Ureaplasma diversum clearance in lung mice infection is mediated by neutrophils.

Jamile R Da Silva,Percíllia V.S De Oliveira,Robson A.A Da Silva,Izadora S Rezende,Lucas M Marques,Patricia Nolasco,Denisar P Dos Santos,Hugo Santana,Jorge Timenetsky,Tiana B Figueiredo

doi:10.1590/0001-3765202120200424

Abstract

Pneumonia in cattle is one of the causes of morbidity rates and economic loss. The host response to lung infections caused by Ureaplasma diversum in bovines is virtually unknown. Here in the immune response was evaluated in a murine model for an experimental pulmonary infection by U. diversum. Therefore, AJ, BALB/C and C57BL/6 mice received intratracheal inoculation of U. diversum and were evaluated after 1, 2, 3, 7 and 14 days and the clinical specimens were collected. In bronchoalveolar lavages (BAL) an increase of inflammatory cells was observed. Neutrophils were the main cells recruited to the site of infection and the infiltration was coincided with the production of pro-inflammatory cytokines. We found a large amount of neutrophil in this initial period, followed by a decrease 7 and 14 days post infection, accompanied by bacterial clearance. Our results evidenced the presence of U. diversum within the neutrophil that suggests a phagocytic role of this cell in the elimination of the infection. The immune response features reported here are the initial evidence that healthy immune systems may control these microorganisms. This may be the first step to design new strategies immune based to control the infections in naturally infected hosts.

Highlights

Bloodstream circulating neutrophils have a short-life and are important in initiating defenses against foreign microorganisms (Summers et al 2010)
U. diversum induced a significant recruitment of cells to the site of infection; total bronchoalveolar lavages (BAL) cell counts were higher at 1, 2 and 3 days postinoculation (Fig. 1)
Peaks of BAL cell accumulation occurred at 24 hours in BALB/c and A/J lineage while C57BL/6 reached highest cell count at 48 hours in Ureaplasma-inoculated mice vs. in saline-inoculated controls

Summary

Introduction

Bloodstream circulating neutrophils have a short-life and are important in initiating defenses against foreign microorganisms (Summers et al 2010). After an infection or inflammation, these cells are attracted by mediators, such as complement fragment C5a (Dragomir et al 2012), leukotriene B4 (Afonso et al 2012), CXCL2 (Uchida et al 2009), myeloperoxidase (Klinke et al 2011) and antimicrobial peptides (Ma et al 2012). These cells migrate and interact with the stimulated endothelial cell surface (Rigby & DeLeo 2012). As with all Mollicutes, U. diversum lacks a cell wall but may present an external glycocalix

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