The Neonatal Immune System and Respiratory Pathogens

Abstract

Neonates are more susceptible to some pathogens, particularly those that cause infection in the respiratory tract. This is often attributed to an incompletely developed immune system, but recent work demonstrates effective neonatal immune responses to some infection. The emerging view is that neonates have a distinctly different immune response that is well-adapted to deal with unique immunological challenges of the transition from a relatively sterile uterus to a microbe-rich world, tending to suppress potentially dangerous inflammatory responses. Problematically, few animal models allow a mechanistic examination of the roles and effects of various immune functions in this critical transition period. This limits our understanding of neonatal immunity, and therefore our ability to rationally design and develop vaccines and therapeutics to best protect newborns. This review summarizes what is known of the neonatal immune system, focusing on protection against respiratory pathogens and describes challenges of various animal models. Highlighting recent advances in the mouse model, we identify knowledge gaps to be addressed.

Maternal Vaccination for the Prevention of Infantile RSV Disease: An Overview of the Authorized, In-Progress, and Unsuccessful Vaccine Candidates.

“…Further factors impacting function include numerical insufficiency, along with diminished leucocyte activation upon chemotactic signaling [37]. The functionality of monocytes and macrophages in neonates closely resemble that of adults, albeit with distinct activation patterns [38]. Neonatal immunity tends to lean towards Th2 induction, explained by the reduced MHC-II expression [36].…”

Making friends: active selection of symbionts and rejection of pathogens by the neonatal immune system

“…Contrary to the current dogma, neonates are not highly susceptible to all pathogens; the NIS can protect the host against most pathogens and therefore must possess some competent, albeit different, immune defenses ( 3 ). To understand the important differences between the NIS and AIS, it may be useful to consider the very different challenges that are unique to the NIS.…”