Modulation of cutaneous inflammation by angiotensin-converting enzyme

Exploring the Impact of ACE Inhibition in Immunity and Disease

Angiotensin-converting enzyme (ACE) is a zinc-dependent dipeptidyl carboxypeptidase and is crucial in the renin-angiotensin-aldosterone system (RAAS) but also implicated in immune regulation. Intrinsic ACE has been detected in several immune cell populations, including macrophages and neutrophils, where its overexpression results in enhanced bactericidal and antitumour responses, independent of angiotensin II. With roles in antigen presentation and inflammation, the impact of ACE inhibitors must be explored to understand how ACE inhibition may impact our ability to clear infections or malignancy, particularly in the wake of the coronavirus (SARS-CoV2) pandemic and as antibiotic resistance grows. Patients using ACE inhibitors may be more at risk of postsurgical complications as ACE inhibition in human neutrophils results in decreased ROS and phagocytosis whilst angiotensin receptor blockers (ARBs) have no effect. In contrast, ACE is also elevated in certain autoimmune diseases such as rheumatoid arthritis and lupus, and its inhibition benefits patient outcome where inflammatory immune cells are overactive. Although the ACE autoimmune landscape is changing, some studies have conflicting results and require further input. This review seeks to highlight the need for further research covering ACE inhibitor therapeutics and their potential role in improving autoimmune conditions, cancer, or how they may contribute to immunocompromise during infection and neurodegenerative diseases. Understanding ACE inhibition in immune cells is a developing field that will alter how ACE inhibitors are designed in future and aid in developing therapeutic interventions.

Genetic variants affecting chemical mediated skin immunotoxicity

The skin is an immune-competent organ and this function may be impaired by exposure to chemicals, which may ultimately result in immune-mediated dermal disorders. Interindividual variability to chemical-induced skin immune reactions is associated with intrinsic individual characteristics and their genomes. In the last 30-40 years, several genes influencing susceptibility to skin immune reactions were identified. The aim of this review is to provide information regarding common genetic variations affecting skin immunotoxicity. The polymorphisms selected for this review are related to xenobiotic-metabolizing enzymes (CYPA1 and CYPB1 genes), antioxidant defense (GSTM1, GSTT1, and GSTP1 genes), aryl hydrocarbon receptor signaling pathway (AHR and ARNT genes), skin barrier function transepidermal water loss (FLG, CASP14, and SPINK5 genes), inflammation (TNF, IL10, IL6, IL18, IL31, and TSLP genes), major histocompatibility complex (MHC) and neuroendocrine system peptides (CALCA, TRPV1, ACE genes). These genes present variants associated with skin immune responses and diseases, as well as variants associated with protecting skin immune homeostasis following chemical exposure. The molecular and association studies focusing on these genetic variants may elucidate their functional consequences and contribution in the susceptibility to skin immunotoxicity. Providing information on how genetic variations affect the skin immune system may reduce uncertainties in estimating chemical hazards/risks for human health in the future.

The Immunogenetics of Vitiligo: An Approach Toward Revealing the Secret of Depigmentation

Vitiligo is a hypomelanotic skin disease and considered to be of autoimmune origin due to breaching of immunological self-tolerance, resulting in inappropriate immune responses against melanocytes. The development of vitiligo includes a strong heritable component. Different strategies ranging from linkage studies to genome-wide association studies are used to explore the genetic factors responsible for the disease. Several vitiligo loci containing the respective genes have been identified which contribute to vitiligo and genetic variants for some of the genes are still unknown. These genes include mainly the proteins that play a role in immune regulation and a few other genes important for apoptosis and regulation of melanocyte functions. Despite the available data on genetic variants and risk alleles which influence the biological processes, only few immunological pathways have been found responsible for all ranges of severity and clinical manifestations of vitiligo. However, studies have concluded that vitiligo is of autoimmune origin and manifests due to complex interactions in immune components and their inappropriate response toward melanocytes. The genes involved in the immune regulation and processing the melanocytes antigen and its presentation can serve as effective immune-therapeutics that can target specific immunological pathways involved in vitiligo. This chapter highlights those immune-regulatory genes involved in vitiligo susceptibility and loci identified to date and their implications in vitiligo pathogenesis.

Disclosing the involvement of proteases in an eczema murine animal model: Perspectives for protease inhibitor-based therapies

Eczema is a skin condition characterized by itchy and inflammatory patches. The accumulation of neutrophils and the imbalance between enzymes and their inhibitors appears to be related to this condition. We proposed a neutrophil elastase (NE)-based eczema model in mice in order to verify histopathological features as well as the expression and activity of proteases and inhibitors. Mice skins were topically administered with human NE (0-2 pmol/cm²) for 24-168 h. It was observed thickening of epidermis, parakeratosis, spongiosis and leukocyte infiltration. Also, NE-treated skins presented high activity of epidermal kallikreins 5 and 7, and cathepsin B on synthetic substrates, and expression evaluated by RT-qPCR. The proteolytic activity was inhibited by soybean trypsin inhibitor, CA074 and Caesalpinia echinata kallikrein inhibitor (CeKI). The topic application of CeKI reversed eczema phenotype in NE-treated skins. Elafin expression was shown to be increased in NE-treated skins. These results suggest that the NE may trigger morphological and biochemical changes in skin similar to those observed in eczematous diseases. In addition to the establishment of this in vivo model, this work opens perspectives for the use of protease inhibitor-based drugs for the management of this skin condition.

The Immunogenicity of Hyaluronic Fillers and Its Consequences

Hyaluronic acid (HA) is a glycosaminoglycan, a natural component of the extracellular matrix. The identical structure of the molecule in all living organisms is its main advantage, as it translates into the minimal probability of immunogenicity. Therefore, it is the closest to the ideal preparation used as a filler, due to its biocompatibility and stability at the site of implantation. This paper includes the discussion of the potential mechanisms of adverse immune reactions to HA along with the mechanisms of reaction following vaccinations against SARS-CoV-2. Based on the literature, we tried to systematize adverse immune reactions with systemic manifestations to HA. The occurrence of unpredictable reactions to hyaluronic acid indicates that they may not be treated as neutral or non-allergenic. The modifications of the chemical structure of HA, additives and individual tendencies in a patient may be the cause of unpredictable reactions, leading to serious health consequences. Preparations of unknown origin, poorly purified, or including bacterial DNA are particularly dangerous. Therefore, long-lasting follow-up of the patient and the selection of a preparation approved by the FDA or EMA are of high importance. Patients are often unaware of the consequences of cheaper procedures performed by persons without suitable knowledge with the use of unregistered products, so the public should be educated and legal regulations should be introduced.

Current views on neuropeptides in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease involving skin barrier dysfunction and immune imbalance. However, the mechanism of AD is not clear completely and may be related to heredity and environment. Neuropeptides are a class of peptides secreted by nerve endings, they may play roles in promoting vasodilation, plasma extravasation, chemotaxis of inflammatory cells and mediating pruritus. Since itching and immune cell infiltration are the main manifestations of atopic dermatitis, to further investigate the impact of neuropeptides on AD, our review summarized the mechanisms of several common neuropeptides in AD and hypothesized that neuropeptides may be the novel potential targets in AD treatment.

"COVID-19/SARS-CoV-2 virus spike protein-related delayed inflammatory reaction to hyaluronic acid dermal fillers: a challenging clinical conundrum in diagnosis and treatment"

We present the first reported cases of delayed inflammatory reactions (DIR) to hyaluronic acid (HA) dermal fillers after exposure to the COVID-19 spike protein. DIR to HA is reported to occur in the different scenarios including: secondary to poor injection technique, following dental cleaning procedures, following bacterial/viral illness, and after vaccination. In this report of 4 cases with distinct clinical histories and presentations: one case occured following a community acquired COVID-19 infection, one case occured in a study subject in the mRNA-1273 clinical phase III trial, one case occurred following the first dose of publically available mRNA-1273 vaccine (Moderna, Cambridge MA), and the last case occurred after the second dose of BNT162b2 vaccine (Pfizer, New York, NY). Injectable HA dermal fillers are prevalent in aesthetic medicine for facial rejuvenation. Structural modifications in the crosslinking of HA fillers have enhanced the products’ resistance to enzymatic breakdown and thus increased injected product longevity, however, have also led to a rise in DIR. Previous, DIR to HA dermal fillers can present clinically as edema with symptomatic and inflammatory erythematous papules and nodules. The mechanism of action for the delayed reaction to HA fillers is unknown and is likely to be multifactorial in nature. A potential mechanism of DIR to HA fillers in COVID-19 related cases is binding and blockade of angiotensin 2 converting enzyme receptors (ACE2), which are targeted by the SARS-CoV-2 virus spike protein to gain entry into the cell. Spike protein interaction with dermal ACE2 receptors favors a pro-inflammatory, loco-regional TH1 cascade, promoting a CD8+T cell mediated reaction to incipient granulomas, which previously formed around residual HA particles. Management to suppress the inflammatory response in the native COVID-19 case required high-dose corticosteroids (CS) to suppress inflammatory pathways, with concurrent ACE2 upregulation, along with high-dose intralesional hyaluronidase to dissolve the inciting HA filler. With regards to the two vaccine related cases; in the mRNA-1273 case, a low dose angiotensin converting enzyme inhibitor (ACE-I) was utilized for treatment, to reduce pro-inflammatory Angiotensin II. Whereas, in the BNT162b2 case the filler reaction was suppressed with oral corticosteroids. Regarding final disposition of the cases; the vaccine-related cases returned to baseline appearance within 3 days, whereas the native COVID-19 case continued to have migratory, evanescent, periorbital edema for weeks which ultimately subsided.

Angiotensin-converting enzyme gene insertion/deletion polymorphism and susceptibility to psoriasis: a systematic review and meta-analysis

BACKGROUND

Psoriasis is a multifactorial disorder, impacted by both genetic and environmental factors. Herein, a meta-analysis assessed the association of angiotensin-converting enzyme gene insertion/deletion (ACE I/D) polymorphism and psoriasis susceptibility.

METHODS

A systematic search was used in databases of PubMed/Medline, Scopus, Web of Science, and Cochrane Library up to January 2019 without language restriction. A dichotomous analysis was carried out by RevMan 5.3 using crude odds ratio (OR) and 95% confidence interval (CI) to investigate the association between ACE I/D polymorphisms and the risk of psoriasis. A funnel plot analysis was used by CMA 2.0 to estimate a significant existence of publication bias.

RESULTS

Out of 61 studies retrieved from the databases, 16 studies were included in the meta-analysis. The pooled ORs for models of D vs. I, DD vs. II, ID vs. II, ID + DD vs. II, and DD vs. II + ID genotypes were 0.96 [95%CI: 0.82, 1.12; P = 0.58], 0.99 [95%CI, 0.73, 1.36; P = 0.96], 0.81 [95%CI, 0.72, 0.91; p: 0.0003], 0.91 [95%CI, 0.73, 1.13; P = 0.40], and 1.05 [95%CI, 0.85, 1.30; P = 0.68], respectively. A significant difference between ACE polymorphisms in patients with/without family history for the disease [OR = 1.44; 95%CI: 1.24, 1.67; P < 0.001] and also in patients mild/severe psoriasis [OR = 0.70; 95%CI: 0.55, 0.88; P = 0.002] was identified.

CONCLUSION

The results of the meta-analysis showed that ACE I/D polymorphism may be associated with psoriasis susceptibility, while ID genotype seemed to have a protective role in Caucasian patients affected by psoriatic arthritis and in studies with hospital-based controls.

Risk and severity of psoriasis vulgaris in relation to angiotensin II type 1 receptor gene polymorphism and metabolic syndrome

Background

Psoriasis vulgaris is a chronic inflammatory and proliferative skin disease, characterized by the formation of itchy, erythematous skin patches or plaques. Patients with psoriasis are at an increased risk of developing metabolic syndrome, including obesity, hypertension, diabetes, and atherosclerosis. Recently, angiotensin II (Ang II) has been reported to be associated with the development of psoriasis. Ang II not only increases the blood pressure but is also a potent proinflammatory modulator and functions through interaction with angiotensin II type 1 receptor (AT1R). Moreover, it is hypothesized that the AT1R gene expression could be correlated with the severity of psoriasis and/or metabolic syndrome.

Aim

We examined the association of Ang II type 1 receptor (AT1R) A1166C gene polymorphisms and metabolic syndrome with the severity of psoriasis.

Patients and methods

The present case-control study included 25 patients with psoriasis vulgaris and 25 healthy subjects in Egypt. The psoriasis lesions in the patient group were assessed using the psoriasis area and severity index (PASI) score. The AT1R polymorphism A1166C (rs5186) was studied using restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR) amplification of the gene from the whole blood sample in both groups. Serum lipid profile and blood sugar levels were assessed post 12 h and 8 h fasting, respectively, in both groups. The severity of metabolic syndrome was evaluated using the severity score.

Results

The results of the present study demonstrated that the AT1R A1166C gene polymorphisms increased the risk of developing psoriasis in the Egyptian population. We found that 70% of patients with AC genotype and 100% of patients CC genotype reported a PASI score >20 and were considered to be severe cases with a statistically significant difference as compared with patients with AA genotype (p=0.003). In addition, a high statistically significant difference (p=0.001) existed among AT1R genotypes with respect to the percentage of metabolic syndrome in psoriasis patients. Similarly, a statistically significant difference (p=0.004) among AT1R genotypes with respect to metabolic score was found, with the highest level of score and percentage observed in patients with CC genotype than in patients with AC genotype. The lowest level was present among those with AA genotype.

Conclusion

Patients with psoriasis expressing the C allele of AT1R1166 are susceptible to developing metabolic syndrome and have higher PASI scores as compared with patients carrying the A allele.

Angiotensin-Converting Enzyme (ACE) D Allele as a Risk Factor for Increase Serum Interleukin-6 and Interleukin-8 in Psoriasis Patients

BACKGROUND:

Psoriasis is a chronic, recurrent inflammatory skin disease. It is characterised by autoimmune, environmental factors and complex genetic disorder.

AIM:

To explore the role of IL-6, IL-8, and ACE I/D polymorphism in the pathogenesis of Psoriasis and investigation of the relationship between ACE polymorphism and occurrence of psoriasis.

PATIENTS AND METHODS:

In this study, we took 73 psoriasis patients and 47 healthy patients as a control. These two groups subjected to analysis for ACE gene I/D polymorphism by PCR and biochemical methods.

RESULTS:

The serum levels of ACE, IL-8 and IL-6 were statistically significantly higher in psoriasis patients compared to healthy subjects (P < 0.001). ID and DD polymorphism were more common in psoriasis patients than healthy subjects. Also, D allele was significantly over-represented in patients compared to controls (52.7% Vs 35.1%).

CONCLUSION:

ACE gene polymorphism might grant susceptibility to develop psoriasis.

NK-1 Antagonists and Itch

Substance P (SP) is an important mediator of pro-inflammatory mechanisms in the skin. It targets multiple cells such as keratinocytes, mast cells, and fibroblasts which are involved in the cutaneous generation of pruritus. This suggests that SP is an interesting target for therapy. In fact, in recent case reports and case series, SP antagonists demonstrated a significant antipruritic effect in acute and chronic pruritus such as drug-induced pruritus, paraneoplastic pruritus, prurigo nodularis, cutaneous T-cell lymphoma, and brachioradial pruritus.

Serum Angiotensin converting enzyme in pemphigus vulgaris

Background:

Pemphigus vulgaris is an autoimmune blistering skin disease with unknown etiology. Drugs such as angiotensin-converting enzyme (ACE) inhibitors may contribute in the pathogenesis of pemphigus.

Objective:

We plan this essay to evaluate the serum ACE level in pemphigus vulgaris patients in comparison with healthy controls to recognize its possible role in disease pathogenesis or activity.

Methods:

This study was planned and performed in the dermatology clinics of Shahid Beheshti University of MedicalSciences’ Hospitals between July 2010 and June 2011. Patients with new onset of pemphigus vulgaris were enrolled in our study. Control subjects were frequency-matched to cases by sex and age. Serum ACE was determined by the spectrophotometric method.

Results:

Thirty-four patients with pemphigus vulgaris and 35 healthy individuals were recruited in the study. No statistical significant difference was detected in the mean level of serum ACE of the two groups (t-test, P = 0.11). The mean ACE level was significantly lower in male patients compared with male controls (P = 0.04). Moreover, a significant higher serum ACE level of patients with cutaneous involvement was observed compared to patients with mucosal involvement (P = 0.02).

Conclusions:

Despite lack of any significant difference of serum ACE level between pemphigus and control group, the serum ACE level was considerably lower in male pemphigus vulgaris patients compared with male controls. Therefore, ACE might have some association with pemphigus vulgaris especially in male patients; however, further studies are required to confirm this association.

Genetically Modified Mice as a Tool to Study Inflammatory Skin Diseases

Although mice have a long tradition as models for human skin diseases, they have recently received increasingly more attention. This is because of the rapid advancement of genetic engineering methods which made it possible to create mice with precisely defined genetic changes. Many of these mice develop impressive and sometimes unexpected, puzzling phenotypes. Their interpretation is a major challenge to the basic researcher and can often be ameliorated by the input of an experienced dermatologist. Together with recent examples of genetically modified mouse models of inflammatory skin diseases we give a short overview of the methods used to generate such mice, describe possible ways to analyse them, and discuss problems that arise in the interpretation of the findings.

Research in practice: substance P antagonism in chronic pruritus

Pruritus is an unpleasant sensation of the skin, which triggers a desire to scratch or rub. The chronic form (≥6 weeks' duration) often occurs as a side effect of many diseases and is usually accompanied by a high loss in quality of life for patients, especially in cases in which the symptom is chronic without adequate treatment options. In recent years, the situation improved continuously, guidelines for chronic pruritus have been defined and standard medications have been proposed. For many reasons, there are still patients who are unable to obtain relief. New therapeutic approaches are therefore urgently needed. Blocking the neuropeptide substance P is a promising strategy; substance P mediates clinically relevant pro-inflammatory effects by binding to the neurokinin 1 receptor (NK-1R). This led us to hypothesize that NK-1R antagonists are promising therapeutic options for chronic pruritus. Several international case series have meanwhile proven the antipruritic effect of the NK-1R antagonist aprepitant for various forms of chronic pruritus. Initiation of clinical trials with new NK-1R-antagonists as a new therapeutic option continues this trend.

The angiotensin-converting enzyme gene insertion/deletion polymorphism in Indian patients with vitiligo: a case-control study and meta-analysis

BACKGROUND

Vitiligo is a common, acquired, idiopathic depigmenting skin disorder. Although the exact pathogenesis remains unknown, genetic susceptibility and autoimmune responses play a role in vitiligo development. Previous studies have suggested that the D allele of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with vitiligo in Indians and Koreans. Furthermore, significantly higher serum ACE levels have been demonstrated in patients with some autoimmune and autoinflammatory disorders.

OBJECTIVES

The objectives were to investigate any association between the ACE I/D polymorphism and vitiligo susceptibility in an Indian population, and to compare serum ACE levels in patients with vitiligo and healthy subjects.

METHODS

The ACE I/D genotypes of 79 patients with vitiligo and 100 normal individuals were determined by polymerase chain reaction amplification. A meta-analysis was done to compare the distribution of the ACE I/D alleles and genotypes in the current and three previous studies. Serum ACE levels were evaluated by enzyme-linked immunosorbent assay.

RESULTS

A significant increase in the frequency of the ACE I/D D allele was evident in patients with vitiligo in both the case-control study [P=0·005; odds ratio (OR) 1·87; 95% confidence intervals (CI) 1·22-2·85] and the meta-analysis (P=0·044; OR 1·44; 95% CI 1·01-2·06). Serum ACE levels were significantly increased in patients with vitiligo compared with healthy subjects (P<0·0001).

CONCLUSIONS

In agreement with earlier reports, the ACE I/D D allele is associated with vitiligo susceptibility in the Indian population. The significantly elevated serum ACE levels in our cohort of patients with vitiligo concur with those previously found in patients with some other autoimmune diseases.

Angiotensin-converting enzyme gene polymorphisms and the risk of psoriasis: a meta-analysis

BACKGROUND

The gene coding for angiotensin-converting enzyme (ACE) has been reported to be associated with the development of psoriasis.

AIM

To evaluate the association of psoriasis risk and ACE polymorphisms.

METHODS

We carried out a retrieval of studies that explored associations between ACE polymorphism and psoriasis, and analysed the genotype frequencies.

RESULTS

In total, 8 studies with 1242 patients and 1646 controls were included. The genotype frequencies in all studies were in Hardy-Weinberg equilibrium. After pooling all studies, the results indicated that the I/I genotype was associated with risk of psoriasis (OR = 1.41, 95% CI 1.11-1.80, P = 0.005), whereas the I/D genotype may decrease the risk of psoriasis (OR = 0.71, 95% CI 0.56-0.90, P = 0.005) in Asian, but not in white populations.

CONCLUSIONS

Our study suggests that ACE polymorphism are associated with the risk of psoriasis in Asians, especially the I/I genotype and I allele. Further studies are needed to confirm our results.

Angiotensin-converting enzyme insertion/deletion polymorphism and susceptibility to psoriasis in a Chinese population

INTRODUCTION

The relationship between the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism and psoriasis has previously been studied mainly in Caucasians and only once in Asians. The aim of this study is to evaluate the association between the ACE I/D polymorphism and the risk of psoriasis in a Chinese population.

MATERIALS AND METHODS

The study population consisted of 668 psoriasis patients and 668 matched control subjects. The ACE I/D gene polymorphism was analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The frequency of the ACE II genotype (odds ratio (OR) = 1.32, 95% confidence interval (CI) = 1.06, 1.63; P = 0.01) and I allele (OR = 1.25, 95% CI = 1.06, 1.48; P = 0.01) in patients with psoriasis was significantly higher than that in the control group. And the D allele frequency in patients with psoriasis was significantly lower (OR = 0.80, 95% CI = 0.68, 0.95; P = 0.01) than that in the control group. When stratified by family history, the frequency of the DD genotype was marginally significantly lower in patients with a positive family history of psoriasis (familial psoriasis) than in those with negative (sporadic psoriasis) (OR = 0.47, 95% CI = 0.23, 0.97; P = 0.04). When stratified by onset of the disease, type of psoriasis and the severity of psoriasis, no statistically significant result was observed.

CONCLUSION

Our study suggested that the ACE II genotype and I allele might confer susceptibility to psoriasis in a Chinese population.

[Genetics of contact allergy]

The genetics of contact allergy (CA) is still only partly understood, despite decades of research. This might be due to inadequately defined phenotypes used in the past. Therefore we suggested studying an extreme phenotype, namely, polysensitization (sensitization to 3 or more unrelated allergens). Another approach to unravel the genetics of CA has been the study of candidate genes. In this review, we summarize studies on the associations between genetic variation (e.g. SNPs) in certain candidate genes and CA. The following polymorphisms and mutations were studied: (1) filaggrin, (2) N-acetyltransferase (NAT1 and 2), (3) glutathione-S-transferase (GST M and T), (4) manganese superoxide dismutase, (5) angiotensin-converting enzyme (ACE), (6) tumor necrosis factor (TNF), and (7) interleukin-16 (IL16). The polymorphisms of NAT1/2, GST M/T, ACE, TNF, and IL16 were shown to be associated with an increased risk of CA. In one of our studies, the increased risk conferred by the TNF and IL16 polymorphisms was confined to polysensitized individuals. Other relevant candidate genes may be identified by studying diseases related to CA in terms of clinical symptoms, a more general pathology (inflammation) and possibly an overlapping genetic background, such as irritant contact dermatitis.

Genetic factors in contact allergy--review and future goals

The genetics of contact allergy are still only partly understood, despite decades of research; this might be a consequence of inadequately defined phenotypes used in the past. A recommendation is to study an extreme phenotype, namely, polysensitization (sensitization to three or more unrelated allergens). Another approach to unravel the genetics of contact allergy is the study of candidate genes. In this review, we summarize studies on the associations between genetic variation (e.g. single-nucleotide polymorphisms) in certain candidate genes and contact allergy. Polymorphisms and mutations affecting the following proteins were studied: (i) filaggrin; (ii) N-acetyltransferase (NAT) 1 and 2; (iii) glutathione-S-transferase (GST) M and T; (iv) manganese superoxide dismutase; (v) angiotensin-converting enzyme (ACE); (vi) tumour necrosis factor (TNF); and (vii) interleukin-16 (IL-16). The polymorphisms of NAT1, NAT2, GSTM, GSTT, ACE, TNF and IL-16 were shown to be associated with an increased risk of contact allergy. In one of our studies, the increased risk conferred by the TNF and IL-16 polymorphisms was confined to polysensitized individuals. Other relevant candidate genes may be identified by studying diseases related to contact allergy in terms of clinical symptoms, a more general pathology (inflammation), and possibly an overlapping genetic background, such as irritant contact dermatitis.

Association of angiotensin converting enzyme gene insertion/deletion polymorphism with lung cancer in Turkey

Angiotensin-converting enzyme (ACE) plays an important role in the physiological control of blood pressure and inflammation. We investigated an insertion/deletion (I/D) polymorphism of the gene for ACE in relation to cardiovascular, cerebrovascular, neurodegenerative, and inflammatory diseases. The purpose of the present study was to investigate a possible association between lung cancer and insertion/deletion polymorphism of the ACE gene. A total of 125 patients with lung cancer and 165 control subjects were enrolled in the present study. ACE I/D genotypes were determined by polymerase chain reaction. Allelic frequencies and genotype distribution of the ACE I/D polymorphism in the patient group were significantly different from control subjects (ACE II genotype 29.6 vs. 17.6%, P = 0.011; ACE I allele 49.6 vs. 39.4%, P =0.009). Our data suggest that the ACE I/D polymorphism could be a risk factor for patients with lung cancer.

The Role of Neuropeptide Endopeptidases in Cutaneous Immunity

Proteolytic processing and degradation plays an important role in modulating the generation and bioactivity of neuroendocrine peptide mediators, a class of key molecules in cutaneous biology.

Accordingly, the cellular localization and expression, and the molecular biology and structural properties of selected intracellular prohormone convertases and ectopically expressed zinc-binding metalloendoproteases are discussed.

A special reference will be made to the physiologic and pathophysiologic significance of these endopeptidases in cutaneous immunobiology.

Because of the number of pathologically relevant changes in inflammation and tumor progression that can be directly attributed to neprilysin and angiotensin-converting enzyme, a particular focus will be on the role of these enzymes in modulating innate and adaptive immune responses in the skin.

Characterization of angiotensin-converting enzyme expression during epidermis morphogenesis in humans: a potential marker for epidermal stem cells

BACKGROUND

Recent evidence has revealed that angiotensin-converting enzyme (ACE) participates in cutaneous wound healing and contributes to the pathophysiological process of some skin diseases. However, little is known about the role of ACE in epidermis morphogenesis during development.

OBJECTIVE

To clarify the expression pattern of ACE during embryonic development of human skin.

METHODS

Skin samples were obtained from aborted fetuses at different gestational ages and from healthy individuals. Localization of ACE, together with beta(1)-integrin, keratin 19 (K19) and p63 was examined by immunofluorescence and immunohistochemical staining.

RESULTS

In human fetal skin, at 11-13 weeks of gestation, ACE-positive cells were observed in the primitive epidermis. As the fetuses developed, ACE-positive cells appeared in all the epidermal layers. From 21 weeks of gestation, ACE expression was largely restricted to the basal layer of the fetal epidermis. In contrast, ACE-positive cells were found only in the adult skin basal layer which harbours epidermal stem cells. To explore the possible link between ACE and epidermal stem cells, we further examined the expression of beta(1)-integrin, K19 and p63, the putative markers for epidermal stem cells. Consistent with the results of ACE expression, from 21 weeks of gestation, the expression of beta(1)-integrin, K19 and p63 was mainly confined to the basal layer. Immunofluorescent double labelling revealed that ACE-positive cells substantially overlapped with beta(1)-integrin-, K19- and p63-positive cells.

CONCLUSIONS

Our results suggest that ACE may play a role in human epidermis morphogenesis during fetal life and serve as an unrecognized marker for keratinocyte progenitor cells.

Angiotensin-converting enzyme limits inflammation elicited by Trypanosoma cruzi cysteine proteases: a peripheral mechanism regulating adaptive immunity via the innate kinin pathway

Tissue injury by pathogens induces a stereotyped inflammatory response that alerts the innate immune system of the potential threat to host integrity. Here, we review knowledge emerging from investigations of the role of the kinin system in the mechanisms that link innate to the adaptive phase of immunity. Progress in this field started with results demonstrating that bradykinin is an endogenous danger signal that induces dendritic cell (DC) maturation via G protein-coupled bradykinin B2 receptors (B2R). The immunostimulatory role of kinins was recently confirmed in two different mouse models of Trypanosoma cruzi infection, a parasitic protozoan equipped with kinin-releasing cysteine proteases (cruzipain). Infection by the intraperitoneal route showed that DCs from B2R-/- mice (susceptible phenotype) failed to sense kinin 'danger' signals proteolytically released by parasites, explaining why these mutant mice display lower frequencies of interferon-gamma-producing effector T-cells. Studies of the dynamics of inflammation in the subcutaneous model of infection revealed that the balance between cruzipain and angiotensin-converting enzyme, respectively acting as kinin-generating and degrading enzymes, governs extent of DC maturation and TH1 development via the B2R-dependent innate pathway. Studies of the kinin role in immunity may shed light on the relationship between proteolytic networks and the cytokine circuits that guide T-cell development.

Role of the renin-angiotensin system in age-related sarcopenia and diastolic dysfunction

The purpose of this review is to describe how recent pharmacological and genetic studies have contributed to our understanding of the role of the renin-angiotensin system (RAS) in age-related sarcopenia and diastolic dysfunction. Treatment strategies are limited in the context of both of these conditions, although interventions, which include blockade of the RAS (using angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers) are successful and lead to improvements in functional outcomes that are not necessarily mediated by hemodynamic effects of the drugs. Studies in animal models of sarcopenia and diastolic dysfunction point to ubiquitous effects of RAS blockade on multiple biological mechanisms, including inflammation, oxidative damage and metabolic dysregulation. Therefore, a re-evaluation of the use of these drugs in other conditions should be considered for maintaining functional independence in older individuals.

Association of angiotensin-converting enzyme gene insertion/deletion polymorphism with allergic contact dermatitis

Angiotensin-converting enzyme (ACE) plays an important role in the physiological control of blood pressure and inflammation. Insertion/deletion (I/D) polymorphism of the gene for ACE was investigated in relation to cardiovascular, cerebrovascular, neurodegenerative and inflammatory diseases. The purpose of the present study was to investigate the possible association between allergic contact dermatitis and insertion/deletion polymorphism of the ACE gene. A total of 90 patients with allergic contact dermatitis and 160 control persons were enrolled in the present study. ACE I/D genotypes were determined by the polymerase chain reaction. Allelic frequencies and genotype distribution of the ACE I/D polymorphism in the patient group were significantly different from control group (ACE II genotype 30.0% versus 17.5%, P = 0.022; ACE I allele 51.7% versus 39.4%, P = 0.008). Our data suggest that the ACE polymorphism could be a risk factor for patients with allergic contact dermatitis.

Protective Effect of Quercetin on the Homocysteine-Injured Human Umbilical Vein Vascular Endothelial Cell Line (ECV304)

Homocysteine is responsible for the occurrence of many cardiovascular diseases for instance by injuring the vascular endothelial cells. Quercetin has many beneficial effects on the cardiovascular system, but it is unknown whether it provides protection against homocysteine-injured vascular endothelial cells. The aim of the present study was to investigate the protective effect and mechanism of quercetin on the homocysteine-injured human umbilical vein vascular endothelial cell line (ECV304) (i.e. morphology, viability and nuclear factor kappa B (NF-kappaB) expression of ECV304 injured with 1.0 mM homocysteine) by determination of lipid peroxidant and endothelium-derived factors in the cultural medium of homocysteine-injured ECV304. Quercetin at 6.25, 12.5, 25, 50 and 100 microM attenuated the morphological changes and increased viability of homocysteine-injured ECV304 in a dose-dependent manner (P < 0.05 or P < 0.01 versus the homocysteine-injured group). At the same time, quercetin at 12.5, 25 and 50 microM decreased malondialdehyde level, endothelin release and NF-kappaB expression, and increased superoxide dismutase activity, nitric oxide and 6-keto-prostaglandin F1alpha releases in homocysteine-injured ECV304 (P < 0.05 or P < 0.01 versus the homocysteine-injured group). These results suggest that quercetin has a protective effect on homocysteine-injured vascular endothelial cells by antioxidant and anti-inflammatory mechanisms.

Administration of substance P during a primary immune response amplifies the secondary immune response via a long-lasting effect on CD8+ T lymphocytes

Atopic dermatitis can be exacerbated or induced by scratching or psychological stress; both cause the release of substance P (SP) from sensory nerves. Therefore, SP may have an etiological role in mechanisms underlying AD. Here, we show that administration of SP during the primary immune response (PIR) imprinted long-lasting pro-inflammatory immunity, resulting in exacerbation of the secondary immune response (SIR) in the absence of further SP. Five days after sensitization with dinitrofluorobenzene (DNFB), challenge with DNFB together with SP ("SP-Group") resulted in an increased PIR (as evaluated by ear swelling and granulocyte infiltration) compared to DNFB only ("Control-Group"). On day 26, after inflammation completely subsided, a second challenge with DNFB only (without SP) caused an increased SIR in the "SP-Group" compared to controls. Pretreatment on day 5 with spantide, an SP receptor antagonist, prevented increased ear swelling in the "SP-Group" not only on day 5 (PIR) but also on day 26 (SIR). In contrast, spantide treatment on day 26 did not affect the SIR. Adoptive transfer experiments suggested that CD8(+) T cells were involved in mediating enhanced SIR in animals pretreated on day 5 with SP. The present study offers a novel experimental approach to an uninvestigated facet of the pro-inflammatory effect of SP, i.e., exacerbation of inflammation via a long-term and indirect influence on CD8(+) T lymphocytes.

Terminating the stress: peripheral peptidolysis of proopiomelanocortin-derived regulatory hormones by the dermal microvascular endothelial cell extracellular peptidases neprilysin and angiotensin-converting enzyme

The skin including the microvascular endothelium is an established peripheral source and target of the immunomodulatory proopiomelanocortin (POMC) peptides ACTH and alpha-MSH. Whereas intracellular POMC peptide generation is well characterized, less is known on their extracellular processing in peripheral tissues by the neuropeptide-specific zinc metalloproteases neprilysin (NEP) and angiotensin-converting enzyme (ACE). This may locally control POMC peptide bioavailability and activation of ACTH/alpha-MSH-specific melanocortin receptors (MCs). In a cell-free system, endothelial cell (EC) membranes prepared from ACE(high)/NEP(low)-expressing primary human dermal microvascular ECs and the ACE(low)/NEP(high) expressing EC line HMEC-1 degraded ACTH(1-39) over time, resulting in temporary increased alpha-MSH immunoreactivity. Matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy peptide mapping and electrospray ionization-mass spectroscopy sequencing identified several stable fragments generated from ACTH(1-39), ACTH(1-24), and alpha-MSH by EC membranes or recombinant NEP and ACE. Whereas some fragments could be assigned to a cell-specific NEP or ACE activity, other degradation products require additional enzyme activity. Pharmacological NEP inhibition enhanced the ACTH and alpha-MSH-mediated activation of EC ectopically expressing MC(1). Likewise, selected peptides such as alpha-MSH(2-12) generated from ACTH(1-39) and alpha-MSH by recombinant NEP displayed equipotent MC(1)-activating properties in vitro and antiinflammatory activity in murine allergic contact dermatitis in vivo as compared with the parental peptides. Thus, NEP and ACE significantly contribute to the EC processing of stress hormones (ACTH) and antiinflammatory peptides (alpha-MSH), which modulates MC(1) activation but does not completely inactivate the peptide ligand. Because NEP and ACE are regulated by inflammatory mediators and UV light, this may be important for ACTH/MSH-modulated skin inflammation.