Effects of N-glycans on the structure of human IgA2

The transition of IgA antibodies into clinical development is crucial because they have the potential to create a new class of therapeutics with superior pathogen neutralization, cancer cell killing, and immunomodulation capacity compared to IgG. However, the biological role of IgA glycans in these processes needs to be better understood. This study provides a detailed biochemical, biophysical, and structural characterization of recombinant monomeric human IgA2, which varies in the amount/locations of attached glycans. Monomeric IgA2 antibodies were produced by removing the N-linked glycans in the CH1 and CH2 domains. The impact of glycans on oligomer formation, thermal stability, and receptor binding was evaluated. In addition, we performed a structural analysis of recombinant IgA2 in solution using Small Angle X-Ray Scattering (SAXS) to examine the effect of glycans on protein structure and flexibility. Our results indicate that the absence of glycans in the Fc tail region leads to higher-order aggregates. SAXS, combined with atomistic modeling, showed that the lack of glycans in the CH2 domain results in increased flexibility between the Fab and Fc domains and a different distribution of open and closed conformations in solution. When binding with the Fcα-receptor, the dissociation constant remains unaltered in the absence of glycans in the CH1 or CH2 domain, compared to the fully glycosylated protein. These results provide insights into N-glycans' function on IgA2, which could have important implications for developing more effective IgA-based therapeutics in the future.

Impact of mutations on the plant-based production of recombinant SARS-CoV-2 RBDs

Subunit vaccines based on recombinant viral antigens are valuable interventions to fight existing and evolving viruses and can be produced at large-scale in plant-based expression systems. The recombinant viral antigens are often derived from glycosylated envelope proteins of the virus and glycosylation plays an important role for the immunogenicity by shielding protein epitopes. The receptor-binding domain (RBD) of the SARS-CoV-2 spike is a principal target for vaccine development and has been produced in plants, but the yields of recombinant RBD variants were low and the role of the N-glycosylation in RBD from different SARS-CoV-2 variants of concern is less studied. Here, we investigated the expression and glycosylation of six different RBD variants transiently expressed in leaves of Nicotiana benthamiana. All of the purified RBD variants were functional in terms of receptor binding and displayed almost full N-glycan occupancy at both glycosylation sites with predominately complex N-glycans. Despite the high structural sequence conservation of the RBD variants, we detected a variation in yield which can be attributed to lower expression and differences in unintentional proteolytic processing of the C-terminal polyhistidine tag used for purification. Glycoengineering towards a human-type complex N-glycan profile with core α1,6-fucose, showed that the reactivity of the neutralizing antibody S309 differs depending on the N-glycan profile and the RBD variant.

An oligosaccharyltransferase from Leishmania donovani increases the N-glycan occupancy on plant-produced IgG1

N-Glycosylation of immunoglobulin G1 (IgG1) at the heavy chain Fc domain (Asn297) plays an important role for antibody structure and effector functions. While numerous recombinant IgG1 antibodies have been successfully expressed in plants, they frequently display a considerable amount (up to 50%) of unglycosylated Fc domain. To overcome this limitation, we tested a single-subunit oligosaccharyltransferase from the protozoan Leishmania donovani (LdOST) for its ability to improve IgG1 Fc glycosylation. LdOST fused to a fluorescent protein was transiently expressed in Nicotiana benthamiana and confocal microscopy confirmed the subcellular location at the endoplasmic reticulum. Transient co-expression of LdOST with two different IgG1 antibodies resulted in a significant increase (up to 97%) of Fc glycosylation while leaving the overall N-glycan composition unmodified, as determined by different mass spectrometry approaches. While biochemical and functional features of "glycosylation improved" antibodies remained unchanged, a slight increase in FcγRIIIa binding and thermal stability was observed. Collectively, our results reveal that LdOST expression is suitable to reduce the heterogeneity of plant-produced antibodies and can contribute to improving their stability and effector functions.

Transient Expression of Glycosylated SARS-CoV-2 Antigens in Nicotiana benthamiana

The current COVID-19 pandemic very dramatically shows that the world lacks preparedness for novel viral diseases. In addition to newly emerging viruses, many known pathogenic viruses such as influenza are constantly evolving, leading to frequent outbreaks with severe diseases and deaths. Hence, infectious viruses are a recurrent burden to our daily life, and powerful strategies to stop the spread of human pathogens and disease progression are of utmost importance. Transient plant-based protein expression is a technology that allows fast and highly flexible manufacturing of recombinant viral proteins and, thus, can contribute to infectious disease detection and prevention. This review highlights recent progress in the transient production of viral glycoproteins in N. benthamiana with a focus on SARS-CoV-2-derived viral antigens.

Probing Vulnerability of the gp41 C-Terminal Heptad Repeat as Target for Miniprotein HIV Inhibitors

One of the therapeutic strategies in HIV neutralization is blocking membrane fusion. In this process, tight interaction between the N-terminal and C-terminal heptad-repeat (NHR and CHR) regions of gp41 is essential to promote membranes apposition and merging. We have previously developed single-chain proteins (named covNHR) that accurately mimic the complete gp41 NHR region in its trimeric conformation. They tightly bind CHR-derived peptides and show a potent and broad HIV inhibitory activity in vitro. However, the extremely high binding affinity (sub-picomolar) is not in consonance with their inhibitory activity (nanomolar), likely due to partial or temporal accessibility of their target in the virus. Here, we have designed and characterized two single-chain covNHR miniproteins each encompassing one of the two halves of the NHR region and containing two of the four sub-pockets of the NHR crevice. The two miniproteins fold as trimeric helical bundles as expected but while the C-terminal covNHR (covNHR-C) miniprotein is highly stable, the N-terminal counterpart (covNHR-N) shows only marginal stability that could be improved by engineering an internal disulfide bond. Both miniproteins bind their respective complementary CHR peptides with moderate (micromolar) affinity. Moreover, the covNHR-N miniproteins can access their target in the context of trimeric native envelope proteins and show significant inhibitory activity for several HIV pseudoviruses. In contrast, covNHR-C cannot bind its target sequence and neither inhibits HIV, indicating a higher vulnerability of C-terminal part of CHR. These results may guide the development of novel HIV inhibitors targeting the gp41 CHR region.

Tannic Acid Induces in vitro Acantholysis of Keratinocytes via IL-1α and TNF-α

The mechanism of acantholysis in pemphigus vulgaris (PV) is an intriguing argument since several chemical mediators are implicated. We previously reported a central role for IL-1α and TNF-α, both able to regulate complement activation and plasminogen activators. Very little is known about what triggers the disease (drugs, viruses or food). In this study, we evaluate the molecular role of tannins in acantholysis. By HPLC chromatography we measured tannic acid (TA) and gallic acid (GA) in blister fluid of 4 groups of patients divided according to their dietary habits, including a regular diet, a diet rich in tannins, a diet free of tannins, and a group of pemphigus patients. Blister fluid was obtained from patients using a suction blister apparatus. We show that people with a diet rich in tannins have increased tannin metabolites (TA and GA) in the skin in respect to controls (tannin-rich diet: GA = 194.52±2.39 nmol/ml; TA = 348.28±1.4 nmol/ml versus tannin-Mediterranean diet: GA = 15.28±1.63 nmol/ml; TA = 22.81±1.68 nmol/ml). PV patients showed similar values to the Mediterranean diet population (PV patients: GA = 95.8±1.97 nmol/ml; TA = 199.09±4.15 nmol/ml versus Mediterranean diet: GA = 83.53±2.35 nmol/ml; TA = 195.1±2.50 nmol/ml). In an in vitro acantholysis system using TA and PV-IgG we show that TA 0.1 mM in NHEK culture is able to induce acantholysis. This effect was able to amplify the acantholytic action of PV-IgG in vitro. A blocking study using anti IL-1α and anti TNF-α antibodies showed a reduction in TA-induced acantholysis. Taken together, these results suggest that a diet rich in tannins could be a trigger in genetically predisposed patients. If these data are confirmed, a complementary diet poor in tannins may be useful in patients affected by PV.

Crohn's disease and skin

Crohn's disease is a chronic inflammatory bowel disease potentially involving any segment of the gastrointestinal tract. Extra-intestinal manifestations may occur in 6%-40% of patients, and disorders of the skin are among the most common. This manuscript will review skin manifestations associated to Crohn's disease, with a particular focus on lesions associated to anti-tumour necrosis factor therapy.

Helicobacter pylori infection but not small intestinal bacterial overgrowth may play a pathogenic role in rosacea

BACKGROUND AND AIMS

Recent studies suggest a potential relationship between rosacea and Helicobacter pylori (H. pylori) infection or small intestinal bacterial overgrowth (SIBO), but there is no firm evidence of an association between rosacea and H. pylori infection or SIBO. We performed a prospective study to assess the prevalence of H. pylori infection and/or SIBO in patients with rosacea and evaluated the effect of H. pylori or SIBO eradication on rosacea.

METHODS

We enrolled 90 patients with rosacea from January 2012 to January 2013 and a control group consisting of 90 patients referred to us because of mapping of nevi during the same period. We used the (13)C Urea Breath Test and H. pylori stool antigen (HpSA) test to assess H. pylori infection and the glucose breath test to assess SIBO. Patients infected by H. pylori were treated with clarithromycin-containing sequential therapy. Patients positive for SIBO were treated with rifaximin.

RESULTS

We found that 44/90 (48.9%) patients with rosacea and 24/90 (26.7%) control subjects were infected with H. pylori (p = 0.003). Moreover, 9/90 (10%) patients with rosacea and 7/90 (7.8%) subjects in the control group had SIBO (p = 0.6). Within 10 weeks from the end of antibiotic therapy, the skin lesions of rosacea disappeared or decreased markedly in 35/36 (97.2%) patients after eradication of H. pylori and in 3/8 (37.5%) patients who did not eradicate the infection (p < 0.0001). Rosacea skin lesions decreased markedly in 6/7 (85.7%) after eradication of SIBO whereas of the two patients who did not eradicate SIBO, one (50%) showed an improvement in rosacea (p = 0.284).

CONCLUSIONS

Prevalence of H. pylori infection was significantly higher in patients with rosacea than control group, whereas SIBO prevalence was comparable between the two groups. Eradication of H. pylori infection led to a significant improvement of skin symptoms in rosacea patients.

The practical use of cytology for diagnosis in dermatology

Exfoliative cytology for diagnostic purposes is rarely used in Dermatology despite the rapid and reliable results which this procedure can offer in many clinical conditions. This simple procedure may prove advantageous in a wide range of skin diseases, including genodermatoses (Hailey-Hailey disease), infections (mainly herpetic infections, molluscum contagiosum, leishmaniasis), immune disorders (early oral pemphigus) and tumours (basal and squamous cell carcinomas, Paget disease, erythroplasia of Queyrat, and others). The specific circumstances where cytological examination provides a very helpful and practical aid to confirmation or exclusion of a clinically suspected diagnosis are briefly reviewed. Cytological patterns, along with some technical hints on how to take and stain Tzanck smears correctly, are described in connection with the diseases considered.

Beneficial long-term effects of combined oral/topical antioxidant treatment with the carotenoids lutein and zeaxanthin on human skin: a double-blind, placebo-controlled study

BACKGROUND

The skin is exposed to numerous environmental assaults that can lead to premature aging. Of these agents, perhaps none is more ubiquitous than the ultraviolet (UV) wavelengths of sunlight. The primary immediate defense against environmental skin damage is the antioxidant capacity of the skin. However, this defense system can be compromised by moderate exposure to UV light. Therefore, bolstering the antioxidant defense system of the skin is a potentially important strategy for reducing environmentally induced skin damage.

AIM OF THE STUDY

This clinical trial was designed to study the efficacy of lutein and zeaxanthin, two potentially important antioxidants found naturally in the skin, upon five skin physiology parameters (surface lipids, hydration, photoprotective activity, skin elasticity and skin lipid peroxidation - malondialdehyde) of human subjects. These xanthophyllic carotenoids were administered either orally, topically, or in combination (both oral and topical routes).

RESULTS

The results obtained indicate that the combined oral and topical administration of lutein and zeaxanthin provides the highest degree of antioxidant protection. However, oral and topical administration of these antioxidants individually also provides significant activity in the skin. In addition, oral administration of lutein may provide better protection than that afforded by topical application of this antioxidant when measured by changes in lipid peroxidation and photoprotective activity in the skin following UV light irradiation.

Comparison of reactivity and epitope recognition between sera from American and Italian patients with oral pemphigoid

Mucous membrane pemphigoid (MMP) (also known as cicatricial pemphigoid) is a rare autoimmune mucocutaneous blistering disease that affects mucous membranes derived from stratified squamous epithelium and the skin. A subset of MMP affects only the oral cavity and is referred to as the oral pemphigoid (OP). MMP and OP are characterized by subepithelial vesicles on histology and in vivo deposition of immunoglobulins and complement at the basement membrane zone (BMZ) on immunopathology. Previous studies have shown that sera of patients with MMP bind to human integrin beta4, while sera of patients with oral pemphigoid bind to the integrin alpha6 component of the heterodimer. The prognosis in MMP is grave but excellent in OP. In this study we compare the binding of sera from patients with OP from Boston, MA, USA to Naples, Italy, and attempt to identify an epitope to which the anti-integrin alpha6 human autoantibody binds. Our results indicate that the sera from Boston and Naples are identical in their reactivity. They recognize a fragment I (AA 23-462) and its subfragment IB (AA 217-462) only, in the human integrin alpha6 molecule. Blocking studies, immunoprecipitation and immunoabsorbtion studies confirm the presence of this single 245 AA region. Antibodies to subfragment IB cause BMZ separation in organ culture using normal human oral mucosa as substrate. This preliminary study indicates that patients on both continents may have similar reactivity and suggests that an intercontinental study group could be established to advance our understanding of the pathogenesis of OP and the biology of anti-alpha6 integrin autoantibodies.

Pemphigus serum and captopril induce heat shock protein 70 and inducible nitric oxide synthase overexpression, triggering apoptosis in human keratinocytes

BACKGROUND

Captopril is an angiotensin-converting enzyme inhibitor with sulphydryl groups in its chemical structure. It is commonly used as an antihypertensive drug. The occurrence of pemphigus vulgaris has repeatedly been reported in patients receiving captopril. The capacity of captopril and pemphigus serum to induce acantholysis, in vivo or in vitro, has been demonstrated experimentally.

OBJECTIVES

To show that captopril and pemphigus serum, acting by a biochemical and immunological mechanism, respectively, trigger apoptosis.

METHODS

Human keratinocyte cells were treated with 15 mmol L-1 captopril or with pemphigus serum. DNA was extracted and the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling method was used to detect apoptosis.

RESULTS

DNA fragmentation occurred after 72 h of treatment. Increased expression of p53, c-myc and inducible nitric oxide (NO) synthase (iNOS) mRNA were observed by polymerase chain reaction (PCR) in the treated cells compared with the untreated ones. The increase in iNOS gene expression was associated with overproduction of NO. Moreover, the addition of 1 mmol L-1N-monomethyl-L-arginine, a structural analogue of arginine, reduced nitrite levels by about 70% in cells treated with captopril or pemphigus serum. Western blot analysis revealed an overexpression of heat shock protein 70 (hsp70) in cells treated with captopril or pemphigus serum. Finally, total inhibition of the keratinocyte transglutaminase gene was shown by PCR analysis in the same samples, compared with control cells.

CONCLUSIONS

These data demonstrate the involvement of apoptosis in keratinocytes treated with captopril or pemphigus serum, with induction of the iNOS gene and hsp70 in the cascade of events leading to programmed cell death.

Clinically equivocal melanocytic skin lesions with features of regression: a dermoscopic-pathological study

BACKGROUND

Benign melanocytic skin lesions may be difficult to differentiate from melanoma both clinically and dermoscopically. One of the most confounding dermoscopic features, commonly seen in melanoma but in our experience also in melanocytic naevi, is represented by the so-called blue-white structures (BWS).

OBJECTIVES

To evaluate diagnostic significance and histopathological correlates of BWS seen by dermoscopy in a series of clinically equivocal melanocytic skin lesions that were excised.

METHODS

Patients were recruited from six specialized pigmented lesion clinics in Austria, Italy and Spain over a period of 9 months. All consecutive patients showing one or more melanocytic lesions with BWS, but not classified as melanoma dermoscopically, were included. Each lesion was photographed clinically and dermoscopically. All images were reviewed by one of us and the degree, type and location of BWS evaluated for each lesion. A panel of four experienced dermatopathologists independently reviewed all specimens for diagnosis and one of them evaluated presence and degree of melanosis and/or fibrosis. The main outcome measures were the percentage and histopathological correlates of lesions with different degree, type and location of BWS.

RESULTS

All included lesions with BWS (n = 158) showed partial or focal regression histopathologically. One hundred and thirty-five (85.4%) lesions were diagnosed as melanocytic naevi (complete histopathological interobserver agreement), whereas 23 (14.6%) were defined as equivocal because at least one of four pathologists diagnosed the given lesion as melanoma. Only one lesion was diagnosed as melanoma by all four pathologists. The majority of naevi exhibited blue areas (84.4%) with a central distribution (57%) and involving < 50% of the lesion surface (89.6%). By contrast, 78.3% of equivocal lesions revealed a combination of white and blue areas with an irregular distribution (60.9%) and involving > 50% of the lesion surface (47.8%).

CONCLUSIONS

Using degree and type of BWS, an algorithm was constructed that can be applied for the management of lesions exhibiting dermoscopic features of regression.

Kaposi's sarcoma: aetiopathogenesis, histology and clinical features

Kaposi's sarcoma (KS) represents today one of the most common skin cancers in transplanted Mediterranean subjects and, since the epidemic of human immunodeficiency virus/acquired immune deficiency syndrome, in young unmarried single men. The disease has been associated with the recent identified human herpesvirus (HHV)-8 or KS herpesvirus and its incidence in the general population shows a north to south gradient that parallels the HHV-8 increasing prevalence from Nordic countries to sub-Saharan regions. The identification of the aetiopathogenetic mechanisms (viral agents and immunodeficiency) involved in the pathogenesis of KS, are relevant for identifying susceptible subjects (HHV-8 seropositive subjects), monitoring the immune levels in iatrogenic immune suppressed patients, and developing new therapeutic approaches based on antiviral and immune modulators.

LEARNING OBJECTIVE

This article should enable the reader: (i) to learn about the clinical and molecular aspects of KS in order to have a multidisciplinary approach to a tumour that shows unique features; (ii) to consider the role of viral agents and immunity; and (iii) to recognize properties of an opportunistic neoplasm. The identification of the HHV-8 role in KS pathogenesis should establish a relevant tool in the clinical management of KS patients.

Precautions and suggestions for pemphigus patients

The onset and course of pemphigus are often the result of an interaction between predisposing genetic factors and environmental triggering agents. The latter are heterogeneous, numerous and increasing, ranging from drug intake (the commonest cause of pemphigus induction) to the exposure to physical agents (heat, UV and ionizing rays, surgical and cosmetic procedures), viral infections (especially by herpesvirus), contact dermatitis, certain diet ingredients and even emotional stress. Alerting physicians and pemphigus patients to the effects that unsuspected precipitating factors may have on the progression of the disease is an important task. In fact, avoiding or limiting deleterious habits (e.g. overindulging in unnecessary drugs) and suggesting alternative ways (e.g. substituting potentially pemphigus-inducing drugs with others considered harmless in this respect) may be a useful precaution in the management of pemphigus patients, since it can improve the efficacy of conventional treatments, reduce the risks of relapses and sometimes result in a cure.

Pemphigus vulgaris: environmental factors. Occupational, behavioral, medical, and qualitative food frequency questionnaire

BACKGROUND

There have been reports suggesting the involvement of environmental factors in the disease process of pemphigus. Factors suggested include exposure to pesticides or certain drugs.

OBJECTIVE

To analyze the association of pemphigus with environmental exposure to various agents, including smoking, recreational and occupational insults, drugs, and food.

DESIGN AND SETTING

In-person interviews of pemphigus patients and control subjects were conducted by trained medical investigators using a structured questionnaire. Questions included occupational, behavioral, medical, and qualitative food frequency details. The multicenter study was conducted at outpatient services of teaching hospitals in Bulgaria, Brazil, India, Israel, Italy, Spain, and the USA.

PARTICIPANTS

A total of 126 pemphigus patients (55 men, 71 women; age, 54 +/- 17 years) and 173 healthy controls (87 men, 86 women; age 50 +/- 19 years) were interviewed in the period between October 1, 1999 and March 31, 2000. The diagnosis of pemphigus was based on clinical, histologic, immunohistologic, and immunohistochemical criteria. The disease duration was 2-27 years (8.4 +/- 7.2 years). Individuals with skin diseases other than pemphigus were selected as control subjects.

MAIN OUTCOME MEASURE

Information on drugs, foods, and occupational, environmental, constitutional, and other possible risk factors was analyzed by t-tests and chi-squared tests as applicable. A multivariate logistic regression model was applied to the data to study simultaneously the independent relationship between each risk factor and pemphigus vulgaris.

RESULTS

The risk for pemphigus vulgaris was lower for ex-smokers and current smokers than for patients who had never smoked. Exposure to pesticides and occupational exposure to metal vapor were associated with an increased risk of pemphigus. Pemphigus patients had more pregnancies than controls. There were differences in environmental factors between countries, with exposure to gardening materials and pesticides being highest among patients from Bulgaria, followed by Israel. Disease characteristics also exhibited differences between countries. Bulgarian patients less frequently had oral mucous membrane lesions: 66% compared to 92% for Israeli patients and 83% for Italians. The distribution of the disease in skin and mucous membranes was similar among patients from all countries. Exclusive skin involvement was seen in 50% of patients, mucous membranes alone in 23% of patients, and both skin and mucous membranes in 27% of patients.

CONCLUSIONS

The beneficial effect of smoking on pemphigus might be explained by its effect on the immune system. In addition, smoking has an antiestrogenic effect, while pesticides have an estrogenic effect. The lower numbers of smokers among patients, the higher exposure rates to pesticides, and the higher number of female patients who had been pregnant may point to the contribution of estrogens to the disease process. It remains to be determined whether measures, such as avoiding exposure to pesticides or metal vapor, may be beneficial in the clinical context. As the present study was a survey, more definitive studies should be conducted to validate the results.

Uptake of Malassezia furfur by human dermal fibroblasts: effect of ketoconazole and cytoskeleton inhibitors

We showed the ability of human dermal fibroblasts to take up Malassezia furfur and the effect of ketoconazole and cytoskeleton inhibitors, including cytochalasin D and colchicine, on invasivity. Engulfment was evaluated by May Grunwald Giemsa stain and confirmed by acridine orange staining and electron microscopy. Both revealed the different steps of engulfment, including a fusion event between lysosomes and phagosomes containing M. furfur. Subinhibitory concentrations of ketoconazole (5 microg/ml) reduced the invasive capacity compared to controls (52.0+/-6.3 vs 10.0+/-1.2). M. furfur induced changes in the cytoskeleton of human dermal fibroblasts, with signs of disaggregation of actin fibres. We also studied the effect of the cytoskeleton inhibitors, cytochalasin D (1 microg/ml) and colchicine (1 microg/ml), on engulfment. Cytochalasin D, an inhibitor of actin polymers, inhibited the uptake of M. furfur by human dermal fibroblasts. Colchicine, a microtubule inhibitor, reduced the uptake of M. furfur less markedly. This suggests that the process of engulfment is F-actin-dependent, but the integrity of microtubules is also important in "non-professional" phagocytic cells such as dermal fibroblasts.

Dermoscopy of pigmented skin lesions

This paper describes the basic concepts of dermoscopy, the various dermoscopic equipments and the standard criteria for diagnosing pigmented skin lesions. In assessing dermoscopic images, both global and local features can be recognized. These features will be systematically described and illustrated in Part I of this article. First, we will focus on 8 morphologically rather distinctive global features that allow a quick, preliminary categorization of a given pigmented skin lesion. Second, we will describe various local features representing the letters of the dermoscopic alphabet. The local features permit a more detailed assessment of pigmented skin lesions.

In vitro tannin acantholysis

BACKGROUND

Exogenous factors, such as certain drugs, may be involved in the induction of pemphigus. Other offenders sharing a similar chemical composition to these drugs may also play a role. Tannins with their considerable biologic activity were suggested as possible factors. To substantiate the role of tannins in the pathomechanism of pemphigus, the present study examined the acantholytic potential of tannins in vitro.

METHODS

Normal human breast skin from patients without any bullous disease was cultured for 3 days in the presence of tannic acid at concentrations of 0.02, 0.05, 0.1, 0.25, 0.5, 1.0, and 2.0 mM. The effect of the tannic acid was microscopically examined in a blind fashion by three independent investigators.

RESULTS

In addition to the cytotoxic effect, tannic acid caused marked acantholytic changes, with a clear suprabasal cleavage and intraepidermal acantholytic cells. The acantholytic changes were the most constant and specific effects. They were constantly observed at 1.0 and 2.0 mM, whereas lower concentrations showed changes only in some of the explants. The concentrations needed to exert this effect were notably low. There was a remarkable variability among the subjects who had provided the explants.

CONCLUSIONS

The results suggest a possible role of tannin in the disease process of pemphigus. The tannin acantholytic potential was much greater than the potential of known acantholytic drugs, such as penicillamine and captopril. The interindividual variability in susceptibility to acantholysis may explain the variability in the individual potential for developing pemphigus.

Implication of tissue transglutaminase and desmoplakin in cell adhesion mechanism in human epidermis

The distribution patterns of both tissue and keratinocyte transglutaminases (TGase), as well as that of desmoplakin (DP), have been immunohistochemically investigated in human skin cultured in the absence or presence of cystamine and enalapril, two acantholytic agents. In the control samples, tissue TGase is predominantly expressed in lower layers of the epidermis and is located intercellularly. Conversely, in tissues cultured with cystamine or enalapril, a diffuse cytoplasmatic staining was observed. Similarly, DP, detected on the cell membrane in the control, shifts into the cytosol of the keratinocytes following treatment. The distribution pattern of the keratinocyte enzyme in the acantholytic epidermis was identical to that observed in the normal one. Since cystamine and enalapril are TGase inhibitors and DP was shown to act as a TGase substrate in vitro, we suggest that DP and tissue enzyme may participate in cell adhesion at the intraepidermal level.

Triggered psoriasis

There are conflicting reports in the literature concerning the use of antimalarials in psoriatic patients with arthropathy or coexisting systemic lupus erythematosus. On the basis of a review of 18 publications in English, it was estimated that up to 18% of patients with psoriasis would develop an exacerbation of their disease following antimalarial therapy. In contrast to lithium and beta-blockers, antimalarials do not induce psoriasis de novo, but they only trigger already existing psoriasis, via a pharmacologic mechanism, probably due to an alteration of the activity of enzymes involved in the epidermal proliferation process. The chemical structure of the antimalarials is very similar to dansylputrescine, a potent transglutaminase (TGase) inhibitor. We suggested therefore that antimalarials trigger psoriasis through the modulation of the TGase activity. To verify this hypothesis, we examined the effect of hydroxychoroquine sulphate (HCQS) on cultured human skin and on TGase activity in vitro. Significant changes of epidermal morphology were seen in all explants cultured in the presence of HCQS. HCQS showed a concentration-dependent inhibition of TGase activity. We suggest that HCQS caused an initial break in the barrier function of the epidermis by inhibiting TGase activity; this was followed by a physiologic response of the epidermis aimed at barrier restoration. This rather non-specific stimulus to epidermal proliferation is probably sufficient to trigger psoriasis in predisposed individuals. Drug eruption is an age-old but timeless and fascinating subject. Of particular interest are those drug eruptions that may mimic idiopathic skin diseases. Apart from their obvious practical importance they are also of theoretical interest, because they provide an opportunity to investigate possible pathogenic mechanisms of the mimicked disease. In this paper, I would like to review briefly the characteristics of drug-induced psoriasis, and then propose a hypothesis concerning the pathogenesis of this phenomenon. In all, we found 258 reported cases of drug-induced psoriasis [1]. The drugs mainly involved are the antimalarials, lithium, beta blockers, and a large group of miscellaneous drugs. Three out of the four groups of drugs (lithium, beta blockers and miscellaneous drugs) can both induce or trigger psoriasis with almost equal frequency, namely they induce psoriasis de novo or they exacerbate an already existing psoriasis in 30-50% of the reported cases. Only one group of drugs, the antimalarials is an exception. In contrast to lithium and beta blockers, antimalarials do not induce psoriasis de novo, but only trigger already existing psoriasis. There are only three reported cases of psoriasis induced by antimalarials in patients who did not have the disease previously. Of these three patients, one had a seronegative arthritis and a family history of psoriasis, and, as stated by the author, there is evidence that the patient had pre-existing latent psoriasis. We believe that the other two cases may also have had latent psoriasis. That antimalarial drugs only trigger latent psoriasis and do not induce psoriasis de novo can be suspected from the fact that psoriasis cleared up completely after withdrawal of the drug in only 30% of patients on antimalarials, as compared with more than 60% of those receiving lithium and nearly 50% of those receiving beta blockers. This is probably also why the incubation period of the cases induced by antimalarial drugs is much shorter than that of lithium and beta blockers. Possibly, in triggered psoriasis (as in antimalarials) the drug only sets off with a chain of pathologic events previously programmed and ready to be set off, whereas in true drug-induced cases (as in some cases of lithium and betablockers) the drug is supposed to cause more profound changes and, therefore, more time is needed for these changes to occur.

Detection of herpesvirus DNA in peripheral blood mononuclear cells and skin lesions of patients with pemphigus by polymerase chain reaction

Pemphigus is an autoimmune disease where both endogenous (genetic) and exogenous (environmental) factors play a part. Viral infections, in particular herpesvirus infections, have been identified as a possible triggering factor for pemphigus. In this study, using the polymerase chain reaction, we studied peripheral blood mononuclear cells (PBMC) and skin biopsies from patients with pemphigus, and in some of these were able to demonstrate the presence of DNA sequences of herpes simplex virus 1/2 (50% in PBMC and 71% in skin biopsies), Epstein-Barr virus (15% in PBMC and 5% in skin biopsies) and human herpesvirus 6 (20% in PBMC only). However, the inability to detect herpesvirus DNA consistently in these cases suggests that viral infection may only be an occasional factor triggering the outbreak or exacerbation of the disease. The possible role of interferons and interleukins in the pathogenesis of virus-induced pemphigus is discussed.

Lesion topography in two cases of nifedipine-related pemphigus

Similar lesion topography which resembled an inverted fir tree in two patients with nifedipine-related pemphigus vulgaris is described. The possible relation of the lesion pattern to the offending drug is discussed.

Common human leukocyte antigen alleles in pemphigus vulgaris and pemphigus foliaceus Italian patients

Pemphigus refers to a group of autoimmune blistering skin diseases, mainly identified as pemphigus vulgaris and pemphigus foliaceus, both characterized by the presence of autoantibodies against keratinocyte adhesion molecules, leading to loss of cell-cell adhesion with consequent blister formation. Pemphigus vulgaris is reported to be associated with human leukocyte antigen DR4 and/or DR6 whereas no data are available on pemphigus foliaceus, except for the endemic Brazilian form (fogo selvagem), which is reported to be associated with DR1 and DR4. We here report human leukocyte antigen molecular typing on a total of 87 patients, 61 with pemphigus vulgaris and 26 with pemphigus foliaceus, versus 128 healthy matched controls. Generic typing showed an increase of DRB1*04 and DRB1*14 and a decrease of DRB1*07 in both pemphigus vulgaris and pemphigus foliaceus patients. Molecular subtyping of DR4+ and DR14+ subjects showed a highly significant association between the DRB1*1401 and both pemphigus vulgaris (p < 0.0001) and pemphigus foliaceus patients (p < 0.0001) together with a significant increase of the linked DQB1*0503 (pemphigus vulgaris p < 0.0001; pemphigus foliaceus p < 0.0001). Moreover, whereas the association between DRB1*0402 and pemphigus vulgaris (p < 0.0001) has been confirmed, no significant association between a specific allele of the DR4 group and pemphigus foliaceus, has been found. Therefore, at least in Italian patients, pemphigus vulgaris and pemphigus foliaceus share DRB1*1401 and DQB1*0503, as susceptible human leukocyte antigen alleles, whereas DRB1*0402 is only found associated with pemphigus vulgaris. The observation that both diseases, pemphigus vulgaris and pemphigus foliaceus, carry the same susceptible human leukocyte antigen alleles has been interpreted as a common genetic background predisposing to pemphigus as, like in other autoimmune disorders, it is not sufficient to explain the onset of the disease on the basis of the sole aforementioned alleles. Other linked genes and/or environmental factors should play a facilitating role in the outbreak of pemphigus, either pemphigus vulgaris or pemphigus foliaceus.

The in vitro effect of hydroxychloroquine on skin morphology in psoriasis

BACKGROUND

In earlier papers, we suggested that the aggravation of psoriasis by antimalarial drugs (analogous to hypolipidemic drugs) could be initiated by a break in the epidermal barrier. We suggested that these drugs exerted their effect by inhibiting epidermal transglutaminase activity, and supported this hypothesis by demonstrating the effect of hydroxychloroquine sulfate (HCQS) on the morphology of cultured skin and on liver transglutaminase activity. In the present article, we describe, for the first time, the morphologic changes induced by HCQS on cultured skin of psoriatic patients.

METHODS

Uninvolved (apparently normal) skin explanted from the back of two psoriatic patients was cultured in the presence of 9.2 and 13.8 mM of HCQS for 3 days. The morphologic changes were evaluated in a blind manner. The experiment was repeated twice.

RESULTS

Significant changes in the epidermal morphology of psoriatic skin cultured in the presence of HCQS, compared with skin cultured without the presence of the drug, were observed. The most striking changes were enhanced and irregular keratinization and dermo-epidermal detachment and cleft formation. No parakeratosis or other characteristics of psoriasis were observed.

CONCLUSIONS

The first changes caused by HCQS on the cultured skin of psoriatic patients are not characteristic of psoriasis, and include hyperproliferation and enhanced and irregular keratinization. The present experimental study gives further support to the hypothesis that HCQS causes an initial break in the barrier function of the epidermis (probably by inhibiting transglutaminase activity), which is followed by a physiologic response of the epidermis aimed at barrier restoration. This rather nonspecific stimulus to epidermal proliferation is probably sufficient to trigger psoriasis, in vivo, among genetically predisposed patients.

Ketoconazole inhibits lipopolysaccharide-induced activation of the nitric oxide synthase gene in the murine macrophage cell line J774

The aim of this study was to determine whether ketoconazole can affect the expression of the nitric oxide (NO) synthase gene in the murine macrophage cell line J774. The inducible enzyme (i-NOS) is activated in murine macrophages by LPS and cytokines. Exposure of the J774 cell line to ketoconazole for 24 h did not induce any NO release. Cells preincubated with ketoconazole and treated with LPS showed a significant decrease in nitrite levels in the culture medium, compared with controls (cells treated with LPS alone). The addition of 1 mM N-monomethyl-L-arginine (L-NMMA), a structural analogue of arginine, reduced nitrite levels by about 88+/-9.2% in cells treated with LPS alone, whereas in those treated with ketoconazole + LPS, the levels were comparable to the baseline values detected in control cells. Northern blotting, used to assess i-NOS mRNA expression in the J774 cells, showed that ketoconazole reduced the LPS-induced increase in i-NOS mRNA activation by about 50%. These results support another mechanism for the antiinflammatory effect of ketoconazole (i.e. reduction in i-NOS gene expression and consequently inhibition of reactive radical NO production), that may explain the antierythema and antiedema action of this compound, besides its antimycotic effects.

Pemphigus and pemphigoid-like effects of nifedipine on in vitro cultured normal human skin explants

BACKGROUND

A variety of drugs have been implicated in the onset and exacerbation of pemphigus and bullous pemphigoid. The demonstration of biochemical acantholysis in skin explants to various drugs in the absence of autoantibodies, in which the tested drugs evoke a biochemical reaction that leads to desmosomal function loss, may be a valuable adjunct to patient management by confirming the suspicion of drug-related pemphigus or bullous pemphigoid.

OBJECTIVE

To determine whether a skin explant model might serve as a possible in vitro correlate of drug-induced pemphigus and pemphigoid-like effects related to the calcium channel blocker nifedipine.

METHODS

Normal human breast skin obtained from nonpemphigus and nonpemphigoid patients undergoing mastectomy was cultured with nifedipine at final concentrations of 2, 4, and 8 mM. The drug effect on skin explants evidenced by morphologic changes was evaluated by microscopy by three observers.

RESULTS

Five out of seven explants cultured with nifedipine at concentrations ranging from 2 to 8 mM exhibited obvious morphologic changes of two types: intraepithelial (or pemphigus-type) splittings and subepithelial (or pemphigoid-type) splittings. Two explants showed no acantholysis and no subepithelial splittings. Control cultures without polyethylene glycol 200 (PEG) showed no changes. Skin control samples cultured in medium supplemented with 10% PEG displayed vacuolar degeneration throughout the entire epidermis, but no sign of cell-cell dyshesion or dermo-epidermal detachment.

CONCLUSIONS

A type of skin susceptibility to nifedipine may be genetically determined, with some nifedipine-treated patients developing an acantholytic reaction and others a subepidermal bullous eruption.

Effects of gemfibrozil on in vitro cultured normal human skin explants

BACKGROUND

Several lipid-lowering agents, when given topically, show a profound effect on skin morphology. Because of low bioavailability of these drugs for keratinocytes, the incidence is extremely low clinically. The most appropriate way to study the effect of hypolipidemic drugs on keratinocytes is by artificial exposure of the skin to high drug concentrations.

OBJECTIVE

To study the effects of gemfibrozil on the morphology of in vitro cultured normal human skin explants. As gemfibrozil induces barrier disruption by inhibiting epidermal sterologenesis, essential for a competent permeability barrier, it is interesting to investigate the morphologic changes associated with this phenomenon. Studying the epidermal changes induced by lipid-lowering agents is important, not only because it might lead to a better understanding of the effects of these drugs on keratinocytes, but as it might also unlock the door to a wider knowledge of the pathomechanism of disorders of cornification.

METHODS

Normal human skin from patients undergoing mastectomy was cultured in the presence of 2, 5, and 10 mM of gemfibrozil for 4 days The morphologic changes were evaluated by three blinded observers. Their reports were matched and collated.

RESULTS

The cultured skin in the presence of gemfibrozil showed cell crowding of keratinocytes in the lower part of the epidermis, indicating epidermal hyperplasia and increased proliferation. Intercellular edema with the formation of small cavities in the epidermis, intracellular edema, and vacuolar alteration of keratinocytes in the upper portion of the epidermis were also observed. The intensity of these changes tended to parallel the gemfibrozil concentration. Some dermo-epidermal detachments did not correlate with the gemfibrozil concentration, but rather with tissue characteristics peculiar to each explant.

CONCLUSIONS

The morphologic changes caused by gemfibrozil to normal human skin were not characteristic of psoriasis, and included intracellular and intercellular edema in the upper portion of the epidermis and cell crowding, indicating epidermal hyperplasia in the lower portion of the epidermis. The present experimental study gives further support to the hypothesis that hypolipidemic drugs cause an initial break in the barrier function of the epidermis, followed by a physiologic epidermal response, aimed at barrier restoration. This rather nonspecific stimulus to epidermal proliferation may trigger psoriasis in predisposed patients.