Effect of Lonicera caerulea var. emphyllocalyx Extracts on Murine Streptococcus pyogenes Infection by Modulating Immune System

Abstract

Streptococcus pyogenes (S. pyogenes) causes several infectious diseases such as tonsillitis, cellulitis, and streptococcal toxic shock syndrome. The general treatment of S. pyogenes infection is by using β-lactam antibiotics; however, the cases of treatment failure were increasing as serious problems. Lonicera caerulea var. emphyllocalyx (LCE) has been used in the folk medicine in the northern part of Japan, the northern part of China, Korea, and Russia. In this study, we investigated the efficacy of three parts (fruit, stem, and leaf) of Lonicera caerulea var. emphyllocalyx extract (LCEEs) against murine S. pyogenes infection. Oral administration of LCEEs increased the mortality in murine model, and the extracts of its stems and leaves were more effective than the fruit extract significantly. Murine splenocytes and mesenteric lymph nodal cells treated with LCEEs suppressed the excess production of inflammatory cytokine such as TNF-α in comparison to those from untreated cells. LCEEs stimulated the differentiation of pluripotent hematopoietic stem cells in those murine lymph nodal cells. It also activated the proliferative response of murine lymph nodal cells. We also found that the stem and leaf extracts seemed to be more effective than the fruit extract in those phenomena. The concentration of lignins in LCEE prepared from the stems was larger than that from leaves, and that was larger than that from the fruits. Our data suggest that LCE, especially the stems and the leaves, may be useful for the treatment of S. pyogenes infection.