Role of Polymorphonuclear Neutrophils in a Murine Model ofChlamydia psittaci-Induced Abortion

Abstract

To assess the role of polymorphonuclear neutrophils (PMNs) inChlamydia psittaci infection in a pregnant mouse model, pregnant and nonpregnant Swiss OF1 mice were depleted of PMNs by treatment with the RB6-8C5 monoclonal antibody before intraperitoneal infection with C. psittaci serotype 1. Nondepleted mice served as infection controls. Depleted mice aborted earlier and had a much higher mortality rate than nondepleted mice. Bacteriological analysis showed that the number of chlamydiae isolated from the spleens of depleted mice at 5 and 7 days postinfection was 100 times greater than that isolated from nondepleted mice. Histopathological analysis of the placentas of depleted mice showed widespread necrosis of the uteroplacental units, with weak immunoreaction to chlamydial antigen, while the placentas of nondepleted mice showed substantial neutrophil infiltration but no large areas of necrosis, with moderate to strong immunoreaction to chlamydial antigen. The livers of depleted mice showed numerous chlamydial inclusions in the hepatocytes, delayed microgranuloma formation, and in the pregnant animals extensive coagulative periportal necrosis. The livers of nondepleted mice displayed multiple small foci of PMNs and mononuclear cells with microgranuloma formation. Among this group of mice, the pregnant animals always had more hepatic damage than nonpregnant animals. Our results suggest that PMNs play an essential role in the response to C. psittaci primary infection, preventing the uncontrolled multiplication of chlamydiae in the liver and spleen.

Neutropenia alters lung cytokine production in mice and reduces their susceptibility to pulmonary cryptococcosis

“…Investigation of this dendritic cell population in the spleen revealed no difference in cell number between mice given mAb RB6–8C5, rat IgG, and PBS. Our study used a single and relatively small dose of mAb (25 μg/mouse) which was 4–20‐times smaller than the doses used in comparable studies 3, 6, 11–13, 43, 44. Hence, the most straightforward interpretation of the data is that theeffects observed were due to neutrophil depletion.…”

Evaluation of the Efficacy of a New Commercially Available Inactivated Vaccine Against Ovine Enzootic Abortion

“…Aluminum salts promotes formation of multimolecular aggregates, when it interacts with the antigen and these aggregates or multimolecular structure are more easily phagocytized ( 46 ). Moreover, DEAE-Dextran is commonly used to facilitate the infection of cell cultures in vitro ( 33 ) as it is a molecule that enhances the adhesion of Chlamydiae to target cells, which may increase the amount of antigen reaching the antigen presenting cells located in the immunization zone ( 46 ).…”

“…In mice experimental design, the evaluation of the infection was performed by counting the IFUs of the liver and spleen isolated on McCoy cell monolayers, based on the method previously described by Buendia et al ( 33 ). The number of inclusions in McCoy cells was counted under fluorescent microscopy to calculate the number of IFUs per gram of tissue.…”

Chlamydia–host cell interaction not only from a bird's eye view: some lessons from Chlamydia psittaci

“…). These neutrophils produce reactive oxygen species as well as enzymes to eradicate chlamydiae and represent the first line of defense against bacterial infections in functional cooperation with dendritic cells (DCs) and macrophages (Fig. ).…”