Neutrophilic Dermatoses and Their Implication in Pathophysiology of Asthma and Other Respiratory Comorbidities: A Narrative Review

CARD9 Signaling, Inflammation, and Diseases

Caspase-recruitment domain 9 (CARD9) protein is expressed in many cells especially in immune cells, and is critically involved in the function of the innate and adaptive immune systems through extensive interactions between CARD9 and other signaling molecules including NF-κB and MAPK. CARD9-mediated signaling plays a central role in regulating inflammatory responses and oxidative stress through the productions of important cytokines and chemokines. Abnormalities of CARD9 and CARD9 signaling or CARD9 mutations or polymorphism are associated with a variety of pathological conditions including infections, inflammation, and autoimmune disorders. This review focuses on the function of CARD9 and CARD9-mediated signaling pathways, as well as interactions with other important signaling molecules in different cell types and the relations to specific disease conditions including inflammatory diseases, infections, tumorigenesis, and cardiovascular pathologies.

Sweet's Syndrome: A First in Human Lung Transplantation

Sweet’s Syndrome (SS), also known as acute febrile neutrophilic dermatosis, is one of several cutaneous inflammatory disorders classified as neutrophilic dermatoses. Respiratory complications are described in <50 cases in the literature,¹ without prior report of lung transplantation (LT). This article explains the clinical course of the first patient to receive LT for pulmonary SS and presents evidence suggesting recurrence of the primary lung disease in the allograft.

Ribosomal Protein SA-Positive Neutrophil Elicits Stronger Phagocytosis and Neutrophil Extracellular Trap Formation and Subdues Pro-Inflammatory Cytokine Secretion Against Streptococcus suis Serotype 2 Infection

Streptococcus suis serotype 2 (SS2), an important zoonotic pathogen that causes septicemia, arthritis, and irreversible meningitis in pigs and humans, can be transmitted to humans from pigs. S. suis causes huge economic losses to the swine industry and poses a serious threat to public health. Previously, we found that the brain tissues of mice with SS2-induced meningitis showed disrupted structural integrity and significantly enhanced polymorphonuclear neutrophil (PMN) infiltration. We showed that the brain tissues of SS2-infected mice had increased ribosomal protein SA (RPSA)-positive PMN counts. However, the inflammatory responses of RPSA⁺ PMNs to SS2 and their effects on the blood-brain barrier (BBB) remain unclear. Therefore, in studying the pathogenesis of SS2-induced meningitis, it is essential that we explore the functions of RPSA⁺ PMNs and their effects on the BBB. Herein, using flow cytometry and immunofluorescence microscopy analyses, we found that RPSA expression enhances PMN-induced phagocytosis and PMN-induced formation of neutrophil extracellular traps (NETs), which facilitate further elimination of bacteria. PMN surface expression of RPSA also alleviates local inflammation and tissue injuries by inhibiting secretion of the pro-inflammatory cytokines, TNF-α and IL-6. Moreover, the single-cell BBB model showed that RPSA disrupts BBB integrity by downregulating expression of tight junction-associated membrane proteins on PMNs. Taken together, our data suggest that PMN-surface expression of RPSA is a double-edged sword. RPSA+ PMN owns a stronger ability of bacterial cleaning and weakens inflammatory cytokines release which are useful to anti-infection, but does hurt BBB. Partly, RPSA+ PMN may be extremely useful to control the infection as a therapeutic cellular population, following novel insights into the special PMN population.

Improved mouse models and advanced genetic and genomic technologies for the study of neutrophils

Mice have been excellent surrogates for studying neutrophil biology and, furthermore, murine models of human disease have provided fundamental insights into the roles of human neutrophils in innate immunity. The emergence of novel humanized mice and high-diversity mouse populations offers the research community innovative and powerful platforms for better understanding, respectively, the mechanisms by which human neutrophils drive pathogenicity, and how genetic differences underpin the variation in neutrophil biology observed among humans. Here, we review key examples of these new resources. Additionally, we provide an overview of advanced genetic engineering tools available to further improve such murine model systems, of sophisticated neutrophil-profiling technologies, and of multifunctional nanoparticle (NP)-based neutrophil-targeting strategies.

Dietary and metabolic factors in the pathogenesis of hidradenitis suppurativa: a systematic review

Hidradenitis suppurativa (HS) is a systemic recalcitrant inflammatory condition characterized by debilitating lesions with high morbidity. Its known association with obesity and smoking indicate correlation with other environmental factors, such as diet, suggesting a larger role for lifestyle modifications in disease treatment. This study seeks to assess the contribution of weight loss and dietary intake in HS management. A primary literature search was conducted using PubMed, Web of Science, and CINAHL in November 2018 to include association and intervention studies on the influence of diet and weight on HS. Twenty-five articles were included. Meta-analysis of nine case-control studies across Asia, Europe, and the United States showed that HS patients are four times more likely to be obese compared to the general population; random effects pooled odds ratio 4.022 (2.667-6.065), P < 0.001. Five articles assessed weight-loss interventions and revealed mixed findings. The remaining articles included three association studies on micronutrient levels, eight dietary intervention studies, and one article analyzing both micronutrient association and dietary intervention. Included articles in this systematic review reveal that low serum zinc and vitamin D levels are associated with increased lesion count in HS. Supplementation of zinc, vitamin D, vitamin B12, or exclusion of dairy or brewer's yeast can be effective in partial or complete lesion resolution. Reviewed data show that weight loss from bariatric surgery may lead to HS improvement but often results in more severe malnutrition that worsens or even leads to new onset HS post bariatric surgery. Future reporting is needed to conclusively determine the role of diet in HS.