Human Respiratory Syncytial Virus: Role of Innate Immunity in Clearance and Disease Progression

Abstract

Human respiratory syncytial virus (HRSV) infections have worldwide records. The virus is responsible for bronchiolitis, pneumonia, and asthma in humans of different age groups. Premature infants, young children, and immunocompromised individuals are prone to severe HRSV infection that may lead to death. Based on worldwide estimations, millions of cases were reported in both developed and developing countries. In fact, HRSV symptoms develop mainly as a result of host immune response. Due to inability to establish long lasting adaptive immunity, HRSV infection is recurrent and hence impairs vaccine development. Once HRSV attached to the airway epithelia, interaction with the host innate immune components starts. HRSV interaction with pulmonary innate defenses is crucial in determining the disease outcome. Infection of alveolar epithelial cells triggers a cascade of events that lead to recruitment and activation of leukocyte populations. HRSV clearance is mediated by a number of innate leukocytes, including macrophages, natural killer cells, eosinophils, dendritic cells, and neutrophils. Regulation of these cells is mediated by cytokines, chemokines, and other immune mediators. Although the innate immune system helps to clear HRSV infection, it participates in disease progression such as bronchiolitis and asthma. Resolving the mechanisms by which HRSV induces pathogenesis, different possible interactions between the virus and immune components, and immune cells interplay are essential for developing new effective vaccines. Therefore, the current review focuses on how the pulmonary innate defenses mediate HRSV clearance and to what extent they participate in disease progression. In addition, immune responses associated with HRSV vaccines will be discussed.

Altered Natural Killer Cell Function in HIV-Exposed Uninfected Infants

“…However, our sample size was too small to detect significant differences in any of the NK cell parameters. NK cells are thought to be important for the immune response to several respiratory viral infections, including influenza and RSV (22, 23, 46). In addition, NK cell defects might be a marker of global immune dysfunction in HEU infants, which could predispose them to an increased risk of LRTI.…”

“…Natural killer (NK) cells are innate lymphocytes that play an important role in the control of viral infections, especially in early life while the adaptive immune response is immature (22, 23). NK cells also act both as activators and effectors of the adaptive immune response (24).…”

Advanced Role of Neutrophils in Common Respiratory Diseases

“…Human respiratory syncytial virus (HRSV) infections have a close relationship with many respiratory diseases, such as bronchiolitis, asthma, and pneumonia [225]. Neutrophils together with its proteases, NETs, and cytotoxic and direct interaction with infected epithelial cell play an important role in the pathological process [225]. RSV could induce NET formation in vitro.…”

CD38 modulates respiratory syncytial virus‐driven proinflammatory processes in human monocyte‐derived dendritic cells

“…RSV infection initiates a cascade of events leading to the recruitment and activation of immune effectors, including monocyte/macrophages and dendritic cells (DCs) which, in turn, trigger the production of cytokines and chemokines, which orchestrate and potentiate the immune response . However, when exacerbated, the immune response to RSV may lead to tissue damage and to the establishment of bronchiolitis …”