PNPLA3-I148M, the greatest genetic determinant for metabolic dysfunction-associated steatotic liver disease (MASLD), paradoxically associates with reduced cardiovascular disease (CVD); however, the mechanisms are poorly understood. To investigate how PNPLA3-I148M alters hepatic triacylglycerol (TAG) metabolism and influences cardiac function, we expressed human WT-PNPLA3, PNPLA3-I148M, or GFP in the liver of PNPLA3-/- mice and fed them chow or Metabolic Dysfunction-Associated Steatohepatitis (MASH) diet at thermoneutrality. After 4 weeks of MASH diet, PNPLA3‑I148M mice showed reduced hepatic TAG secretion, an effect not observed on chow. Following β3‑adrenergic stimulation to enhance adipose‑derived fatty acid flux, chow‑fed PNPLA3‑I148M mice exhibited additional reductions in TAG secretion and increased hepatosteatosis. After 16 weeks of MASH diet, WT‑PNPLA3 mice developed increased left ventricular mass and reduced E/A ratios, whereas PNPLA3‑I148M mice were protected from both outcomes. No differences in left ventricular function were observed in mice under 16 weeks of chow diet. PNPLA3‑I148M also reshaped the hepatic and plasma lipidome, with minimal effects on cardiac lipids, and did not alter atherosclerotic plaque formation under MASH diet conditions. These findings indicate that PNPLA3-I148M impairs hepatic TAG efflux, which may preserve left ventricular diastolic function during diet-induced steatotic stress.

The storage and release of triacylglycerol (TAG) in lipid droplets (LDs) is regulated by dynamic protein interactions. α/β Hydrolase domain-containing protein 5 (ABHD5; also known as CGI-58) is a membrane/LD-bound protein that functions as a co-activator of patatin-like phospholipase domain-containing 2 (PNPLA2; also known as adipose triglyceride lipase) the rate-limiting enzyme for TAG hydrolysis. The dysregulation of TAG hydrolysis is involved in various metabolic diseases such as metabolic dysfunction-associated steatotic liver disease (MASLD). We previously demonstrated that ABHD5 interacted with PNPLA3, a closely related family member to PNPLA2. Importantly, a common missense variant in PNPLA3 (I148M) is the greatest genetic risk factor for MASLD. PNPLA3 148M functions to sequester ABHD5 and prevent coactivation of PNPLA2, which has implications for initiating MASLD; however, the exact mechanisms involved are not understood. Here, we demonstrate that LD targeting of both ABHD5 and PNPLA3 I148M is required for the interaction. Molecular modeling demonstrates important residues in the C terminus of PNPLA3 for LD binding and fluorescence cross-correlation spectroscopy demonstrates that PNPLA3 I148M has greater association with ABHD5 than WT PNPLA3. Moreover, the C terminus of PNPLA3 is sufficient for functional targeting of PNPLAs to LD and the interaction with ABHD5. In addition, ABHD5 is a general binding partner of LD-bound PNPLAs. Finally, PNPLA3 I148M targeting to LD is required to promote steatosis in vitro and in the liver. Overall results suggest that the interaction of PNPLA3 I148M with ABHD5 on LD is required to promote liver steatosis.

Non-alcoholic fatty liver disease is associated with an irregular serine metabolism. Serine hydroxymethyltransferase 2 (SHMT2) is a liver enzyme that breaks down serine into glycine and one-carbon (1C) units critical for liver methylation reactions and overall health. However, the contribution of SHMT2 to hepatic 1C homeostasis and biological functions has yet to be defined in genetically modified animal models. We created a mouse strain with targeted SHMT2 knockout in hepatocytes to investigate this. The absence of SHMT2 increased serine and glycine levels in circulation, decreased liver methylation potential, and increased susceptibility to fatty liver disease. Interestingly, SHMT2 -deficient mice developed simultaneous fatty liver, but when fed a diet high in fat, fructose, and cholesterol, they had significantly less inflammation and fibrosis. This study highlights the critical role of SHMT2 in maintaining hepatic 1C homeostasis and its stage-specific functions in the pathogenesis of NAFLD.

Metabolic-associated fatty liver disease (MAFLD) and cardiovascular disease (CVD) are commonly associated comorbidities. A common genetic variant in the PNPLA3 gene, rs738409 (I148M), is the greatest genetic risk factor for development and progression of MAFLD; however, MAFLD patients expressing PNPLA3 I148M display modest protection against coronary artery disease (CAD) and adverse cardiovascular events relative to wildtype carriers. Currently, the exact mechanisms by which PNPLA3 I148M causes MAFLD and preserves cardiac health are not well understood. Previous work suggests that the variant increases susceptibility to fatty liver disease by altering hepatic lipid metabolism, which may explain a potential mechanism for its cardioprotective effects. In order to investigate how PNPLA3 I148M might increase susceptibility to MAFLD while reducing risk of CVD we expressed either human wildtype (WT) PNPLA3 or PNPLA3 I148M as well as a GFP control specifically in the livers of PNPLA3 knockout mice. Our data demonstrate that hepatic expression of PNPLA3 I148M reduces secretion of VLDL TAGs from adipose tissue derived fatty acids. In agreement with prior investigations, mice expressing PNPLA3 I148M and fed a chow diet demonstrated significant increases in hepatic accumulation of neutral lipids (triglycerides & cholesterol esters) relative to WT and GFP expressing mice. Similarly, when fed a fatty liver promoting diet (D009100310) high in fructose, cholesterol, and saturated fats there remained a strong trend for greater liver to body weight ratios and hepatic TAGs in mice expressing the variant when compared to WT expressing mice (p=0.052 and p=0.071 respectively). Changes in hepatic lipid accumulation were not due to any alterations in insulin sensitivity, daily food consumption, energy expenditure or oxygen consumption between WT and I148M groups. Echocardiography revealed that hearts of mice expressing WT PNPLA3 had increases in left ventricular thickness (p=0.051) and left ventricle weights following dietary treatment that was not apparent in the I148M expressing mice. Moreover, there was a reduction in E/A ratios, a sensitive measure of diastolic functioning, in GFP and WT expressing mice post-treatment, that was not seen in the I148M mice. Overall, these findings indicate that PNPLA3 I148M promotes fatty liver, yet protects against diet-induced effects on ventricular remodeling and diastolic functioning. Our next steps will be to assess measures of atherosclerotic plaque formation around major blood vessels and investigate the metabolic pathways altered by PNPLA3 I148M. NIH R00 DK114471 NIH R01 DK126743 USDA grant no. 2021-09425 Pilot feasibility grant from University of Michigan: P30DK020572 Detroit Cardiovascular Training grant NIH 2T32HL120822. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The storage and release of triacylglycerol (TAG) in lipid droplets (LDs) is regulated by dynamic protein interactions. α/β hydrolase domain-containing protein 5 (ABHD5; also known as CGI-58) is a membrane/LD bound protein that functions as a co-activator of Patatin Like Phospholipase Domain Containing 2 (PNPLA2; also known as Adipose triglyceride lipase, ATGL) the rate-limiting enzyme for TAG hydrolysis. The dysregulation of TAG hydrolysis is involved in various metabolic diseases such as metabolic dysfunction-associated steatotic liver disease (MASLD). We previously demonstrated that ABHD5 interacted with PNPLA3, a closely related family member to PNPLA2. Importantly, a common missense variant in PNPLA3 (I148M) is the greatest genetic risk factor for MASLD. PNPLA3 148M functions to sequester ABHD5 and prevent co-activation of PNPLA2, which has implications for initiating MASLD; however, the exact mechanisms involved are not understood. Here we demonstrate that LD targeting of both ABHD5 and PNPLA3 I148M is required for the interaction. Molecular modeling demonstrates important resides in the C-terminus of PNPLA3 for LD binding and fluorescence cross-correlation spectroscopy demonstrates that PNPLA3 I148M greater associates with ABHD5 than WT PNPLA3. Moreover, the C-terminus of PNPLA3 is sufficient for functional targeting of PNPLAs to LD and the interaction with ABHD5. In addition, ABHD5 is a general binding partner of LD-bound PNPLAs. Finally, PNPLA3 I148M targeting to LD is required to promote steatosis in vitro and in the liver. Overall results suggest that PNPLA3 I148M is a gain of function mutation and that the interaction with ABHD5 on LD is required to promote liver steatosis.

Epithelial Ovarian Cancer (EOC) is the most lethal gynecologic cancer with limited genetic alterations identified that can be therapeutically targeted. In tumor bearing mice, short-term fasting, fasting mimicking diet and calorie restriction enhance the activity of antineoplastic treatment by modulating systemic metabolism and boosting anti-tumor immunity. We tested the outcome of sixteen-hour intermittent fasting (IF) on mouse EOC progression with focus on fasting driven antitumor immune responses. IF resulted in consistent decrease of tumor promoting metabolic growth factors and cytokines, recapitulating changes that creates a tumor antagonizing environment. Immune profiling revealed that IF profoundly reshapes anti-cancer immunity by inducing increase in CD4 + and CD8 + cells, paralleled by enhanced antitumor Th1 and cytotoxic responses, by enhancing their metabolic fitness. Metabolic studies revealed that IF generated bioactive metabolite BHB which can be a potential substitute for simulating the antitumor benefits of IF. However, in a direct comparison, IF surpassed exogenous BHB therapy in improving survival and activating anti-tumor immune response. Thus, our data provides strong evidence for IF and its metabolic mediator BHB for ameliorating EOC progression and as a viable approach in maintaining and sustaining an effective anti-tumor T cell response.

Metabolism and energy processes governing oligodendrocyte function during neuroinflammatory disease are of great interest. However, how varied cellular environments affect oligodendrocyte activity during neuroinflammation is unknown. We demonstrate that activated microglial energy metabolism controls oligodendrocyte mitochondrial respiration and activity. Lipopolysaccharide/interferon gamma promote glycolysis and decrease mitochondrial respiration and myelin protein synthesis in rat brain glial cells. Enriched microglia showed an early burst in glycolysis. In microglia-conditioned medium, oligodendrocytes did not respire and expressed less myelin. SCENITH revealed metabolic derangement in microglia and O4-positive oligodendrocytes in endotoxemia and experimental autoimmune encephalitogenic models. The early burst of glycolysis in microglia was mediated by PDPK1 and protein kinase B/AKT signaling. We found that microglia-produced NO and itaconate, a tricarboxylic acid bifurcated metabolite, reduced mitochondrial respiration in oligodendrocytes. During inflammation, we discovered a signaling pathway in microglia that could be used as a therapeutic target to restore mitochondrial function in oligodendrocytes and induce remyelination.

Metformin is being actively repurposed for the treatment of gynecologic malignancies including ovarian cancer. We investigated if metformin induces analogous metabolic changes across ovarian cancer cells. Functional metabolic analysis showed metformin caused an immediate and sustained decrease in oxygen consumption while increasing glycolysis across A2780, C200, and SKOV3ip cell lines. Untargeted metabolomics showed metformin to have differential effects on glycolysis and TCA cycle metabolites, while consistent increased fatty acid oxidation intermediates were observed across the three cell lines. Metabolite set enrichment analysis showed alpha-linolenic/linoleic acid metabolism as being most upregulated. Downstream mediators of the alpha-linolenic/linoleic acid metabolism, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were abundant in all three cell lines. EPA was more effective in inhibiting SKOV3 and CaOV3 xenografts, which correlated with inhibition of inflammatory markers and indicated a role for EPA-derived specialized pro-resolving mediators such as Resolvin E1. Thus, modulation of the metabolism of omega-3 fatty acids and their anti-inflammatory signaling molecules appears to be one of the common mechanisms of metformin’s antitumor activity. The distinct metabolic signature of the tumors may indicate metformin response and aid the preclinical and clinical interpretation of metformin therapy in ovarian and other cancers.

Epithelial Ovarian Cancer (EOC) is the most lethal gynecologic cancer with no predominant genetic alteration identified that can be therapeutically targeted. Low-cost non-toxic approaches such as dietary modulations alter the responses of host and the cancer cells. Limited scientific investigations have examined the link between nutrition and EOC. Here, we tested the outcome of intermittent fasting (IF) on EOC progression with focus on fasting driven anti-tumor immune responses. Female C57/B6 mice were injected intraperitoneally with 5x106 mouse epithelial ovarian cancer ID8 (p53-/-, ID8 p53-/-, PTEN-/- and ID8 p53-/-, BRCA-/-) cells and fed either ad libitum (RD) or subjected to IF, where they underwent 16 hour fasting and 8 hour feeding window for 5 days/week. Tumor progression was monitored by ascites formation and abdominal circumference. Immune profiling was performed by flow cytometry using BD FACS Calibur. Untargeted metabolomics was performed in plasma from RD and IF mice using LC-MS/MS. Enhancement of immunotherapy was tested by combining IF with anti-PD 1 (100 µg/mice, every 5th day, 3 times) in ID8 p53-/- tumor bearing mice and similar parameters were examined. IF reduced the growth of ID8 (p53-/-, ID8 p53-/-, PTEN-/- and ID8 p53-/-, BRCA-/-) tumors, increased overall survival when compared to RD mice. IF promoted anti-tumor T cell response as seen by increase in CD4+ and CD8+ cells with enhanced expression of IFNγ, granzyme B and perforin compared to RD mice bearing ID8 cells in the ascites and blood. A striking observation was that the CD4+ T cells from IF mice exhibited a strong Th1 phenotype (CD4+IFNγ+), while Th2 phenotype (CD4+IL4+) was significantly decreased. IF when combined with anti-PD-1 treatment significantly improved survival and potentiated the T cell mediated anti-tumor response. Metabolic analysis revealed an enrichment in ketone body biosynthetic pathway as reflected by 5fold increase in serum ketone bodies such as beta hydroxy butyrate (BHB) and acetoacetate, when compared to RD. Receptors that have been reported to response to BHB as a ligand, specifically GPR109A and GPR41, were highly expressed on T cells derived from IF mice. BHB treatment enhanced the CD8+ T cell effector function as reflected by increased levels of IFNγ, granzyme B and perforin compared to untreated CD8+ T cells. Our study shows that IF significantly restricts EOC growth, improve survival, potentiate chemotherapy and immunotherapy anti-tumor response by augmenting T cell mediated anti-tumor immune responses. We also provide evidence that IF generated bioactive metabolite BHB which can be a potential substitute for availing the ant-tumor benefits of IF. Thus, our data provides strong evidence for IF and its metabolic mediator BHB for ameliorating EOC progression and as a viable approach in maintaining and sustaining an effective anti-tumor T cell response alone and in combination with immunotherapy. Citation Format: Mary Priyanka Udumula, Laila Poisson, Lin Chun-Hui, Nivedita Tiwari, Harshit Singh, Giri Shailendra, Ramandeep Rattan. Fasting fueled ketogenesis inhibits ovarian cancer and promotes anti-tumor T cell response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2161.

Idiopathic pulmonary fibrosis (IPF) is a life-threatening disease resulting from dysregulated repair responses to lung injury. Excessive extracellular matrix deposition by expanding myofibroblasts and fibrotic lung fibroblasts (fLfs) has been implicated in the pathogenesis of PF, including IPF. We explored fLfs' microRNA-34a (miR-34a) expression from IPF tissues. Basal miR-34a levels were decreased with reduced binding of p53 to the promoter DNA and 3′UTR mRNA sequences. Overexpression of miR-34a in fLfs increased p53, PAI-1, and reduced pro-fibrogenic markers. The regulatory effects of miR-34a were altered by modifying the p53 expression. Precursor-miR-34a lung transduction reduced bleomycin-induced PF in wild-type mice. fLfs treated with caveolin-1 scaffolding domain peptide (CSP) or its fragment, CSP7, restored miR-34a, p53, and PAI-1. CSP/CSP7 reduced PDGFR-β and pro-fibrogenic markers, which was abolished in fLfs following blockade of miR-34a expression. These peptides failed to resolve PF in mice lacking miR-34a in fLfs, indicating miR-34a-p53-feedback induction required for anti-fibrotic effects.

Objectives: The purpose of this study was to identify genes and pathways differentially expressed in platinum resistant high grade serous ovarian cancer (HGSOC) when compared to sensitive HGSOC. Methods: A total of 37 patients with HGSOC tissue samples underwent RNA sequencing performed by TEMPUS (N=37, 21 platinum sensitive, 16 resistant; 85% Stage III-IV; 58% received neoadjuvant chemotherapy). RNA gene expression data and significantly impacted pathways were analyzed using Advaita Bio's iPathwayGuide. Differentially expressed (DE) genes were identified using FDR of 0.05 and fold-change of 1.5. Genes from several impacted canonical metabolic pathways were validated by PCR against external data sets in a separate ovarian cancer sample group (n=15), platinum resistant ovarian cancer mouse tumor model, and wild-type sensitive and platinum resistant ovarian cancer cell lines. Relative gene expression was calculated using the comparative Ct method, also referred to as the “2 DDCT”, using L27 as internal control gene. Results: We identified 177 differentially expressed (DE) genes out of a total of 16,607 genes (1.1%) with measured expression. 15 pathways were found to be significantly impacted. Of the 15 canonical pathways, all were up regulated in the resistant HGSOC and the majority of the most significantly altered (5/10) were related to metabolism (Retinol metabolism (p-value = 0.002); Tyrosine Metabolism (p-value = 0.005); Tryptophan Metabolism (p-value = 0.009); and Phenylalanine Metabolism (p-value = 0.012); CYP Drug Metabolism (p-value = 0.022)). A total of 3 separate genes from the CYP family and two from the Dopa Decarboxylase family of genes were validated against an external data set of human ovarian tissue samples, cell lines, mouse ovarian tumor model, and found to have similarly increased gene expression in the genes tested in the platinum resistant groups. Compilation of KEGG analysis and the common network genes revealed pathways associated with amino acid metabolism to be most significantly altered. Conclusions: We describe the identification of a unique transcriptomic profile associated with platinum resistance. Interestingly, the main pathways identified are related to metabolism, suggesting that the survival to chemotherapy demands a major metabolic adaptation. These findings also represent a first step towards the identification of biomarkers for the detection of chemo-resistant disease and metabolism-based drug targets specific for chemo-resistant tumors. Further validation of this model is required in order to determine its clinical value. The purpose of this study was to identify genes and pathways differentially expressed in platinum resistant high grade serous ovarian cancer (HGSOC) when compared to sensitive HGSOC. A total of 37 patients with HGSOC tissue samples underwent RNA sequencing performed by TEMPUS (N=37, 21 platinum sensitive, 16 resistant; 85% Stage III-IV; 58% received neoadjuvant chemotherapy). RNA gene expression data and significantly impacted pathways were analyzed using Advaita Bio's iPathwayGuide. Differentially expressed (DE) genes were identified using FDR of 0.05 and fold-change of 1.5. Genes from several impacted canonical metabolic pathways were validated by PCR against external data sets in a separate ovarian cancer sample group (n=15), platinum resistant ovarian cancer mouse tumor model, and wild-type sensitive and platinum resistant ovarian cancer cell lines. Relative gene expression was calculated using the comparative Ct method, also referred to as the “2 DDCT”, using L27 as internal control gene. We identified 177 differentially expressed (DE) genes out of a total of 16,607 genes (1.1%) with measured expression. 15 pathways were found to be significantly impacted. Of the 15 canonical pathways, all were up regulated in the resistant HGSOC and the majority of the most significantly altered (5/10) were related to metabolism (Retinol metabolism (p-value = 0.002); Tyrosine Metabolism (p-value = 0.005); Tryptophan Metabolism (p-value = 0.009); and Phenylalanine Metabolism (p-value = 0.012); CYP Drug Metabolism (p-value = 0.022)). A total of 3 separate genes from the CYP family and two from the Dopa Decarboxylase family of genes were validated against an external data set of human ovarian tissue samples, cell lines, mouse ovarian tumor model, and found to have similarly increased gene expression in the genes tested in the platinum resistant groups. Compilation of KEGG analysis and the common network genes revealed pathways associated with amino acid metabolism to be most significantly altered. We describe the identification of a unique transcriptomic profile associated with platinum resistance. Interestingly, the main pathways identified are related to metabolism, suggesting that the survival to chemotherapy demands a major metabolic adaptation. These findings also represent a first step towards the identification of biomarkers for the detection of chemo-resistant disease and metabolism-based drug targets specific for chemo-resistant tumors. Further validation of this model is required in order to determine its clinical value.

Accumulation of inflammatory cells and elevated interleukin-17A levels contributes to chronic inflammation, which results in the narrowing of small airways and alveolar wall destruction. Interleukin-17A is produced by T-lymphocytes, macrophages and mast cells, and augments lung inflammation. We hypothesized that interleukin-17A-mediated induction of plasminogen activator inhibitor-1 (PAI-1) expression leads to abnormal fibrin turnover and death of airway and alveolar epithelial cells (AECs) during lung injury. Wild-type and interleukin-17A-deficient mice were exposed to 20 weeks of environmental tobacco smoke (ETS) to induce lung injury. We analyzed lung tissues of patients with severe (stage III and IV) COPD and mice exposed to 20 weeks of ETS for elaboration of interleukin-17A, inflammatory cytokines and chemokines, PAI-1 and AEC apoptosis to test the hypothesis. This was further confirmed using primary human and mouse AECs treated with interleukin-17A in vitro, and lung tissues and AECs isolated from wild-type and PAI-1-deficient mice exposed to interleukin-17A in vivo. We found elevated levels of T-lymphocytes, macrophages and neutrophils, and interleukin-17A in the lungs of patients with COPD and in wild-type mice exposed to ETS for 20 weeks. ETS and interleukin-17A exposure caused significant increase in PAI-1 and lung injury in wild-type mice. Mice deficient in interleukin-17A expression resisted ETS-induced lung injury, while those lacking PAI-1 expression resisted both ETS and interleukin-17A-induced lung injury. Induction of PAI-1 expression due to increased interleukin-17A is associated with lung inflammation, AEC apoptosis and worsening of lung injury. Inhibition of this feedforward induction mitigates AEC apoptosis, inflammation and severity of lung injury.

Idiopathic pulmonary fibrosis (IPF) is a debilitating, incurable, and life-threatening disease. A cardinal feature of the pathogenesis of IPF is excessive extracellular matrix deposition attributable to proliferation of activated fibrotic lung fibroblasts (fLfs). To assess the underlying mechanism, we analyzed the status of the tumor suppressor protein p53 in fLfs from the lungs of IPF patients or mice with bleomycin-induced established PF. We report that basal expression of p53 is markedly reduced in fLfs. Forced expression of caveolin-1 in fLfs increased basal p53 and reduced profibrogenic proteins, including collagen-1. Transduction of fLfs with adenovirus expressing p53 reduced expression of these proteins. Conversely, inhibition of baseline p53 in control lung fibroblasts from lung tissues increased profibrogenic protein expression. Lung transduction of adenovirus expressing p53 reduced bleomycin-induced PF in wild-type or caveolin-1-deficient mice. Furthermore, treatment of fLfs or fibrotic lung tissues with caveolin-1 scaffolding domain peptide (CSP) or its fragment, CSP7, restored p53 and reduced profibrogenic proteins. Treatment of wild-type mice with i.p. CSP or CSP7 resolved bleomycin-induced PF. These peptides failed to resolve PF in inducible conditional knockout mice lacking p53 in fLfs, indicating the induction of baseline fLf p53 as the basis of the antifibrotic effects.

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease. The pathogenesis of interstitial lung diseases, including its most common form, IPF, remains poorly understood. Alveolar epithelial cell (AEC) apoptosis, proliferation, and accumulation of myofibroblasts and extracellular matrix deposition results in progressive loss of lung function in IPF. We found induction of tumor suppressor protein, p53, and apoptosis with suppression of urokinase-type plasminogen activator (uPA) and the uPA receptor in AECs from the lungs of IPF patients, and in mice with bleomycin, cigarette smoke, silica, or sepsis-induced lung injury. Treatment with the caveolin-1 scaffolding domain peptide (CSP) reversed these effects. Consistent with induction of p53, AECs from IPF lungs or mice with diverse types of lung injuries showed increased p53 acetylation and miR-34a expression with reduction in Sirt1. This was significantly reduced after treatment of wild-type mice with CSP, and uPA-deficient mice were unresponsive. Bleomycin failed to induce miR-34a in p53- or plasminogen activator inhibitor-1 (PAI-1)-deficient mice. CSP-mediated inhibition of miR-34a restored Sirt1, suppressed p53 acetylation and apoptosis in injured AECs, and prevented pulmonary fibrosis (PF). AEC-specific suppression of miR-34a inhibited bleomycin-induced p53, PAI-1, and apoptosis and prevented PF, whereas overexpression of precursor-miR-34a increased p53, PAI-1, and apoptosis in AECs of mice unexposed to bleomycin. Our study validates p53-miR-34a feedback as a potential therapeutic target in PF.

We previously demonstrated that tumor suppressor protein p53 augments plasminogen activator inhibitor-1 (PAI-1) expression in alveolar epithelial cells (AECs) during chronic cigarette smoke (CS) exposure-induced lung injury. Chronic lung inflammation with elevated p53 and PAI-1 expression in AECs and increased susceptibility to and exacerbation of respiratory infections are all associated with chronic obstructive pulmonary disease (COPD). We recently demonstrated that preventing p53 from binding to the endogenous PAI-1 mRNA in AECs by either suppressing p53 expression or blockading p53 interactions with the PAI-1 mRNA mitigates apoptosis and lung injury. Within this context, we now show increased expression of the C-X-C chemokines (CXCL1 and CXCL2) and their receptor CXCR2, and the intercellular cellular adhesion molecule-1 (ICAM-1), in the lung tissues of patients with COPD. We also found a similar increase in lung tissues and AECs from wild-type (WT) mice exposed to passive CS for 20 wk and in primary AECs treated with CS extract in vitro. Interestingly, passive CS exposure of mice lacking either p53 or PAI-1 expression resisted an increase in CXCL1, CXCL2, CXCR2, and ICAM-1. Furthermore, inhibition of p53-mediated induction of PAI-1 expression by treatment of WT mice exposed to passive CS with caveolin-1 scaffolding domain peptide reduced CXCL1, CXCL2, and CXCR2 levels and lung inflammation. Our study reveals that p53-mediated induction of PAI-1 expression due to chronic CS exposure exacerbates lung inflammation through elaboration of CXCL1, CXCL2, and CXCR2. We further provide evidence that targeting this pathway mitigates lung injury associated with chronic CS exposure.

Influenza A virus causes significant morbidity and mortality each year worldwide due to antigenic drift, punctuated by infrequent pandemics following antigenic shift. H1N1 subtype of pandemic 2009 (pH1N1) influenza virus lineages has continued to circulate in humans and raised severe concerns about its pandemic developments. The pathogenesis of the disease and its progression as post‐infectious sequelae is not well understood. Moderate inflammatory response protects against the ill effects and hyper‐inflammatory response promotes the pathogenesis in disease progression. Samples were screened by RT‐PCR and classified in pandemic 2009 (pH1N1), Influenza A virus infected patient. Further antibody titer was analyzed by hemagglutination inhibition assay and cytokine/chemokine response by Cytometric bead array assy. Screening of 216 patients shows 63 were belongs to pH1N1 influenza virus infection and 47 were Influenza A virus infected and 106 samples were negative for these viruses, were used as a disease control. Apart from that 100 samples were taken for healthy control. Lower antibody titer was found in patient infected with pH1N1/Influenza A virus and expression of cytokines (IL‐6, IL‐8, and IL‐10) and chemokine MCP‐1 was higher in patient infected with pH1N1 compare to healthy/disease control however there was no significant difference observed in the expression of pro‐inflammatory cytokines TNF‐α and antiviral cytokine IFN‐γ in pH1N1 influenza virus infected patients. J. Med. Virol. 86:1034–1040, 2014. © 2014 Wiley Periodicals, Inc.