SALI is defined as an acute, secondary hepatic dysfunction that arises during sepsis and is observed in roughly 34 to 46 percent of patients. At the bedside it announces itself through abnormalities in standard liver tests, which can follow hepatocellular, cholestatic, or mixed patterns and range from modest enzyme elevations to profound liver failure. Crucially, the authors insist that SALI be treated as an operational clinical syndrome rather than the signature of a single underlying mechanism. Abnormal liver biochemistry in a septic patient may reflect inflammatory injury, cholestasis, hypoxic hepatitis caused by insufficient oxygen delivery, right-sided cardiac congestion, drug toxicity, or pre-existing conditions such as metabolic dysfunction-associated steatotic liver disease and occult fibrosis. The question, they argue, is not whether SALI has uniform biology, because it does not, but whether routinely available data can flag the patients most likely to deteriorate.

On the mechanistic side, one of the most striking recent findings concerns the gut. In a mouse model of sepsis, Murao and colleagues identified a pathway in which gut-primed neutrophils drive hepatic injury. Gut intraepithelial lymphocytes interact with neutrophils through the molecule CD112, facilitating the formation of neutrophil extracellular traps, the web-like DNA structures that neutrophils eject to ensnare pathogens. These primed neutrophils migrate through the portal vein into the liver, where they release their traps and activate Kupffer cells, the liver’s resident macrophages, triggering the secretion of interleukin-6 and tumor necrosis factor-alpha. Notably, portal vein neutrophils from septic mice produced significantly more neutrophil extracellular traps and induced greater Kupffer cell activation than systemic neutrophils, an effect that disappeared entirely in mice lacking PAD4, the enzyme essential for trap formation. The implication is provocative: the gut does not merely spill inflammatory mediators into the portal circulation, it actively educates immune cells that then inflict damage on distant organs.

Although the authors caution that translation to human disease requires care, the concept has clear clinical resonance. The liver receives most of its blood supply from the portal circulation and is therefore continuously bathed in gut-derived inflammatory signals. During sepsis, disruption of the intestinal barrier allows bacterial translocation and the spillover of pathogen-associated molecular patterns, which activate hepatic Toll-like receptors. Supporting this mechanistic bridge, human data from Czaikoski and colleagues have shown that neutrophil extracellular traps accumulate in organ tissue during experimental and clinical sepsis and correlate with damage. Together, these findings nominate trap formation and downstream Kupffer cell activation as candidate precision-medicine targets in SALI.

A second biological pillar concerns the loss of hepatic immune tolerance. In health, the liver is a strikingly tolerant organ, and Kupffer cells orchestrate that tolerance through antigen clearance and the induction of regulatory T cells. Recent work shows that during hepatic inflammation this tolerogenic phenotype collapses: Kupffer cells lose their signature tolerance markers, and antigen presentation shifts to infiltrating monocyte-derived macrophages. Activated Kupffer cells then recruit further immune cells to the liver, amplifying injury. Evidence from viral hepatitis research suggests that the transition from tolerance to inflammation involves dysregulation of inhibitory pathways, such as the Toll-like receptor pathway inhibitor SHIP, that normally restrain receptor signaling and keep Kupffer cells quiescent. Hepatic stellate cells, likewise, depend on inhibitory signals to remain dormant; when stimulated by microbial products or damage-associated molecular patterns, they produce extracellular matrix proteins and profibrogenic cytokines, and their contractile activation can raise sinusoidal resistance and portal pressure. Toll-like receptor 4-dependent crosstalk between Kupffer cells and stellate cells converts inflammatory signals into profibrogenic activation.

Within sepsis specifically, the inflammatory polarization of Kupffer cells toward the M1 phenotype has emerged as a hallmark of SALI. Extracellular cold-inducible RNA-binding protein, a damage-associated molecular pattern released during stress, promotes this M1 polarization through Toll-like receptor 4 signaling, driving overproduction of inflammatory cytokines. In mouse sepsis models the ratio of M1 to M2 Kupffer cells rises sharply, indicating a decisive shift toward proinflammatory function, and this polarization is not merely a byproduct of inflammation but an active driver of hepatocyte injury through reactive oxygen species, cytokines, and the recruitment of more neutrophils. In parallel, regulated forms of cell death, including apoptosis, necroptosis, pyroptosis, and ferroptosis, appear to contribute to hepatocyte dysfunction. These converging mechanisms point toward the restoration of hepatic immune tolerance as a promising future therapeutic strategy, though no SALI-targeted therapy has yet been established.

It is on the clinical side that the commentary delivers its most immediately practical message. In a retrospective cohort study spanning two large intensive care cohorts, Palmowski and colleagues examined how well routine biomarkers could stratify mortality risk among patients meeting operational criteria for SALI, defined as sepsis-associated liver-test abnormalities within seven days of sepsis onset, excluding pre-existing chronic liver disease. The criteria included alanine aminotransferase at five or more times the upper limit of normal, alkaline phosphatase at twice the upper limit, or elevated bilirubin combined with enzyme elevations. Their central finding was that the De Ritis ratio, the simple ratio of aspartate to alanine aminotransferase, outperformed both the conventional R-factor and alanine aminotransferase alone in predicting thirty-day mortality. A ratio of one or below indicated low risk, values between one and two indicated intermediate risk, and values of two or above flagged the highest risk, a pattern consistent across infection sources and admission types.

The authors of the commentary are careful to frame these strata correctly. The De Ritis ratio is not a liver-specific diagnostic marker or a mechanistic endotype, and elevated aspartate aminotransferase can also signal hypoxic hepatitis, shock, right-sided congestion, systemic inflammation, chronic kidney disease, alcohol-related injury, or cardiometabolic comorbidity. Its pragmatic value lies in risk enrichment among patients who already meet operational SALI criteria, complementing rather than replacing SOFA-bilirubin scoring. Interpreted alongside the SOFA score, lactate, hemodynamic status, cardiac context, and comorbidities, a rising ratio should trigger a structured reassessment: is infection control optimized, are hemodynamics adequate, is the lactate trajectory improving, is there occult congestion or biliary obstruction, are hepatotoxic drugs on board, and does the patient carry underlying fibrosis risk? In this framework, routine liver tests define the dominant biochemical injury pattern, whether hepatocellular, cholestatic, or mixed, and link prediction to the prevention of further hepatic and systemic deterioration and of iatrogenic harm.

The translational pathway forward, the authors suggest, will require prospective studies testing whether serial liver tests, the De Ritis ratio, SOFA scores, lactate, hemodynamic data, and immune readouts such as monocyte HLA-DR expression or ex vivo monocyte cytokine responses can identify reproducible SALI trajectories and clinically actionable phenotypes. Preclinical work has already nominated an unusually rich set of therapeutic targets, including neutrophil extracellular trap formation, Kupffer cell polarization, inflammasome activation, ferroptosis, necroptosis, and the restoration of hepatic immune tolerance. Until such approaches are validated, however, current clinical utility remains deliberately pragmatic: recognize SALI early, classify the dominant biochemical pattern, stratify mortality risk with the De Ritis ratio, hunt actively for reversible contributors, and intensify surveillance in high-risk patients.

For the authors, the larger significance of this work lies in adding an organ-specific decision layer to the 2026 Surviving Sepsis Campaign framework. New-onset liver-test abnormalities in septic adults, they argue, should no longer be treated as incidental laboratory noise. When detected, the humble ratio of two transaminases, a calculation older than modern critical care and available in every hospital on earth, may identify the patients who need intensified monitoring and protection from modifiable second hits, while the expanding immunobiology of the gut-liver axis steadily maps the routes toward genuine precision medicine for a complication that affects as many as one in two patients with sepsis.

Subject of Research: Sepsis-associated liver injury: immunobiology and bedside risk stratification with routine liver tests

Article Title: Sepsis-associated liver injury: from liver-test risk signals to immunobiology-guided precision medicine

Article References: Katsounas, A., Tsochatzis, E., & Rello, J. (2026). Sepsis-associated liver injury: from liver-test risk signals to immunobiology-guided precision medicine. Intensive Care Medicine. https://doi.org/10.1007/s00134-026-08593-1

Image Credits: AI Generated

DOI: 10.1007/s00134-026-08593-1

Keywords: sepsis-associated liver injury, De Ritis ratio, Kupffer cells, neutrophil extracellular traps, gut-liver crosstalk, hepatic immune tolerance, risk stratification, intensive care, Toll-like receptors, precision medicine, Sepsis-associated, liver

The relationship begins with anatomy. Blood from much of the intestine travels directly to the liver through the portal vein, carrying nutrients, microbial products and chemical signals absorbed across the intestinal wall. Under healthy conditions, the liver acts as a biochemical filter, while the intestinal barrier limits the passage of potentially harmful substances. This barrier is maintained by mucus, epithelial cells and protein complexes known as tight junctions, which seal the spaces between neighboring cells. When inflammation, infection, dietary stress or metabolic disease weakens these defenses, bacterial components can cross into the circulation and place the liver under sustained immune pressure.

Among the most important signals are pathogen-associated molecular patterns, or PAMPs, such as lipopolysaccharide from the outer membrane of Gram-negative bacteria. Damage-associated molecular patterns released by injured host cells can intensify the same response. In the liver, these molecules are detected by pattern-recognition receptors, including Toll-like receptors and NOD-like receptors, on immune cells and other hepatic cell types. Activation of these sensors stimulates transcription factors such as NF-κB and promotes the production of cytokines including tumour necrosis factor, interleukin-1β and interleukin-6. A short-lived response can be protective, but persistent signalling may drive chronic inflammation and fibrosis.

The review also highlights the microbiome as a chemical partner in gut–liver communication. Intestinal bacteria transform dietary components into short-chain fatty acids, including acetate, propionate and butyrate, which influence epithelial integrity, immune-cell activity and energy metabolism. Other microbial products can be harmful when produced in excess or insufficiently cleared. Changes in bacterial composition, known as dysbiosis, may increase the generation of ethanol, ammonia, indole derivatives or other metabolites that affect hepatic inflammation. The biological impact depends not only on which microbes are present, but also on their activity, the integrity of the intestinal barrier and the liver’s ability to process incoming compounds.

Bile acids create a second major communication circuit. Produced in the liver and released into the intestine, these molecules aid fat digestion before being modified by intestinal bacteria and returned through the enterohepatic circulation. Beyond their digestive role, bile acids act as signalling molecules through receptors such as the farnesoid X receptor and the G-protein-coupled bile acid receptor TGR5. These pathways help regulate lipid and glucose metabolism, immune responses and the composition of the microbiome. Disrupted bile-acid synthesis, transport or microbial conversion can therefore affect both intestinal inflammation and liver disease, linking metabolic disorders to changes in immune signalling.

This network becomes particularly important in conditions such as metabolic dysfunction-associated steatotic liver disease, alcohol-associated liver disease, inflammatory bowel disease and advanced liver fibrosis. In metabolic liver disease, excess dietary energy and insulin resistance can promote fat accumulation in hepatocytes, while microbial products and inflammatory mediators amplify cellular stress. Kupffer cells, the liver’s resident macrophages, respond to these signals and communicate with stellate cells. Once activated, stellate cells produce extracellular matrix proteins, including collagen, that gradually remodel liver tissue. Persistent matrix deposition can lead to fibrosis and, in severe cases, cirrhosis.

The authors describe the gut–liver axis as a therapeutic opportunity, but the review also suggests why simple solutions have often failed. Antibiotics may reduce selected bacterial signals but can disrupt beneficial communities and promote resistance. Probiotics and prebiotics can influence microbial ecology, although their effects may vary according to the patient’s diet, baseline microbiome and disease stage. Approaches under investigation include targeted microbial consortia, postbiotics, faecal microbiota transplantation, engineered bacteria and dietary strategies designed to restore production of protective metabolites. The central challenge is to modify the ecosystem precisely rather than suppressing it indiscriminately.

Drug development is also moving toward the molecular links that connect intestinal signals with hepatic inflammation. Potential targets include receptors that detect microbial products, enzymes involved in bile-acid metabolism, inflammatory cytokine pathways and mechanisms controlling epithelial tight junctions. Therapies designed to alter bile-acid signalling or reduce fibrogenic activation in the liver could potentially interrupt disease progression. However, the review emphasizes that the gut–liver axis is highly individualized. Sex, age, genetics, medication use, diet and environmental exposures can all influence microbial communities and immune responses, making broad treatment strategies difficult to apply uniformly.

Future progress may depend on combining multiple forms of biological information. Metagenomic sequencing can identify microbial genes, while metabolomics reveals the compounds actually produced in the intestine and transported to the liver. Imaging, immune profiling and computational modelling may then connect these molecular signals to tissue damage and clinical outcomes. Such integrated approaches could help distinguish harmless dysbiosis from the specific microbial and metabolic patterns that predict inflammation or fibrosis. The emerging picture is not of a single disease pathway, but of a dynamic network that can be measured, manipulated and, potentially, reset.

By bringing together immunology, microbiology, hepatology and metabolism, Murao, Aziz and Wang position inflammatory gut–liver crosstalk as a central problem in modern medicine. The review’s message is both cautionary and promising: damage in one organ can reverberate through the entire network, but that same connectivity creates several points for intervention. Treatments that protect the intestinal barrier, rebalance microbial chemistry and calm excessive hepatic immune activation could eventually offer more precise ways to prevent chronic liver disease before irreversible scarring develops.

Subject of Research: Inflammatory communication between the gut and liver, including the roles of the intestinal barrier, microbiome, microbial metabolites, bile acids, immune signalling and potential therapeutic targets.

Article Title: Inflammatory gut–liver crosstalk: mechanisms and therapeutic targets

Article References: Murao, A., Aziz, M. & Wang, P. “Inflammatory gut–liver crosstalk: mechanisms and therapeutic targets.” Experimental & Molecular Medicine (2026). https://doi.org/10.1038/s12276-026-01810-3

Image Credits: AI Generated

DOI: 10.1038/s12276-026-01810-3

Keywords: gut–liver axis, intestinal barrier, microbiome, bile acids, inflammation, liver disease, fibrosis, microbial metabolites, immune signalling, therapeutic targets