Etanercept.

Infection by the hepatitis C virus (HCV) is prevalent in approximately 4 million people in the United States, where it is the most common blood-borne infectious disease, and 20 million people worldwide (Frankel et al. 2009). Chronic HCV infection must be monitored carefully, as it may pave the way for eventual cirrhosis of the liver, end-stage liver disease, or hepatocellular carcinoma (Frankel et al. 2009). One unfavorable drawback to a treatment option for this infection, pegylated interferon and interferon alfa, is the initiation or worsening of psoriasis and psoriatic arthritis in patients who have concomitant hepatitis C infection and psoriasis (Frankel et al. 2009; Citro et al. 2007; Taylor et al. 2007). Tumor necrosis factor (TNF) alpha is a common cytokine in both diseases, leading to psoriatic skin and joint inflammation and HCV-associated liver cirrhosis and diabetes mellitus. Thus, a prior study found that HCV infection might play a role in triggering psoriasis due to overproduction of TNF-alpha (Imafuku et al. 2013). In another study, biopsies of both lesional and non-lesional HCV-positive patients showed increased mRNA levels of cathelicidin, TLR9, and IFN-γ. Therefore, it has been demonstrated that HCV infection enhances various inflammatory cytokines, increasing the chances of being diagnosed with psoriasis (Chun et al. 2016). The severity of psoriasis can also be measured by the presence of HCV antibodies and overexpression of apoptosis-regulating proteins, such as p53 and tTG (Gabr et al. 2014).