Statins are a class of therapeutics used to regulate serum cholesterol and reduce the risk of heart disease. Although statins are highly effective in removing cholesterol from the blood, their consumption has been linked to potential adverse effects in some individuals. The most common events associated with statin intolerance are myopathy and increased risk of developing type 2 diabetes mellitus. However, the pathological mechanism through which statins cause these adverse effects is not well understood. Using a murine model, we describe for the first time profound changes in the microbial composition of the gut following statin treatment. This remodelling affected the diversity and metabolic profile of the gut microbiota and was associated with reduced production of butyrate. Statins altered both the size and composition of the bile acid pool in the intestine, tentatively explaining the observed gut dysbiosis. As also observed in patients, statin-treated mice trended towards increased fasting blood glucose levels and weight gain compared to controls. Statin treatment affected the hepatic expression of genes involved in lipid and glucose metabolism. Using gene knockout mice, we demonstrated that the observed effects were mediated through pregnane X receptor (PXR). This study demonstrates that statin therapy drives a profound remodelling of the gut microbiota, hepatic gene deregulation and metabolic alterations in mice through a PXR-dependent mechanism. Since the demonstrated importance of the intestinal microbial community in host health, this work provides new perspectives to help prevent the statin-associated unintended metabolic effects.

Background and purpose:  Fibrosis, a pathological accumulation of collagen in tissues, represents a major global disease burden. Effective characterization of potential antifibrotic drugs has been constrained by poor formation of the extracellular matrix in vitro, due to tardy procollagen processing by collagen C‐proteinase/BMP‐1, and difficulties in relating this matrix to cell numbers in experimental samples.Experimental approach:  The Scar‐in‐a‐Jar model provided, in vitro, the complete biosynthetic cascade of collagen matrix formation including complete conversion of procollagen by C‐proteinase/BMP‐1, its subsequent extracellular deposition and lysyl oxidase‐mediated cross‐linking, achieved by applying the biophysical principle of macromolecular ‘crowding’. Collagen matrix deposition, velocity and morphology can be controlled using negatively charged ‘crowders’ in a rapid (2 days) mode or a mixture of neutral ‘crowders’ in an accelerated (6 days) mode. Combined with quantitative optical bioimaging, this novel system allows for in situ assessment of the area of deposited collagen(s) per cell.Key results:  Optical evaluation of known and novel antifibrotic compounds effective at the epigenetic, post‐transcriptional/translational/secretional level correlated excellently with corresponding biochemical analyses. Focusing on quantitation of deposited collagen, the Scar‐in‐a‐Jar was most effective in assessing novel inhibitors that may have multiple targets, such as microRNA29c, found to be a promising antifibrotic agent.Conclusions and implications:  This novel screening system supersedes current in vitro fibroplasia models, as a fast, quantitative and non‐destructive technique. This method distinguishes a reduction in collagen I deposition, excluding collagen cross‐linking, and allows full evaluation of inhibitors of C‐proteinase/BMP‐1 and other matrix metalloproteinases.

The construction of stable engineered tissue depends on the formation of a functional connective tissue produced by cells locally. A major component of connective tissue is collagen. Its deposition into a stable matrix depends on the enzymatic extracellular conversion of procollagen to collagen. This step is very slow in vitro and we hypothesized that this is due to a lack of crowdedness and insufficient excluded volume effect (EVE) in culture media. We used neutral (670 kDa) and negatively charged dextran sulfate (DxS, 500 kDa) to create EVE in cell cultures and to enhance in vitro matrix formation by accelerating procollagen conversion. Biochemical analyses in 2 human fibroblast lines revealed mostly unprocessed procollagen in uncrowded culture medium, whereas in the presence of DxS, procollagen conversion occurred and most of the collagen was associated with the cell layer. Immunocytochemistry confirmed DxS-related collagen deposition that colocalized with fibronectin. The large neutral dextran showed, in identical concentration ranges, no effects that correlated well with its smaller hydrodynamic radius as determined by dynamic light scattering. This predicted a 10 times bigger crowding power of DxS and benchmarks it as a potentially promising crowding agent facilitating the formation of extracellular matrix in vitro.

Apoptosis has been found to occur during regression of the corpus luteum (CL) in many species. The Fas (APO-1/CD95) receptor, a transmembrane protein that induces apoptosis in the cell when bound to Fas ligand (FasL), may be involved. This study established and quantitated the presence and regulation of Fas receptor and FasL in the rat CL during pregnancy and postpartum. Using immunohistochemistry, FasL was localized in CL during pregnancy and postpartum. Fas was localized at Day 1 of pregnancy and at the time of luteolysis. Both Fas and FasL mRNA were found to be expressed throughout pregnancy and postpartum using reverse transcription-polymerase chain reaction (RT-PCR). Relative quantitative RT-PCR established that expression of FasL mRNA increased significantly at Day 22 of pregnancy and decreased by Day 3 postpartum. Spontaneous apoptosis of rat CL placed in an in vitro culture model with serum-free medium was examined by analysis of extracted DNA using 3′ end-labeling. Treatment with an anti-rat Fas monoclonal antibody demonstrated a reduction in the occurrence of spontaneous apoptosis. These data support a role for Fas receptor and FasL in rat CL apoptosis during luteolysis.

Pulmonary fibrosis represents a fatal stage of interstitial lung diseases of known and idiopathic aetiology. No effective therapy is currently available. Based on an indication-discovery approach we present novelin vitroevidence that the histone deacetylases inhibitor suberoylanilide hydroxamic acid (SAHA), an FDA approved anti-cancer drug, has antifibrotic and anti-inflammatory potential.Human lung fibroblasts (fetal, adult and idiopathic adult pulmonary fibrosis) were treated with transforming growth factor (TGF)-β1 with or without SAHA. Collagen deposition, α-smooth muscle actin (α-SMA) expression, matrix metalloproteinase (MMP)1 activity, tissue inhibitor of MMP (TIMP)1 production, apoptosis and cell proliferation were assessed. Pro-inflammatory cytokines relevant to pulmonary fibrosis were assayed in SAHA-treated human peripheral blood mononuclear cells (PBMC) and its subpopulations.SAHA abrogated TGF-β1 effects on all the fibroblast lines by preventing their transdifferentiation into α-SMA positive myofibroblasts and increased collagen deposition without inducing apoptosis. However, MMP1 activity and TIMP1 production was modulated without a clear fibrolytic effect. SAHA also inhibited serum-induced proliferation of the fibroblast lines and caused hyperacetylation of α-tubulin and histone. Cytokine secretion was inhibited from PBMC and lymphocytes at nonapoptotic concentrations.Taken together, these data demonstrate combined antifibrotic and anti-inflammatory properties of SAHA, suggesting its therapeutic potential for pulmonary fibrosis.