Chymotrypsin activity signals to intestinal epithelium by protease-activated receptor-dependent mechanisms.

Background And Purpose: Chymotrypsin is a pancreatic protease secreted into the lumen of the small intestine to digest food proteins. We hypothesized that chymotrypsin activity may be found close to epithelial cells and that chymotrypsin signals to them via protease-activated receptors (PARs). We deciphered molecular pharmacological mechanisms and gene expression regulation for chymotrypsin signalling in intestinal epithelial cells.

Involvement of mutation in a familial context of unexplained infertility and fertilization failure associated with hearing loss: a case report.

Objective: To explore the functional implications of a homozygous (cation channel for sperm) deletion within the acrosome reaction pathway during fertilization in 2 brothers, who have unexplained infertility and hearing loss.

Design: Case report.

Patients: Two twin brothers aged 30 years with hearing loss and unexplained infertility.

Elafin and its precursor trappin-2: What is their therapeutic potential for intestinal diseases?

Elafin and its precursor trappin-2 are known for their contribution to the physiological mucosal shield against luminal microbes. Such a contribution seems to be particularly relevant in the gut, where the exposure of host tissues to heavy loads of microbes is constant and contributes to mucosa-associated pathologies. The expression of trappin-2/elafin has been shown to be differentially regulated in diseases associated with gut inflammation.

Epithelial production of elastase is increased in inflammatory bowel disease and causes mucosal inflammation.

Imbalance between proteases and their inhibitors plays a crucial role in the development of Inflammatory Bowel Diseases (IBD). Increased elastolytic activity is observed in the colon of patients suffering from IBD. Here, we aimed at identifying the players involved in elastolytic hyperactivity associated with IBD and their contribution to the disease.

Colitis Linked to Endoplasmic Reticulum Stress Induces Trypsin Activity Affecting Epithelial Functions.

Background And Aims: Intestinal epithelial cells [IECs] from inflammatory bowel disease [IBD] patients exhibit an excessive induction of endoplasmic reticulum stress [ER stress] linked to altered intestinal barrier function and inflammation. Colonic tissues and the luminal content of IBD patients are also characterized by increased serine protease activity. The possible link between ER stress and serine protease activity in colitis-associated epithelial dysfunctions is unknown.

A role for early oral exposure to house dust mite allergens through breast milk in IgE-mediated food allergy susceptibility.

Background: Successful prevention of food allergy requires the identification of the factors adversely affecting the capacity to develop oral tolerance to food antigen in early life.

Objectives: This study sought to determine whether oral exposure to Dermatophagoides pteronyssinus through breast milk affects gut mucosal immunity with long-term effects on IgE-mediated food allergy susceptibility.

Methods: Gut immunity was explored in 2-week-old mice breast-fed by mothers exposed to D pteronyssinus, protease-inactivated D pteronyssinus, or to PBS during lactation.

House dust mites activate nociceptor-mast cell clusters to drive type 2 skin inflammation.

Allergic skin diseases, such as atopic dermatitis, are clinically characterized by severe itching and type 2 immunity-associated hypersensitivity to widely distributed allergens, including those derived from house dust mites (HDMs). Here we found that HDMs with cysteine protease activity directly activated peptidergic nociceptors, which are neuropeptide-producing nociceptive sensory neurons that express the ion channel TRPV1 and Tac1, the gene encoding the precursor for the neuropeptide substance P. Intravital imaging and genetic approaches indicated that HDM-activated nociceptors drive the development of allergic skin inflammation by inducing the degranulation of mast cells contiguous to such nociceptors, through the release of substance P and the activation of the cationic molecule receptor MRGPRB2 on mast cells.

Sexual dimorphism in PAR-dependent regulation of primitive colonic cells.

Background: Sexual dimorphism in biological responses is a critical knowledge for therapeutic proposals. However, gender differences in intestinal stem cell physiology have been poorly studied. Given the important role of the protease-activated receptor PAR in the control of colon epithelial primitive cells and cell cycle genes, we have performed a sex-based comparison of its expression and of the effects of PAR activation or knockout on cell proliferation and survival functions.

Active thrombin produced by the intestinal epithelium controls mucosal biofilms.

Proteolytic homeostasis is important at mucosal surfaces, but its actors and their precise role in physiology are poorly understood. Here we report that healthy human and mouse colon epithelia are a major source of active thrombin. We show that mucosal thrombin is directly regulated by the presence of commensal microbiota.

Functional Proteomic Profiling of Secreted Serine Proteases in Health and Inflammatory Bowel Disease.

While proteases are essential in gastrointestinal physiology, accumulating evidence indicates that dysregulated proteolysis plays a pivotal role in the pathophysiology of inflammatory bowel disease (IBD). Nonetheless, the identity of overactive proteases released by human colonic mucosa remains largely unknown. Studies of protease abundance have primarily investigated expression profiles, not taking into account their enzymatic activity.

Protease-activated receptor 2 contributes to Toxoplasma gondii-mediated gut inflammation.

Toxoplasma gondii is a widespread intracellular parasite, which naturally enters the organism via the oral route and crosses the intestinal barrier to disseminate. In addition to neuronal and ocular pathologies, this pathogen also causes gut inflammation in a number of animals. This infection-triggered inflammation has been extensively studied in the C57BL/6 mice, highlighting the importance of the immune cells and their mediators in the development of gut pathology.

PAR2-dependent activation of GSK3β regulates the survival of colon stem/progenitor cells.

Protease-activated receptors PAR1 and PAR2 play an important role in the control of epithelial cell proliferation and migration. However, the survival of normal and tumor intestinal stem/progenitor cells promoted by proinflammatory mediators may be critical in oncogenesis. The glycogen synthase kinase-3β (GSK3β) pathway is overactivated in colon cancer cells and promotes their survival and drug resistance.

Presence of commensal house dust mite allergen in human gastrointestinal tract: a potential contributor to intestinal barrier dysfunction.

Background: Abnormal gut barrier function is the basis of gut inflammatory disease. It is known that house dust mite (HDM) aero-allergens induce inflammation in respiratory mucosa. We have recently reported allergen from Dermatophagoides pteronyssinus (Der p1) to be present in rodent gut.

Mutations in TFIIH causing trichothiodystrophy are responsible for defects in ribosomal RNA production and processing.

The basal transcription/repair factor II H (TFIIH), found mutated in cancer-prone or premature aging diseases, plays a still unclear role in RNA polymerase I transcription. Furthermore, the impact of this function on TFIIH-related diseases, such as trichothiodystrophy (TTD), remains to be explored. Here, we studied the involvement of TFIIH during the whole process of ribosome biogenesis, from RNAP1 transcription to maturation steps of the ribosomal RNAs.

Mammalian HCA66 protein is required for both ribosome synthesis and centriole duplication.

Ribosome production, one of the most energy-consuming biosynthetic activities in living cells, is adjusted to growth conditions and coordinated with the cell cycle. Connections between ribosome synthesis and cell cycle progression have been described, but the underlying mechanisms remain only partially understood. The human HCA66 protein was recently characterized as a component of the centrosome, the major microtubule-organizing center (MTOC) in mammalian cells, and was shown to be required for centriole duplication and assembly of the mitotic spindle.

Elastase 2 is expressed in human and mouse epidermis and impairs skin barrier function in Netherton syndrome through filaggrin and lipid misprocessing.

The human epidermis serves 2 crucial barrier functions: it protects against water loss and prevents penetration of infectious agents and allergens. The physiology of the epidermis is maintained by a balance of protease and antiprotease activities, as illustrated by the rare genetic skin disease Netherton syndrome (NS), in which impaired inhibition of serine proteases causes severe skin erythema and scaling. Here, utilizing mass spectrometry, we have identified elastase 2 (ELA2), which we believe to be a new epidermal protease that is specifically expressed in the most differentiated layer of living human and mouse epidermis.

Evolutionarily conserved function of RRP36 in early cleavages of the pre-rRNA and production of the 40S ribosomal subunit.

Ribosome biogenesis in eukaryotes is a major cellular activity mobilizing the products of over 200 transcriptionally coregulated genes referred to as the rRNA and ribosome biosynthesis regulon. We investigated the function of an essential, uncharacterized gene of this regulon, renamed RRP36. We show that the Rrp36p protein is nucleolar and interacts with 90S and pre-40S preribosomal particles.

Kallikrein 5 induces atopic dermatitis-like lesions through PAR2-mediated thymic stromal lymphopoietin expression in Netherton syndrome.

Netherton syndrome (NS) is a severe genetic skin disease with constant atopic manifestations that is caused by mutations in the serine protease inhibitor Kazal-type 5 (SPINK5) gene, which encodes the protease inhibitor lymphoepithelial Kazal-type-related inhibitor (LEKTI). Lack of LEKTI causes stratum corneum detachment secondary to epidermal proteases hyperactivity. This skin barrier defect favors allergen absorption and is generally regarded as the underlying cause for atopy in NS.

Increased serine protease activity and cathelicidin promotes skin inflammation in rosacea.

Acne rosacea is an inflammatory skin disease that affects 3% of the US population over 30 years of age and is characterized by erythema, papulopustules and telangiectasia. The etiology of this disorder is unknown, although symptoms are exacerbated by factors that trigger innate immune responses, such as the release of cathelicidin antimicrobial peptides. Here we show that individuals with rosacea express abnormally high levels of cathelicidin in their facial skin and that the proteolytically processed forms of cathelicidin peptides found in rosacea are different from those present in normal individuals.

LEKTI fragments specifically inhibit KLK5, KLK7, and KLK14 and control desquamation through a pH-dependent interaction.

LEKTI is a 15-domain serine proteinase inhibitor whose defective expression underlies the severe autosomal recessive ichthyosiform skin disease, Netherton syndrome. Here, we show that LEKTI is produced as a precursor rapidly cleaved by furin, generating a variety of single or multidomain LEKTI fragments secreted in cultured keratinocytes and in the epidermis. The identity of these biological fragments (D1, D5, D6, D8-D11, and D9-D15) was inferred from biochemical analysis, using a panel of LEKTI antibodies.

Kallikrein-mediated proteolysis regulates the antimicrobial effects of cathelicidins in skin.

The presence of cathelicidin antimicrobial peptides provides an important mechanism for prevention of infection against a wide variety of microbial pathogens. The activity of cathelicidin is controlled by enzymatic processing of the proform (hCAP18 in humans) to a mature peptide (LL-37 in human neutrophils). In this study, elements important to the processing of cathelicidin in the skin were examined.

SPINK5, the defective gene in netherton syndrome, encodes multiple LEKTI isoforms derived from alternative pre-mRNA processing.

The multidomain serine protease inhibitor lymphoepithelial Kazal-type related inhibitor (LEKTI) represents a key regulator of the proteolytic events occurring during epidermal barrier formation and hair development, as attested by the severe autosomal recessive ichthyosiform skin condition Netherton syndrome (NS) caused by mutations in its encoding gene, serine protease inhibitor Kazal-type 5 (SPINK5). Synthesized as a proprotein, LEKTI is rapidly cleaved intracellularly, thus generating a number of potentially bioactive fragments that are secreted. Here, we show that SPINK5 generates three classes of transcripts encoding three different LEKTI isoforms, which differ in their C-terminal portion.

LEKTI is localized in lamellar granules, separated from KLK5 and KLK7, and is secreted in the extracellular spaces of the superficial stratum granulosum.

Lympho-epithelial Kazal-type-related inhibitor (LEKTI) is a putative serine protease inhibitor encoded by serine protease inhibitor Kazal-type 5 (SPINK5). It is strongly expressed in differentiated keratinocytes in normal skin but expression is markedly reduced or absent in Netherton syndrome (NS), a severe ichthyosis caused by SPINK5 mutations. At present, however, both the precise intracellular localization and biological roles of LEKTI are not known.