Study Of β-defensin-2 Gene Expression In The Pulmonary Tissues Of Rat Stimulated By Pneumococcal Vaccine Polyvalent

BACKGROUND AND AIM Following physiological function of each organand immunity in the local and the whole body declining, The elderly are easily susceptible to infections, especially in the airway tract. Now antibiotics are the commonest drugs to dealing with infections, thus which increases bacterial resistance to antibiotics and even destroys all of organs' function. Infection and multi-resistance of bacteria are servere dilemma in all over the world . So it is very urgent to develop a new antibacterial strategy to solve the infections problems, especially in the elderly. Defensin is a kind of endogenous peptide in the innate immunity that enhances mucosal defensing from bacterial infections. β defensin-2 is found to be predominantly expressed in the respiratory tract and is a effectively agent against opportunistic infections. β defensin-2 gene expression is induced by various proinflammatory agents such as tumor necrosis factor(TNF)-alpha, interleukin (IL)-lbeta,IL-8, LPS, bateria, and yeasts. Twenty-three valent pneumococcal polysaccharide vaccine includes twenty-three subtype pneumococci polysaccharide and effectivelyprotect the body from pneumococci infection by producing specific antibody. The aim of the study is to investigate whether there is the difference between levels of P -defensin-2 in the pulmonary of the older and young rats, the effect of pneumovax?23 on P -defensin-2 gene expression in rat lung.METHODS Twenty wistar old rats (18—20 month) weighing 600±50g andtwenty young rats(2~3month)weighing 250±25g were randomly divided into two groups, one is experimental group and another is control group. In the experimental group, pneumococcal vaccine polyvalent(0.2ml/kg)is injected into intraperiton of rats, in the control group equivalent normal saline are injected intointraperiton. Lungs are harvested twenty-four hours after pneumococcal vaccine polyvalent stimulation. Total RNA was extracted from pulmonary tissue and RBD-2 mRNA was measured by RT-PCR. P -actin was used as internal standard. DNA sequencing was used to confirm the specificity of RBD-2 cDNA fragment. Agarose radial diffusion assay was appllied to detect the antibacterial activity of rat bronchoalveolar lavage fluid. Lungs in all groups are made of pathologic H&E specimen to know about the lungs' destrution.RESULTS P -defensin-2 gene expression can be detected in the pulmonary of the older rats, it is a lower in the older rats than in the young rats, however, it is not statistically different; a marked increase in pulmonary rBD-2 mRNA was found in experimental groups as compared with that in control groups(P<0.05). That is to say, Pneumococcal vaccine Polyvalent can upregulate the P -defensin-2 gene expression in old rats and young rats. Lungs 'H&E specimen showed that in the experimental groups, there areleukocytes exudation, alveolar figure destruction, except control groups. CONCLUSI ON Pneumococcal vaccine Polyvalent can effectively upregulateP -defensin-2 gene expression in rat lung, and increase bactericidal activity of rat lung, thus it may be an inducer to improve the body immunity.