Role of lung ornithine aminotransferase in idiopathic pulmonary fibrosis: regulation of mitochondrial ROS generation and TGF-ß1 activity.

Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant lung remodeling and the excessive accumulation of extracellular matrix (ECM) proteins. In a previous study, we found that the levels of ornithine aminotransferase (OAT), a principal enzyme in the proline metabolism pathway, were increased in the lungs of patients with IPF. However, the precise role played by OAT in the pathogenesis of IPF is not yet clear. The mechanism by which OAT affects fibrogenesis was assessed in vitro using OAT-overexpressing and OAT-knockdown lung fibroblasts. The therapeutic effects of OAT inhibition were assessed in the lungs of bleomycin-treated mice. OAT expression was increased in fibrotic areas, principally in interstitial fibroblasts, of lungs affected by IPF. OAT levels in the bronchoalveolar lavage fluid of IPF patients were inversely correlated with lung function. The survival rate was significantly lower in the group with an OAT level >75.659 ng/mL than in the group with an OAT level ≤75.659 ng/mL (HR, 29.53; p = 0.0008). OAT overexpression and knockdown increased and decreased ECM component production by lung fibroblasts, respectively. OAT knockdown also inhibited transforming growth factor-ß1 (TGF)-ß1 activity and TGF-ß1 pathway signaling. OAT overexpression increased the generation of mitochondrial reactive oxygen species (ROS) by activating proline dehydrogenase. The OAT inhibitor L-canaline significantly attenuated bleomycin-induced lung injury and fibrosis. In conclusion, increased OAT levels in lungs affected by IPF contribute to the progression of fibrosis by promoting excessive mitochondrial ROS production, which in turn activates TGF-ß1 signaling. OAT may be a useful target for treating patients with fibrotic lung diseases, including IPF.

Overexpression of fatty acid synthase attenuates bleomycin induced lung fibrosis by restoring mitochondrial dysfunction in mice.

Proper lipid metabolism is crucial to maintain alveolar epithelial cell (AEC) function, and excessive AEC death plays a role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). The mRNA expression of fatty acid synthase (FASN), a key enzyme in the production of palmitate and other fatty acids, is downregulated in the lungs of IPF patients. However, the precise role of FASN in IPF and its mechanism of action remain unclear. In this study, we showed that FASN expression is significantly reduced in the lungs of IPF patients and bleomycin (BLM)-treated mice. Overexpression of FASN significantly inhibited BLM-induced AEC death, which was significantly potentiated by FASN knockdown. Moreover, FASN overexpression reduced BLM-induced loss of mitochondrial membrane potential and the production of mitochondrial reactive oxygen species (ROS). Oleic acid, a fatty acid component increased by FASN overexpression, inhibited BLM-induced cell death in primary murine AECs and rescue BLM induced mouse lung injury/fibrosis. FASN transgenic mice exposed to BLM exhibited attenuated lung inflammation and collagen deposition compared to controls. Our findings suggest that defects in FASN production may be associated with the pathogenesis of IPF, especially mitochondrial dysfunction, and augmentation of FASN in the lung may have therapeutic potential in preventing lung fibrosis.

Ileocolic intussusception caused by giant submucosal colonic lipoma: A rare case report.

INTRODUCTION: An adult intussusception is associated with a pathological lesion involving a lead point, such as a benign polyp, enlarged mesenteric lymph node, lipoma, Meckel's diverticulum, lymphoma, gastrointestinal stromal tumor, primary, or metastatic adenocarcinoma. A lipoma is usually asymptomatic, however, lipomas >2 cm may cause intussusception by forming a lead point. PRESENTATION OF CASE: A 46-year-old South Korean man was admitted and presented with a two-week history of intermittent abdominal pain and discomfort. Abdominal pelvic computed tomography scan revealed that about 6.5 cm of fat attenuation mass is present in the ascending colonic loop with about 15 cm of ileal loop pulled into the ascending colonic loop through the ileocecal valve. Mechanical obstruction with ileocolic intussusception was found in distal ileum. The colonoscopy detected a huge mass in the mid-ascending colon blocking the passage of the colonoscope. The patient was diagnosed with an ileocolic intussusception which was suspected to be a huge lipoma. Laparoscopic assisted right hemicolectomy was performed and the follow-up pathologic examination showed that it is a submucosal lipoma. CONCLUSION: The present case report concerns a 46-year-old male with a long segment ileocolic intussusception due to a giant lipoma arising from the ascending colon and whose intussusception was surgically resected.

Spermidine attenuates bleomycin-induced lung fibrosis by inducing autophagy and inhibiting endoplasmic reticulum stress (ERS)-induced cell death in mice.

Spermidine is an endogenous biological polyamine that plays various longevity-extending roles and exerts antioxidative, antiaging, and cell growth-promoting effects. We previously reported that spermidine levels were significantly reduced in idiopathic pulmonary fibrosis (IPF) of the lung. The present study assessed the potential beneficial effects of spermidine on lung fibrosis and investigated the possible mechanism. Lung fibrosis was established in mice using bleomycin (BLM), and exogenous spermidine was administered daily by intraperitoneal injection (50 mg/kg in phosphate-buffered saline). BLM-induced alveolar epithelial cells showed significant increases in apoptosis and endoplasmic reticulum stress (ERS)-related mediators, and spermidine attenuated BLM-induced apoptosis and activation of the ERS-related pathway. Senescence-associated ß-gal staining and decreased expression of p16 and p21 showed that spermidine ameliorated BLM-induced premature cellular senescence. In addition, spermidine enhanced beclin-1-dependent autophagy and autophagy modulators in IPF fibroblasts and BLM-induced mouse lungs, in which inflammation and collagen deposition were significantly decreased. This beneficial effect was related to the antiapoptotic downregulation of the ERS pathway, antisenescence effects, and autophagy activation. Our findings suggest that spermidine could be a therapeutic agent for IPF treatment.

IL-37 Attenuates Lung Fibrosis by Inducing Autophagy and Regulating TGF-ß1 Production in Mice.

Idiopathic pulmonary fibrosis (IPF) is a progressive and destructive lung disease with a poor prognosis resulting in a high mortality rate. IL-37 is an anti-inflammatory cytokine that inhibits innate and adaptive immunity by downregulating proinflammatory mediators and pathways. However, the exact role of IL-37 in lung fibrosis is unclear. In this study, we found that the IL-37 protein was expressed in alveolar epithelial cells (AECs) and alveolar macrophages in healthy controls but significantly reduced in patients with IPF. IL-37 significantly inhibited oxidative stress-induced primary mouse AEC death in a dose-dependent manner, and knockdown of IL-37 significantly potentiated human lung cancer-derived AEC (A549 cells) death. IL-37 attenuated constitutive mRNA and protein expression of fibronectin and collagen I in primary human lung fibroblasts. IL-37 inhibited TGF-ß1-induced lung fibroblast proliferation and downregulated the TGF-ß1 signaling pathway. Moreover, IL-37 enhanced beclin-1-dependent autophagy and autophagy modulators in IPF fibroblasts. IL-37 significantly decreased inflammation and collagen deposition in bleomycin-exposed mouse lungs, which was reversed by treatment with the autophagy inhibitor 3-methyladenine. Our findings suggested that a decrease in IL-37 may be involved in the progression of IPF and that IL-37 inhibited TGF-ß1 signaling and enhancement of autophagy in IPF fibroblasts. Given its antifibrotic activity, IL-37 could be a therapeutic target in fibrotic lung diseases, including IPF.

Involvement of Alveolar Epithelial Cell Necroptosis in Idiopathic Pulmonary Fibrosis Pathogenesis.

Alveolar epithelial cell (AEC) injury leading to cell death is involved in the process of fibrosis development during idiopathic pulmonary fibrosis (IPF). Among regulated/programmed cell death, the excessive apoptosis of AECs has been widely implicated in IPF pathogenesis. Necroptosis is a type of regulated/programmed necrosis. A multiprotein complex composed of receptor-interacting protein kinase (RIPK)-1 and -3 plays a key regulatory role in initiating necroptosis. Although necroptosis participates in disease pathogeneses through the release of damage-associated molecular patterns, its association with IPF progression remains elusive. In this study, we attempted to illuminate the involvement of RIPK3-regulated necroptosis in IPF pathogenesis. IPF lung tissues were used to detect necroptosis, and the role of RIPK3 was determined using cell culturing models of AECs. Lung fibrosis models of bleomycin (BLM) treatment were also used. RIPK3 expression levels were increased in IPF lungs, and both apoptosis and necroptosis were detected mainly in AECs. Necrostatin-1 and RIPK3 knockout experiments in AECs revealed the participation of necroptosis in BLM and hydrogen peroxide-induced cell death. BLM treatment induced RIPK3 expression in AECs and increased high-mobility group box 1 and IL-1ß levels in mouse lungs. The efficient attenuation of BLM-induced lung inflammation and fibrosis was determined in RIPK3 knockout mice and by necrostatin-1 with a concomitant reduction in high-mobility group box 1 and IL-1ß. RIPK3-regulated necroptosis in AECs is involved in the mechanism of lung fibrosis development through the release of damage-associated molecular patterns as part of the pathogenic sequence of IPF.

Preauricular angioleiomyoma.

Preauricular masses are commonly seen in the otology clinic. Excisional biopsy is essential for diagnosis, and treatment is necessary to reduce the risk of malignancy and for cosmetic purposes. We recently treated a rare case of angioleiomyoma of the preauricular area. Angioleiomyoma is a benign tumor arising from smooth muscle within blood vessel walls. These tumors can arise anywhere in the body; however, they are usually found in the lower extremities and present as a painful mass. Angioleiomyoma of the preauricular area in an elderly person is rare, and only a few cases have been reported. Here, we report the case of an 85-year-old male patient with angioleiomyoma of the preauricular area and provide a literature review.