Biological functions of IL-17-producing cells in mycoplasma respiratory infection

Abstract

Mycoplasmas are the smallest and simplest bacteria that lack a cell wall but have the capability of self-replication. Among them, Mycoplasma pneumoniae is one of the most common causes of community-acquired pneumonia. The hallmark of mycoplasma respiratory diseases is the persistence of lung inflammation that involves both innate and adaptive immune responses. In recent years, a growing body of evidence demonstrates that IL-17 plays an important role in respiratory mycoplasma infection, and associates with the pathologic outcomes of infection, such as pneumonitis and asthma. Numerous studies have shown that a variety of cells, in particular Th17 cells, in the lung can secrete IL-17 during respiratory mycoplasma infection. In this article, we review the biological functions of distinct IL-17-producing cells in mycoplasma respiratory infection with a focus on the effect of IL-17 on the outcomes of infection.

Keywords: IL-17; Th17; lung inflammation; mycoplasma infection.

FIGURE 1

Role of IL‐17‐producing cells in respiratory mycoplasma infection. In the early stage of infection, IL‐17 produced by different immune cells probably plays a protective role by inducing acute inflammation and clearing mycoplasma (left). Nevertheless, the persistent infection of mycoplasma causes aberrant IL‐17 production by immune cells, especially Th17 cells. Thus, IL‐17 contributes to chronic inflammation and tissue damage in the late stage of infection (right). Unknown cells may include neutrophils and monocytes [45]. Dashed line indicates possible regulatory relationships