Decreased Levels of Spleen Tissue CD4⁺CD25⁺Foxp3⁺ Regulatory T Lymphocytes in Mice Exposed to Berberine

The effects of isoquinoline alkaloid berberine (BER) on spleen tissue $CD4^+CD25^+Foxp3^+$ regulatory T ($T_{reg}$) cells were evaluated in BALB/c mice. Here, BER was administered daily by intraperitoneal injection at doses of 5 mg/kg and 10 mg/kg for 14 days. Following the exposure, mice spleen cellularities, IL-10 production by splenocytes, and spleen $T_{reg}/CD4^+$ cell profiles were studied in all the test groups of animals. The results showed that a high dose of BER (10 mg/kg) could decrease both the absolute and relative percentages of spleen $T_{reg}$ cells as well as decrease the production of IL-10 by splenocytes in the treated mice (p < 0.05). BER at 5 mg/kg did not appear to affect any of these parameters. Based on the finding here, it would seem that BER has effective immunostimulatory properties, which contradicts the results from other studies indicating immunosuppressive effects of BER. Depending on the doses of BER used, it might have a broad spectrum from immunosuppressive to stimulatory effects. Further studies, including more doses, are required to better evaluate the effects of this natural product. Mechanistic studies are required, particularly in case of redox state of the immune cells, to elucidate and determine how BER functions to impart the toxicity effects demonstrated here and in other studies.