The Role of Macrophages in the Host's Defense against Sporothrix schenckii.

Estela Ruiz-Baca,Javier Ventura-Juárez,Yolanda Romo-Lozano,Armando Pérez-Torres,Carlos A Alba-Fierro,Daniel Cervantes-García,Conchita Torriello

doi:10.3390/pathogens10070905

Abstract

The role of immune cells associated with sporotrichosis caused by Sporothrix schenckii is not yet fully clarified. Macrophages through pattern recognition receptors (PRRs) can recognize pathogen-associated molecular patterns (PAMPs) of Sporothrix, engulf it, activate respiratory burst, and secrete pro-inflammatory or anti-inflammatory biological mediators to control infection. It is important to consider that the characteristics associated with S. schenckii and/or the host may influence macrophage polarization (M1/M2), cell recruitment, and the type of immune response (1, 2, and 17). Currently, with the use of new monocyte-macrophage cell lines, it is possible to evaluate different host–pathogen interaction processes, which allows for the proposal of new mechanisms in human sporotrichosis. Therefore, in order to contribute to the understanding of these host–pathogen interactions, the aim of this review is to summarize and discuss the immune responses induced by macrophage-S. schenckii interactions, as well as the PRRs and PAMPs involved during the recognition of S. schenckii that favor the immune evasion by the fungus.

Highlights

Sporotrichosis is a subcutaneous mycosis frequently found in tropical and sub-tropical areas of Latin America and other countries throughout the world [1,2,3]
Macrophages are activated and differentiated by cytokines secreted from lymphocytes and other local tissue cells, and this activation gives them the capacity to respond to diverse challenges [32]
Macrophage receptors play a key role in activating an effective immune response against the fungus, as they mediate phagocytosis, signaling cascades, intracellular trafficking, inflammatory responses, and antigen presentation

Summary

Introduction

Sporotrichosis is a subcutaneous mycosis frequently found in tropical and sub-tropical areas of Latin America and other countries throughout the world [1,2,3]. As in other subcutaneous mycoses, host infection occurs by traumatic inoculation through the skin of materials contaminated with fragments of hyphae or conidia of the fungus This infection is acquired by spore inhalation leading to a primary lung disease [4,6]. The key role of macrophages as innate immune response cells depends on the expression of surface receptors, which can be activated by factors derived from the host and pathogens [18]. This review tries to explain how the immune response induced by the fungus relies on the activated signaling pathway, the nature of the antigen, and the morphology of the fungus These phagocytic cells are able to act as reservoirs for the immune evasion of intracellular pathogens and as triggers of specific immune responses mediated by antigen presentation and proinflammatory cytokines and chemokines secretion [20]. We will discuss the role of macrophages in the host’s defense against S. schenckii and the strategies used by the fungus for immune evasion

Macrophages: A Brief Overview

Macrophage Subtypes

Macrophages Recruitment

Phagocytosis

Macrophages and the Immune Responses in Sporotrichosis

Conclusions