Impact of common risk factors of fibrosis progression in chronic hepatitis C

OBJECTIVE

The natural course of chronic hepatitis C varies widely. To improve the profiling of patients at risk of developing advanced liver disease, we assessed the relative contribution of factors for liver fibrosis progression in hepatitis C.

DESIGN

We analysed 1461 patients with chronic hepatitis C with an estimated date of infection and at least one liver biopsy. Risk factors for accelerated fibrosis progression rate (FPR), defined as ≥ 0.13 Metavir fibrosis units per year, were identified by logistic regression. Examined factors included age at infection, sex, route of infection, HCV genotype, body mass index (BMI), significant alcohol drinking (≥ 20 g/day for ≥ 5 years), HIV coinfection and diabetes. In a subgroup of 575 patients, we assessed the impact of single nucleotide polymorphisms previously associated with fibrosis progression in genome-wide association studies. Results were expressed as attributable fraction (AF) of risk for accelerated FPR.

RESULTS

Age at infection (AF 28.7%), sex (AF 8.2%), route of infection (AF 16.5%) and HCV genotype (AF 7.9%) contributed to accelerated FPR in the Swiss Hepatitis C Cohort Study, whereas significant alcohol drinking, anti-HIV, diabetes and BMI did not. In genotyped patients, variants at rs9380516 (TULP1), rs738409 (PNPLA3), rs4374383 (MERTK) (AF 19.2%) and rs910049 (major histocompatibility complex region) significantly added to the risk of accelerated FPR. Results were replicated in three additional independent cohorts, and a meta-analysis confirmed the role of age at infection, sex, route of infection, HCV genotype, rs738409, rs4374383 and rs910049 in accelerating FPR.

CONCLUSIONS

Most factors accelerating liver fibrosis progression in chronic hepatitis C are unmodifiable.

Identification of a novel G245R polymorphism in the IL-2 receptor beta membrane proximal domain associated with human visceral leishmaniasis

Binding of the interleukin-2 (IL-2) to the IL-2 receptor (IL-2R) triggers a series of intracellular events culminating in lymphocyte proliferation and differentiation. We report here the identification of a novel G245R polymorphism in the membrane proximal domain of the IL-2 receptor beta chain (IL-2Rbeta). Present at a frequency of 7.2%, the IL-2-Rbeta G245R was identified in a population of Eastern Sudan exposed to a severe outbreak of visceral leishmaniasis (VL), a disease associated with a marked depression of T-cell antigen-specific responses. The location of the G245R polymorphism next to the box1/box2 proximal cytokine receptor homology segment and suggestive genetic association with the development of disease (P=0.043), suggest that it may affect Janus kinase (JAK) association and impair growth signal transduction. However, additional genetic association with a synonymous single nucleotide polymorphism (IL2RB+8777T) suggests that other variations of IL2RB or nearby genes participate in the highly significant linkage with VL at 22q12 previously reported for this population.

Mepe, the gene encoding a tumor-secreted protein in oncogenic hypophosphatemic osteomalacia, is expressed in bone

The MEPE (matrix extracellular phosphoglycoprotein) gene is a strong candidate for the tumor-derived phosphaturic factor in oncogenic hypophosphatemic osteomalacia (OHO). X-linked hypophosphatemia (XLH) is phenotypically similar to OHO and results from mutations in PHEX, a putative metallopeptidase believed to process a factor(s) regulating bone mineralization and renal phosphate reabsorption. Here we report the isolation of the murine homologue of MEPE, from a bone cDNA library, that encodes a protein of 433 amino acids, 92 amino acids shorter than human MEPE. Mepe, like Phex, is expressed by fully differentiated osteoblasts and down-regulated by 1,25-(OH)2D3. In contrast to Phex, Mepe expression is markedly increased during osteoblast-mediated matrix mineralization. Greater than normal Mepe mRNA levels were observed in bone and osteoblasts derived from Hyp mice, the murine homologue of human XLH. Our data provide the first evidence that MEPE/Mepe is expressed by osteoblasts in association with mineralization.

Production of Sm37-GAPDH, a major therapeutical target in human schistosomiasis

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key enzyme in the glycolytic metabolism and the production of energy. This probably explains why GAPDH was evidenced as a major therapeutical target in several parasitic diseases; either as a vaccine candidate or as a target for chemotherapeutic treatments. Schistosoma mansoni GAPDH (Sm37-GAPDH) is one of the main schistosome vaccine candidates. The production of recombinant Sm37-GAPDH is essential to evaluate the ability of this molecule to induce protective immunity in animals and possibly in humans. The cDNA encoding Sm37-GAPDH has been cloned and sequenced. In addition, five B cell (including the major B-cell epitope Sm35-5) and two T cell epitopes have been localized on the molecule. Different expression systems have been evaluated in respect with the production yield and the GAPDH enzymatic activity. Some of them have led to either a high production of insoluble material (E. coli) or to an inactive enzyme (Pischia pastoris). The present article describes the production setting of rSm37-GAPDH using the baculovirus-insect cell system. Large amounts of soluble rSm37-GAPDH with enzymatic activity were obtained. Most sera from individuals living in an area endemic for S. mansoni recognised the rSm37 molecule and inhibited its catalytic activity.

Induction of a protection against S. mansoni with a MAP containing epitopes of Sm37-GAPDH and Sm10-DLC. Effect of coadsorption with GM-CSF on alum

Studies of anti-S. mansoni immunological responses in individuals living in endemic areas identified immunogens (Sm37-GAPDH and Sm10-DLC) with vaccine candidate properties. Analysis of the epitopes of these immunogens indicated that: (i) Sm37-5 is a major B-cell epitope of Sm37-GAPDH and the IgG antibody reactivity toward this determinant is associated with resistance to reinfection; (ii) Sm10-T is a T-cell epitope of the major T-cell immunogen Sm10-DLC. This led us to test a multiple antigen peptide (MAP) containing Sm37-5 and Sm10-T as an anti-schistosome vaccine. This MAP induced a significant protective immune response in mice when injected in Freund's adjuvant or coadsorbed with GM-CSF on aluminium hydroxide. In the latter case the physical link between the cytokine and the antigen via the coadsorption on alum was necessary to obtain a protective response. Results of the antibody response indicated that when the MAP and GM-CSF were coadsorbed on alum, the antibody response against the Sm10-T epitope located in the NH(2)-terminal position was significantly amplified up to 30% of the anti-Sm37-5 response.

Induction of a protective immunity against Schistosoma mansoni with ovalbumin-coupled Sm37-5 coadsorbed with granulocyte-macrophage colony stimulating factor (GM-CSF) or IL-12 on alum

A previous study has shown that Sm37-5 is a major B cell epitope of Sm37-GAPDH. This epitope is highly antigenic in human infections and IgG antibody reactivity toward this determinant is associated with adolescent resistance to reinfection. This led us to test a synthetic peptide corresponding to Sm37-5, coupled to ovalbumin, as an anti-schistosome vaccine. Although mice injected with Sm37-5-OVA in Freund's adjuvant showed significant protection, immunization in aluminium hydroxide failed to induce protection. The adjuvant effect of cytokines (GM-CSF or IL-12) associated with the antigen on alum was investigated. With each of these two cytokines, significant reductions in the worm burden were obtained (32-38% with GM-CSF and 27% with IL-12, respectively). In addition, a reduction of the egg number trapped in the liver of immunized mice was also observed. Thus, protections were obtained with formulations that could potentially be used in humans.