Chemokine Gene Methylation Tied to Liver Inflammation in Chronic Hepatitis B

Chronic hepatitis B remains one of the world’s most burdensome viral infections, silently driving liver inflammation, fibrosis and, in many patients, hepatocellular carcinoma. A study published in Virology Journal by Zhezhe Tian and colleagues at Qilu Hospital of Shandong University now adds an epigenetic dimension to how physicians might gauge that inflammatory damage. The researchers report that methylation of the promoter region of CXCL16, a gene encoding a chemokine implicated in hepatic injury, is significantly reduced in patients with chronic hepatitis B virus (HBV) infection, and that this hypomethylation tracks closely with the intensity of inflammation in the liver. The work, conducted at the Department of Hepatology of Qilu Hospital and the Institute of Hepatology of Shandong University, was supported by the National Natural Science Foundation of China and approved by the hospital’s Medical Ethical Committee in accordance with the Declaration of Helsinki.

The biological logic behind the study rests on a well-established principle of gene regulation. DNA methylation, the addition of methyl groups to cytosine bases within gene promoter regions, generally acts as a brake on transcription. When a promoter is heavily methylated, the chromatin adopts a closed configuration that limits access of transcriptional machinery, and the downstream gene is expressed at low levels. Conversely, loss of methylation, known as hypomethylation, often permits increased gene expression. For chemokines, which are potent signalling molecules that recruit immune cells to sites of infection or damage, the methylation state of the promoter can therefore dictate how strongly an inflammatory signal is broadcast. CXCL16, or C-X-C motif chemokine ligand 16, is one such chemokine, recognized as a key mediator in liver injury, yet its epigenetic regulation in chronic hepatitis B had remained unclear prior to this investigation.

To address that gap, the team assembled a study population of 217 patients with chronic hepatitis B, subdivided into 113 who were positive for hepatitis B e antigen (HBeAg) and 104 who were HBeAg-negative, alongside 27 healthy controls. HBeAg status is a clinically meaningful marker in HBV infection: HBeAg-positive patients are typically considered to carry a higher viral replicative activity and a distinct immunological profile compared with those who have seroconverted. By stratifying patients this way, the researchers could ask whether epigenetic changes at the CXCL16 promoter differed not only between diseased and healthy livers, but also between the two major immunological phases of chronic infection.

Across three molecular layers, the same pattern emerged. First, the percentage of methylation reference, a quantitative measure of promoter methylation, was significantly lower in chronic hepatitis B patients than in healthy controls, and the reduction was especially pronounced in HBeAg-positive cases. Second, mRNA levels of CXCL16 were markedly higher in the patient groups, again most prominently among those who were HBeAg-positive. Third, serum concentrations of the CXCL16 protein were elevated in patients relative to controls. The concordance across methylation, transcript and protein measurements is what gives the finding its mechanistic weight, because it suggests a coherent pathway from epigenetic derepression to enhanced chemokine production rather than an isolated correlation at a single molecular level.

The inverse relationship between methylation and expression was borne out statistically. CXCL16 promoter methylation was negatively correlated with CXCL16 expression, which is precisely what promoter methylation biology would predict: the less the promoter is methylated, the more the gene is transcribed and translated. Notably, methylation also showed negative correlations with several clinical and immunological markers. These included HBeAg status itself, the liver injury enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and the pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β). In practical terms, patients with the lowest CXCL16 promoter methylation tended to have the highest levels of transaminases, the canonical blood markers of hepatocyte damage, and the highest circulating concentrations of inflammatory cytokines that drive and amplify hepatic inflammation.

ALT and AST are enzymes released when hepatocytes are injured, and their serum activities form the backbone of non-invasive monitoring in viral hepatitis. TNF-α and IL-1β, meanwhile, are central cytokines in the innate immune response, capable of activating hepatic stellate cells, promoting leukocyte recruitment and sustaining the inflammatory milieu that, over years, leads to fibrosis and malignant transformation. The observation that CXCL16 promoter methylation aligns with all of these parameters simultaneously positions the epigenetic mark as a potential integrator of inflammatory burden. Rather than reflecting a single laboratory value, hypomethylation appears to sit upstream of a network of destructive processes in the HBV-infected liver.

To test whether the methylation measurement could do more than describe associations, the researchers performed receiver operating characteristic (ROC) analysis, a standard method for evaluating the discriminative capacity of a biomarker. The analysis demonstrated that CXCL16 promoter methylation had a favourable ability to distinguish HBeAg-positive patients, with an area under the curve (AUC) of 0.749. An AUC of 0.5 would indicate performance no better than chance, while 1.0 would indicate perfect discrimination, so a value of 0.749 represents a moderate-to-good level of diagnostic accuracy. Taken together with the significant correlations with inflammatory markers, the authors suggest that CXCL16 promoter methylation could serve as a complementary indicator for identifying chronic hepatitis B patients who carry a higher inflammatory burden.

The clinical appeal of such a marker lies in its non-invasive character. Assessing liver inflammation today often relies on serum transaminases, which can fluctuate and normalise even in the presence of ongoing disease, or on liver biopsy, which remains the gold standard for grading inflammation and staging fibrosis but carries procedural risks, sampling variability and patient reluctance. A blood-based epigenetic measurement that reflects the regulatory state of a chemokine gene could, if validated further, offer a repeatable and safer window into hepatic inflammatory activity. The authors conclude that CXCL16 promoter hypomethylation is closely associated with elevated CXCL16 expression and exacerbated hepatic inflammation in chronic hepatitis B patients, and propose it as a potential non-invasive biomarker for assessing CHB-related liver inflammation.

Beyond its diagnostic promise, the study enriches the mechanistic picture of how HBV infection translates into chronic liver damage. Viral persistence triggers innate and adaptive immune responses in the liver, and chemokines such as CXCL16 help orchestrate the recruitment of immune cells that both contain the virus and injure hepatocytes. The demonstration that this process is governed, at least in part, by promoter methylation adds an epigenetic layer to the known immunopathology of hepatitis B, and it identifies CXCL16 as a novel target for clinical evaluation and intervention. If future work confirms that modulating CXCL16 methylation or expression can influence inflammatory outcomes, the pathway could become more than a passive marker and evolve into a genuine therapeutic axis.

Several considerations temper immediate application. The study reports associations in a cross-sectional design, so causality between hypomethylation, chemokine expression and inflammation cannot be fully disentangled from the present data, and longitudinal follow-up would be needed to determine whether CXCL16 promoter methylation predicts disease progression, response to antiviral therapy or the later development of hepatocellular carcinoma. Moreover, methylation patterns can be influenced by age, environment and comorbidities, so the findings will require replication in larger and more diverse cohorts before any routine clinical use. The article was published open access on 14 October 2026 under a Creative Commons licence, and the authors, led by corresponding author Kai Wang, declare no competing interests. Even with those caveats, the convergence of methylation data, gene expression, protein levels and inflammatory correlations in a well-characterised cohort of 217 patients makes a compelling case that an epigenetic signature at the CXCL16 promoter mirrors the inflammatory fires burning in chronically HBV-infected livers, and offers researchers a fresh molecular handle on a disease that affects hundreds of millions of people worldwide.

Subject of Research: Epigenetic regulation of the CXCL16 chemokine gene in chronic hepatitis B liver inflammation

Article Title: CXCL16 gene promoter methylation is associated with inflammation in patients with chronic hepatitis B

Article References: CXCL16 gene promoter methylation is associated with inflammation in patients with chronic hepatitis B. (n.d.). https://doi.org/10.1186/s12985-026-03322-y

Image Credits: AI Generated

DOI: 10.1186/s12985-026-03322-y

Keywords: chronic hepatitis B, HBV, CXCL16, DNA methylation, epigenetics, liver inflammation, biomarker, HBeAg, chemokine, TNF-alpha, IL-1beta, transaminases