protein phosphatase 2A (PP2A), a serine-threonine phosphatase, is reduced in the lung fibroblasts of idiopathic pulmonary fibrosis (IPF) patients. Chemical reactivation of PP2A can reduce bleomycin-induced fibrosis in a mouse model. However, the mechanism for reduced PP2A activity in IPF is currently unknown. Objective or Hypothesis: The objective of this study was to determine if the PP2A inhibitor, cancerous inhibitor of PP2A (CIP2A), suppressed PP2A activity and enhanced fibrotic signaling in lung fibroblasts. Materials and/or Methods: Multiple known endogenous inhibitors of PP2A were characterized in primary lung fibroblasts collected from control and IPF subjects.The endogenous PP2A inhibitor, cancerous inhibitor of PP2A (CIP2A), was overexpressed in primary lung fibroblasts using lentiviral technology. Fibroblasts were stimulated with TGFβ or bleomycin (BLM). Results and/or Discussion: The expression levels of endogenous PP2A inhibitors were unaltered in fibroblasts isolated from IPF subjects, compared to controls. Stimulation of lung fibroblasts with TGFβ did not enhance the expression of PP2A inhibitors. Surprisingly, CIP2A expression was reduced in fibroblasts acutely treated with BLM. CIP2A suppression correlated with upregulation of the senescence marker p21. Overexpression of CIP2A in fibroblasts enhanced COL1A1 expression and TGFβ induction of SMAD3 phosphorylation but prevented BLM induction of PP2A activity and suppressed p21 responses. Interestingly, treatment with a PP2A activator did not suppress BLM induction of p21 expression. Conclusions: This study indicates that CIP2A negatively regulates PP2A activity and p21 expression in lung fibroblasts, while enhancing COL1A1 expression and SMAD3 signaling. However, CIP2A regulation of p21 expression appears to be independent of PP2A responses.

Patients with chronic limb-threatening ischemia, advanced foot wounds, and no pedal revascularization targets often face amputation. Deep vein arterialization has significant drawbacks. We report three cases using flow-through free flaps with microvascular distal foot arterialization to salvage ischemic feet with complex wounds. All flaps survived. Patients achieved wound healing and ambulation. Two maintained perfusion at 3 and 6 years. One required transmetatarsal amputation at 14 months but remains ambulatory. This technique provides a novel salvage option for the “no-option” foot by combining soft tissue coverage and selective arterialization of small distal veins, avoiding complications of deep vein arterialization and offering durable perfusion.

Promising protein targets are observed to play a role in multiple pathways across a variety of diseases, such as the regulation of immune responses, cell cycle, senescence, and DNA repair. The oncoprotein cancerous inhibitor of protein phosphatase 2A (CIP2A) can coordinate all these cell characteristics predominately by inhibiting the activity of the serine threonine protein phosphatase 2A (PP2A). CIP2A directly interacts with PP2A and other proteins, such as the DNA damage protein topoisomerase II-binding protein 1, to regulate signal transduction. CIP2A is overexpressed in many human cancers, including small and non-small cell lung cancers. High CIP2A expression in lung cancer correlates with poor prognosis, increased tumor proliferation, and resistance to targeted therapies or chemotherapy. Interestingly, CIP2A expression or signaling is also observed in several non-cancerous pulmonary diseases, such as chronic obstructive pulmonary disease. CIP2A can determine whether DNA-damaged cells enter mitosis and can mediate whether DNA repair occurs. CIP2A is also a regulator of inflammation and possibly fibrotic responses. Its functions are linked to altered NFκB activation and TNFα, IL-1β, IL-4, IL-6, IL-10, IL-13, and TGFβ signaling. This review outlines the possible impact of CIP2A-mediated signaling in pulmonary diseases, the processes that regulate CIP2A responses, CIP2A-dependent pathways, and potential therapeutic strategies targeting CIP2A. Substantial medicinal chemistry efforts are underway to develop therapeutics aimed at modulating CIP2A activity. The development of specific inhibitors of CIP2A that selectively target its expression or protein stability could improve our understanding of CIP2A’s function in pulmonary diseases.

BACKGROUND:Chronic lower extremity (LE) wounds in diabetic and vasculopathic populations frequently lead to amputation. Microvascular free tissue transfer (FTT) is a limb salvage option, but outcomes in patients with peripheral vascular disease (PVD) are variable. This study aimed to assess the severity of PVD using accepted standardized metrics to predict morbidity and negative outcomes in patients undergoing LE FTT. METHODS:A retrospective review of 97 FTT procedures performed between January of 2018 and April of 2023 was conducted. PVD severity was assessed using Wound, Ischemia, and Foot Infection (WIfI), Global Limb Anatomic Staging System (GLASS), and medial arterial calcification (MAC) scores. Outcomes of interest included flap failure, amputation, mortality, and major morbidity at various time points. RESULTS:Overall, flap failure occurred within 30 days in 8.2% of cases, and amputation within 90 days occurred at a rate of 5.2%. In patients with incomplete pedal arches (ie, pedal GLASS scores of P1 or P2), there were increased rates of 90-day mortality (11.1% versus 0; P = 0.026) and 30-day flap failure (18.5% versus 3.2%; P = 0.026). Severe MAC scores were associated with increased 90-day mortality ( P = 0.002), 1-year mortality ( P = 0.003), and major morbidity. WIfI scores were not significantly associated with negative outcomes. CONCLUSIONS:PVD severity can be objectively assessed using pedal GLASS and MAC scores to guide patient selection for LE FTT. In patients with an incomplete pedal arch and extensive vascular calcifications, there is a significantly higher risk of major adverse outcomes, emphasizing the need for careful preoperative assessment and shared decision-making in limb salvage procedures.

BACKGROUND:Endovascular revascularization of below-the-knee lesions is a crucial treatment for patients with chronic limb-threatening ischemia (CLTI). However, the optimal approach to revascularizing infrapopliteal arteries remains uncertain. This study aims to compare the safety and efficacy outcomes of various endovascular treatment modalities for infrapopliteal artery disease and provide an evidence-based update through a network meta-analysis. METHODS:We performed a systematic literature search in MEDLINE, EMBASE, and the Cochrane Database for randomized controlled trials published between January 01, 2005, and January 12, 2025. The study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was prospectively registered in PROSPERO database (CRD42022323480). The primary safety outcome was major adverse events defined as a composite of all-cause death, major amputation, and any re-intervention of the target limb at 30 days. The primary efficacy outcomes included freedom from composite of major amputation, target lesion occlusion, and clinically driven target lesion revascularization (CD-TLR) and primary patency defined as freedom from binary restenosis and CD-TLR at 6 months. The network meta-analysis was conducted in the frequentist framework using random effects model and conventional percutaneous transluminal angioplasty (PTA) as the reference intervention. Treatment effects were reported as odds ratio (OR) with 95% confidence interval (CI) compared with conventional PTA and interventions were ranked using P-scores. RESULTS:Twenty-three studies including 3091 patients treated with PTA, paclitaxel drug-coated balloons (DCB), drug-eluting stents (DES), bare metal stents (BMS), bioresorbable vascular scaffold (BVS), and atherectomy were included. There were no significant differences in the primary safety outcome between different treatment modalities. At 6 months, DCB, atherectomy with DCB, and DES produced the largest benefit for primary efficacy outcomes. DCB (OR, 3.68; 95% CI, 1.37-9.92) had a higher freedom from the primary composite, and atherectomy with DCB (OR, 7.65; 95% CI, 1.03-56.98) and DES (OR, 5.48; 95% CI, 1.54-19.49) had higher primary patency compared with PTA. At 12 months, the benefit of atherectomy with DCB was sustained for primary patency, and BVS was ranked first for freedom from the primary composite. There was no benefit of BMS compared with PTA at any timepoint. CONCLUSIONS:This network meta-analysis evaluating 7 endovascular treatment modalities provides evidence of improved efficacy outcomes with DCB, atherectomy with DCB, DES, and BVS compared with PTA for treating infrapopliteal lesions in patients with CLTI.Clinical ImpactLocal antiproliferative drug delivery, whether by balloon-expandable sirolimus/everolimus DES or paclitaxel DCB or everolimus BVS, is necessary to improve patency and efficacy outcomes for the treatment of infrapopliteal artery disease. Furthermore, combining atherectomy with drug delivery shows promising potential. Emerging endovascular targeted drug delivery therapies with limus-based DCB or scaffolds promise to provide greater drug transfer efficiency and a more effective therapeutic alternative that overcomes the limitations of metallic stents in one of the most challenging vascular beds.

Chronic limb-threatening ischemia (CLTI) is the end stage of advanced peripheral artery disease (PAD), a condition that is estimated to affect more than 200 million individuals globally. CLTI poses significant risks to many patients, particularly those from underserved populations (e.g., racial/ethnic minorities, low-income individuals, and rural populations) who experience significant disparities in care and outcomes, including higher rates of amputation, reduced quality of life, and lower survival rates. In 2021, the non-profit Foundation to Advance Vascular Cures, with support from the Patient Centered Outcomes Research Institute (PCORI), created a working group made up of patients, caregivers, researchers, industry experts, and non-profit advocates to develop a roadmap to increase patient engagement in CLTI research. Following a literature review, the working group used surveys, interviews, collaborative discussions, and focus groups to gain information from multiple stakeholder groups over a two-year period. This project built capacity on education and learning with the key observations presented. Our observations include: (1) early engagement of patients and caregivers in the research process improves the study design and enables more meaningful research; (2) frequent interpersonal contact paired with targeted, minimally burdensome education in research and disease increases meaningful engagement of patients with CLTI and their caregivers; (3) building trust between patients, caregivers, and researchers is essential to the success of these initiatives; (4) qualitative research complements quantitative results because it can lead to a nuanced understanding of patient experiences, goals, and perspectives; and (5) patients and caregivers are more likely to engage when research-related information is easy to access and has low burden in terms of time and resources. These observations underscore the need for stakeholder input to research design as well as the plans of funders and investigators in this field. Stakeholders noted the particular need for outreach to traditionally underrepresented and underserved populations, with whom more research is needed to meaningfully address health disparities.

Rationale: The integrity of the cellular plasma membrane (PM) is critical for cells to resist damage and initiate repair. Cigarette smoke, and many of its individual constituents, can damage the PM of lung cells. Ca2+ influx rapidly triggers PM repair by activating processes, such as lysosomal exocytosis, microparticle shedding, patch formation, and endocytosis. In this study, we investigated the role of the Ca2+-binding extended synaptotagmins (ESyts) protein family, which coordinates endoplasmic reticulum tethering and lipid trafficking to the PM in lung PM repair. Methods: A screen of a yeast deletion collection for PM repair genes suggested that extended synaptotagmins, which are mammalian homologs of the top yeast repair candidates, play a role in membrane repair. Stable knockdown of ESyt gene expression was carried out by employing lentiviral vectors encoding short hairpin RNA targeting ESYT1, ESYT2, and ESYT3 within A549 cells. Real-time PCR and Western blotting were used to quantify gene and protein silencing efficacy, respectively. ESyt-deficient A549 cells were exposed to cigarette smoke extract (CSE) under both Ca2+-containing and -depleted conditions. Results: CSE induced PM damage in A459 cells only under calcium-depleted conditions. PM damage was assessed by using SYTOX Orange, a membrane-impermeable fluorescent dye. Under calcium-depleted conditions, 5% CSE enhanced the expression of three ESyt genes, ESYT1, ESYT2, and ESYT3 by 150, 70, and 177%, respectively, in A549 cells. CSE induced-PM damage was approximately 2.2-, 2.3-, and 1.9-fold higher in A549 cells depleted of ESYT1, ESYT2 and ESYT3, respectively, compared to controls. CSE exposure induced the highest PM damage in ESYT2-deficient cells under Ca2+-depleted conditions. Saponin, a nonionic detergent and an established PM-damaging reagent was used to examine PM damage in ESyt-depleted cells. Silencing each ESyt gene enhanced saponin induced-PM damage. Saponin-induced PM damage was greatest in ESYT2-deficient cells and comparable to that of CSE-induced PM damage. Conclusion: Decreased expression of the ESyt gene family members, especially ESyt2, exacerbated CSE-induced PM damage. Additionally, CSE enhanced ESYT gene expression in a Ca²⁺-dependent manner. Together these results demonstrate that ESyt2 plays a major role in PM integrity and repair, underscoring the importance of further studies on PM repair genes in pulmonary diseases.

Reactivation and dysregulation of the mTOR signaling pathway are a hallmark of aging and chronic lung disease; however, the impact on microvascular progenitor cells (MVPCs), capillary angiostasis, and tissue homeostasis is unknown. While the existence of an adult lung vascular progenitor has long been hypothesized, these studies show that Abcg2 enriches for a population of angiogenic tissue-resident MVPCs present in both adult mouse and human lungs using functional, lineage, and transcriptomic analyses. These studies link human and mouse MVPC-specific mTORC1 activation to decreased stemness, angiogenic potential, and disruption of p53 and Wnt pathways, with consequent loss of alveolar-capillary structure and function. Following mTOR activation, these MVPCs adapt a unique transcriptome signature and emerge as a venous subpopulation in the angiodiverse microvascular endothelial subclusters. Thus, our findings support a significant role for mTOR in the maintenance of MVPC function and microvascular niche homeostasis as well as a cell-based mechanism driving loss of tissue structure underlying lung aging and the development of emphysema.

Alveolar capillary barrier disruption induces local edema and inflammation that impairs pulmonary function and promotes alveolar destruction in COPD. This study aimed to determine how cigarette smoke modulated the serine-threonine phosphatase protein phosphatase 2 A (PP2A) to alter the barrier function of human lung microvascular endothelial cells (HLMVECs). Cigarette smoke exposure lowered overall PP2A activity and enhanced endothelial permeability in HLMVECs. However, directly decreasing PP2A activity with Fostriecin significantly reduced endothelial cell permeability. Protein fractionation studies determined that cigarette smoke diminished cytosolic PP2A activity but increased membrane and cytoskeletal activity. These changes coincided with the translocation of PP2A to the membrane, which reduced occludin phosphorylation in the membrane. Cigarette smoke decreased protein tyrosine phosphatase 1B (PTP1B) activity, a PP2A activator which also counters calcium intracellular influx. The decrease in PTP1B activity correlated with reduced calcium efflux in endothelial cells and these changes in calcium flux regulated PP2A activity. Indeed, culturing endothelial cells in low calcium medium prevented the decrease in cytosolic PP2A activity mediated by cigarette smoke. Together, these findings outline a mechanism whereby cigarette smoke acts via calcium to traffic PP2A from the cytosol to the membrane where it dephosphorylates occludin to increase endothelial cell permeability.

INTRODUCTION:Altered complement component 3 (C3) activation in patients with alpha-1 antitrypsin (AAT) deficiency (AATD) has been reported. To understand the potential impact on course of inflammation, the aim of this study was to investigate whether C3d, a cleavage-product of C3, triggers interleukin (IL)-1β secretion via activation of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome. The objective was to explore the effect of AAT augmentation therapy in patients with AATD on the C3d/complement receptor 3 (CR3) signalling axis of monocytes and on circulating pro-inflammatory markers. METHODS:Inflammatory mediators were detected in blood from patients with AATD (n=28) and patients with AATD receiving augmentation therapy (n=19). Inflammasome activation and IL-1β secretion were measured in monocytes of patients with AATD, and following C3d stimulation in the presence or absence of CR3 or NLRP3 inhibitors. RESULTS:C3d acting via CR3 induces NLRP3 and pro-IL-1β production, and through induction of endoplasmic reticulum (ER) stress and calcium flux, triggers caspase-1 activation and IL-1β secretion. Treatment of individuals with AATD with AAT therapy results in decreased plasma levels of C3d (3.0±1.2 µg/mL vs 1.3±0.5 µg/mL respectively, p<0.0001) and IL-1β (115.4±30 pg/mL vs 73.3±20 pg/mL, respectively, p<0.0001), with a 2.0-fold decrease in monocyte NLRP3 protein expression (p=0.0303), despite continued ER stress activation. DISCUSSION:These results provide strong insight into the mechanism of complement-driven inflammation associated with AATD. Although the described variance in C3d and NLRP3 activation decreased post AAT augmentation therapy, results demonstrate persistent C3d and monocyte ER stress, with implications for new therapeutics and clinical practice.

Glucose is essential for energy metabolism, and its usage can determine other cellular functions, depending on the cell type. In some pathological conditions, cells are exposed to high concentrations of glucose for extended periods. In this study, we investigated metabolic, oxidative stress, and cellular senescence pathways in human bronchial epithelial cells (HBECs) cultured in media with physiologically low (5 mm) and high (12.5 mm) glucose concentrations. HBECs exposed to 12.5 mm glucose showed increased glucose routing toward the pentose phosphate pathway, lactate synthesis, and glycogen, but not triglyceride synthesis. These metabolic shifts were not associated with changes in cell proliferation rates, oxidative stress, or cellular senescence pathways. Since hyperglycemia is associated with fibrosis in the lung, we asked whether HBECS could activate fibroblasts. Primary human lung fibroblasts cultured in media conditioned by 12.5 mm glucose‐exposed HBECs showed a 1.3‐fold increase in the gene expression of COL1A1 and COL1A2, along with twofold increased protein levels of smooth muscle cell actin and 2.4‐fold of COL1A1. Consistently, HBECs cultured with 12.5 mm glucose secreted proteins associated with inflammation and fibrosis, such as interleukins IL‐1β, IL‐10, and IL‐13, CC chemokine ligands CCL2 and CCL24, and with extracellular matrix remodeling, such as metalloproteinases (MMP)‐1, MMP‐3, MMP‐9, and MMP‐13 and tissue inhibitors of MMPs (TIMP)‐1 and ‐2. This study shows that HBECs undergo metabolic reprogramming and increase the secretion of profibrotic mediators following exposure to high concentrations of glucose, and it contributes to the understanding of the metabolic crosstalk of neighboring cells in diabetes‐associated pulmonary fibrosis.

CASE:We present a case of a 66-year-old man with lumbar vertebral body erosions after glue embolization of a Type II endoleak secondary to endovascular repair of an infrarenal aortic aneurysm. Multiple biopsies of the affected vertebrae were culture-negative confirming no evidence of infection. He underwent posterior spinal fusion from L2 to L5 with complete resolution of mechanical low back pain and improved functional outcomes. CONCLUSION:Vertebral body osseous erosion is a rare complication of aortic endoleak intervention that can be successfully treated with spinal fusion.

Introduction/rationale to the study: We previously reported that the activity of protein phosphatase 2A (PP2A), a serine threonine phosphatase, is reduced in cells from alpha‐1 antitrypsin (AAT) deficient patients. Our group recently demonstrated that chemical activation of PP2A reduces loss of lung function in smoke‐exposed mice. Here we hypothesis that treatment with a PP2A activator would reduce loss of lung function decline in aged AAT deficient mice. Methods used: Male and female age‐matched Serpina1a‐e knockout mice daily received 5 mg/kg of an improved small molecule activator of PP2A, ATUX‐792, by oral administration for 4 months. Forced oscillation and expiratory measurements were recorded in each animal using the Scireq Flexivent System. Airspace enlargements were quantified by mean linear intercept measurements. The PP2A activator utilized here, ATUX‐792, is a tricyclic‐sulfonamide compound with improved metabolic stability and oral bioavailability compared to the prototype PP2A activator used in our previous study. Results of the study: Long‐term ATUX‐792 administration resulted in no notable toxicity in mice, with external appearance, behavior, and body weight similar to vehicle groups. As expected, aged AAT deficient animals receiving a placebo had changes in pressure volume loops, airway inflammation, lung compliance, inspiratory capacity and FEV0.05/FVC compared to wild type age matched controls. Importantly, treatment with ATUX‐792 reduced progression of these disease parameters in AAT deficient mice. ATUX‐792 treated animals had enhanced PP2A activity within their lungs and reduced phosphorylation of MAP kinases. Conclusions of the study: Our study indicates that the decrease in PP2A activity that occurs in AAT deficiency could be restored by PP2A