The role of human β-defensins in allergic diseases

Human Beta Defensin-2 mRNA and Proteasome Subunit β Type 8 mRNA Analysis, Useful in Differentiating Skin Biopsies from Atopic Dermatitis and Psoriasis Vulgaris Patients

(1): Atopic dermatitis and psoriasis vulgaris are chronic, inflammatory diseases. Clinical presentation usually leads to a proper diagnosis, but sometimes neither clinical examination nor histopathological evaluation can be conclusive. Therefore, we aimed to build up a novel diagnostic tool and check it for accuracy. The main objective of our work was to differentiate between healthy skin (C), atopic dermatitis (AD) and psoriasis vulgaris (PV) biopsies on the base of involucrin (IVL) and human β-defensin-2 (hBD-2) concentrations and their mRNA, as well as mRNA for TPP2 and PSMB8. (2): ELISA for IVL and hBD-2 proteins and Real-time PCR for the relative expression of mRNA for: IVL (IVL mRNA), hBD-2 (hBD-2 mRNA), PSMB8 (PSMB8 mRNA) and TPP2 (TPP2 mRNA), isolated from skin biopsies taken from AD and PV patients and healthy volunteers were performed. (3): hBD-2 mRNA and PSMB8 mRNA correlated with some parameters of clinical assessment of inflammatory disease severity. hBD-2 mRNA expression, exclusively, was sufficient to distinguish inflammatory skin biopsies from the healthy ones. (4): hBD-2 mRNA and PSMB8 mRNA analysis were the most valuable parameters in differentiating AD and PV biopsies.

S100A alarmins and thymic stromal lymphopoietin (TSLP) regulation in severe asthma following bronchial thermoplasty

RATIONALE

Severe asthma affects a small proportion of asthmatics but represents a significant healthcare challenge. Bronchial thermoplasty (BT) is an interventional treatment approach preconized for uncontrolled severe asthma after considering biologics therapy. It was showed that BT long-lastingly improves asthma control. These improvements seem to be related to the ability of BT to reduce airway smooth muscle remodeling, reduce the number of nerve fibers and to modulate bronchial epithelium integrity and behavior. Current evidence suggest that BT downregulates epithelial mucins expression, cytokine production and metabolic profile. Despite these observations, biological mechanisms explaining asthma control improvement post-BT are still not well understood.

OBJECTIVES

To assess whether BT affects gene signatures in bronchial epithelial cells (BECs).

METHODS

In this study we evaluated the transcriptome of cultured bronchial epithelial cells (BECs) of severe asthmatics obtained pre- and post-BT treatment using microarrays. We further validated gene and protein expressions in BECs and in bronchial biopsies with immunohistochemistry pre- and post-BT treatment.

MEASUREMENTS AND MAIN RESULTS

Transcriptomics analysis revealed that a large portion of differentially expressed genes (DEG) was involved in anti-viral response, anti-microbial response and pathogen induced cytokine storm signaling pathway. S100A gene family stood out as five members of this family where consistently downregulated post-BT. Further validation revealed that S100A7, S100A8, S100A9 and their receptor (RAGE, TLR4, CD36) expressions were highly enriched in severe asthmatic BECs. Further, these S100A family members were downregulated at the gene and protein levels in BECs and in bronchial biopsies of severe asthmatics post-BT. TLR4 and CD36 protein expression were also reduced in BECs post-BT. Thymic stromal lymphopoietin (TSLP) and human β-defensin 2 (hBD2) were significantly decreased while no significant change was observed in IL-25 and IL-33.

CONCLUSIONS

These data suggest that BT might improve asthma control by downregulating epithelial derived S100A family expression and related downstream signaling pathways.

The Skin Barrier and Moisturization: Function, Disruption, and Mechanisms of Repair

BACKGROUND

The anatomic layers of the skin are well-defined, and a functional model of the skin barrier has recently been described. Barrier disruption plays a key role in several skin conditions, and moisturization is recommended as an initial treatment in conditions such as atopic dermatitis. This review aimed to analyze the skin barrier in the context of the function model, with a focus on the mechanisms by which moisturizers support each of the functional layers of the skin barrier to promote homeostasis and repair.

SUMMARY

The skin barrier is comprised of four interdependent layers - physical, chemical, microbiologic, and immunologic - which maintain barrier structure and function. Moisturizers target disruption affecting each of these four layers through several mechanisms and were shown to improve transepidermal water loss in several studies. Occlusives, humectants, and emollients occlude the surface of the stratum corneum (SC), draw water from the dermis into the epidermis, and assimilate into the SC, respectively, in order to strengthen the physical skin barrier. Acidic moisturizers bolster the chemical skin barrier by supporting optimal enzymatic function, increasing ceramide production, and facilitating ideal conditions for commensal microorganisms. Regular moisturization may strengthen the immunologic skin barrier by reducing permeability and subsequent allergen penetration and sensitization.

KEY MESSAGES

The physical, chemical, microbiologic, and immunologic layers of the skin barrier are each uniquely impacted in states of skin barrier disruption. Moisturizers target each of the layers of the skin barrier to maintain homeostasis and facilitate repair.

Mechanisms and regulation of defensins in host defense

As a family of cationic host defense peptides, defensins are mainly synthesized by Paneth cells, neutrophils, and epithelial cells, contributing to host defense. Their biological functions in innate immunity, as well as their structure and activity relationships, along with their mechanisms of action and therapeutic potential, have been of great interest in recent years. To highlight the key research into the role of defensins in human and animal health, we first describe their research history, structural features, evolution, and antimicrobial mechanisms. Next, we cover the role of defensins in immune homeostasis, chemotaxis, mucosal barrier function, gut microbiota regulation, intestinal development and regulation of cell death. Further, we discuss their clinical relevance and therapeutic potential in various diseases, including infectious disease, inflammatory bowel disease, diabetes and obesity, chronic inflammatory lung disease, periodontitis and cancer. Finally, we summarize the current knowledge regarding the nutrient-dependent regulation of defensins, including fatty acids, amino acids, microelements, plant extracts, and probiotics, while considering the clinical application of such regulation. Together, the review summarizes the various biological functions, mechanism of actions and potential clinical significance of defensins, along with the challenges in developing defensins-based therapy, thus providing crucial insights into their biology and potential clinical utility.

Antibacterial peptides-loaded bioactive materials for the treatment of bone infection

Bacterial bone infection in open fractures is an urgent problem to solve in orthopedics. Antimicrobial peptides (AMPs), as a part of innate immune defense, have good biocompatibility. Their antibacterial mechanism and therapeutic application against bacteria have been widely studied. Compared with traditional antibiotics, AMPs do not easily cause bacterial resistance and can be a reliable substitute for antibiotics in the future. Therefore, various physical and chemical strategies have been developed for the combined application of AMPs and bioactive materials to infected sites, which are conducive to maintaining the local stability of AMPs, reducing many complications, and facilitating bone infection resolution. This review explored the molecular structure, function, and direct and indirect antibacterial mechanisms of AMPs, introduced two important AMPs (LL-37 and β-defensins) in bone tissues, and reviewed advanced AMP loading strategies and different bioactive materials. Finally, the latest progress and future development of AMPs-loaded bioactive materials for the promotion of bone infection repair were discussed. This study provided a theoretical basis and application strategy for the treatment of bone infection with AMP-loaded bioactive materials.

The Antimicrobial Peptide AMP-IBP5 Suppresses Dermatitis-like Lesions in a Mouse Model of Atopic Dermatitis through the Low-Density Lipoprotein Receptor-Related Protein-1 Receptor

The antimicrobial peptide derived from insulin-like growth factor-binding protein 5 (AMP-IBP5) exhibits antimicrobial activities and immunomodulatory functions in keratinocytes and fibroblasts. However, its role in regulating skin barrier function remains unclear. Here, we investigated the effects of AMP-IBP5 on the skin barrier and its role in the pathogenesis of atopic dermatitis (AD). 2,4-Dinitrochlorobenzene was used to induce AD-like skin inflammation. Transepithelial electrical resistance and permeability assays were used to investigate tight junction (TJ) barrier function in normal human epidermal keratinocytes and mice. AMP-IBP5 increased the expression of TJ-related proteins and their distribution along the intercellular borders. AMP-IBP5 also improved TJ barrier function through activation of the atypical protein kinase C and Rac1 pathways. In AD mice, AMP-IBP5 ameliorated dermatitis-like symptoms restored the expression of TJ-related proteins, suppressed the expression of inflammatory and pruritic cytokines, and improved skin barrier function. Interestingly, the ability of AMP-IBP5 to alleviate inflammation and improve skin barrier function in AD mice was abolished in mice treated with an antagonist of the low-density lipoprotein receptor-related protein-1 (LRP1) receptor. Collectively, these findings indicate that AMP-IBP5 may ameliorate AD-like inflammation and enhance skin barrier function through LRP1, suggesting a possible role for AMP-IBP5 in the treatment of AD.

Could Chronic Rhinosinusitis Increase the Risk of Ulcerative Colitis? A Nationwide Cohort Study

Chronic rhinosinusitis (CRS) is a common chronic inflammatory disease of the sinonasal mucosa with an inflammatory or infectious etiology. Inflammatory bowel disease (IBD) causes chronic intestinal inflammation. Thus, both diseases share innate immune and epithelial barrier dysfunctions of the mucosa. However, the association between sinusitis and IBD is not well-known. We aimed to determine the association between CRS and the risk for IBDs, such as Crohn’s disease (CD) and ulcerative colitis (UC). In this long-term retrospective cohort study, 15,175 patients with CRS and 30,350 patients without CRS (comparison group) were enrolled after 1:2 propensity score matching. The incidence rates of CD and UC were 0.22 and 0.51 (1000 person-years), respectively. The adjusted hazard ratio (HR) for developing CD and UC in CRS patients was 1.01 (95% confidence interval (CI), 0.66–1.54) and 1.72 (95% CI, 1.26–2.36), respectively. Additionally, in the subgroup analysis using the CRS phenotype, the adjusted HRs of UC were significantly increased in patients with CRS without nasal polyps (adjusted HR = 1.71; 95% CI, 1.24–2.35), but not in those with CRS with nasal polyps. CRS without nasal polyps is associated with an increased incidence of UC but not CD. Therefore, clinicians should pay attention to the early detection of UC when treating patients with CRS without nasal polyps.

The Antimicrobial Peptides Human β-Defensins Induce the Secretion of Angiogenin in Human Dermal Fibroblasts

The skin produces a plethora of antimicrobial peptides that not only show antimicrobial activities against pathogens but also exhibit various immunomodulatory functions. Human β-defensins (hBDs) are the most well-characterized skin-derived antimicrobial peptides and contribute to diverse biological processes, including cytokine production and the migration, proliferation, and differentiation of host cells. Additionally, hBD-3 was recently reported to promote wound healing and angiogenesis, by inducing the expression of various angiogenic factors and the migration and proliferation of fibroblasts. Angiogenin is one of the most potent angiogenic factors; however, the effects of hBDs on angiogenin production in fibroblasts remain unclear. Here, we investigated the effects of hBDs on the secretion of angiogenin by human dermal fibroblasts. Both in vitro and ex vivo studies demonstrated that hBD-1, hBD-2, hBD-3, and hBD-4 dose-dependently increased angiogenin production by fibroblasts. hBD-mediated angiogenin secretion involved the epidermal growth factor receptor (EGFR), Src family kinase, c-Jun N-terminal kinase (JNK), p38, and nuclear factor-kappa B (NF-κB) pathways, as evidenced by the inhibitory effects of specific inhibitors for these pathways. Indeed, we confirmed that hBDs induced the activation of the EGFR, Src, JNK, p38, and NF-κB pathways. This study identified a novel role of hBDs in angiogenesis, through the production of angiogenin, in addition to their antimicrobial activities and other immunomodulatory properties.

Glycosaminoglycan, Antimicrobial Defence Molecule and Cytokine Appearance in Tracheal Hyaline Cartilage of Healthy Humans

Hyaline cartilage is an important tracheal structure, yet little is known about its molecular composition, complicating investigation of pathologies and replacement options. Our aim was to research tracheal hyaline cartilage structure, protective tissue factors and variations in healthy humans. The tissue material was obtained from 10 cadavers obtained from the Riga Stradins University Institute of Anatomy and Anthropology archive. Tissues were stained with Bismarck brown and PAS for glycosaminoglycans, and immunohistochemistry was performed for HBD-2, HBD-3, HBD-4, IL-10 and LL-37. The slides were inspected by light microscopy and Spearman's rank correlation coefficient was calculated. The extracellular matrix was positive across hyaline cartilage for PAS, yet Bismarck brown marked positive proliferation and growth zones. Numerous positive cells for both factors were found in all zones. All of the antimicrobial defence molecules and cytokines were found in a moderate number of cells, except in the mature cell zone with few positive cells. Spearman's rank correlation coefficient revealed strong and moderate correlations between studied factors. Hyaline cartilage is a tracheal defence structure with a moderate number of antimicrobial defence protein and cytokine immunoreactive cells as well as numerous glycosaminoglycan positive cells. The extracellular matrix glycosaminoglycans provide structural scaffolding and intercellular signalling. The correlations between the studied factors confirm the synergistic activity of them.

Peripheral itch sensitization in atopic dermatitis

Atopic dermatitis is a skin disorder caused by skin dryness and barrier dysfunction, resulting in skin inflammation and chronic itch (or pruritus). The pathogenesis of atopic dermatitis is thought to be initiated by a lowering of the itch threshold due to dry skin. This lowering of the itch threshold is at least partially due to the increase in intraepidermal nerve fibers and sensitization of sensory nerves by interleukin (IL)-33 produced and secreted by keratinocytes. Such skin is easily prone to itch due to mechanical stimuli, such as rubbing of clothing and chemical stimuli from itch mediators. In patients with atopic dermatitis, once itch occurs, further itch is induced by scratching, and the associated scratching breaks down the skin barrier. Disruption of the skin barrier allows entry into the epidermis of external foreign substances, such as allergens derived from house dust mites, leading to an increased induction of type 2 inflammatory responses. As a result, type 2 cytokines IL-4, IL-13, and IL-31 are mainly secreted by Th2 cells, and their action on sensory nerve fibers causes further itch sensitization. These sequences of events are thought to occur simultaneously in patients with atopic dermatitis, leading to a vicious itch-scratch cycle. This vicious cycle becomes a negative spiral that leads to disease burden. Therefore, controlling itch is essential for the treatment of atopic dermatitis. In this review, we summarize and discuss advances in the mechanisms of peripheral itch sensitization in atopic dermatitis, focusing on skin barrier-neuro-immune triadic connectivity.

Increased fecal human beta-defensin-2 expression in preterm infants is associated with allergic disease development in early childhood

Background

This study aimed to investigate whether fecal human beta-defensins (HBD)-2 and eosinophil cationic protein (ECP) expression in preterm infants are associated with allergic disease development by age 2 years.

Methods

Preterm infants' stool samples were collected at the age of 6 and 12 months postnatally. Information regarding medication exposure histories (antibiotics, antipyretics, probiotics) and physician-diagnosed allergic diseases was obtained using age-specific questionnaires and medical records. We compared the 6-month and 12-month fecal HBD-2 and ECP concentrations between the medication exposure and non-exposure group, respectively, and between children who developed allergic diseases and those who did not by 2 years of age. Univariate and multivariable logistic regression analyses were performed to investigate independent variables related to physician-diagnosed allergic diseases by 2 years of age.

Results

Seventy-four preterm infants (gestational age, 31–36 weeks) were included. Fecal HBD-2 levels were significantly increased at 12 months of age among children who developed allergic diseases compared to those who did not (37.18 ± 11.80 ng/g vs. 8.56 ± 4.33 ng/g, P = 0.011). This association was more apparent among allergic children given antibiotics (50.23 ± 16.15 ng/g vs. 9.75 ± 7.16 ng/g, P = 0.008) or antipyretics (46.12 ± 14.22 ng/g vs. 10.82 ± 6.81 ng/g, P = 0.018) during the first year, whereas among allergic children who were previously not exposed to antibiotics or antipyretics, the differences were not significant. Results of the multivariable logistic regression analysis indicated that HBD-2 concentration in 12-month stools was an independent indicator associated with physician-diagnosed allergic diseases by 2 years of age (adjusted odds ratio: 1.03 [95% confidence interval: 1.00–1.05], P = 0.036). Our data revealed a lack of association between fecal ECP and allergic diseases.

Conclusions

We found that preterm infants who expressed high fecal HBD-2 at 12 months of age were associated with physician-diagnosed allergic diseases by the age of 2 years. Further studies are needed to determine the role of fecal HBD-2 in the development of allergic diseases.

Immunomodulatory and Allergenic Properties of Antimicrobial Peptides

With the growing problem of the emergence of antibiotic-resistant bacteria, the search for alternative ways to combat bacterial infections is extremely urgent. While analyzing the effect of antimicrobial peptides (AMPs) on immunocompetent cells, their effect on all parts of the immune system, and on humoral and cellular immunity, is revealed. AMPs have direct effects on neutrophils, monocytes, dendritic cells, T-lymphocytes, and mast cells, participating in innate immunity. They act on B-lymphocytes indirectly, enhancing the induction of antigen-specific immunity, which ultimately leads to the activation of adaptive immunity. The adjuvant activity of AMPs in relation to bacterial and viral antigens was the reason for their inclusion in vaccines and made it possible to formulate the concept of a “defensin vaccine” as an innovative basis for constructing vaccines. The immunomodulatory function of AMPs involves their influence on cells in the nearest microenvironment, recruitment and activation of other cells, supporting the response to pathogenic microorganisms and completing the inflammatory process, thus exhibiting a systemic effect. For the successful use of AMPs in medical practice, it is necessary to study their immunomodulatory activity in detail, taking into account their pleiotropy. The degree of maturity of the immune system and microenvironment can contribute to the prevention of complications and increase the effectiveness of therapy, since AMPs can suppress inflammation in some circumstances, but aggravate the response and damage of organism in others. It should also be taken into account that the real functions of one or another AMP depend on the types of total regulatory effects on the target cell, and not only on properties of an individual peptide. A wide spectrum of biological activity, including direct effects on pathogens, inactivation of bacterial toxins and influence on immunocompetent cells, has attracted the attention of researchers, however, the cytostatic activity of AMPs against normal cells, as well as their allergenic properties and low stability to host proteases, are serious limitations for the medical use of AMPs. In this connection, the tasks of searching for compounds that selectively affect the target and development of an appropriate method of application become critically important. The scope of this review is to summarize the current concepts and newest advances in research of the immunomodulatory activity of natural and synthetic AMPs, and to examine the prospects and limitations of their medical use.

The Antimicrobial Peptide Human β-Defensin-3 Accelerates Wound Healing by Promoting Angiogenesis, Cell Migration, and Proliferation Through the FGFR/JAK2/STAT3 Signaling Pathway

In addition to its antimicrobial activity, the skin-derived antimicrobial peptide human β-defensin-3 (hBD-3) promotes keratinocyte proliferation and migration to initiate the wound healing process; however, its effects on fibroblasts, which are the major cell type responsible for wound healing, remain unclear. We investigated the role of hBD-3 in cell migration, proliferation and production of angiogenic growth factors in human fibroblasts and evaluated the in vivo effect of hBD-3 on promoting wound healing and angiogenesis. Following hBD-3 treatment, the mouse wounds healed faster and showed accumulation of neutrophils and macrophages in the early phase of wound healing and reduction of these phagocytes 4 days later. hBD-3-treated wounds also displayed an increased number of fibroblasts and newly formed vessels compared to those of the control mice. Furthermore, the expression of various angiogenic growth factors was increased in the hBD-3-treated wounds. Additionally, in vitro studies demonstrated that hBD-3 enhanced the secretion of angiogenic growth factors such as fibroblast growth factor, platelet-derived growth factor and vascular endothelial growth factor and induced the migration and proliferation of human fibroblasts. The hBD-3-mediated activation of fibroblasts involves the fibroblast growth factor receptor 1 (FGFR1)/Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathways, as evidenced by the inhibitory effects of pathway-specific inhibitors. We indeed confirmed that hBD-3 enhanced the phosphorylation of FGFR1, JAK2 and STAT3. Collectively, the current study provides novel evidence that hBD-3 might be a potential candidate for the treatment of wounds through its ability to promote wound healing, angiogenesis and fibroblast activation.

Specific β-Defensins Stimulate Pruritus through Activation of Sensory Neurons

Pruritus is a common symptom of dermatological disorders and has a major negative impact on QOL. Previously, it was suggested that human β-defensin peptides elicit itch through the activation of mast cells. In this study, we investigated in more detail the mechanisms by which β-defensins induce itch by defining the receptors activated by these peptides in humans and mice, by establishing their action in vivo, and by examining their expression in inflammatory dermal diseases. We found that elevated expression of DEFB103 is highly correlated with skin lesions in psoriasis and atopic dermatitis. We showed that the peptide encoded by this gene and related genes activate Mas-related G protein-coupled receptors with different potencies that are related to their charge density. Furthermore, we establish that although these peptides can activate mast cells, they also activate sensory neurons, with the former cells being dispensable for itch reactions in mice. Together, our studies highlight that specific β-defensins are likely endogenous pruritogens that can directly stimulate sensory neurons.

Role of antimicrobial peptides in atopic dermatitis

Host defense peptides (HDPs) or antimicrobial peptides (AMPs) are short cationic amphipathic peptides of divergent sequences, which are part of the innate immune system and produced by various types of cells and tissues. The predominant role of HDPs is to respond to and protect humans against infection and inflammation. Common human HDPs include defensins, cathelicidin, psoriasin, dermcidin, and ribonucleases, but these peptides may be dysregulated in the skin of patients with atopic dermatitis (AD). Current evidence suggests that the antimicrobial properties and immunomodulatory effects of HDPs are involved in AD pathogenesis, making HDPs research a promising area for predicting disease severity and developing novel treatments for AD. In this review, we describe a potential role for human HDPs in the development, exacerbation, and progression of AD and propose their potential therapeutic benefits.

Human beta-defensin-1 rs2738047 polymorphism is associated with shisha smoking risk among Saudi population

Human β-defensin (HBD), a member of the antimicrobial peptides, is essential for respiratory epithelial cells' microbial defense, and is affected by cigarette smoking (CS). Its expression is upregulated by stimulation from microbes or inflammation. Genetic polymorphisms in the HBD-1 gene have been implicated in the development of various smoking-related diseases, including chronic obstructive pulmonary disease and asthma. Thus, we sought to analyze possible associations between HBD-1 single-nucleotide polymorphism (SNP) in HBD-1 gene and CS in ethnic Saudi Arabian subjects. Variants rs1047031 (C/T), rs1799946 (C/T), rs2738047 (C/T), and rs11362 (C/T) were investigated by genotyping 575 blood specimens from males and females, smokers/non-smokers: 288/287. The CT and CT+TT genotypes of rs1799946 presented an ~5-fold increased correlation with CS among the female smokers, compared with the female controls (OR = 5.473, P = 0.02003; and OR = 5.211, P = 0.02028, respectively), an observation similar to rs11362 SNP in female smokers, but with protective effects in TT genotype, compared with the CC reference allele (OR = 0.143, P = 0.04368). In shisha smokers, the heterozygous CT and the CT/TT genotype of rs2738047 polymorphism showed the same results with ~3-fold increased correlation with CS (OR = 2.788; P = 0.03448), compared with the cigarette smokers category. No significant association was shown in genotypic distributions and allelic frequencies of rs1047031. Further investigations, including large study samples, are required to investigate the effects of shisha on human beta-defensin expression and protein levels.

Intractable Itch in Atopic Dermatitis: Causes and Treatments

Itch or pruritus is the hallmark of atopic dermatitis and is defined as an unpleasant sensation that evokes the desire to scratch. It is also believed that itch is a signal of danger from various environmental factors or physiological abnormalities. Because histamine is a well-known substance inducing itch, H₁-antihistamines are the most frequently used drugs to treat pruritus. However, H₁-antihistamines are not fully effective against intractable itch in patients with atopic dermatitis. Given that intractable itch is a clinical problem that markedly decreases quality of life, its treatment in atopic dermatitis is of high importance. Histamine-independent itch may be elicited by various pruritogens, including proteases, cytokines, neuropeptides, lipids, and opioids, and their cognate receptors, such as protease-activated receptors, cytokine receptors, Mas-related G protein-coupled receptors, opioid receptors, and transient receptor potential channels. In addition, cutaneous hyperinnervation is partly involved in itch sensitization in the periphery. It is believed that dry skin is a key feature of intractable itch in atopic dermatitis. Treatment of the underlying conditions that cause itch is necessary to improve the quality of life of patients with atopic dermatitis. This review describes current insights into the pathophysiology of itch and its treatment in atopic dermatitis.

Reduced Expression of Antimicrobial Protein Secretory Leukoprotease Inhibitor and Clusterin in Chronic Rhinosinusitis with Nasal Polyps

Introduction

Antimicrobial peptides and proteins (AMPs) constitute the first line of defense against pathogenic microorganisms in the airway. The association between AMPs and chronic rhinosinusitis with nasal polyps (CRSwNP) requires further investigations. This study is aimed at investigating the expression and regulation of major dysregulated AMPs in the nasal mucosa of CRSwNP.

Methods

The expression of AMPs was analyzed in nasal tissue from patients with eosinophilic (E) CRSwNP and nonECRSwNP and healthy subjects using RNA sequencing. The 10 most abundant AMPs expressed differentially in CRSwNP patients were verified by real-time PCR, and of these, the expression and regulation of secretory leukoprotease inhibitor (SLPI) and clusterin (CLU) were investigated further.

Results

The 10 most abundant AMPs expressed differentially in CRSwNP compared to healthy control, regardless of subtypes, included BPIFA1, BPIFB1, BPIFB2, CLU, LTF, LYZ, and SLPI, which were downregulated, and S100A8, S100A9, and HIST1H2BC, which were upregulated. ELISA and immunofluorescence confirmed the decreased expression of SLPI and CLU levels in CRSwNP. SLPI is expressed in both nasal epithelial cells and glandular cells, whereas CLU is mainly expressed in glandular cells. AB/PAS staining further demonstrated that both SLPI and CLU were mainly produced by mucous cells in submucosal glands. Furthermore, the numbers of submucosal glands were significantly decreased in nasal polyp tissue of CRSwNP compared to nasal tissue of controls. SLPI was downregulated by TGF-β1 and IL-4 in cultured nasal tissues in vitro, while CLU expression was inhibited by TGF-β1. Glucocorticoid treatment for 2 weeks significantly increased the expression of all downregulated AMPs, but not LYZ. Additionally, budesonide significantly increased the expression of SLPI and CLU in cultured nasal tissues.

Conclusion

The expression of major antimicrobial proteins is significantly decreased in nasal tissue of CRSwNP. The expression of SLPI and CLU is correlated with the numbers of submucosal glands and regulated by inflammatory cytokines and glucocorticoids.

Adults with inflammatory bowel disease are at a greater risk of developing chronic rhinosinusitis: A nationwide population-based study

BACKGROUND

Both inflammatory bowel disease (IBD) and chronic rhinosinusitis (CRS) are characterised by dysregulated immune responses. Though previous studies have demonstrated the coexistence of IBD and CRS, investigations of their association using large sets of epidemiologic data are lacking.

METHODS

We examined IBD and the subsequent risk of CRS in a nationwide setting. For 1 January 2000 to 31 December 2010, we identified in the National Health Insurance Dataset of Taiwan a total of 8313 patients over the age of 20 years with IBD. We randomly extracted 33 252 cases without IBD to create a comparison group matching patients by age, sex and index year. Cumulative incidences were obtained using the Kaplan-Meier method, and we calculated risk estimates for the development of CRS using the Cox proportional hazards model.

RESULTS

In 295 007 person-years, we identified 521 (1.25%) cases of IBD. The IBD cohort had a 1.26-fold (95% confidence interval [CI], 1.17-1.35) greater risk of developing CRS than the comparison group; for ulcerative colitis, it was 1.73-fold (95% CI, 1.48-2.05) and for Crohn's disease it was 1.20-fold (95% CI = 1.11-1.29). Subsequent analysis stratified by age revealed that the risk was highest among the population with IBD aged 50 to 64 years (adjusted hazard ratio = 1.37; 95% CI, 1.18-1.59). A follow-up-specific analysis demonstrated that the risk appeared to be highest with a follow-up duration of less than 2 years.

CONCLUSION

The present analysis indicates that personal history of IBD, especially the phenotype ulcerative colitis, is associated with increased risk of subsequent CRS.

Reconsidering the "protective" hypothesis of Helicobacter pylori infection in eosinophilic esophagitis

Since its discovery, Helicobacter pylori (H. pylori) has attracted attention in the biomedical world with its numerous pathophysiologic implications, both gastrointestinal and systemic. Beyond its well-established carcinogenic properties, emerging evidence also supports "harmful" proinflammatory and neurodegenerative roles of H. pylori. On the other hand, H. pylori infection has been proposed to be "protective" against several diseases, such as asthma and gastroesophageal reflux disease. Eosinophilic esophagitis (EoE) is a relatively new, allergen/immune-mediated disease, which has also been linked to these considerations. Main arguments are a postulated shift of immune responses by H. pylori from T helper 2 (T_H 2) to T_H 1 polarization, as well as a potential decline of the H. pylori burden with the dramatic parallel rise of ΕοΕ: a series of observational studies reported an inverse association. In this review, we counter these arguments by providing further epidemiological data, which point out that this generalization might be rather incomplete. We also discuss the limitations of the existing studies evaluating a possible association. Furthermore, we provide current evidence on common pathogenetic components, which share both entities. In summary, the claim that H. pylori is protective against EoE is rather incomplete, and further mechanistic studies are necessary to elucidate a possible association.

Dietary Nutrients Mediate Intestinal Host Defense Peptide Expression

The intestinal tract is the shared locus of intestinal epithelial cells, immune cells, nutrient digestion and absorption, and microbial survival. The gut in animals faces continuous challenges in communicating with the external environment. Threats from endogenous imbalance and exogenous feeds, especially pathogens, could trigger a disorder of homeostasis, leading to intestinal disease and even systematic disease risk. As a part of the intestinal protective barrier, endogenous host defense peptides (HDPs) play multiple beneficial physiological roles in the gut mucosa. Moreover, enhancing endogenous HDPs is being developed as a new strategy for resisting pathogens and commensal microbes, and to maintain intestinal health and reduce antibiotic use. In recent years, multiple nutrients such as branched-chain amino acids, SCFAs, lactose, zinc, and cholecalciferol (vitamin D3) have been reported to significantly increase HDP expression. Nutritional intervention has received more attention and is viewed as a promising means to defend against pathogenic infections and intestinal inflammation. The present review focuses on current discoveries surrounding HDP expression and nutritional regulation of mechanisms in the gut. Our aim is to provide a comprehensive overview, referable tactics, and novel opinions.

Epidermal Growth Factor Relieves Inflammatory Signals in Staphylococcus aureus-Treated Human Epidermal Keratinocytes and Atopic Dermatitis-Like Skin Lesions in Nc/Nga Mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a defective immunologic barrier, which is aggravated by Staphylococcus aureus (S. aureus). Epidermal growth factor (EGF) suppresses inflammation and EGF receptor inhibitors increased S. aureus colonization. Thus, we investigated the potential roles of EGF in AD, which is often aggravated by S. aureus. We determined how EGF affects the expression of inflammatory cytokines and antimicrobial peptides (AMPs) in human epidermal keratinocytes (HEKs) treated with heat-inactivated S. aureus (HKSA) in vitro and 2,4-dinitrochlorobenzene-induced AD-like skin lesions in Nc/Nga mice. HKSA increased IL-6 and NFκB expression; EGF treatment had the opposite effect. EGF increased human β defensin-2 expression in HEKs and murine β defensin-3 in mice. In mice, both EGF and pimecrolimus groups showed less erythema with significantly reduced inflammation and decreased expression of thymic stromal lymphopoietin. EGF relieved S. aureus-induced inflammation and AD-like skin lesions in Nc/Nga mice. Therefore, EGF could be a potential topical treatment for AD.

Innate defense regulator IDR-1018 activates human mast cells through G protein-, phospholipase C-, MAPK- and NF-ĸB-sensitive pathways

Host defense (antimicrobial) peptides not only display antimicrobial activities against numerous pathogens but also exert a broader spectrum of immune-modulating functions. Innate defense regulators (IDRs) are a class of host defense peptides synthetically developed from natural or endogenous cationic host defense peptides. Of the IDRs developed to date, IDR-1018 is more efficient not only in killing bacteria but also in regulating the various functions of macrophages and neutrophils and accelerating the wound healing process. Because mast cells intimately participate in wound healing and a number of host defense peptides involved in wound healing are also known to activate mast cells, this study aimed to investigate the effects of IDR-1018 on mast cell activation. Here, we showed that IDR-1018 induced the degranulation of LAD2 human mast cells and caused their production of leukotrienes, prostaglandins and various cytokines and chemokines, including granulocyte-macrophage colony-stimulating factor, interleukin-8, monocyte chemoattractant protein-1 and -3, macrophage-inflammatory protein-1α and -1β, and tumor necrosis factor-α. Furthermore, IDR-1018 increased intracellular calcium mobilization and induced mast cell chemotaxis. The mast cell activation was markedly suppressed by pertussis toxin, U-73122, U0126, SB203580, JNK inhibitor II, and NF-κB activation inhibitor II, suggesting the involvement of G-protein, phospholipase C, ERK, p38, JNK and NF-κB pathways, respectively, in IDR-1018-induced mast cell activation. Notably, we confirmed that IDR-1018 caused the phosphorylation of MAPKs and IκB. Altogether, the current study suggests a novel immunomodulatory role of IDR-1018 through its ability to recruit and activate human mast cells at the sites of inflammation and wounds.

HIGHLIGHTS

We report that IDR-1018 stimulates various functions of human mast cells. IDR-1018-induced mast cell activation is mediated through G protein, PLC, MAPK and NF-κB pathways. IDR-1018 will be a useful therapeutic agent for wound healing.

The antimicrobial peptide, human β-defensin-1, potentiates in vitro osteoclastogenesis via activation of the p44/42 mitogen-activated protein kinases

Previous studies have demonstrated increased expression and raised levels of human β-defensin (hBD)-1 in gingival tissue and crevicular fluid of patients with chronic periodontitis and peri-implantitis, oral bone-resorbing diseases caused by enhanced osteoclastogenesis. Therefore, we aimed to investigate the effect of hBD-1 on osteoclast formation and function and to elucidate the involved signaling pathway in vitro. Human peripheral blood mononuclear cells (PBMCs) were first incubated with various doses of hBD-1 and cell viability was assayed by MTT. PBMCs were treated with macrophage-colony stimulating factor and receptor activator of nuclear factor kappa-B ligand (RANKL) in the presence or absence of non-toxic doses of hBD-1. In vitro osteoclastogenesis was analyzed by tartrate-resistant acid phosphatase (TRAP) staining, osteoclast-specific gene expression, and a resorption pit assay. Involvement of mitogen-activated protein kinases (MAPKs) was studied by immunoblotting and specific MAPK inhibitors. HBD-1 potentiated induction of in vitro osteoclastogenesis by RANKL, as shown by significantly increased number of TRAP-positive multinuclear cells and resorption areas on the dentin slices, and further up-regulated expressions of osteoclast-specific genes compared to those by RANKL treatment (p <0.05). However, hBD-1 treatment without RANKL failed to induce formation of osteoclast-like cells. A significant and further increase in transient phosphorylation of the p44/42 MAPKs was demonstrated by hBD-1 co-treatment (p<0.05), consistent with the inhibitory effect by pretreatment with U0126 or PD98059 on hBD-1-enhanced osteoclastogenesis. Collectively, hBD-1 potentiates the induction of in vitro osteoclastogenesis by RANKL via enhanced phosphorylation of the p44/42 MAPKs.

Current insights into the role of human β-defensins in atopic dermatitis

Anti-microbial peptides or host defence peptides are small molecules that display both anti-microbial activities and complex immunomodulatory functions to protect against various diseases. Among these peptides, the human β-defensins (hBDs) are localized primarily in epithelial surfaces, including those of the skin, where they contribute to protective barriers. In atopic dermatitis skin lesions, altered skin barrier and immune dysregulation are believed to be responsible for reduced hBD synthesis. Impaired hBD expression in the skin is reportedly the leading cause of increased susceptibility to bacterial and viral infection in patients with atopic dermatitis. Although hBDs have considerable beneficial effects as anti-microbial agents and immunomodulators and may ameliorate atopic dermatitis clinically, recent evidence has also suggested the negative effects of hBDs in atopic dermatitis development. In the current review, we provide an overview of the regulation of hBDs and their role in the pathogenesis of atopic dermatitis. The efforts to utilize these molecules in clinical applications are also described.

The Role of Defensins in HIV Pathogenesis

Profound loss of CD4⁺ T cells, progressive impairment of the immune system, inflammation, and sustained immune activation are the characteristics of human immunodeficiency virus-1 (HIV-1) infection. Innate immune responses respond immediately from the day of HIV infection, and a thorough understanding of the interaction between several innate immune cells and HIV-1 is essential to determine to what extent those cells play a crucial role in controlling HIV-1 in vivo. Defensins, divided into the three subfamilies α-, β-, and θ-defensins based on structure and disulfide linkages, comprise a critical component of the innate immune response and exhibit anti-HIV-1 activities and immunomodulatory capabilities. In humans, only α- and β-defensins are expressed in various tissues and have broad impacts on HIV-1 transmission, replication, and disease progression. θ-defensins have been identified as functional peptides in Old World monkeys, but not in humans. Instead, θ-defensins exist only as pseudogenes in humans, chimpanzees, and gorillas. The use of the synthetic θ-defensin peptide “retrocyclin” as an antiviral therapy was shown to be promising, and further research into the development of defensin-based HIV-1 therapeutics is needed. This review focuses on the role of defensins in HIV-1 pathogenesis and highlights future research efforts that warrant investigation.

Denatonium-induced sinonasal bacterial killing may play a role in chronic rhinosinusitis outcomes

BACKGROUND

Sinonasal bitter taste receptors (T2Rs) contribute to upper airway innate immunity and correlate with chronic rhinosinusitis (CRS) clinical outcomes. A subset of T2Rs expressed on sinonasal solitary chemosensory cells (SCCs) are activated by denatonium, resulting in a calcium-mediated secretion of bactericidal antimicrobial peptides (AMPs) in neighboring ciliated epithelial cells. We hypothesized that there is patient variability in the amount of bacterial killing induced by different concentrations of denatonium and that the differences correlate with CRS clinical outcomes.

METHODS

Bacterial growth inhibition was quantified after mixing bacteria with airway surface liquid (ASL) collected from denatonium-stimulated sinonasal air-liquid interface (ALI) cultures. Patient ASL bacterial killing at 0.1 mM denatonium and baseline characteristics and sinus surgery outcomes were compared between these populations.

RESULTS

There is variability in the degree of denatonium-induced bacterial killing between patients. In CRS with nasal polyps (CRSwNP), patients with increased bacterial killing after stimulation with low levels of denatonium undergo significantly more functional endoscopic sinus surgeries (FESSs) (p = 0.037) and have worse 6-month post-FESS 22-item Sino-Nasal Outcome Test (SNOT-22) scores (p = 0.012).

CONCLUSION

Bacterial killing after stimulation with low levels of denatonium correlates with number of prior FESS and postoperative SNOT-22 scores in CRSwNP. Some symptoms of CRS in patients with hyperresponsiveness to low levels of denatonium may be due to increased airway immune activity or inherent disease severity.

Bile acids deoxycholic acid and ursodeoxycholic acid differentially regulate human β-defensin-1 and -2 secretion by colonic epithelial cells

Bile acids and epithelial-derived human β-defensins (HβDs) are known to be important factors in the regulation of colonic mucosal barrier function and inflammation. We hypothesized that bile acids regulate colonic HβD expression and aimed to test this by investigating the effects of deoxycholic acid (DCA) and ursodeoxycholic acid on the expression and release of HβD1 and HβD2 from colonic epithelial cells and mucosal tissues. DCA (10-150 µM) stimulated the release of both HβD1 and HβD2 from epithelial cell monolayers and human colonic mucosal tissue in vitro In contrast, ursodeoxycholic acid (50-200 µM) inhibited both basal and DCA-induced defensin release. Effects of DCA were mimicked by the Takeda GPCR 5 agonist, INT-777 (50 μM), but not by the farnesoid X receptor agonist, GW4064 (10 μM). INT-777 also stimulated colonic HβD1 and HβD2 release from wild-type, but not Takeda GPCR 5^-/-, mice. DCA stimulated phosphorylation of the p65 subunit of NF-κB, an effect that was attenuated by ursodeoxycholic acid, whereas an NF-κB inhibitor, BMS-345541 (25 μM), inhibited DCA-induced HβD2, but not HβD1, release. We conclude that bile acids can differentially regulate colonic epithelial HβD expression and secretion and discuss the implications of our findings for intestinal health and disease.-Lajczak, N. K., Saint-Criq, V., O'Dwyer, A. M., Perino, A., Adorini, L., Schoonjans, K., Keely, S. J. Bile acids deoxycholic acid and ursodeoxycholic acid differentially regulate human β-defensin-1 and -2 secretion by colonic epithelial cells.