Recent discovery of occult hepatitis C virus (HCV) infection persisting after spontaneous or antiviral therapy-induced resolution of hepatitis C was made possible by the introduction of nucleic acid amplification assa...Recent discovery of occult hepatitis C virus (HCV) infection persisting after spontaneous or antiviral therapy-induced resolution of hepatitis C was made possible by the introduction of nucleic acid amplification assays capable of detecting HCV RNA at sensitivities superseding those offered by clinical tests. Although individuals with this seemingly silent HCV infection are usually anti-HCV antibody reactive and have normal liver function tests, occult HCV infection has also been reported in anti-HCV-negative individuals with persistently elevated liver enzymes of unknown etiology. Studies have shown that HCV RNA can persist for years in serum, lymphomononuclear cells and liver in the absence of clinical symptoms, although histological evidence of a mild inflammatory liver injury can be occasionally encountered. Furthermore, while HCV RNA can be detected in circulating lymphoid cells in approximately 30% of cases, a short-term culture under stimulatory conditions augments HCV replication in these cells allowing detection of virus in otherwise HCV-negative cases. HCV infects different immune cell subsets, including CD4+ and CD8+ T lymphocytes, B cells and monocytes. Studies employing clonal sequencing and single-stranded conformational polymorphism analyses have revealed unique HCV variants residing in immune cells, further strengthening the notion of HCV lymphotropism. Overall, the data accumulated suggest that occult HCV infection is a common consequence of resolution of symptomatic hepatitis C and that examination of the cells of the immune system is an effective approach to diagnosis of HCV infection and its long-term persistence. Further work is required to fully realize pathogenic and epidemiological consequences of occult HCV persistence.展开更多
To the Editor:The incidence and mortality of colorectal cancer(CRC)in China have increased significantly in recent years.Surpassing gastric cancer,CRC has become one of the main cancers threatening the life and health...To the Editor:The incidence and mortality of colorectal cancer(CRC)in China have increased significantly in recent years.Surpassing gastric cancer,CRC has become one of the main cancers threatening the life and health of Chinese people and causing a serious social burden.Early detection of CRC is critical for improving outcomes.Although colonoscopy remains the primary diagnostic and screening method,its invasiveness and low patient compliance hinder broad application.Non-invasive methods including fecal occult blood tests and carcinoembryonic antigen(CEA)lack sensitivity(20–40%)and specificity for early detection.Therefore,non-invasive biomarkers with high sensitivity and specificity for detecting CRC and precancerous adenomas are urgently needed.Altered gut microbiota is closely associated with colorectal carcinogenesis but exhibits high interindividual variability,limiting its clinical utility.Microbiota-derived metabolites such as bile acids and short-chain fatty acids are critical in CRC progression.Serum metabolite levels are strongly correlated with gut microbial abundance,providing a new direction for noninvasive diagnosis of CRC.展开更多
文摘Recent discovery of occult hepatitis C virus (HCV) infection persisting after spontaneous or antiviral therapy-induced resolution of hepatitis C was made possible by the introduction of nucleic acid amplification assays capable of detecting HCV RNA at sensitivities superseding those offered by clinical tests. Although individuals with this seemingly silent HCV infection are usually anti-HCV antibody reactive and have normal liver function tests, occult HCV infection has also been reported in anti-HCV-negative individuals with persistently elevated liver enzymes of unknown etiology. Studies have shown that HCV RNA can persist for years in serum, lymphomononuclear cells and liver in the absence of clinical symptoms, although histological evidence of a mild inflammatory liver injury can be occasionally encountered. Furthermore, while HCV RNA can be detected in circulating lymphoid cells in approximately 30% of cases, a short-term culture under stimulatory conditions augments HCV replication in these cells allowing detection of virus in otherwise HCV-negative cases. HCV infects different immune cell subsets, including CD4+ and CD8+ T lymphocytes, B cells and monocytes. Studies employing clonal sequencing and single-stranded conformational polymorphism analyses have revealed unique HCV variants residing in immune cells, further strengthening the notion of HCV lymphotropism. Overall, the data accumulated suggest that occult HCV infection is a common consequence of resolution of symptomatic hepatitis C and that examination of the cells of the immune system is an effective approach to diagnosis of HCV infection and its long-term persistence. Further work is required to fully realize pathogenic and epidemiological consequences of occult HCV persistence.
基金supported by a grant from the Beijing Hope Run Special Fund of Cancer Foundation of China(No.LC2021L02).
文摘To the Editor:The incidence and mortality of colorectal cancer(CRC)in China have increased significantly in recent years.Surpassing gastric cancer,CRC has become one of the main cancers threatening the life and health of Chinese people and causing a serious social burden.Early detection of CRC is critical for improving outcomes.Although colonoscopy remains the primary diagnostic and screening method,its invasiveness and low patient compliance hinder broad application.Non-invasive methods including fecal occult blood tests and carcinoembryonic antigen(CEA)lack sensitivity(20–40%)and specificity for early detection.Therefore,non-invasive biomarkers with high sensitivity and specificity for detecting CRC and precancerous adenomas are urgently needed.Altered gut microbiota is closely associated with colorectal carcinogenesis but exhibits high interindividual variability,limiting its clinical utility.Microbiota-derived metabolites such as bile acids and short-chain fatty acids are critical in CRC progression.Serum metabolite levels are strongly correlated with gut microbial abundance,providing a new direction for noninvasive diagnosis of CRC.
