Bariatric Surgery May Help Normalize Monocyte Levels in People with Obesity

Dr Himanshu Sharma, Sr consultant and Head , Department of endocrinology Yashoda Medicity

Bariatric surgery and the associated weight loss were linked to reductions in total monocyte counts and several monocyte subpopulations over 12 months.

Obesity is associated with many comorbid conditions, including type 2 diabetes, fatty liver disease, coronary artery disease, and some cancers. Chronic inflammation is also linked to obesity, with macrophages and other immune cells adding to the inflammatory response. This study looked at changes in blood monocyte subpopulations before and after bariatric surgery and examined their relationship with weight loss and inflammation.

The study included 111 people with obesity, of whom 59.5% were female, with a mean age of 45.2 ± 11.3 years and a median body mass index (BMI) of 48.4 kg/m². Blood samples were taken before surgery and at 6 and 12 months after surgery. Researchers used flow cytometry to measure different monocyte populations, along with routine clinical and laboratory measures such as C-reactive protein.

Median weight loss after surgery was 44.5 kg. Total monocyte counts decreased significantly over the 12-month period (p = 0.0035). Classical, non-classical, and intermediate monocytes, as well as monocytic myeloid-derived suppressor cells, also decreased significantly between 6 and 12 months after surgery.

Changes were also seen in monocyte surface markers. CD14 expression increased in classical and intermediate monocytes within 6 months, while CD16 expression decreased across all monocyte subpopulations during follow-up. CD14bright/CD56+ monocytes did not change significantly during the 12-month observation period. Total monocyte counts and non-classical monocytes were higher in participants who also had type 2 diabetes.

Overall, the findings showed that bariatric surgery and the associated weight loss were accompanied by changes in the monocyte compartment, with several monocyte populations decreasing after surgery. Normalizing total monocyte levels and specific monocyte subpopulations, particularly intermediate monocytes, may help reduce obesity-related inflammation and other associated health risks.

(Reference: Krasselt M, Friedrich K, Braune L, Rothe K, Blüher M, Kovacs P, Dietrich A, Rossol M, Stumvoll M, Wagner U. Bariatric surgery and subsequent weight loss lead to a reversal of peripheral blood monocytosis in obesity: Bariatric Surgery. International Journal of Obesity. 2026 Apr 24:1-9.)