Secretory Leukocyte Protease Inhibitor Is Present in Circulating and Tissue-Recruited Human Eosinophils and Regulates Their Migratory Function

Progressively differentiated TFH13 cells are stabilized by JunB to mediate allergen germinal center responses

Allergic diseases are common and affect a large proportion of the population. Interleukin-13 (IL-13)-expressing follicular helper T (TFH13) cells are a newly identified population of TFH cells that have been associated with high-affinity IgE responses. However, the origins, developmental signals, transcriptional programming and precise functions of TFH13 cells are unknown. Here, we examined the developmental signals for TFH13 cells and found a direct and progressive differentiation pathway marked by the production of IL-21. These two pathways differed in kinetics and extrinsic requirements. However, both pathways converged, forming transcriptionally similar TFH13 cells that express the transcription factor JunB as a critical stabilizing factor. Using an intersectional genetics-based TFH13-diphtheria toxin receptor model to perturb these cells, we found that TFH13 cells were essential to drive broad germinal center responses and allergen-specific IgG and IgE. Moreover, we found that IL-21 is a broad positive regulator of allergen germinal center B cells and synergizes with IL-13 produced by TFH13 cells to amplify allergic responses. Thus, TFH13 cells orchestrate multiple features of allergic inflammation.

SLPI controls neutrophil migration abilities and impacts neutrophil skin infiltration in experimental psoriasis

Skin infiltration by neutrophils is a hallmark of the chronic inflammatory skin disease psoriasis, yet the mechanisms underlying neutrophil recruitment and positioning in chronically inflamed skin remain poorly understood. In this study, we demonstrate the significant impact of a total genetic deficiency of secretory leukocyte protease inhibitor (SLPI) on neutrophil migration in mouse skin. Without SLPI, neutrophils displayed an unconventional migratory pattern, characterized by altered interactions with vessel walls and reduced efficiency in extravasating from blood vessels into skin tissue during the early stages of experimental psoriasis. This was associated with changes in tissue motility, positioning neutrophils farther from the skin entry vessels and closer to the skin surface. Neutrophil diapedesis was partially dependent on SLPI within the neutrophils themselves. The impact of SLPI on neutrophil movement was further supported by the increased migration of human neutrophils in the presence of neutrophil-penetrant recombinant SLPI. Additionally, our data suggest that neutrophils with varying capacities for vessel wall interaction are released from the bone marrow into circulation in an SLPI-dependent manner. These findings establish a role for SLPI in regulating the spatiotemporal infiltration of neutrophils into the skin in psoriasis, highlighting its relevance to psoriasis pathophysiology.

The Roles of Innate Immune Cells in Atopic Dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by recurrent eczematous lesions and severe pruritus. The economic burden and time penalty caused by the relapse of AD reduce patients' life quality.

SUMMARY

AD has complex pathogenesis, including genetic disorders, epidermal barrier dysfunction, abnormal immune responses, microbial dysbiosis of the skin, and environmental factors. Recently, the role of innate immune cells in AD has attracted considerable attention. This review highlighted recent findings on innate immune cells in the onset and progression of AD.

KEY MESSAGES

Innate immune cells play essential roles in the pathogenesis of AD and enough attention should be given for treating AD from the perspective of innate immunity in clinics.

Secretory leukocyte protease inhibitor protects against severe urinary tract infection in mice

Millions suffer from urinary tract infections (UTIs) worldwide every year with women accounting for the majority of cases. Uropathogenic Escherichia coli (UPEC) causes most of these primary infections and leads to 25% becoming recurrent or chronic. To repel invading pathogens, the urinary tract mounts a vigorous innate immune response that includes the secretion of antimicrobial peptides (AMPs), rapid recruitment of phagocytes, and exfoliation of superficial umbrella cells. Here, we investigate secretory leukocyte protease inhibitor (SLPI), an AMP with antiprotease, antimicrobial, and immunomodulatory functions, known to play protective roles at other mucosal sites, but not well characterized in UTIs. Using a preclinical model of UPEC-caused UTI, we show that urine SLPI increases in infected mice and that SLPI is localized to bladder epithelial cells. UPEC-infected SLPI-deficient (Slpi-/-) mice suffer from higher urine bacterial burdens, prolonged bladder inflammation, and elevated urine neutrophil elastase (NE) levels compared to wild-type (Slpi+/+) controls. Combined with bulk bladder RNA sequencing, our data indicate that Slpi-/- mice have a dysregulated immune and tissue repair response following UTI. We also measure SLPI in urine samples from a small group of female subjects 18-49 years old and find that SLPI tends to be higher in the presence of a uropathogen, except in patients with a history of recent or recurrent UTI, suggesting a dysregulation of SLPI expression in these women. Taken together, our findings show SLPI promotes clearance of UPEC in mice and provides preliminary evidence that SLPI is likewise regulated in response to uropathogen exposure in women.IMPORTANCEAnnually, millions of people suffer from urinary tract infections (UTIs) and more than $3 billion are spent on work absences and treatment of these patients. While the early response to UTI is known to be important in combating urinary pathogens, knowledge of host factors that help curb infection is still limited. Here, we use a preclinical model of UTI to study secretory leukocyte protease inhibitor (SLPI), an antimicrobial protein, to determine how it protects the bladder against infection. We find that SLPI is increased during UTI, accelerates the clearance of bacteriuria, and upregulates genes and pathways needed to fight an infection while preventing prolonged bladder inflammation. In a small clinical study, we show SLPI is readily detectable in human urine and is associated with the presence of a uropathogen in patients without a previous history of UTI, suggesting SLPI may play an important role in protecting from bacterial cystitis.

A 69 kb Deletion in chr19q13.42 including PRPF31 Gene in a Chinese Family Affected with Autosomal Dominant Retinitis Pigmentosa

We aimed to identify the genetic cause of autosomal dominant retinitis pigmentosa (adRP) and characterize the underlying molecular mechanisms of incomplete penetrance in a Chinese family affected with adRP. All enrolled family members underwent ophthalmic examinations. Whole-genome sequencing (WGS), multiplex ligation-dependent probe amplification (MLPA), linkage analysis and haplotype construction were performed in all participants. RNA-seq was performed to analyze the regulating mechanism of incomplete penetrance among affected patients, mutation carriers and healthy controls. In the studied family, 14 individuals carried a novel heterozygous large deletion of 69 kilobase (kb) in 19q13.42 encompassing exon 1 of the PRPF31 gene and five upstream genes: TFPT, OSCAR, NDUFA3, TARM1, and VSTM1. Three family members were sequenced and diagnosed as non-penetrant carriers (NPCs). RNA-seq showed significant differential expression of genes in deletion between mutation carriers and healthy control. The RP11 pedigree in this study was the largest pedigree compared to other reported RP11 pedigrees with large deletions. Early onset in all affected members in this pedigree was considered to be a special phenotype and was firstly reported in a RP11 family for the first time. Differential expression of PRPF31 between affected and unaffected subjects indicates a haploinsufficiency to cause the disease in the family. The other genes with significant differential expression might play a cooperative effect on the penetrance of RP11.