Background: Total parenteral nutrition (TPN) alters both specific and nonspecific immune functions, resulting in immunosuppression. Short-chain fatty acids have been shown to improve the adaptive responses of the gut after surgery. The following study investigates the effects of adding short-chain fatty acids to TPN on the immune system after an 80% small bowel resection.
Methods: Rats (237 +/- 3 g) were infused with either TPN (n = 25) or TPN supplemented with short-chain fatty acids (n = 26) for 3 or 7 days. Hematologic analysis was performed on peripheral blood and splenocytes were isolated to characterize cell phenotypes, natural killer cell cytotoxicity and to estimate proliferative response.
Results: The relative percent of T (CD3+) cells increased (p < .05) and the relative percent of macrophages decreased (p < .001, n = 13) in the spleens of the 3-day TPN-fed rats. By day 7, these differences disappeared. The natural killer cells from rats that were supplemented with short-chain fatty acids had higher (p < .0001) cytotoxic activity than the TPN groups at day 3. Mitogenic response did not differ between groups but were depressed compared with sham-treated rats. By day 7, rats on standard TPN had larger (p < .0001) spleens than all other groups. This group also had a higher total white blood cell count because of increased numbers of macrophages and neutrophils (p < .02).
Conclusion: Short-chain fatty acids improve components of nonspecific immune responses and may be beneficial in reducing certain aspects of TPN-associated immunosuppression after major surgery.