# Distinct fibrin clot characteristics in individuals with severe obesity and metabolic liver disease: 2-year follow-up after bariatric surgery

## TL;DR

Severe obesity and liver disease are linked to changes in fibrin clot properties, which may reflect underlying metabolic issues.

## Contribution

This study is the first to examine fibrin clot characteristics in humans with severe obesity and metabolic liver disease over a 2-year bariatric surgery follow-up.

## Key findings

- Severe obesity is associated with increased plasma and hepatic fibrin formation.
- Metabolic liver disease correlates with decreased plasma fibrin formation.
- Bariatric surgery alters fibrin clot characteristics compared to controls.

## Abstract

Obesity predisposes individuals to metabolic dysfunction–associated steatotic liver disease (MASLD), the hepatic manifestation of metabolic syndrome. Studies in mice suggest that fibrin deposition in adipose tissue and liver promotes obesity and MASLD, but whether similar mechanisms are linked to metabolic disease in humans is incompletely studied.

This study determined the relationship between plasma fibrin clot characteristics and hepatic fibrin deposition with obesity and MASLD severity and examined changes in fibrin measures 2 years after bariatric surgery.

We included 195 individuals with body mass index (BMI) of > 35 kg/m2 in a cohort study. A subgroup of 93 individuals who underwent bariatric surgery (n = 35) or served as nonsurgical controls (n = 58) was followed for 2 years. Clot characteristics were studied by turbidity. Hepatic tissue samples were scored for MASLD, and in 3 individuals with varying BMI, tissues were stained for fibrin.

Examination of plasma clots revealed that individuals with BMI > 45 kg/m2 had lower clot lysis and fiber density, while maximal turbidity increment (Vmax), fiber diameter, and maximum absorbance (MA) were higher than those in individuals with BMI < 40 kg/m2. Vmax, fiber density, and MA were lower in individuals with metabolic dysfunction–associated steatohepatitis than those in patients without MASLD. After bariatric surgery, clot lysis and fiber density were higher than that in controls, whereas Vmax, fiber diameter, and MA were lower. Staining intensity of hepatic fibrin deposits increased with obesity severity but was not clearly reduced postsurgery.

Severe obesity and MASLD are associated with altered fibrin characteristics in plasma clots and liver tissue, suggesting fibrin(ogen) reflects metabolic alterations although the directionality remains to be clarified.

•Fibrin formation promotes severe obesity and metabolic liver disease in mice.•We studied fibrin formation in patients with severe obesity before and after bariatric surgery.•Severe obesity was linked to increased plasma and hepatic tissue fibrin formation.•Metabolic liver disease was linked to decreased plasma fibrin formation.

Fibrin formation promotes severe obesity and metabolic liver disease in mice.

We studied fibrin formation in patients with severe obesity before and after bariatric surgery.

Severe obesity was linked to increased plasma and hepatic tissue fibrin formation.

Metabolic liver disease was linked to decreased plasma fibrin formation.