Human thioredoxin, a damage-associated molecular pattern and Malassezia-crossreactive autoallergen, modulates immune responses via the C-type lectin receptors Dectin-1 and Dectin-2

A systematic review of allergen cross-reactivity: Translating basic concepts into clinical relevance

Access to the molecular culprits of allergic reactions allows for the leveraging of molecular allergology as a new precision medicine approach-one built on interdisciplinary, basic, and clinical knowledge. Molecular allergology relies on the use of allergen molecules as in vitro tools for the diagnosis and management of allergic patients. It complements the conventional approach based on skin and in vitro allergen extract testing. Major applications of molecular allergology comprise accurate identification of the offending allergen thanks to discrimination between genuine sensitization and allergen cross-reactivity, evaluation of potential severity, patient-tailored choice of the adequate allergen immunotherapy, and prediction of its expected efficacy and safety. Allergen cross-reactivity, defined as the recognition of 2 or more allergen molecules by antibodies or T cells of the same specificity, frequently interferes with allergen extract testing. At the mechanistic level, allergen cross-reactivity depends on the allergen, the host's immune response, and the context of their interaction. The multiplicity of allergen molecules and families adds further difficulty. Understanding allergen cross-reactivity at the immunologic level and translating it into a daily tool for the management of allergic patients is further complicated by the ever-increasing number of characterized allergenic molecules, the lack of dedicated resources, and the need for a personalized, patient-centered approach. Conversely, knowledge sharing paves the way for improved clinical use, innovative diagnostic tools, and further interdisciplinary research. Here, we aimed to provide a comprehensive and unbiased state-of-the art systematic review on allergen cross-reactivity. To optimize learning, we enhanced the review with basic, translational, and clinical definitions, clinical vignettes, and an overview of online allergen databases.

Emerging trends in clinical research on Janus kinase inhibitors for atopic dermatitis treatment

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects millions of people worldwide, characterized by immune function imbalance and impaired epidermal barrier function. It is a complex disorder that involves multiple pathogenic pathways, including the JAK/STAT signaling pathway, which plays a critical role in regulating immune and inflammatory responses. The therapeutic potential of Janus kinase inhibitors (JAKi) in the management of atopic dermatitis (AD) has garnered significant interest in recent years. AD is a chronic inflammatory skin condition characterized by impaired epidermal barrier function and immune function imbalance, and its pathogenesis is closely associated with dysregulated JAK/signal transducer and activator of transcription (STAT) signaling pathways. JAKi offer a novel therapeutic approach by selectively inhibiting JAK enzymes, thereby blocking downstream STAT signaling and preventing the expression of cytokines involved in AD pathogenesis. This review will focus on several JAKi including tofacitinib, baricitinib, ruxolitinib and upadacitinib, and provide a comprehensive overview of the latest research on the application of JAKi in AD treatment, including its mechanism of action, clinical trial results and safety profile.

Common carp intelectin 3 (cITLN3) plays a role in the innate immune response

Intelectin is a lectin with the capacity to recognize and bind to carbohydrates. In this study, we successfully cloned cITLN3 from common carp, which consists of a signal peptide domain, a FReD domain, and an intelectin domain. The expression levels of cITLN3 were detected in various organs of common carp, including the liver, head kidney, spleen, foregut, midgut, and hindgut, with the highest expression observed in the liver. Following infection with Staphylococcus aureus (S. aureus) or Aeromonas hydrophila (A. hydrophila), the expression level of cITLN3 was significantly upregulated in all organs of common carp. Subsequently, we expressed and purified the recombinant cITLN3 protein using an E. coli expression system. The cITLN3 could aggregate both gram-positive and gram-negative bacteria in the presence of Ca2+, with a stronger affinity for gram-positive bacteria. Moreover, our study demonstrated that cITLN3 displayed a higher binding affinity towards PGN compared to LPS. Furthermore, we observed that cITLN3 had the potential to inhibit bacterial proliferation in common carp and safeguard intestinal integrity during bacterial stimulation. And the results also indicated that cITLN3 might played a role in the Toll-like receptors (TLRs) signaling pathway activation.

Common carp Peptidoglycan Recognition Protein 2 (CcPGRP2) plays a role in innate immunity for defense against bacterial infections

PGRP is a family of pattern recognition molecules of the innate immune system. PGRPs are conserved from insects to mammals and have diverse functions in antimicrobial defense. Here we cloned a common carp PGRP ortholog, CcPGRP2 containing a conserved C-terminal PGRP domain. We tested the expression levels of CcPGRP2 in the liver, spleen, kidney, foregut, midgut, and hindgut of the highest level in the liver. The expression of CcPGRP2 upregulated in common carp infected with Aeromonas hydrophila (A. hydrophila) or Staphylococcus aureus (S. aureus). Recombinant CcPGRP2 protein expressed in Escherichia coli (E. coli) system and the purified CcPGRP2 could maintain the integrity of intestinal mucosa of common carp infected with A. hydrophila. In addition, CcPGRP2 could agglutinate or bind both gram-positive and gram-negative bacteria in a Zn²⁺-dependent manner. CcPGRP2 has a stronger agglutination and bacterial binding ability in gram-positive bacteria than in gram-negative bacteria. It is perhaps because CcPGRP2 could bind peptidoglycan (PGN) with a higher degree to lipopolysaccharide (LPS). And CcPGRP2 shows antimicrobial activities in the presence of Zn²⁺. Our results of CcPGRP2 provided new insight into the function of PGRP in the innate immunity of the common carp.

Single-cell profiles reveal distinctive immune response in atopic dermatitis in contrast to psoriasis

BACKGROUND

Understanding the complex orchestrated inflammation in atopic dermatitis (AD), one of the most common chronic inflammatory diseases worldwide, is essential for therapeutic approaches. However, a comparative analysis on the single-cell level of the inflammation signatures correlated with the severity is missing so far.

METHODS

We applied single-cell RNA and T-cell receptor (TCR) sequencing on immune cells enriched from skin biopsies and matched blood samples of AD in comparison with psoriasis (PS) patients.

RESULTS

Clonally propagated skin-derived T cells showed disease-specific TCR motifs shared between patients which was more pronounced in PS compared to AD. The disease-specific T-cell clusters were mostly of a Th2/Th22 sub-population in AD and Th17/Tc17 in PS, and their numbers were associated with severity scores in both diseases. Herein, we provide for the first time a list that associates cell type-specific gene expression with the severity of the two most common chronic inflammatory skin diseases. Investigating the cell signatures in the patients´ PBMCs and skin stromal cells, a systemic involvement of type-3 inflammation was clearly detectable in PS circulating cells, while in AD inflammatory signatures were most pronounced in fibroblasts, pericytes, and keratinocytes. Compositional and functional analyses of myeloid cells revealed the activation of antiviral responses in macrophages in association with disease severity in both diseases.

CONCLUSION

Different disease-driving cell types and subtypes which contribute to the hallmarks of type-2 and type-3 inflammatory signatures and are associated with disease activities could be identified by single-cell RNA-seq and TCR-seq in AD and PS.

Gut mycobiome dysbiosis contributes to the development of hypertension and its response to immunoglobulin light chains

Objectives

Human gut microbiome has gained great attention for its proposed roles in the development of hypertension. The fungal microbiome in the human gut (i.e. the mycobiome) is beginning to gain recognition as a fundamental part of our microbiome. However, the existing knowledge of human mycobiome has never revealed the association between gut mycobiome and hypertension. It is known that inflammation and immunity contribute to human hypertension. Here, we sought to investigate whether gut mycobiome could predict the development of hypertension and its association with immunoglobulin light chains.

Methods and materials

Participants were classified into three cohorts: prehypertension (pre-HTN), hypertension (HTN), and normal-tension (NT) based on their blood pressure. Fresh samples were collected, and the ITS transcribed spacer ribosomal RNA gene sequence was performed. An immunoturbidimetric test was used to examine the serum levels of immunological light chains.

Results

Subjects in both of the states of pre-HTN and HTN had different fungal microbiome community compared to the NT group (FDR<0.05). Slightly higher levels of fungal richness and diversity were observed in the groups of pre-HTN and HTN. The relative abundance of Malassezia increased in the HTN group compared to that in the NT group, and the relative abundance of Mortierella enriched in the NT group. For the pre-HTN group, the relative abundance of Malassezia was positively associated with serum the concentration of light chain (LC) κ (r=0.510, P=0.044); for the HTN group, the relative abundance of Mortierella was positively associated with the serum concentration of LC κ (P<0.05), the relative abundance of Malassezia was positively associated with both the serum concentrations of LC κ and LC λ (r>0.30, P<0.05).

Conclusions

Our present study demonstrated that gut fungal dysbiosis occurred in the state of prehypertension, and fungal dysbiosis can predict the dysregulation of serum light chains in hypertension patients. Further study on modulating gut fungal community should be focused on balancing the immunological features in hypertension.

Fungal exposome, human health, and unmet needs: A 2022 update with special focus on allergy

Humans inhale, ingest, and touch thousands of fungi each day. The ubiquity and diversity of the fungal kingdom, reflected by its complex taxonomy, are in sharp contrast with our scarce knowledge about its distribution, pathogenic effects, and effective interventions at the environmental and individual levels. Here, we present an overview of salient features of fungi as permanent players of the human exposome and key determinants of human health, through the lens of fungal allergy and other fungal hypersensitivity reactions. Improved understanding of the fungal exposome sheds new light on the epidemiology of fungal-related hypersensitivity diseases, their immunological substratum, the currently available methods, and biomarkers for environmental and medical fungi. Unmet needs are described and potential approaches are highlighted as perspectives.

Mixed lineage kinase-like protein protects against Clostridium perfringens infection by enhancing NLRP3 inflammasome-extracellular traps axis

Despite intense research in understanding Clostridium perfringens (C. perfringens) pathogenesis, the mechanisms by which it is cleared from the host are largely unclarified. In C. perfringens gas gangrene and enterocolitis model, Mlkl ^-/- mice, lacking mixed lineage kinase-like protein (MLKL), are more susceptible to C. perfringens infection. Mlkl deficiency results in a defect in inflammasome activation, and IL-18 and IL-1β releases. Exogenous administration of recombinant IL-18 is able to rescue the susceptibility of Mlkl ^-/- mice. Notably, K⁺ efflux-dependent NLRP3 inflammasome signaling downstream of active MLKL promotes bacterial killing and clearance. Interestingly, the defect of bactericidal activity is also mediated by decreased classical extracellular trap formation in the absence of Mlkl. Our results demonstrate that MLKL mediates extracellular trap formation in a NLRP3 inflammasome-dependent manner. These findings highlight the requirement of MLKL for host defense against C. perfringens infection through enhancing NLRP3 inflammasome-extracellular traps axis.

Antifungal immunity mediated by C-type lectin receptors may be a novel target in immunotherapy for urothelial bladder cancer

Immunotherapies, such as immune-checkpoint blockade and adoptive T-cell therapy, offer novel treatment options with good efficacy for patients with urothelial bladder cancer. However, heterogeneity and therapeutic resistance have limited the use of immunotherapy. Further research into immune-regulatory mechanisms in bladder cancer is urgently required. Emerging evidence demonstrates that the commensal microbiota and its interactions with host immunity play pivotal roles in a variety of physiological and pathological processes, including in cancer. The gut microbiota has been identified as a potentially effective target of treatment that can be synergized with immunotherapy. The urothelial tract is also a key site for multiple microbes, although the immune-regulatory role of the urinary microbiome in the process of carcinogenesis of bladder cancer remains to be elucidated. We performed a comprehensive analysis of the expression and biological functions of C-type lectin receptors (CLRs), which have been recognized as innate pathogen-associated receptors for fungal microbiota, in bladder cancer. In line with previous research on fungal colonization of the urothelial tract, we found that CLRs, including Dectin-1, Dectin-2, Dectin-3, and macrophage-inducible Ca²⁺-dependent lectin receptor (Mincle), had a significant association with immune infiltration in bladder cancer. Multiple innate and adaptive pathways are positively correlated with the upregulation of CLRs. In addition, we found a significant correlation between the expression of CLRs and a range of immune-checkpoint proteins in bladder cancer. Based on previous studies and our findings, we hypothesize that the urinary mycobiome plays a key role in the pathogenesis of bladder cancer and call for more research on CLR-mediated anti-fungal immunity against bladder cancer as a novel target for immunotherapy in urothelial bladder cancer.

Towards a new model of trained immunity: Exposure to bacteria and β-glucan protects larval zebrafish against subsequent infections

Once thought to be a feature exclusive to lymphocyte-driven adaptive immunity, immune memory has also been shown to operate as part of the innate immune system following infection to provide an elevated host response to subsequent pathogenic challenge. This evolutionarily conserved process, termed 'trained immunity', enables cells of the innate immune system to 'remember' previous pathogen encounters and mount stronger responses to the same, or different, pathogens after returning to a non-activated state. Here we show that challenging larval zebrafish, that exclusively rely on innate immunity, with live or heat-killed Salmonella typhimurium provides protection to subsequent infection with either Salmonella typhimurium or Streptococcus iniae, that lasts for at least 12 days. We also show that larvae injected with β-glucan, the well-known trigger of trained immunity, demonstrate enhanced survival to similar live bacterial infections, a phenotype supported by increased cxcl8 expression and neutrophil recruitment to the infection site. These results support the conservation of a trained immunity-like phenotype in larval zebrafish and provide a foundation to exploit the experimental attributes of larval zebrafish to further understand this form of immunological memory.

Deletion of both Dectin-1 and Dectin-2 affects the bacterial but not fungal gut microbiota and susceptibility to colitis in mice

BACKGROUND

Innate immunity genes have been reported to affect susceptibility to inflammatory bowel diseases (IBDs) and colitis in mice. Dectin-1, a receptor for fungal cell wall β-glucans, has been clearly implicated in gut microbiota modulation and modification of the susceptibility to gut inflammation. Here, we explored the role of Dectin-1 and Dectin-2 (another receptor for fungal cell wall molecules) deficiency in intestinal inflammation.

DESIGN

Susceptibility to dextran sodium sulfate (DSS)-induced colitis was assessed in wild-type, Dectin-1 knockout (KO), Dectin-2KO, and double Dectin-1KO and Dectin-2KO (D-1/2KO) mice. Inflammation severity, as well as bacterial and fungal microbiota compositions, was monitored.

RESULTS

While deletion of Dectin-1 or Dectin-2 did not have a strong effect on DSS-induced colitis, double deletion of Dectin-1 and Dectin-2 significantly protected the mice from colitis. The protection was largely mediated by the gut microbiota, as demonstrated by fecal transfer experiments. Treatment of D-1/2KO mice with opportunistic fungal pathogens or antifungal agents did not affect the protection against gut inflammation, suggesting that the fungal microbiota had no role in the protective phenotype. Amplicon-based microbiota analysis of the fecal bacterial and fungal microbiota of D-1/2KO mice confirmed the absence of changes in the mycobiota but strong modification of the bacterial microbiota. We showed that bacteria from the Lachnospiraceae family were at least partly involved in this protection and that treatment with Blautia hansenii was enough to recapitulate the protection.

CONCLUSIONS

Deletion of both the Dectin-1 and Dectin-2 receptors triggered a global shift in the microbial gut environment, affecting, surprisingly, mainly the bacterial population and driving protective effects in colitis. Members of the Lachnospiraceae family seem to play a central role in this protection. These findings provide new insights into the role of the Dectin receptors, which have been described to date as affecting only the fungal population, in intestinal physiopathology and in IBD. Video Abstract.

Thioredoxin-1: A Promising Target for the Treatment of Allergic Diseases

Thioredoxin-1 (Trx1) is an important regulator of cellular redox homeostasis that comprises a redox-active dithiol. Trx1 is induced in response to various stress conditions, such as oxidative damage, infection or inflammation, metabolic dysfunction, irradiation, and chemical exposure. It has shown excellent anti-inflammatory and immunomodulatory effects in the treatment of various human inflammatory disorders in animal models. This review focused on the protective roles and mechanisms of Trx1 in allergic diseases, such as allergic asthma, contact dermatitis, food allergies, allergic rhinitis, and drug allergies. Trx1 plays an important role in allergic diseases through processes, such as antioxidation, inhibiting macrophage migration inhibitory factor (MIF), regulating Th1/Th2 immune balance, modulating allergic inflammatory cells, and suppressing complement activation. The regulatory mechanism of Trx1 differs from that of glucocorticoids that regulates the inflammatory reactions associated with immune response suppression. Furthermore, Trx1 exerts a beneficial effect on glucocorticoid resistance of allergic inflammation by inhibiting the production and internalization of MIF. Our results suggest that Trx1 has the potential for future success in translational research.

Chronic Diseases Associated with Malassezia Yeast

Malassezia are a lipid-dependent basidiomycetous yeast of the normal skin microbiome, although Malassezia DNA has been recently detected in other body sites and has been associated with certain chronic human diseases. This new perspective raises many questions. Are these yeasts truly present in the investigated body site or were they contaminated by other body sites, adjacent or not? Does this DNA contamination come from living or dead yeast? If these yeasts are alive, do they belong to the resident mycobiota or are they transient colonizers which are not permanently established within these niches? Finally, are these yeasts associated with certain chronic diseases or not? In an attempt to shed light on this knowledge gap, we critically reviewed the 31 published studies focusing on the association of Malassezia spp. with chronic human diseases, including psoriasis, atopic dermatitis (AD), chronic rhinosinusitis (CRS), asthma, cystic fibrosis (CF), HIV infection, inflammatory bowel disease (IBD), colorectal cancer (CRC), and neurodegenerative diseases.

Janus kinase inhibitors for the therapy of atopic dermatitis

The JAK-STAT pathway is involved in the signaling of multiple cytokines driving cutaneous inflammation in atopic dermatitis (AD). Janus kinase (JAK) inhibitors target individual receptor-associated kinases, thereby preventing the mediation of inflammatory signals. Several JAK inhibitors with varying mechanism of action, potency, and safety represent potential therapeutic options for AD in both topical and systemic application. The JAK1/2 selective JAK inhibitor baricitinib was the first substance from this class of drugs approved by the EMA for the systemic oral treatment of AD. The clinical development program of the JAK1 selective inhibitors upadacitinib and abrocitinib is finalized with positive results for AD. The PAN-JAK inhibitor delgocitinib was the first substance being approved for the treatment of AD (in Japan). This review article covers the rising data on investigational and approved JAK inhibitors in the context of the treatment of AD.

HECT E3 Ubiquitin Ligase Nedd4 Is Required for Antifungal Innate Immunity

Candida albicans is the most common cause of fungal infections in humans, and disseminated candidiasis has become one of the leading causes of hospital-acquired bloodstream infections with a high mortality rate. However, little is known about the host-pathogen interactions and the mechanisms of antifungal immunity. Here, we report that Nedd4 (neuronal precursor cell-expressed developmentally downregulated 4) is essential for signaling through Dectin-1 and Dectin-2/3. We showed that mice that lack Nedd4 globally or only in the myeloid compartment are highly susceptible to systemic C. albicans infection, which correlates with heightened organ fungal burden, defective inflammatory response, impaired leukocyte recruitment to the kidneys, and defective reactive oxygen species expression by granulocytes. At the molecular level, Nedd4 -/- macrophages displayed impaired activation of TGF-β-activating kinase-1 and NF-κB, but normal activation of spleen tyrosine kinase and protein kinase C-δ on C. albicans yeast and hyphal infections. These data suggest that Nedd4 regulates signaling events downstream of protein kinase C-δ but upstream of or at TGF-β-activating kinase-1.

The Role of IL-17-Producing Cells in Cutaneous Fungal Infections

The skin is the outermost layer of the body and is exposed to many environmental stimuli, which cause various inflammatory immune responses in the skin. Among them, fungi are common microorganisms that colonize the skin and cause cutaneous fungal diseases such as candidiasis and dermatophytosis. The skin exerts inflammatory responses to eliminate these fungi through the cooperation of skin-component immune cells. IL-17 producing cells are representative immune cells that play a vital role in anti-fungal action in the skin by producing antimicrobial peptides and facilitating neutrophil infiltration. However, the actual impact of IL-17-producing cells in cutaneous fungal infections remains unclear. In this review, we focused on the role of IL-17-producing cells in a series of cutaneous fungal infections, the characteristics of skin infectious fungi, and the recognition of cell components that drive cutaneous immune cells.

Autoreactive T cells and their role in atopic dermatitis

Atopic dermatitis (AD) is an itchy, non-contagious relapsing and chronic inflammatory skin disease that usually develops in early childhood. This pathology is associated with food allergy, allergic asthma, allergic rhinitis and anaphylaxis which may persist in adulthood. The underlying mechanisms of AD (endotypes) are just beginning to be discovered and show a complex interaction of various pathways including skin barrier function and immune deviation. Immune reactions to self-proteins (autoantigens) of the skin have been identified in patients with inflammatory skin diseases, such as chronic spontaneous urticaria, connective tissue disease, pemphigus vulgaris and bullous pemphigoid. IgE antibodies and T cells directed against epitopes of the skin were observed in adult patients with severe and chronic AD as well. This was associated with disease severity and suggests a progression from allergic inflammation to severe autoimmune processes against the skin. IgE-mediated autoimmunity and self-reactive T cells might accelerate the ongoing skin inflammation or might contribute to the relapsing course of the disease. However, to date, the exact mechanisms of IgE-mediated autoimmunity and self-reactive T cells in the pathophysiology of AD are still unclear. The aim of this review is to evaluate the development of (autoreactive) T cells and their response to (auto)antigens, as well as the role of the peripheral tolerance in autoimmunity in the pathophysiology of AD, including the unmet needs and gaps.

Dectin-1 limits autoimmune neuroinflammation and promotes myeloid cell-astrocyte crosstalk via Card9-independent expression of Oncostatin M

Pathologic roles of innate immunity in neurologic disorders are well described, but their beneficial aspects are less understood. Dectin-1, a C-type lectin receptor (CLR), is largely known to induce inflammation. Here, we report that Dectin-1 limited experimental autoimmune encephalomyelitis (EAE), while its downstream signaling molecule, Card9, promoted the disease. Myeloid cells mediated the pro-resolution function of Dectin-1 in EAE with enhanced gene expression of the neuroprotective molecule, Oncostatin M (Osm), through a Card9-independent pathway, mediated by the transcription factor NFAT. Furthermore, we find that the Osm receptor (OsmR) functioned specifically in astrocytes to reduce EAE severity. Notably, Dectin-1 did not respond to heat-killed Mycobacteria, an adjuvant to induce EAE. Instead, endogenous Dectin-1 ligands, including galectin-9, in the central nervous system (CNS) were involved to limit EAE. Our study reveals a mechanism of beneficial myeloid cell-astrocyte crosstalk regulated by a Dectin-1 pathway and identifies potential therapeutic targets for autoimmune neuroinflammation.

Human Proteinase 3, an important autoantigen of c-ANCA associated vasculitis, shares cross-reactive epitopes with serine protease allergens from mites: an in silico analysis

Background: In autoimmune vasculitis, autoantibodies to Human Proteinase 3 (PR3), a human serine protease, seems to have a role on the inception of c-ANCA associated vasculitis. The origin of this autoreactive response remains unclear. However, for several autoreactive responses, molecular mimicry between environmental antigens and human proteins is key to trigger autoantibodies and finally autoimmunity manifestations. Considering that PR3 is a serine protease and house dust mite (HDM) group 3 allergens share this biochemical activity, the aim of this study was to identify cross-reactive epitopes between serine proteases from human and mites using an in silico approach. Methods: Multi alignment among amino acid sequences of PR3 and HDM group 3 allergens was performed to explore identity and structural homology. ElliPro and BepiPred  in silico tools were used to predict B and T cell epitopes. Consurf tool was used to conduct identification of conserved regions in serine proteases family. Results: PR3 and HDM group 3 allergens shared moderate identity and structural homology (root mean square deviation < 1). One B cell cross reactive epitope among serine proteases was identified (29I, 30V, 31G, 32G, 34E, 36K, 37A, 38L, 39A and 54C) and two T cell epitopes. Conclusions: PR3 have structural homology and share cross reactive epitopes with HDM group 3 allergens.

Human Proteinase 3, an important autoantigen of c-ANCA associated vasculitis, shares cross-reactive epitopes with serine protease allergens from mites: an in silico analysis

Background: In autoimmune vasculitis, autoantibodies to Human Proteinase 3 (PR3), a human serine protease, seems to have a role on the inception of c-ANCA associated vasculitis. The origin of this autoreactive response remains unclear. However, for several autoreactive responses, molecular mimicry between environmental antigens and human proteins is key to trigger autoantibodies and finally autoimmunity manifestations. Considering that PR3 is a serine protease and house dust mite (HDM) group 3 allergens share this biochemical activity, the aim of this study was to identify cross-reactive epitopes between serine proteases from human and mites using an in silico approach. Methods: Multi alignment among amino acid sequences of PR3 and HDM group 3 allergens was performed to explore identity and structural homology. ElliPro and BepiPred  in silico tools were used to predict B and T cell epitopes. Consurf tool was used to conduct identification of conserved regions in serine proteases family. Results: PR3 and HDM group 3 allergens shared moderate identity and structural homology (root mean square deviation < 1). One B cell cross reactive epitope among serine proteases was identified (29I, 30V, 31G, 32G, 34E, 36K, 37A, 38L, 39A and 54C) and two T cell epitopes. Conclusions: PR3 have structural homology and share cross reactive epitopes with HDM group 3 allergens.

Host Responses in an Ex Vivo Human Skin Model Challenged With Malassezia sympodialis

Malassezia species are a major part of the normal mycobiota and colonize mainly sebum-rich skin regions of the body. This group of fungi cause a variety of infections such as pityriasis versicolor, folliculitis, and fungaemia. In particular, Malassezia sympodialis and its allergens have been associated with non-infective inflammatory diseases such as seborrheic dermatitis and atopic eczema. The aim of this study was to investigate the host response to M. sympodialis on oily skin (supplemented with oleic acid) and non-oily skin using an ex vivo human skin model. Host-pathogen interactions were analyzed by SEM, histology, gene expression, immunoassays and dual species proteomics. The skin response to M. sympodialis was characterized by increased expression of the genes encoding β-defensin 3 and RNase7, and by high levels of S100 proteins in tissue. Supplementation of oleic acid onto skin was associated with direct contact of yeasts with keratinocytes and epidermal damage. In oily conditions, there was increased expression of IL18 but no expression of antimicrobial peptide genes in the skin’s response to M. sympodialis. In supernatants from inoculated skin plus oleic acid, TNFα, IL-6, and IL1-β levels were decreased and IL-18 levels were significantly increased.

Characterization of a common carp intelectin gene with bacterial binding and agglutination activity

Intelectin (ITLN) is a type of glycan-binding lectin involved in many physiological processes and some human diseases. Here we report a common carp intelectin (cITLN). Like other orthologs, cITLN also contains a conserved fibrinogen-related domain (FReD) and a unique intelectin domain, expresses in all the tissues tested with the highest level in the hindgut, and responds to bacterial challenge in the acute phase. We also expressed cITLN in Escherichia coli (E. coli) system, and the purified recombinant cITLN could neither affect the surface of bacteria nor inhibit the growth of bacteria, but it can agglutinate both gram-positive and gram-negative bacteria in a calcium-dependent manner. The cITLN's ability of agglutination of gram-positive bacteria is stronger than that of gram-negative bacteria. This is probably because recombinant cITLN could binding peptidoglycan (PGN) with a higher degree to lipopolysaccharide (LPS). Our results of cITLN provided new insight into the function of intelectin in the intestinal mucosal immunity.

The clinical impact of cross-reactions between allergens on allergic skin diseases

PURPOSE OF REVIEW

The route of allergen sensing via the skin appears to influence the immune system towards mounting a type 2 response, especially in genetically predisposed individuals. Allergens recognized this way may derive from microbial, animal, food, or other plant sources and trigger atopic dermatitis. Allergens can be grouped into families depending on their structure and function, harboring significant structural and sequence similarities. Cross-reactivity between allergens is believed to arise as a consequence, and to underlie the development of further atopic diseases.

RECENT FINDINGS

Especially for the plant allergens of the families of PR10-related proteins and profilins, immune cross-reactions have been described. Actual studies support that food and pollen allergens can aggravate skin lesions in patients suffering from atopic dermatitis. Further on, allergens derived from air-borne or skin-borne fungi belong to common allergen families and bear cross-reactivity potential. Cross-reactivity to human homologous proteins, so-called autoallergens, is discussed to contribute to the chronification of atopic dermatitis.

SUMMARY

Due to high evolutionary conservation, allergic reactions can be triggered by highly homologous members of allergen families on the humoral as well as on the cellular level.

The allergenic activity and clinical impact of individual IgE-antibody binding molecules from indoor allergen sources

A large number of allergens have been discovered but we know little about their potential to induce inflammation (allergenic activity) and symptoms. Nowadays, the clinical importance of allergens is determined by the frequency and intensity of their IgE antibody binding (allergenicity). This is a rather limited parameter considering the development of experimental allergology in the last 20 years and the criteria that support personalized medicine. Now it is known that some allergens, in addition to their IgE antibody binding properties, can induce inflammation through non IgE mediated pathways, which can increase their allergenic activity. There are several ways to evaluate the allergenic activity, among them the provocation tests, the demonstration of non-IgE mediated pathways of inflammation, case control studies of IgE-binding frequencies, and animal models of respiratory allergy. In this review we have explored the current status of basic and clinical research on allergenic activity of indoor allergens and confirm that, for most of them, this important property has not been investigated. However, during recent years important advances have been made in the field, and we conclude that for at least the following, allergenic activity has been demonstrated: Der p 1, Der p 2, Der p 5 and Blo t 5 from HDMs; Per a 10 from P. americana; Asp f 1, Asp f 2, Asp f 3, Asp f 4 and Asp f 6 from A. fumigatus; Mala s 8 and Mala s 13 from M. sympodialis; Alt a 1 from A. alternata; Pen c 13 from P. chrysogenum; Fel d 1 from cats; Can f 1, Can f 2, Can f 3, Can f 4 and Can f 5 from dogs; Mus m 1 from mice and Bos d 2 from cows. Defining the allergenic activity of other indoor IgE antibody binding molecules is necessary for a precision-medicine-oriented management of allergic diseases.

A comparative review of intelectins

Intelectin (ITLN) is a new type of glycan-binding lectin. It has been demonstrated to agglutinate bacteria probably due to its carbohydrate-binding capacity, suggesting its role in an innate immune response. It is involved not only in many physiological processes but also in some human diseases such as asthma, heart disease, inflammatory bowel disease, chronic obstructive pulmonary disease and cancer. Up to now, intelectin orthologs have been identified in placozoans, urochordatas, cephalochordates and several vertebrates, such as cyclostomata, fish, amphibians and mammals. Although the sequences of intelectins in different species are conserved, their expression patterns, quaternary structures and functions differ considerably among and within species. We summarize the evolution of the intelectin gene family, the tissue distribution, structure and functions of intelectins. We conclude that intelectin plays a role in innate immune response and there are still potential functions of intelectin awaiting discovery.