Blocking integrin α4ß7-mediated CD4 T cell recruitment to the intestine and liver protects mice from western diet-induced non-alcoholic steatohepatitis.

BACKGROUND & AIMS: The heterodimeric integrin receptor α4ß7 regulates CD4 T cell recruitment to inflamed tissues, but its role in the pathogenesis of non-alcoholic steatohepatitis (NASH) is unknown. Herein, we examined the role of α4ß7-mediated recruitment of CD4 T cells to the intestine and liver in NASH. METHODS: Male littermate F11r+/+ (control) and junctional adhesion molecule A knockout F11r-/- mice were fed a normal diet or a western diet (WD) for 8 weeks. Liver and intestinal tissues were analyzed by histology, quantitative reverse transcription PCR (qRT-PCR), 16s rRNA sequencing and flow cytometry. Colonic mucosa-associated microbiota were analyzed using 16s rRNA sequencing. Liver biopsies from patients with NASH were analyzed by confocal imaging and qRT-PCR. RESULTS: WD-fed knockout mice developed NASH and had increased hepatic and intestinal α4ß7+ CD4 T cells relative to control mice who developed mild hepatic steatosis. The increase in α4ß7+ CD4 T cells was associated with markedly higher expression of the α4ß7 ligand mucosal addressin cell adhesion molecule 1 (MAdCAM-1) in the colonic mucosa and livers of WD-fed knockout mice. Elevated MAdCAM-1 expression correlated with increased mucosa-associated Proteobacteria in the WD-fed knockout mice. Antibiotics reduced MAdCAM-1 expression indicating that the diet-altered microbiota promoted colonic and hepatic MAdCAM-1 expression. α4ß7 blockade in WD-fed knockout mice significantly decreased α4ß7+ CD4 T cell recruitment to the intestine and liver, attenuated hepatic inflammation and fibrosis, and improved metabolic indices. MAdCAM-1 blockade also reduced hepatic inflammation and fibrosis in WD-fed knockout mice. Hepatic MAdCAM-1 expression was elevated in patients with NASH and correlated with higher expression of α4 and ß7 integrins. CONCLUSIONS: These findings establish α4ß7/MAdCAM-1 as a critical axis regulating NASH development through colonic and hepatic CD4 T cell recruitment. LAY SUMMARY: Non-alcoholic steatohepatitis (NASH) is an advanced and progressive form of non-alcoholic fatty liver disease (NAFLD), and despite its growing incidence no therapies currently exist to halt NAFLD progression. Herein, we show that blocking integrin receptor α4ß7-mediated recruitment of CD4 T cells to the intestine and liver not only attenuates hepatic inflammation and fibrosis, but also improves metabolic derangements associated with NASH. These findings provide evidence for the potential therapeutic application of α4ß7 antibody in the treatment of human NASH.

Western diet-induced increase in colonic bile acids compromises epithelial barrier in nonalcoholic steatohepatitis.

There is compelling evidence implicating intestinal permeability in the pathogenesis of nonalcoholic steatohepatitis (NASH), but the underlying mechanisms remain poorly understood. Here we examined the role of bile acids (BA) in western diet (WD)-induced loss of colonic epithelial barrier (CEB) function in mice with a genetic impairment in intestinal epithelial barrier function, junctional adhesion molecule A knockout mice, F11r-/- . WD-fed knockout mice developed severe NASH, which was associated with increased BA concentration in the cecum and loss of CEB function. Analysis of cecal BA composition revealed selective increases in primary unconjugated BAs in the WD-fed mice, which correlated with increased abundance of microbial taxa linked to BA metabolism. In vitro permeability assays revealed that chenodeoxycholic acid (CDCA), which was elevated in the cecum of WD-fed mice, increased paracellular permeability, while the BA-binding resin sevelamer hydrochloride protected against CDCA-induced loss of barrier function. Sequestration of intestinal BAs by in vivo delivery of sevelamer to WD-fed knockout mice attenuated colonic mucosal inflammation and improved CEB. Sevelamer also reduced hepatic inflammation and fibrosis, and improved metabolic derangements associated with NASH. Collectively, these findings highlight a hitherto unappreciated role for BAs in WD-induced impairment of the intestinal epithelial barrier in NASH.

Identification of species and genetic variation in Taenia isolates from human and swine of North India.

Taenia solium is the major cause of taeniasis and cysticercosis/neurocysticercosis (NCC) in the developing countries including India, but the existence of other Taenia species and genetic variation have not been studied in India. So, we studied the existence of different Taenia species, and sequence variation in Taenia isolates from human (proglottids and cysticerci) and swine (cysticerci) in North India. Amplification of cytochrome c oxidase subunit 1 gene (cox1) was done by polymerase chain reaction (PCR) followed by sequencing and phylogenetic analysis. We identified two species of Taenia i.e. T. solium and Taenia asiatica in our isolates. T. solium isolates showed similarity with Asian genotype and nucleotide variations from 0.25 to 1.01 %, whereas T. asiatica displayed nucleotide variations ranged from 0.25 to 0.5 %. These findings displayed the minimal genetic variations in North Indian isolates of T. solium and T. asiatica.

Expression of adhesion molecules, chemokines and matrix metallo- proteinases (MMPs) in viable and degenerating stage of Taenia solium metacestode in swine neurocysticercosis.

Neurocysticercosis (NCC) is a parasitic infection of central nervous system (CNS). Expression of adhesion molecules, chemokines and matrix metalloproteinases (MMPs) were investigated on brain tissues surrounding viable (n=15) and degenerating cysticerci (n=15) of Taenia solium in swine by real-time RT-PCR and ELISA. Gelatin gel zymography was performed for MMPs activity. ICAM-1 (intercellular adhesion molecule-1), E-selectin, MIP-1α (macrophage inflammatory protein-1α), Eotaxin-1 and RANTES (regulated on activation, normal T cell expressed and secreted) were associated with degenerating cysticerci (cysts). However, VCAM-1 (vascular cell adhesion molecule-1), MCP-1 (monocyte chemotactic protein-1), MMP-2 and MMP-9 were associated with both viable and degenerating cysts. In conclusion, viable and degenerating cysticerci have different immune molecule profiles and role of these molecules in disease pathogenesis needs to be investigated.

Immune response to Taenia solium cysticerci after anti-parasitic therapy.

Albendazole is the drug of choice for Taenia solium infection. Concomitant administration of steroid has been advocated to avoid adverse reactions to albendazole therapy in neurocysticercosis. Some T. solium cysticerci (larvae) respond to albendazole therapy while others do not and the reasons remain unexplained. We hypothesise that the immune response differs between treatment responder and non-responder cysticerci and this may determine the outcome. Twenty swine naturally infected with T. solium were purchased from the market and the infection was confirmed by magnetic resonance imaging. Swine were divided into two groups; swine in group 1 were treated with albendazole and those in group 2 were treated with albendazole plus steroid (prednisolone). All the animals underwent follow-up MRIs at 6 and 12 weeks after start of therapy and were then sacrificed. Tissues surrounding the cysticerci were collected and studied for the expression of different cytokines by reverse transcriptase PCR and ELISA. Albendazole therapy was found to be more effective in parasite killing than albendazole plus steroid (94.11% versus 70.96%, P=0.011). Albendazole therapy provoked a pro-inflammatory, Th1 (IFN-γ) and pleiotropic (IL-6) cytokine response around the dead cysticerci. Despite a heavy parasite burden in the brain, all the pigs treated with albendazole plus steroid survived. In this group of animals, a mixed pro-inflammatory Th1, Th2 (IL-4) and regulatory cytokine (IL-10) response was associated with responder cysticerci. Further, Th2 and regulatory cytokine responses were associated with non-responder cysticerci.

Glycopeptide and daptomycin susceptibility trends among clinical isolates of methicillin-resistant Staphylococcus aureus in a tertiary care center in North India.

Increased vancomycin minimum inhibitory concentration (MIC) levels in Staphylococcus aureus and their association with vancomycin treatment failure are well-known problems. Few studies have recognized progressive increases in glycopeptide MIC levels for S. aureus strains in recent years. This study determined glycopeptide and daptomycin susceptibility among methicillin resistant S. aureus (MRSA) strains. A total of 776 clinical isolates of MRSA recovered from 2009 to 2012 were studied for glycopeptide and daptomycin susceptibility using the E-test method. The vancomycin MIC geometric mean (GM) of the MRSA isolates was 0.923, 0.944, 1.134 and 1.294 mg/L in the years 2009, 2010, 2011 and 2012, respectively, and the trend significantly increased over the years (P < 0.0001). Similarly, the teicoplanin MIC GM was 1.47, 1.49, 1.8 and 2.04 mg/L in the years from 2009 to 2012, respectively (P < 0.0001). MIC shifts were not found for daptomycin (P > 0.232). A significant increase in the MIC for glycopeptides was observed among the clinical MRSA isolates at our center over a 4-year period. However, the daptomycin MIC did not increase in the observed MRSA isolates.