Humanisation of a claudin-1-specific monoclonal antibody for clinical prevention and cure of HCV infection without escape

OBJECTIVE

HCV infection is a leading cause of chronic liver disease and a major indication for liver transplantation. Although direct-acting antivirals (DAAs) have much improved the treatment of chronic HCV infection, alternative strategies are needed for patients with treatment failure. As an essential HCV entry factor, the tight junction protein claudin-1 (CLDN1) is a promising antiviral target. However, genotype-dependent escape via CLDN6 and CLDN9 has been described in some cell lines as a possible limitation facing CLDN1-targeted therapies. Here, we evaluated the clinical potential of therapeutic strategies targeting CLDN1.

DESIGN

We generated a humanised anti-CLDN1 monoclonal antibody (mAb) (H3L3) suitable for clinical development and characterised its anti-HCV activity using cell culture models, a large panel of primary human hepatocytes (PHH) from 12 different donors, and human liver chimeric mice.

RESULTS

H3L3 pan-genotypically inhibited HCV pseudoparticle entry into PHH, irrespective of donor. Escape was likely precluded by low surface expression of CLDN6 and CLDN9 on PHH. Co-treatment of a panel of PHH with a CLDN6-specific mAb did not enhance the antiviral effect of H3L3, confirming that CLDN6 does not function as an entry factor in PHH from multiple donors. H3L3 also inhibited DAA-resistant strains of HCV and synergised with current DAAs. Finally, H3L3 cured persistent HCV infection in human-liver chimeric uPA-SCID mice in monotherapy.

CONCLUSIONS

Overall, these findings underscore the clinical potential of CLDN1-targeted therapies and describe the functional characterisation of a humanised anti-CLDN1 antibody suitable for further clinical development to complement existing therapeutic strategies for HCV.

Occludin Content Modulates Hydrogen Peroxide-Induced Increase in Renal Epithelial Paracellular Permeability

The ability of hydrogen peroxide (H2O2) to increase paracellular permeability of renal epithelial cell monolayers was examined and the role of occludin in this regulation was investigated. H2O2 treatment increased the paracellular movement of calcein, a marker for the leak pathway permeability, across monolayers of two renal epithelial cell lines, MDCK and LLC-PK1, in a concentration-dependent manner. At the same concentrations, H2O2 did not alter transepithelial resistance (TER) nor increase cell death. The magnitude of the H2O2-induced increase in leak pathway permeability was inversely related to cellular occludin protein content. H2O2 treatment did not produce any major change in total cellular content or Triton X-100-soluble or -insoluble fraction content of occludin protein. Occludin protein staining at the tight junction region was diminished following H2O2 treatment. The most dramatic effect of H2O2 was on the dynamic mobility of GFP-occludin into the tight junction region. H2O2 treatment slowed lateral movement of GFP-occludin into the tight junction region but not on the apical membrane. Further, removal of the cytoplasmic C-terminal region of occludin protein eliminated the effect of H2O2 on GFP-occludin lateral movement into the tight junction region. An increase in the mobile fraction of GFP-occludin was associated with a loss of response to H2O2. These data indicate that the H2O2-induced increase in renal epithelial cell paracellular permeability is mediated, at least in part, through occludin protein, possibly through a slowing of the rate of occludin movement into the tight junction region.

Helicobacter pylori targets cancer-associated apical-junctional constituents in gastroids and gastric epithelial cells

OBJECTIVE

Helicobacter pylori strains that express the oncoprotein CagA augment risk for gastric cancer. However, the precise mechanisms through which cag(+) strains heighten cancer risk have not been fully delineated and model systems that recapitulate the gastric niche are critical for understanding pathogenesis. Gastroids are three-dimensional organ-like structures that provide unique opportunities to study host-H. pylori interactions in a preclinical model. We used gastroids to inform and direct in vitro studies to define mechanisms through which H. pylori modulates expression of the cancer-associated tight junction protein claudin-7.

DESIGN

Gastroids were infected by luminal microinjection, and MKN28 gastric epithelial cells were cocultured with H. pylori wild-type cag(+) strains or isogenic mutants. β-catenin, claudin-7 and snail localisation was determined by immunocytochemistry. Proliferation was assessed using 5-ethynyl-2'-deoxyuridine, and levels of claudin-7 and snail were determined by western blot and flow cytometry.

RESULTS

Gastroids developed into a self-organising differentiation axis and H. pylori induced mislocalisation of claudin-7 and increased proliferation in a CagA- and β-catenin-dependent manner. In MKN28 cells, H pylori-induced suppression of claudin-7 was regulated by β-catenin and snail. Similarly, snail expression was increased and claudin-7 levels were decreased among H. pylori-infected individuals.

CONCLUSIONS

H. pylori increase proliferation in a strain-specific manner in a novel gastroid system. H. pylori also alter expression and localisation of claudin-7 in gastroids and human epithelial cells, which is mediated by β-catenin and snail activation. These data provide new insights into molecular interactions with carcinogenic potential that occur between H. pylori and epithelial cells within the gastric niche.

Functional bowel symptoms in quiescent inflammatory bowel diseases: role of epithelial barrier disruption and low-grade inflammation

OBJECTIVE

To determine the role of colonic barrier defects and low-grade inflammation in irritable bowel syndrome (IBS)-like symptoms in quiescent inflammatory bowel disease (IBD).

DESIGN

Caecal biopsies were collected from 51 IBS, 49 quiescent IBD (31 Crohn's disease (CD) and 18 ulcerative colitis (UC)) patients and 27 controls. IBS was assessed using the Rome III criteria and the IBS severity score. Epithelial barrier integrity was evaluated by determining the paracellular permeability of biopsies mounted in Ussing chambers and the mRNA expression of tight junction proteins (ZO-1, α-catenin and occludin). Low-grade inflammation was evaluated by counting cells, including intraepithelial lymphocytes (IELs), eosinophils and mast cells, and by determining the mRNA and protein expression of tumour necrosis factor (TNF)-α in biopsies and culture supernatants.

RESULTS

IBS-like symptoms were present in 35.4 and 38% of CD and UC patients, respectively. Paracellular permeability was significantly increased in both quiescent IBD with IBS-like symptoms and IBS compared with quiescent IBD without IBS-like symptoms (p<0.01, respectively) or controls (p<0.01, respectively). Significantly lower expression of ZO-1 and α-catenin was detected in IBS and quiescent IBD with IBS-like symptoms. IELs and TNF-α were significantly increased in quiescent IBD with IBS-like symptoms, but not in IBS.

CONCLUSIONS

In quiescent IBD, IBS-like symptoms related to persistent subclinical inflammation associated with increased colonic paracellular permeability. A persistent increase in TNF-α in colonic mucosa may contribute to the epithelial barrier defects associated with abdominal pain in quiescent IBD, but not in IBS. Optimisation of anti-inflammatory therapy may be considered in quiescent IBD with IBS-like symptoms.