Blocking IL-6 Trans-Signaling Protects the Heart in Mouse Sepsis Study

Sepsis can leave the heart struggling to pump, a complication known as sepsis-induced myocardial dysfunction, and it carries a high mortality risk. A new study published in BMC Immunology reports that a selective inhibitor of the IL-6 trans-signaling pathway, a fusion protein called sgp130Fc, improved cardiac function and survival in a mouse model of this condition, and identifies suppression of the JAK/STAT3 signaling pathway as the likely mechanism behind the protection.

The research team, led by Xuefang Liu and Zhenjie Hu, began with human evidence. Analyzing serum samples from septic patients with and without cardiac dysfunction, they found that concentrations of IL-6, its soluble receptor sIL-6R, and cardiac injury biomarkers including troponin I (cTnI), CK-MB, and NT-proBNP were significantly elevated in sepsis, and highest in patients whose hearts were affected. Markers of fibrosis and endothelial dysfunction also rose, while levels of sgp130, the natural decoy receptor that normally restrains IL-6 trans-signaling, were notably reduced. This pattern suggested that the pathway is hyperactivated precisely when the myocardium is under attack.

To test whether blocking the pathway helps, the researchers used a mouse model of sepsis-induced myocardial dysfunction created by cecal ligation and puncture, a standard surgical technique that induces polymicrobial sepsis. Treated animals received sgp130Fc, a selective inhibitor of IL-6 trans-signaling. According to the study, the intervention significantly enhanced survival rates and cardiac function, assessed by echocardiography through two standard pumping measures: left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS).

The structural evidence supported the functional gains. Histopathological analysis, including hematoxylin and eosin staining, Masson’s trichrome staining for collagen deposition, and TUNEL assays for cell death, showed that sgp130Fc suppressed inflammatory cytokine production and circulating injury biomarkers, decreased cardiomyocyte apoptosis, and mitigated myocardial fibrosis. Transmission electron microscopy added a subcellular dimension: the treated mice preserved the integrity of mitochondria and other myocardial ultrastructure that sepsis typically disrupts.

Because the heart is built from more than one cell type, the team extended the work in vitro using LPS-stimulated cardiomyocytes, cardiac fibroblasts, and cardiac microvascular endothelial cells, the three major cell populations implicated in septic myocardial injury. In all three, sgp130Fc restored cell viability, attenuated inflammatory and fibrotic responses, and improved functional properties including proliferation, migration, and the regulation of apoptosis. The authors describe this as comprehensive, multi-cellular cardioprotection rather than an effect confined to contracting muscle cells.

The mechanistic core of the study lies in rescue experiments with a JAK agonist. When the agonist was administered alongside sgp130Fc in both the mouse model and the cell cultures, it effectively counteracted the protective effects of the inhibitor. Conversely, sgp130Fc treatment markedly inhibited activation of the JAK/STAT3 pathway, and the agonist restored that activity. This bidirectional experiment supports the conclusion that the benefits of blocking IL-6 trans-signaling run primarily through multi-cellular inhibition of JAK/STAT3 signaling.

The findings fit a broader biological logic. The observation that endogenous sgp130 falls in septic patients with cardiac dysfunction, while ligand and soluble receptor rise, frames the disease state as one in which the pathway’s natural brake fails.

Important limitations temper the excitement. The therapeutic results come from a mouse model and from cells exposed to a bacterial endotoxin in a dish, not from human trials; the human data are observational serum measurements showing association, not evidence that blocking the pathway improves outcomes in patients. The article is also being shared early as a peer-reviewed, accepted manuscript that remains subject to further editorial revision before the final version of record.

Even so, the study offers a coherent preclinical case: IL-6 trans-signaling is hyperactivated in sepsis-induced myocardial dysfunction, contributes to myocardial injury through JAK/STAT3-driven inflammation, apoptosis, fibrosis, and mitochondrial damage, and can be targeted with a pathway-selective inhibitor that protected survival, pumping function, and tissue architecture in mice. The authors conclude that targeting IL-6 trans-signaling with sgp130Fc represents a promising therapeutic strategy for SIMD, one that now awaits validation in human studies.

Subject of Research: Preclinical evaluation of IL-6 trans-signaling inhibition with sgp130Fc in sepsis-induced myocardial dysfunction

Article Title: Study on the effect of inhibiting IL-6 trans-signaling pathway on cardiac function in sepsis-induced heart dysfunction mice and its mechanism

Article References: Liu, X., Yu, N., Tian, W., Chen, Y., Zhang, X., Yang, K., Liu, Y., & Hu, Z. (2026). Study on the effect of inhibiting IL-6 trans-signaling pathway on cardiac function in sepsis-induced heart dysfunction mice and its mechanism. BMC Immunology. https://doi.org/10.1186/s12865-026-00894-w

Image Credits: AI Generated

DOI: 10.1186/s12865-026-00894-w

Keywords: sepsis, sepsis-induced myocardial dysfunction, IL-6 trans-signaling, sgp130Fc, JAK/STAT3 pathway, cardiac function, cardiomyocyte apoptosis, myocardial fibrosis, echocardiography, preclinical study, BMC Immunology, effect