Idiopathic pulmonary fibrosis (IPF) is a progressive chronic disorder characterized by activation of fibroblasts and overproduction of extracellular matrix (ECM). Caveolin-1 (cav-1), a principal component of caveolae, has been implicated in the regulation of numerous signaling pathways and biological processes. We observed marked reduction of cav-1 expression in lung tissues and in primary pulmonary fibroblasts from IPF patients compared with controls. We also demonstrated that cav-1 markedly ameliorated bleomycin (BLM)-induced pulmonary fibrosis, as indicated by histological analysis, hydroxyproline content, and immunoblot analysis. Additionally, transforming growth factor β1 (TGF-β1), the well-known profibrotic cytokine, decreased cav-1 expression in human pulmonary fibroblasts. cav-1 was able to suppress TGF-β1–induced ECM production in cultured fibroblasts through the regulation of the c-Jun N-terminal kinase (JNK) pathway. Interestingly, highly activated JNK was detected in IPF- and BLM-instilled lung tissue samples, which was dramatically suppressed by ad–cav-1 infection. Moreover, JNK1-null fibroblasts showed reduced smad signaling cascades, mimicking the effects of cav-1. This study indicates a pivotal role for cav-1 in ECM regulation and suggests a novel therapeutic target for patients with pulmonary fibrosis.

Caveolin-1 (cav-1), the principle structural protein of plasmalemmal caveolae, regulates inflammatory signaling processes originating at the membrane. We show that cav-1 bound to TLR4 and inhibited LPS-induced proinflammatory cytokine (TNF-␣ and IL-6) production in murine macrophages. Mutation analysis revealed a cav-1 binding motif in TLR4, essential for this interaction and for attenuation of proinflammatory signaling. Cav-1 was required for the anti-inflammatory effects of carbon monoxide (CO), a product of heme oxygenase-1 (HO-1) activity. CO augmented the cav-1/TLR4 interaction. Upon LPS stimulation, HO-1 trafficked to the caveolae by a p38 MAPK-dependent mechanism, where it down-regulated proinflammatory signaling. These results reveal an anti-inflammatory network involving cav-1 and HO-1. The Journal of Immunology, 2009, 182: 3809 -3818. P lasma membranes contain specialized lipid microdomains occurring as planar (lipid-rafts) or flask-shaped structures (caveolae) that are enriched in glycosphingolipids and cholesterol (1). The caveolae mediate nonclathrin-dependent endocytosis, and regulate the internalization of particles such as viruses (2) and bacteria (3-5). Caveolin-1 (cav-1), 3 the major structural component of caveolae, exerts pleiotropic cellular functions including the regulation of cholesterol homeostasis, vesicular transport, proliferation, and apoptosis in a diversity of cell types (1). Cav-1 null mice develop cardiac and pulmonary hypertrophy and fibrosis (6, 7). Furthermore, cardiac fibroblasts derived from cav-1 null mice display deregulated signaling pathways, with hyperactivation of ERK1/2 MAPK and NO synthase (NOS) activity (6). Such observations have indicated a critical role for caveolae and cav-1 in cellular signal transduction. Indeed, numerous transmembrane growth factor receptors (e.g., platelet-derived growth factor, epidermal growth factor, and nerve growth factor receptors) and other diverse signaling molecules (e.g., GTPases) localize to caveolae (8). Cav-1 can regulate membrane receptor signaling either by direct binding to the receptor, or downstream molecules, through interactions mediated by its scaffolding domain (8).Recently, cav-1 has also been implicated as a modulator of innate immunity and inflammation (9 -12). Cav-1 null mice displayed increased susceptibility to Salmonella infection, whereas macrophages derived from these mice exhibited enhanced inflammatory responses to bacterial LPS (9). The effects of cav-1 on inflammatory processes are potentially mediated through the regulation of NF-B and NOSII/III activities (10 -12). Previously, we have demonstrated an anti-inflammatory function of cav-1 expression in vitro with respect to the inhibition of proinflammatory cytokines production during LPS-induced inflammation in macrophages (13).Genetic studies in mice have identified TLR4 as the principle membrane receptor for LPS (14). TLRs function as primary sensors of pathogens, which activate signaling pathways leading to the expression of cytokine genes (14). Inflamma...

Caveolin-1 has been reported to regulate apoptosis, lipid metabolism, and endocytosis in macrophages. In the present study, we demonstrate that caveolin-1 can act as a potent immunomodulatory molecule. We first observed caveolin-1 expression in murine alveolar macrophages by Western blotting and immunofluorescence microscopy. Loss-of-function experiments using small interfering RNA showed that down regulating caveolin-1 expression in murine alveolar and peritoneal macrophages increased LPS-induced proinflammatory cytokine TNF-alpha and IL-6 production but decreased anti-inflammatory cytokine IL-10 production. Gain-of-function experiments demonstrated that overexpression of caveolin-1 in RAW264.7 cells decreased LPS-induced TNF-alpha and IL-6 production and augmented IL-10 production. p38 mitogen-activated protein kinase (MAPK) phosphorylation was increased by overexpressing caveolin-1 in RAW264.7 cells, whereas c-Jun N-terminal kinase, extracellular signal-regulated kinase MAPK, and Akt phosphorylation were inhibited. The antiinflammatory modulation of LPS-induced cytokine production by caveolin-1 was significantly abrogated by the administration of p38 inhibitor SB203580 in RAW264.7 cells. Peritoneal macrophages isolated from MKK3 null mice did not demonstrate any modulation of LPS-induced cytokine production by caveolin-1. LPS-induced activation of NF-kappaB and AP-1 determined by electrophoretic mobility shift assay were significantly reduced by overexpressing caveolin-1 in RAW264.7 cells. The reductions were attenuated by the administration of p38 inhibitor SB203580. Taken together, our data suggest that caveolin-1 acts as a potent immunomodulatory effector molecule in immune cells and that the regulation of LPS-induced cytokine production by caveolin-1 involves the MKK3/p38 MAPK pathway.

Cyclooxygenase-2 (COX-2) is a key enzyme involved in the inflammatory process that is rapidly induced in macrophages in response to LPS. Carbon monoxide (CO), a byproduct of heme oxygnease-1, can suppress proinflammatory response in various in vitro and in vivo models of inflammation. This study was undertaken to examine whether CO can regulate (and if so, to delineate the mechanism by which CO regulates) LPS-induced COX-2 expression in macrophages. RAW 264.7 murine macrophages were stimulated with LPS (0-10 ng/ml) with or without CO (500 ppm). Northern and Western blot analysis was done. Progstaglandin E 2 and nitrite concentration was measured from cell culture supernatant. Electrophoretic mobility shift assay was performed to assess nuclear factor binding. CO downregulated LPS-induced COX-2 mRNA and protein expression. CO also inhibited LPS-induced prostaglandin E 2 secretion (P Ͻ 0.05). CO also decreased LPS-induced CCAAT/enhancer-binding protein (C/EBP) ␤ and ␦ protein expression in LPS-treated RAW 264.7 cells. Gel shift analysis revealed that CO treatment decreased LPSinduced activation of protein binding to C/EBP consensus oligonucleotides of murine cyclooxygenase-2 promoter. CO also decreased LPS-induced nitric oxide synthase-2 protein expression and nitrite production, and decreased LPS-induced activation of protein binding to C/EBP consensus oligonucleotides of murine nitric oxide synthase-2 promoter. CO may act as an important regulator of inflammation by virtue of its ability to regulate C/EBPs. Keywords: heme oxygenase; lipopolysaccharides; nitric oxide synthase Heme oxygenase-1 (HO-1) is a microsomal enzyme responsible for degradation of heme, generating biliverdin, iron, and carbon monoxide (CO) (1). HO-1 can be induced by a wide variety of stimuli, and the enzyme is involved in cellular and tissue defense against oxidative stress possessing potent anti-inflammatory properties (2, 3). There is growing interest in the role of CO in the anti-inflammatory and cytoprotective function of HO-1 (4-7), but the pathways involved in the anti-inflammatory effect of CO are poorly understood. CO can modulate mitogen-activated protein kinase (5) and guanylate cyclase/3Ј,5Ј-guanylate cyclic monophospate (cGMP) pathway (8) to inhibit secretion of proinflammatory cytokines. CO also modulates several transcription factors, including NF-B (4, 6) and activating protein-1 (4), which are involved in inflammation. But whether other pathways or molecules are involved in the anti-inflammatory effect of CO is not known.

An CH, Wang XM, Lam HC, Ifedigbo E, Washko GR, Ryter SW, Choi AMK. TLR4 deficiency promotes autophagy during cigarette smoke-induced pulmonary emphysema.

We suggest that the significant changes in GM structures in multiple brain regions of CD patients can be partially explained by the higher levels of anxiety and depression in these patients. Specific profiles of altered GM structures in CD patients were correlated with disease duration.

Our findings suggest that moxibustion exerts its therapeutic effect by repairing mucosal tissue damage and modulating the gut microbiome and intestinal mucosal immunity.

Caveolin 1 (Cav-1) is a major protein of a specific membrane lipid raft known as caveolae. Cav-1 interacts with the gp41 of the human immunodeficiency virus (HIV) envelope, but the role of Cav-1 in HIV replication and pathogenesis is not known. In this report, we demonstrate that HIV infection in primary human monocytederived macrophages (MDMs), THP-1 macrophages, and U87-CD4 cells results in a dramatic upregulation of Cav-1 expression mediated by HIV Tat. The activity of p53 is essential for Tat-induced Cav-1 expression, as our findings show enhanced phosphorylation of serine residues at amino acid positions 15 and 46 in the presence of Tat with a resulting Cav-1 upregulation. Furthermore, inhibition of p38 mitogen-activated protein kinase (MAPK) blocked phosphorylation of p53 in the presence of Tat. Infection studies of Cav-1-overexpressing cells reveal a significant reduction of HIV production. Taken together, these results suggest that HIV infection enhances the expression of Cav-1, which subsequently causes virus reduction, suggesting that Cav-1 may contribute to persistent infection in macrophages.