Investigation of The Protective Effects of Beta-D-Glucan Against Invasive Encapsulated Streptococcus pneumoniae Sepsis in Splenectomized Rats

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In asplenic individuals depending on the weakness of the immune response, sepsis are known to be developed with a high mortality rate. The most common species which are responsible for sepsis are encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis. Sepsis caused by immune deficiencies linked to splenectomy leads to infections particularly in the lungs and liver and causes multiple organ failure. On the other hand, -D-glucan (BDG), a branched glucose polymer, shows immunomodulatory activity, by enhancing the resistance of the host against microbial agents, and promotes phagocytic and proliferative activities of reticuloendothelial system. The aim of this experimental study was to investigate the effects of BDG alone and in combination with ceftriaxone on sepsis caused by encapsulated invasive S.pneumoniae serotype 19F. A total of 36 Sprague-Dawley rats were used in the study, and the animals (6 in each group) were equally divided into six groups as control, splenectomy, sepsis, BDG, ceftriaxone and BDG+ceftriaxone groups. Treatment groups were intravenously infected with S.pneumoniae 19F strain, and after sacrification, microbiological [bacterial counts (cfu/mL)], biochemical (myeloperoxidase activity, DNA oxidation, specific IgM and IgG levels) and histopathological analysis were performed in the tissue samples. In the study, BDG, ceftriaxone and BDG+ceftriaxone groups had statistically significant decrease in the amount of bacteria in all tissues when compared to the sepsis group (p<0.05). We demonstrated that, BDG alone or combined treatment partially recovered the low serum IgM levels in splenectomized rats (p<0.001 ve p<0.02, respectively) and completely inhibited oxidative DNA damage in lung and liver after S.pneumoniae infection (p<0.00001). In addition, BDG alone or combined treatment fairly minimized the presence of bacteria in all tissues, when compared with sepsis group (p<0.00001). The data of our study suggests that, BDG, an immunomodulatory agent, alone and in combination with ceftriaxone can reverse the systemic inflammatory reaction in S.pneumoniae sepsis and thereby can reduce multiple organ failure.