IRS1 Expression in Hepatic Tissue and Leukocytes in Chronic Hepatitis C Virus Infected Patients: A Comparative Study

REDUCED HAND GRIP STRENGTH IN OVERWEIGHT AND OBESE CHRONIC HEPATITIS C PATIENTS

BACKGROUND

Hepatitis C is a liver disease that causes significant changes in metabolism, and also has an impact on nutritional status.

OBJECTIVE

To evaluate the nutritional status and cardiovascular risk in patients with chronic hepatitis C.

METHODS

This cross-sectional study investigated 58 patients with chronic hepatitis C, non-cirrhotic and were not under active pharmacological treatment. Patients with significant alcohol consumption (greater than 10 g ethanol/day) were excluded. Patients underwent nutritional assessment through anthropometric measurements and functional assessment using hand grip strength by dynamometry. The physical activity was assessed using the International Physical Activity Questionnaire. Patients also underwent clinical and laboratory evaluation. Cardiovascular risk was calculated by the Framingham score.

RESULTS

The mean age of patients was 51.6±9.7 years, 55.2% were female, and 79.3% had genotype 1. The most prevalent degree of fibrosis was F1 (37.9%) followed by F2 (27.6%) and F3 (1.7%). The prevalence of overweight/obesity considering the body mass index was 70.7%. However, 57.7% of men and 68.8% of women were considered malnourished according to hand grip strength. These patients also had waist circumference (93.5±10.7 cm) and neck circumference (37.0±3.6 cm) high. Almost 60% of patients were considered sedentary or irregularly active. In relation to cardiovascular risk, 50% of patients had high risk of suffering a cardiovascular event within 10 years.

CONCLUSION

Although most patients with hepatitis C presented overweight, associated with high cardiovascular risk, they also have reduced functional capacity, indicative of protein-caloric commitment. Therefore, body mass index can not be considered the only method of assessment for nutritional diagnosis of patients with liver disease. Adopting methods such as hand grip strength can be important for a better understanding of nutritional status of these patients.

Investigation of the roles of trace elements during hepatitis C virus infection using protein-protein interactions and a shortest path algorithm

BACKGROUND

Hepatitis is a type of infectious disease that induces inflammation of the liver without pinpointing a particular pathogen or pathogenesis. Type C hepatitis, as a type of hepatitis, has been reported to induce cirrhosis and hepatocellular carcinoma within a very short amount of time. It is a great threat to human health. Some studies have revealed that trace elements are associated with infection with and immune rejection against hepatitis C virus (HCV). However, the mechanism underlying this phenomenon is still unclear.

METHODS

In this study, we aimed to expand our knowledge of this phenomenon by designing a computational method to identify genes that may be related to both HCV and trace element metabolic processes. The searching procedure included three stages. First, a shortest path algorithm was applied to a large network, constructed by protein-protein interactions, to identify potential genes of interest. Second, a permutation test was executed to exclude false discoveries. Finally, some rules based on the betweenness and associations between candidate genes and HCV and trace elements were built to select core genes among the remaining genes.

RESULTS

12 lists of genes, corresponding to 12 types of trace elements, were obtained. These genes are deemed to be associated with HCV infection and trace elements metabolism.

CONCLUSIONS

The analyses indicate that some genes may be related to both HCV and trace element metabolic processes, further confirming the associations between HCV and trace elements. The method was further tested on another set of HCV genes, the results indicate that this method is quite robustness.

GENERAL SIGNIFICANCE

The newly found genes may partially reveal unknown mechanisms between HCV infection and trace element metabolism. This article is part of a Special Issue entitled "System Genetics" Guest Editor: Dr. Yudong Cai and Dr. Tao Huang.

Diabetes and infections-hepatitis C: is there type 2 diabetes excess in hepatitis C infection?

Individual epidemiologic studies as well as the pooled analysis of observational studies have indicated the association between type 2 diabetes (T2D) and hepatitis C virus infection (HCV). Whether HCV infection is the cause of diabetes or diabetic patients are more prone to get HCV infection is still in question. The objective of the present review was to provide answers to this issue, based on available evidence from epidemiologic, molecular, experimental and therapeutic studies. Our current understanding of how chronic HCV infection could induce T2D is incomplete, but it seems twofold based on both direct and indirect roles of the virus. HCV may directly induce insulin resistance (IR) through its proteins. HCV core protein was shown to stimulate suppressor of cytokine signaling, resulting in ubiquitination and degradation of tyrosine kinase phosphorylated insulin receptor substrates (IRS1/2) in proteasomes. HCV-nonstructural protein could increase protein phosphatase 2A which has been shown to inactivate the key enzyme Akt by dephosphorylating it. Insulin signaling defects in hepatic IRS-1 tyrosine phosphorylation and PI3-kinase association/activation may contribute to IR, which leads to the development of T2D in patients with HCV infection. The peroxisome proliferator-activated receptors (PPARs) are also implicated. PPARα/γ, together with their obligate partner RXR, are the main nuclear receptors expressed in the liver. PPARα upregulates glycerol-3-phosphate dehydrogenase, glycerol kinase, and glycerol transport proteins, which allows for glucose synthesis during fasting states. Decreased activity of PPARs could attribute to HCV-induced IR. Immune-mediated mechanisms may be involved in the indirect role of HCV in inducing IR. It is speculated that TNF-alpha plays a major role in the pathogenesis of IR through lowering IRS1/2. Furthermore, HCV infection- triggered ER stress could lead to the activation of PP2A, which inhibits both Akt and the AMP-activated kinase, the regulators of gluconeogenesis. In summary, we illustrate that HCV infection is accompanied by multiple defects in the upstream insulin signaling pathway in the liver that may contribute to the observed prevalence of IR and diabetes. Future studies are needed to resolve this issue.