Schizophrenia is a devastating
psychiatric disorder that impacts on social functioning and quality of life, and there is accumulating evidence that
inflammation is a potential pathogenic mechanism of
schizophrenia. However, the mechanism of
inflammation possibly occurred in
schizophrenia has not been well understood. The endogenous retroviral
protein syncytin-1 and inflammatory marker CRP are both abnormally expressed in
schizophrenia patients. CRP is one of the markers of
bacterial infection generally. Less clear is whether virus or
viral protein can trigger the activation of CRP. Here, we detected a robust increase of the levels of
syncytin-1 and CRP in
schizophrenia patients, and displayed a positive correlation and marked consistency between expressions of
syncytin-1 and CRP in
schizophrenia patients. Furthermore, overexpression of
syncytin-1 significantly elevated the levels of CRP, TLR3, and
IL-6 in both human microglia and astrocytes. TLR3 deficiency impaired the expressions of CRP and
IL-6 induced by
syncytin-1. Importantly, we observed a cellular co-localization and a direct interaction between
syncytin-1 and TLR3. Additionally, knockdown of
IL-6 inhibited the syncytin-1-induced CRP expression. Thus, the totality of these results showed that
viral protein syncytin-1 could trigger the activation of CRP, which might explain the elevated CRP in sterile
inflammation and exhibit a novel mechanism for regulation of
inflammation by
syncytin-1 in
schizophrenia.