Elsevier

Tuberculosis

Volume 95, Issue 4, July 2015, Pages 447-451
Tuberculosis

Immunological aspects
Neutrophils exacerbate tuberculosis infection in genetically susceptible mice

https://doi.org/10.1016/j.tube.2015.03.007Get rights and content

Summary

Mice of the I/St inbred strain genetically hyper-susceptible to TB infection and prone to form neutrophil-abundant necrotic lung lesions and relatively resistant mice of the C57BL/6 (B6) strain were infected with 100 CFU of M. tuberculosis H37Rv. To verify the role of neutrophils in TB immunity, we selectively depleted neutrophils from infected mice with highly specific 1A8 anti-Ly6G antibodies at day 2 and 6 post-challenge. Depletion of neutrophils resulted in reduced lung tissue pathology, mycobacterial CFU counts and an increase of the survival time in genetically susceptible I/St, but not in B6 mice. Furthermore, we demonstrated that in vivo neutrophil depletion at the onset of TB infection results in a significant increase in numbers of mycobacteria-specific IFN-γ-producing T-cells at the time point when the acquired immunity to mycobacteria is fully developed. These results suggest antagonistic activity of neutrophils and immune T-cells in the course of TB infection and provide further evidence of deleterious rather than protective role of the former.

Introduction

Neutrophils had in the past been treated as the outcast when studying complex interrelated networks of natural and adaptive immunity. Their prominent features include extremely short life span, rapid replacement of their pool in the periphery from the bone marrow and almost indiscriminative capacity to rapidly engulf and kill different bacteria without obvious cooperation with other cells of the immune system. This implied the conclusion that these cells are important element of bacterial clearance and acute inflammation, often accompanied by significant tissue damage, but have little to do with sophisticated immune responses during chronic inflammatory diseases (reviewed in [1], [2], [3]). Not the least, inherent difficulties in working with these fragile cells delayed acquisition of a critical amount of data required for a more comprehensive interpretation of the neutrophil physiology. However, during the last decade this traditional simplified view practically vanished.

Two lines of evidence changed diametrically our perception of the role of neutrophils in immunity. Firstly, an increasing amount of data indicates that neutrophils are actively involved in chronic inflammatory conditions, such as chronic obstructive pulmonary disease [4], pulmonary tuberculosis [5], [6], arthritis [7] and inflammatory bowel disease [8]. Secondly, and more importantly, a series of recent publications directly demonstrated that neutrophils are competent participants in the cross-talk between virtually all cells of the immune system. Thus, both in mice and humans, neutrophils regulate mononuclear cell recruitment to the site of inflammation (reviewed in [9], [10]) and development and function of NK cells [11]. We have shown that in mice B-lymphocytes delayed neutrophil recruitment to the site of BCG injection, the type of interaction crucial for development of efficient vaccination against tuberculosis (TB) infection [12]; more recently, data were obtained indicating the involvement of IL-17A in this regulatory pathway [13]. On the other hand, in a non-infectious experimental system neutrophils inhibited B-cell response to protein antigens [14]. Even broader influence of neutrophils on innate and adaptive immunity, involving regulation of B and T lymphocytes activation, monocyte/dendritic cell infiltration and the balance between type 1 vs. type 2 immune responses, was demonstrated in the mouse models of chronic Brucella abortus infection [15].

An interesting observation regarding capacity of neutrophils to shape phenotypes of other leukocytes was published by D'Avila et al. [16]. In their model of BCG-induced pleurisy in B6 mice, neutrophils rapidly engulfed BCG, underwent apoptosis and were phagocytosed by macrophages. The latter increased lipid body formation, as well as PGE2 and TGF-β syntheses. These results imply an interesting link between two important features of mycobacterial pathogenesis. On the one hand, foamy macrophages containing huge amounts of lipid vacuoles are considered as a niche for mycobacterial survival and latency development, rather than effector antimycobacterial or antigen-presenting cells [17]. On the other hand, TGF-β and PGE2 are potent inhibitors of T-cell immune responses and their increased production may down-regulate protective anti-mycobacterial immunity [18], [19], [20]. Thus, mycobacteria-containing neutrophils might have a dual deleterious effect on the host response to mycobacteria, stimulating foamy macrophage accumulation and inhibiting CD4+ T-cell activation.

In the present work, we further verified the role of neutrophils in TB immunity. To this end, we infected mice of I/St inbred strain, which are genetically hyper-susceptible to TB infection and prone to neutrophil-abundant necrotic lung lesions [21], with virulent Mycobacterium tuberculosis and demonstrated that selective neutrophil depletion in vivo reduced lung tissue pathology and mycobacterial CFU counts, resulting in an increase of the survival time. These results are in line with the data obtained in other TB-susceptible mouse strains [22], [23]. Furthermore, we demonstrated that in vivo neutrophil depletion at the onset of TB infection results in a significant increase in numbers of mycobacteria-specific IFN-γ-producing T-cells at the time point when the acquired immunity to mycobacteria is fully developed. These results suggest antagonistic activity of neutrophils and immune T-cells in the course of TB infection and provide further evidence of deleterious rather than protective role of the former.

Section snippets

Materials and methods

Mice of inbred strains I/StSnEgYCit (I/St) and C57BL/6JCit (B6) were bred and maintained under conventional, non-SPF conditions at the Animal Facilities of the Central Institute for Tuberculosis (CIT, Moscow, Russia) in accordance with guidelines from the Russian Ministry of Health # 755, and under the NIH Office of Laboratory Animal Welfare (OLAW) Assurance #A5502-11. Water and food were provided ad libitum. Female mice of 8–12 wk of age were used. All experimental procedures were approved by

Selective neutrophil depletion attenuates TB course in genetically susceptible mice

There is evidence suggesting that elimination of PMN cells in vivo at early stages of TB infection diminishes the degree of lung pathology and prolongs survival time of infected mice of TB-susceptible strains [22], [23]. However, a few issues concerning experimental anti-neutrophil TB therapy remained to be addressed. First, in both studies in the majority of experiments neutrophil depletion was achieved by injecting RB6-8C5 antibodies which react not only with Ly-6G+ neutrophils but also with

Acknowledgments

This work was financially supported by the Russian Scientific Foundation (RSF) grant 14-15-00029.

References (29)

  • T.W. Kuijpers et al.

    Neutrophils forever

  • E.B. Eruslanov et al.

    Neutrophil responses to Mycobacterium tuberculosis infection in genetically susceptible and resistant mice

    Infect Immun

    (2005)
  • D. Tanaka

    Essential role of neutrophils in anti-type II collagen antibody and lipopolysaccharide-induced arthritis

    Immunology

    (2006)
  • A.C. Chin et al.

    Neutrophil transepithelial migration and epithelial barrier function in IBD: potential targets for inhibiting neutrophil trafficking

    Ann N. Y Acad Sci

    (2006)
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