Neutrophils have traditionally been thought of as simple foot soldiers of the innate immune system with a restricted set of pro-inflammatory functions. More recently, it has become apparent that neutrophils are, in fact, complex cells capable of a vast array of specialized functions. Although neutrophils are undoubtedly major effectors of acute inflammation, several lines of evidence indicate that they also contribute to chronic inflammatory conditions and adaptive immune responses. Here, we discuss the key features of the life of a neutrophil, from its release from bone marrow to its death. We discuss the possible existence of different neutrophil subsets and their putative anti-inflammatory roles. We focus on how neutrophils are recruited to infected or injured tissues and describe differences in neutrophil recruitment between different tissues. Finally, we explain the mechanisms that are used by neutrophils to promote protective or pathological immune responses at different sites.

Neutrophil recruitment and function in health and inflammation

Epstein-Barr virus.

Epstein–Barr virus (EBV) was discovered 40 years ago from examining electron micrographs of cells cultured from Burkitt's lymphoma, a childhood tumour that is common in sub-Saharan Africa, where its unusual geographical distribution — which matches that of holoendemic malaria —indicated a viral aetiology. However, far from showing a restricted distribution, EBV — a γ-herpesvirus — was found to be widespread in all human populations and to persist in the vast majority of individuals as a lifelong, asymptomatic infection of the B-lymphocyte pool. Despite such ubiquity, the link between EBV and 'endemic' Burkitt's lymphoma proved consistent and became the first of an unexpectedly wide range of associations discovered between this virus and tumours.

Epstein–Barr virus: 40 years on

Neutrophils are innate immune phagocytes that have a central role in immune defence. Our understanding of the role of neutrophils in pathogen clearance, immune regulation and disease pathology has advanced dramatically in recent years. Web-like chromatin structures known as neutrophil extracellular traps (NETs) have been at the forefront of this renewed interest in neutrophil biology. The identification of molecules that modulate the release of NETs has helped to refine our view of the role of NETs in immune protection, inflammatory and autoimmune diseases and cancer. Here, I discuss the key findings and concepts that have thus far shaped the field of NET biology.

Neutrophil extracellular traps in immunity and disease

Spectacular images of neutrophils ejecting nuclear chromatin and bactericidal proteins, in response to microbes, were first reported in 2004. As externalized chromatin could entangle bacteria, these structures were named neutrophil extracellular traps (NETs). Subsequent studies identified microorganisms and sterile conditions that stimulate NETs, as well as additional cell types that release extracellular chromatin. The release of NETs is the most dramatic stage in a cell death process called NETosis. Experimental evidence suggests that NETs participate in pathogenesis of autoimmune and inflammatory disorders, with proposed involvement in glomerulonephritis, chronic lung disease, sepsis, and vascular disorders. Exaggerated NETosis or diminished NET clearance likely increases risk of autoreactivity to NET components. The biological significance of NETs is just beginning to be explored. A more complete integration of NETosis within immunology and pathophysiology will require better understanding of NET properties associated with specific disease states and microbial infections. This may lead to the identification of important therapeutic targets.

Neutrophil Extracellular Traps: Double-Edged Swords of Innate Immunity

https://chemistry-europe.onlinelibrary.wiley.com/doi/pdf/10.1002/cmdc.201200114

Corrigendum: A Synthetic C34 Trimer of HIV‐1 gp41 Shows Significant Increase in Inhibition Potency

Increased reports of measles in a low endemic region during a rubella outbreak in adult populations

(1) Background: General infection control measures have been implemented at the societal level against COVID-19 since the middle of 2020, namely, hand hygiene, universal masking, and social distancing. The suppressive effect of the social implementation of general infection control measures on pediatric infections has not been systematically assessed. (2) Methods: We addressed this issue based on publicly available data on 11 pediatric infections reported weekly by sentinel sites in Osaka and Iwate prefectures in Japan since 2010. We obtained the 5-year average for 2015–2019 and compared it to the weekly report for 2020–2021. (3) Results: The rate of 6 of the 11 pediatric infections decreased significantly during 2020–2021, regardless of the magnitude of the prevalence of COVID-19 in both areas. However, only RSV infection, one of the six infections, was endemic in 2021. Exanthem subitum was not as affected by COVID-19 countermeasures as other diseases. (4) Conclusions: The social implementation of infectious disease control measures was effective in controling certain infectious diseases in younger age groups, where compliance with the countermeasures should not be as high as that of adults.

/pdf/impact-of-covid-19-countermeasures-on-pediatric-infections-3pu5e1tp.pdf

Jun Komano

Papers

Corrigendum: A Synthetic C34 Trimer of HIV‐1 gp41 Shows Significant Increase in Inhibition Potency

Increased reports of measles in a low endemic region during a rubella outbreak in adult populations

Impact of COVID-19 Countermeasures on Pediatric Infections

Conformational properties of the third variable loop of HIV-1AD8 envelope glycoprotein in the liganded conditions.