Innate Immunity of Neonates and Infants

Abstract

Many important events occur at birth. The fetus is suddenly removed from a protected intra-uterine environment that is aquatic, warm, and nearly sterile, to the dry, cold external world laden with microbes. To survive, the neonate must interact with many organisms, making use of some, while vigorously defending against the others like a nation conducting trade with friendly countries and guarding against hostile ones from invading it, waging wars if necessary. Although, the neonatal immune system is plastic, however, it is highly tolerant which is due to both the fetal development during gestation as well as significant sudden changes in fetal environment and enormous exposure to the new antigens and intestinal bacteria and their products. This “quiescent mode” of innate immune system is part of a highly regulated process to fulfill all requirements of multi-layered process of early life, implemented effectively through the cells of innate immune system. While, most of the neonatal innate immune cells (e.g., neutrophils and monocytes) present contained activity and lower frequencies compared to their adult counterparts, innate lymphoid cells (ILCs), a distinct cellular component of innate immunity, show higher level of activity and presence during period of infancy compared to later stages of life and adulthood, which may suggest a role for ILCs in variable susceptibility to certain conditions during life time. In this review, while we focus on the characteristics and status of ILCs in neonatal immune system, we also draw an analogy from a national defense perspective because of the great similarities between that and the immune system by providing the known biological counterparts of all five core operational elements, the five Ds of defense, detection, discrimination, deployment, destruction, and de-escalation, with special focus on innate immunity, maternal support, and influence during the neonatal and infancy periods.

COVID-19 and Cancer: a Comprehensive Review

“…Clinical outcomes are dependent upon factors such as age, ACE2 expression, and comorbidities. Thus, cancer patients by virtue of being older (median age of a cancer diagnosis is 66 years in the USA) [20] and having higher ACE2 expression (ACE2 tends to increase with increasing age) [21] and more comorbidities [22] are at a higher risk of adverse outcomes when infected with SARS-CoV-2. Figure 2 highlights the case-fatality rate by age group in the general population diagnosed with COVID-19 in China along with possible roles of mentioned factors.…”

Gut microbiota in wild and captive Guizhou snub‐nosed monkeys, Rhinopithecus brelichi

“…While we often focus on improving the “macro” elements of captive management—nutrition, enrichment, enclosures, groupings—addressing the “micro” elements of captivity—specifically host‐associated microbial communities—may be just as critical to captive primate health. Recent studies on the gut microbiome indicate that the gastrointestinal (GI) tract is home to trillions of microbes that play an important role in immune development and defense (Belkaid & Hand, ; Cho & Blaser, ; Hachung et al, ; Hooper, Littman, & Macpherson, ; Littman & Pamer, ; Round & Mazmanian, ; Yu et al, ), disease (Petersen & Round, ; Round & Mazmanian, ; Sekirov, Russell, Antunes, & Finlay, ; Young, ), digestion (Backhed et al, ; Martin et al, ; Turnbaugh et al, ; L. S. Zhang & Davies, ), dietary adaptation (David et al, ; Ley et al, ; Tian, Wu, Chen, Yu, & He, ), reproduction (Morimoto, Simpson, & Ponton, ; Rosengaus, Zecher, Schultheis, Brucker, & Bordenstein, ; Sharon et al, ), and behavior (Forsythe, Sudo, Dinan, Taylor, & Bienenstock, ; Heijtz et al, ; Vuong, Yano, Fung, & Hsiao, ). The gut microbiome is also affected by multiple factors including diet (Amato, Leigh et al, ; David et al, ; Hale et al, ), habitat (Amato et al, ), stress (Vlčková et al, ), medications (Maier et al, ; Ursell & Knight, ), disinfectants (Tun et al, ), and social contact (Archie & Tung, ).…”

Immunometabolism and innate immunity in the context of immunological maturation and respiratory pathogens in young children

“…Specifically, these cells may function similar to traditional lymphocytes in antigen‐independent ways . In neonates and infants, like NK cells, innate lymphoid cells (ILCs) may exhibit higher frequencies than in adults and may even exhibit higher functions as well . Further research on the effect of age on these cells and their role especially outside the intestinal tract could help better understand innate immunity in the young child.…”

“…32 In neonates and infants, like NK cells, innate lymphoid cells (ILCs) may exhibit higher frequencies than in adults and may even exhibit higher functions as well. 33 Further research on the effect of age on these cells and their role especially outside the intestinal tract could help better understand innate immunity in the young child. 34 Furthermore, there are other limitations such as diminished respiratory bursts, chemotaxis, and responses to stress in neonates/infants that do not occur in adults.…”