Heat shock proteins in pulmonary fibrosis: pawns of cell homeostasis.

Idiopathic pulmonary fibrosis (IPF) is a fatal disease that primarily affects the elderly. Up to date, the specific pathogenesis of IPF remains unknown. However, it is theorized to be caused by chronic repetitive injuries to the alveolar epithelium, eventually exhausting the stem cell capacity and activating pathological pathways. Heat shock proteins (HSPs), a category of stress response proteins, are also suggested to contribute to IPF pathogenesis. Furthermore, HSPs are key components in the regulation of cell homeostasis and act as chaperones for a multitude of new proteins. This review thoroughly evaluates the roles that specific HSPs, HSP90, HSP70, and HSP47, have in the fibrotic process. A close look into the roles of these HSPs in IPF pathogenesis will give valuable insight into the future of IPF treatment and prevention.

Cellular metabolomics of pulmonary fibrosis, from amino acids to lipids.

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease of unknown etiology with limited treatment options. It is characterized by repetitive injury to alveolar epithelial cells and aberrant activation of numerous signaling pathways. Recent evidence suggests that metabolic reprogramming, metabolic dysregulation, and mitochondria dysfunction are distinctive features of the IPF lungs. Through numerous mechanisms, metabolomic abnormalities in alveolar epithelial cells, myofibroblast, macrophages, and fibroblasts contribute to the abnormal collagen synthesis and dysregulated airway remodeling described in lung fibrosis. This review summarizes the metabolomic changes in amino acids, lipids, glucose, and heme seen in IPF lungs. Simultaneously, we provide new insights into potential therapeutic strategies by targeting a variety of metabolites.

Hermansky-Pudlak syndrome-2 alters mitochondrial homeostasis in the alveolar epithelium of the lung.

BACKGROUND: Mitochondrial dysfunction has emerged as an important player in the pathogenesis of idiopathic pulmonary fibrosis (IPF), a common cause of idiopathic interstitial lung disease in adults. Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder that causes a similar type of pulmonary fibrosis in younger adults, although the role of mitochondrial dysfunction in this condition is not understood. METHODS: We performed a detailed characterization of mitochondrial structure and function in lung tissues and alveolar epithelial cells deficient in the adaptor protein complex 3 beta 1 (Ap3b1) subunit, the gene responsible for causing subtype 2 of HPS (HPS-2). RESULTS: We observed widespread changes in mitochondrial homeostasis in HPS-2 cells, including the acquisition of abnormally shaped mitochondria, with reduced number of cristae, and markedly reduced activity of the electron transport chain and the tricarboxylic acid cycle. We also found that mitochondrial redox imbalance and activity of the mitochondrial unfolded protein response were dysregulated in HPS-2 cells and this associated with various other changes that appeared to be compensatory to mitochondrial dysfunction. This included an increase in glycolytic activity, an upregulation in the expression of mitochondrial biogenesis factors and enhanced activation of the energy-conserving enzyme AMP-activated protein kinase. CONCLUSION: In summary, our findings indicate that mitochondrial function is dramatically altered in HPS-2 lung tissues, suggesting dysfunction of this organelle might be a driver of HPS lung disease.

Mitochondrial Quality Control in Age-Related Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is age-related interstitial lung disease of unknown etiology. About 100,000 people in the U.S have IPF, with a 3-year median life expectancy post-diagnosis. The development of an effective treatment for pulmonary fibrosis will require an improved understanding of its molecular pathogenesis and the "normal" and "pathological' hallmarks of the aging lung. An important characteristic of the aging organism is its lowered capacity to adapt quickly to, and counteract, disturbances. While it is likely that DNA damage, chronic endoplasmic reticulum (ER) stress, and accumulation of heat shock proteins are capable of initiating tissue repair, recent studies point to a pathogenic role for mitochondrial dysfunction in the development of pulmonary fibrosis. These studies suggest that damage to the mitochondria induces fibrotic remodeling through a variety of mechanisms including the activation of apoptotic and inflammatory pathways. Mitochondrial quality control (MQC) has been demonstrated to play an important role in the maintenance of mitochondrial homeostasis. Different factors can induce MQC, including mitochondrial DNA damage, proteostasis dysfunction, and mitochondrial protein translational inhibition. MQC constitutes a complex signaling response that affects mitochondrial biogenesis, mitophagy, fusion/fission and the mitochondrial unfolded protein response (UPRmt) that, together, can produce new mitochondria, degrade the components of the oxidative complex or clearance the entire organelle. In pulmonary fibrosis, defects in mitophagy and mitochondrial biogenesis have been implicated in both cellular apoptosis and senescence during tissue repair. MQC has also been found to have a role in the regulation of other protein activity, inflammatory mediators, latent growth factors, and anti-fibrotic growth factors. In this review, we delineated the role of MQC in the pathogenesis of age-related pulmonary fibrosis.

A Tale of Two Proteolytic Machines: Matrix Metalloproteinases and the Ubiquitin-Proteasome System in Pulmonary Fibrosis.

Pulmonary fibrosis is a chronic and progressive lung disease characterized by the activation of fibroblasts and the irreversible deposition of connective tissue matrices that leads to altered pulmonary architecture and physiology. Multiple factors have been implicated in the pathogenesis of lung fibrosis, including genetic and environmental factors that cause abnormal activation of alveolar epithelial cells, leading to the development of complex profibrotic cascade activation and extracellular matrix (ECM) deposition. One class of proteinases that is thought to be important in the regulation of the ECM are the matrix metalloproteinases (MMPs). MMPs can be up- and down- regulated in idiopathic pulmonary fibrosis (IPF) lungs and their role depends upon their location and function. Furthermore, alterations in the ubiquitin-proteosome system (UPS), a major intracellular protein degradation complex, have been described in aging and IPF lungs. UPS alterations could potentially lead to the abnormal accumulation and deposition of ECM. A better understanding of the specific roles MMPs and UPS play in the pathophysiology of pulmonary fibrosis could potentially drive to the development of novel biomarkers that can be as diagnostic and therapeutic targets. In this review, we describe how MMPs and UPS alter ECM composition in IPF lungs and mouse models of pulmonary fibrosis, thereby influencing the alveolar epithelial and mesenchymal cell behavior. Finally, we discuss recent findings that associate MMPs and UPS interplay with the development of pulmonary fibrosis.

Activation of the mTORC1/PGC-1 axis promotes mitochondrial biogenesis and induces cellular senescence in the lung epithelium.

Cellular senescence is a biological process by which cells lose their capacity to proliferate yet remain metabolically active. Although originally considered a protective mechanism to limit the formation of cancer, it is now appreciated that cellular senescence also contributes to the development of disease, including common respiratory ailments such as chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. While many factors have been linked to the development of cellular senescence, mitochondrial dysfunction has emerged as an important causative factor. In this study, we uncovered that the mitochondrial biogenesis pathway driven by the mammalian target of rapamycin/peroxisome proliferator-activated receptor-γ complex 1α/ß (mTOR/PGC-1α/ß) axis is markedly upregulated in senescent lung epithelial cells. Using two different models, we show that activation of this pathway is associated with other features characteristic of enhanced mitochondrial biogenesis, including elevated number of mitochondrion per cell, increased oxidative phosphorylation, and augmented mitochondrial reactive oxygen species (ROS) production. Furthermore, we found that pharmacological inhibition of the mTORC1 complex with rapamycin not only restored mitochondrial homeostasis but also reduced cellular senescence to bleomycin in lung epithelial cells. Likewise, mitochondrial-specific antioxidant therapy also effectively inhibited mTORC1 activation in these cells while concomitantly reducing mitochondrial biogenesis and cellular senescence. In summary, this study provides a mechanistic link between mitochondrial biogenesis and cellular senescence in lung epithelium and suggests that strategies aimed at blocking the mTORC1/PGC-1α/ß axis or reducing ROS-induced molecular damage could be effective in the treatment of senescence-associated lung diseases.

Fine-tuning the ubiquitin-proteasome system to treat pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is an extremely aggressive lung disease that develops almost exclusively in older individuals, carries a very poor prognosis, and lacks any truly effective therapies. The current conceptual model is that IPF develops because of an age-related decline in the ability of the lung epithelium to regenerate after injury, largely due to death or senescence of epithelial progenitor cells in the distal airways. This loss of regenerative capacity is thought to initiate a chronic and ineffective wound-healing response, characterized by persistent, low-grade lung inflammation and sustained production of collagen and other extracellular matrix materials. Despite recent advances in our understanding of IPF pathobiology, there remains a pressing need to further delineate underlying mechanisms to develop more effective therapies for this disease. In this review, we build the case that many of the manifestations of IPF result from a failure of cells to effectively manage their proteome. We propose that epithelial progenitor cells, as well as immune cells and fibroblasts, become functionally impaired, at least in part, because of an accumulation or a loss in the expression of various crucial proteins. Further, we propose that central to this defect is the dysregulation of the ubiquitin-proteasome system (UPS), which is the major protein-degradation system in eukaryotic cells. Lastly, borrowing concepts from other fields, we discuss how targeting the UPS system could be employed as a novel treatment for IPF and perhaps for other fibrotic lung diseases as well.

Clinical predictors and outcomes of pulmonary infarction in patients with central pulmonary embolism.

BACKGROUND: Given the heterogeneity of predisposing factors associated with pulmonary infarction (PI) and the lack of clinically relevant outcomes among patients with acute pulmonary embolism (PE) complicated by PI, further investigation is required. METHODS: Retrospective study of patients with central PE in an 11-year period. Data were stratified according to the diagnosis of PI. Multivariable logistic regression analysis was used to analyze factors associated with PI development and determine if PI was associated with severe hypoxemic respiratory failure and mechanical ventilation use. RESULTS: Of 645 patients with central PE, 24% (n = 156) had PI. After adjusting for demographics, comorbidities, and clinical features on admission, only age (OR 0.98, CI 0.96-0.99; p = 0.008) was independently associated with PI. Regarding outcomes, 35% (n = 55) had severe hypoxemic respiratory failure, and 19% (n = 29) required mechanical ventilation. After adjusting for demographics, PE severity, and right ventricular dysfunction, PI was independently associated with severe hypoxemic respiratory failure (OR 1.78; CI 1.18-2.69, p = 0.005) and mechanical ventilation (OR 1.92; CI 1.14-3.22, p = 0.013). CONCLUSIONS: Aging is a protective factor against PI. In acute central PE, subjects with PI had higher odds of developing severe hypoxemic respiratory failure and requiring mechanical ventilation.

A model of the aged lung epithelium in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is an age-related disorder that carries a universally poor prognosis and is thought to arise from repetitive micro injuries to the alveolar epithelium. To date, a major factor limiting our understanding of IPF is a deficiency of disease models, particularly in vitro models that can recapitulate the full complement of molecular attributes in the human condition. In this study, we aimed to develop a model that more closely resembles the aberrant IPF lung epithelium. By exposing mouse alveolar epithelial cells to repeated, low doses of bleomycin, instead of usual one-time exposures, we uncovered changes strikingly similar to those in the IPF lung epithelium. This included the acquisition of multiple phenotypic and functional characteristics of senescent cells and the adoption of previously described changes in mitochondrial homeostasis, including alterations in redox balance, energy production and activity of the mitochondrial unfolded protein response. We also uncovered dramatic changes in cellular metabolism and detected a profound loss of proteostasis, as characterized by the accumulation of cytoplasmic protein aggregates, dysregulated expression of chaperone proteins and decreased activity of the ubiquitin proteasome system. In summary, we describe an in vitro model that closely resembles the aberrant lung epithelium in IPF. We propose that this simple yet powerful tool could help uncover new biological mechanisms and assist in developing new pharmacological tools to treat the disease.

Matched Cohort Study of Convalescent COVID-19 Plasma Treatment in Severely or Life Threateningly Ill COVID-19 Patients.

BACKGROUND: The utility of convalescent coronavirus disease 2019 (COVID-19) plasma (CCP) in the current pandemic is not well defined. We sought to evaluate the safety and efficacy of CCP in severely or life threateningly ill COVID-19 patients when matched with a contemporaneous cohort. METHODS: Patients with severe or life-threatening COVID-19 were treated with CCP according to Food and Drug Administration criteria, prioritization by an interdisciplinary team, and based on CCP availability. Individual-level matched controls (1:1) were identified from patients admitted during the prior month when no CCP was available. The safety outcome was freedom from adverse transfusion reaction, and the efficacy outcome was a composite of death or worsening O2 support. Demographic, clinical, and laboratory data were analyzed by univariate and multivariable regression analyses accounting for matched design. RESULTS: Study patients (n = 94, 47 matched pairs) were 62% male with a mean age of 58, and 98% (90/94) were minorities (53% Hispanic, 45% Black, non-Hispanic) in our inner-city population. Seven-day composite and mortality outcomes suggested a nonsignificant benefit in CCP-treated patients (adjusted hazard ratio [aHR], 0.70; 95% CI, 0.23-2.12; P = .52; aHR, 0.23; 95% CI, 0.04-1.51; P = .13, respectively). Stratification by pretransfusion mechanical ventilation status showed no differences between groups. No serious transfusion reactions occurred. CONCLUSIONS: In this short-term matched cohort study, transfusion with CCP was safe and showed a nonsignificant association with study outcomes. Randomized and larger trials to identify appropriate timing and dosing of CCP in COVID-19 are warranted. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04420988.

MicroRNA miR-24-3p reduces DNA damage responses, apoptosis, and susceptibility to chronic obstructive pulmonary disease.

The pathogenesis of chronic obstructive pulmonary disease (COPD) involves aberrant responses to cellular stress caused by chronic cigarette smoke (CS) exposure. However, not all smokers develop COPD and the critical mechanisms that regulate cellular stress responses to increase COPD susceptibility are not understood. Because microRNAs are well-known regulators of cellular stress responses, we evaluated microRNA expression arrays performed on distal parenchymal lung tissue samples from 172 subjects with and without COPD. We identified miR-24-3p as the microRNA that best correlated with radiographic emphysema and validated this finding in multiple cohorts. In a CS exposure mouse model, inhibition of miR-24-3p increased susceptibility to apoptosis, including alveolar type II epithelial cell apoptosis, and emphysema severity. In lung epithelial cells, miR-24-3p suppressed apoptosis through the BH3-only protein BIM and suppressed homology-directed DNA repair and the DNA repair protein BRCA1. Finally, we found BIM and BRCA1 were increased in COPD lung tissue, and BIM and BRCA1 expression inversely correlated with miR-24-3p. We concluded that miR-24-3p, a regulator of the cellular response to DNA damage, is decreased in COPD, and decreased miR-24-3p increases susceptibility to emphysema through increased BIM and apoptosis.

Perirenal fat thickness is associated with metabolic risk factors in patients with chronic kidney disease.

BACKGROUND: Adipose tissue accumulation in specific body compartments has been associated with diabetes, hypertension and dyslipidemia. Perirenal fat (PRF) may lead to have direct lipotoxic effects on renal function and intrarenal hydrostatic pressure. This study was undertaken to explore the association of PRF with cardiovascular risk factors and different stages of chronic kidney disease (CKD). METHODS: We studied 103 patients with CKD of different stages (1 to 5). PRF was measured by B-mode renal ultrasonography in the distal third between the cortex and the hepatic border and/or spleen. RESULTS: The PRF thickness was greater in CKD patients with impaired fasting glucose than in those with normal glucose levels (1.10 ± 0.40 cm vs. 0.85 ± 0.39 cm, P < 0.01). Patients in CKD stages 4 and 5 (glomerular filtration rate [GFR] < 30 mL/min/1.73 m2) had the highest PRF thickness. Serum triglyceride levels correlated positively with the PRF thickness; the PRF thickness was greater in patients with triglyceride levels ≥ 150 mg/dL (1.09 ± 0.40 cm vs. 0.86 ± 0.36 cm, P < 0.01). In patients with a GFR < 60 mL/min/1.73 m2, uric acid levels correlated positively with the PRF thickness (P < 0.05). CONCLUSION: In CKD patients, the PRF thickness correlated significantly with metabolic risk factors that could affect kidney function.

Spontaneous tumor lysis syndrome in T-cell malignancy: two case reports.

Tumor lysis syndrome (TLS) refers to a constellation of metabolic abnormalities that result from release of intracellular solutes (potassium, phosphate, and nucleic acid metabolites) from rapidly dying tumor cells. While TLS most commonly occurs following chemotherapy, spontaneous TLS can rarely occur in rapidly dividing liquid or solid malignancies. Here, we report the cases of two patients who presented with non-specific symptoms and were found to have spontaneous TLS. Work-up in both cases led to a diagnosis of T-cell malignancy (i.e., acute lymphoblastic leukemia and angioimmunoblastic lymphoma). Given that spontaneous TLS can be the first manifestation of an underlying malignancy, all physicians should be familiar with this oncologic emergency. Early recognition and prompt management can be lifesaving for patients with an otherwise curable malignancy.

Pyoderma gangrenosum in a patient with type 2 diabetes: a case report / Pioderma gangrenosa en un paciente diabético tipo 2: reporte de un caso

We are presenting a case of patient with type 2 diabetes mellitus that was diagnosed with a soft tissue infection in the lower extremity. This was initially treated as cellulitis and antibiotic treatment was initiated. Due to a poor clinical response, the diagnosis of pyoderma gangrenosum was proposed as part of the differential diagnosis. Skin biopsies and pathology confirmed the diagnosis of pyoderma gangrenosum that had a satisfactory response to steroid treatment

Se presenta el caso de una paciente diabética tipo 2 que inicialmente fue diagnosticada como una celulitis complicada del miembro inferior izquierdo, pero ante la pobre respuesta con el tratamiento antibiótico, se consideró el diagnóstico de pioderma gangrenosa, confirmado anatomopatológicamente, con respuesta satisfactoria al tratamiento esteroideo tópico