Cytokine-mediated immunoregulatory activity of Lactobacillus species in a carrageenan-induced acute inflammatory model

Using paw edema acute inflammatory model induced by carrageenan (1%) in Wistar rats, the immunoregulatory action of Lactobacillus sp., isolated from two locally fermented food products in Nigeria: Nunu (a yogurt-like milk product) and Ogi (guinea corn slurry), was investigated. The rats were distributed into seven groups (A–G). Rats in group A did not receive any therapy or carrageenan inflammation, whereas those in group B received a carrageenan injection only. Groups C–F were orally administered with lactic acid bacteria (LAB) strains (5 × 10(7) CFU/ml), whereas group G received diclofenac sodium (150 mg/kg body weight) following the administration of carrageenan. At regular intervals, paw thickness (mm) was measured. Microscopy was used to count the number of leukocytes; myeloperoxidase (MPO) activity was used to measure the neutrophil accumulation in the paw tissue; and rat serum samples were subjected to ELISA to identify cytokine assays for C-reactive protein (CR-P), interleukin-10 (IL-10), and transforming growth factor-β (TGF-β). All of the LAB-treated groups showed a statistically significant decrease in paw thickness, and their neutrophil and monocyte infiltration was significantly affected. Compared with the control groups, oral administration with LAB significantly suppressed the MPO activity. Lactobacillus fermentum NBRC showed the most significant upregulation of serum levels of IL-10 and TGF-β though serum levels of CR-P were downregulated. Lactobacillus pentosus increased the production of TGF-β, with no significant effect on the production of IL-10. This study presents the role of Lactobacillus sp. in regulating inflammation by modifying the production of anti-inflammatory cytokines IL-10 and TGF-β.