Peripheral blood lymphocytes from psoriatic patients are hyporesponsive to beta-streptococcal superantigens

Advances in psoriasis physiopathology and treatments: Up to date of mechanistic insights and perspectives of novel therapies based on innovative skin drug delivery systems (ISDDS)

Psoriasis is a chronic inflammatory disease affecting mainly the skin but which can be complicated by psoriatic arthritis (PsA).This autoimmune skin disorder concerns 2-5% of the world population. To date, the physiopathology of psoriasis is not still completely elucidated but many researches are ongoing which have led for example to the discovery of the Th17/Th22 pathway. The conventional therapeutic approaches (local or systemic route) appeal to various classes of drugs with complex mechanisms of action and non-negligible side effects. Although there is no therapy capable to cure psoriasis, the current goal is to relieve symptoms as longer as possible with a good benefit/risk ratio. That is one of the principal limits of conventional antipsoriatic drugs. New formulations based on nanoencapsulation are a promising opportunity to answer to this limit by offering an optimization of the conventional antipsoriatic drug use (higher activity, lower side effects and frequency of application, etc.). Herein, we tried to put in perspective the mechanistic insights (histological and immunological views) proposed into scientific literature these last years in order to have a better comprehension of psoriasis physiopathology resulting in skin lesions and PsA. The therapeutic armamentarium and the different strategies in the management of psoriasis are discussed in greater details. To finish, the field of encapsulation in nanoparticles is broached in order to put forward recent advances in innovative skin drug delivery systems (ISDDSs) of antipsoriatic active agents for a better efficacy, safety and compliance.

CD8(+) T cells implicated in the pathogenesis of allergic fungal rhinosinusitis

Fungi in paranasal sinuses are characteristic and considered a major pathogenic factor in a subset of chronic rhinosinusitis (CRS) patients, known as allergic fungal rhinosinusitis (AFRS). CD8⁺ T cells are enriched in AFRS sinuses but their role in fungal-specific responses is unknown. Alternaria alternata– and Aspergillus fumigatus–specific T lymphocyte responses were investigated in 6 AFRS patients, 10 eosinophilic mucus CRS (EMCRS) patients, 10 CRS with nasal polyps (CRSwNPs) patients, 6 allergic rhinitis with fungal allergy (ARFA) patients, and five controls. Fungal-specific proliferation of human peripheral blood mononuclear cells (PBMCs) was studied prospectively. Proliferating cells were examined for CD3, CD4, CD8, and CD25 expression. Relevant clinical characteristics, fungal allergy, detection of fungi in sinuses, and CD4⁺ and CD8⁺ composition of sinus T cells were also examined. CD4⁺ T-cell division to fungi occurred in all samples, regardless of fungal allergy or CRS. Fungal-specific CD8⁺ T-cell division occurred in all ARFA and control samples and the majority of CRSwNP patients; however, CD8⁺ T cells failed to proliferate in AFRS and EMCRS patients. The CD8⁺ T cells from AFRS patients also did not up-regulate the activation marker, CD25, with fungal antigen exposure. Presence of A. alternata– and A. fumigatus–specific CD4⁺ and CD8⁺ T-cell proliferation in healthy individuals, ARFA, and CRSwNP patients suggests that both T-cell subsets may be important in immune responses to these fungi. In AFRS and EMCRS patients, only fungal-specific CD4⁺ T-cell proliferation occurred; hence, a lack of CD8⁺ T-cell proliferation and activation in the presence of sinus eosinophilic mucus in these patients, regardless of fungal allergy, is a novel finding. This raises the question whether a dysfunctional CD8⁺ T-cell response predisposes to ineffective clearance and accumulation of fungi in the sinuses of susceptible patients.

Streptococcal superantigens: categorization and clinical associations

Superantigens are key virulence factors in the immunopathogenesis of invasive disease caused by group A streptococcus. These protein exotoxins have also been associated with severe group C and group G streptococcal infections. A number of novel streptococcal superantigens have recently been described with some resulting confusion in their classification. In addition to clarifying the nomenclature of streptococcal superantigens and proposing guidelines for their categorization, this review summarizes the evidence supporting their involvement in various clinical diseases including acute rheumatic fever.

[Psoriasis: physiopathology and immunogenetics]

Psoriasis is a multifactorial disease that involves genetic, immunological and environmental factors. During the last decade, several studies by genome scan on families or cases/controls helped to highlight more than ten loci "PSORS" located on different chromosomes and containing several candidate genes. Psoriasis appears as a genetic disease that follows the mixed model with the involvement of a major gene (PSORS1) and a set of minor genes with a variable penetrance depending on the locus. Genetic data have focused on the involvement of the immune system in the pathogenesis of psoriasis. It is now accepted that psoriasis is an immunological disease involving the response profiles TH1 and TH17. Much remains to be done to better elucidate the mechanisms involved in the genesis of psoriatic lesions to find new therapeutic targets.

T helper 1 to T helper 2 shift in cytokine expression: an autoregulatory process in superantigen-associated psoriasis progression?

Psoriasis is an inflammatory skin disorder characterized by increased activation of CD4+ T lymphocytes, and systemic and local overexpression of pro-inflammatory cytokines such as interleukin 2 (IL-2), gamma interferon (IFN-γ), IL-6 and tumour necrosis factor alpha, indicating that immunopathogenesis of the disease is T helper 1 (Th1) mediated. Several studies suggest a pivotal role of bacterial superantigens in the initiation and/or exacerbation of this illness. This study was conducted to assess the systemic Th1/Th2 imbalance in Indian psoriasis patients presenting with variable duration of disease by studying systemic superantigen-stimulated peripheral blood mononuclear cell (PBMC) cytokine expression. PBMCs were isolated and stimulated in vitro with superantigens (streptococcal pyrogenic exotoxin A and staphylococcal enterotoxin B), and the cytokines released (IFN-γ for a Th1 response, and IL-4 and IL-10 for a Th2 response) were assayed. In contrast to controls, psoriasis patients in the early course of disease were characterized by significantly increased expression of the pro-inflammatory cytokine IFN-γ, whilst a shift towards IL-10 secretion (Th2 response) was observed in those presenting with increased duration of disease. These observations suggest a possible shift from a Th1 to a Th2 cytokine response with superantigen-associated progression for the duration of psoriasis, perhaps as an adaptive process by the immune system in an attempt to downregulate abnormal inflammatory Th1 immune responses.

IgG class antibodies to heat shock-induced streptococcal antigens in psoriatic patients

BACKGROUND

Psoriasis is a chronic inflammatory skin disease. Probably autoimmune in nature, and associated with streptococcal throat infections as a triggering factor. Although many groups have associated the disease with other pathogens, Streptococcus pyogenes seems to be the most important microorganism related to this disease. Therefore, it is necessary to identify the streptococcal antigens involved in the process.

METHODS

In this work IgG class antibodies to soluble antigens obtained from Staphyloccus aureus, Candica albicans or S. pyogenes before and after heat shock induction, were analyzed by ELISA in 28 psoriatic patients and 30 healthy donors.

RESULTS

In all cases, the patients and the controls had IgG class antibodies to the four antigens. Nevertheless, the IgG levels to the heat shock-induced S. pyognes were statistically different between the patients and the controls (P < 0.001). There was no difference between the groups when the IgG antibodies to the other antigens, including the noninduced streptococcal extract, were analyzed. Additionally, anti-streptolysin O titers and throat cultures were carried out in all patients and controls. No differences between ASO titers were found but the patients were more frequently colonized by pyogenes.

CONCLUSION

Results obtained in this study suggest that heat shock-induced proteins from S. pyogenes are associated with psoriasis.

Decreased IL-10 production by psoriatic peripheral blood mononuclear cells stimulated with streptococcal superantigen

The strong association of acute guttate psoriasis and streptococcal throat infection has suggested a role for streptococcal antigens in the pathogenesis of psoriasis. We have reported that psoriatic peripheral blood mononuclear cells (PBMCs) showed significantly lower responses to cytoplasmic membrane-associated protein (CAP) isolated from group A beta-hemolytic streptococci, a kind of streptococcal superantigen. The objectives were to evaluate the abnormal cytokine production by psoriatic PBMCs to streptococcal superantigen, CAP. We compared the production of four different cytokines, i.e. IL-4, IL-5, IL-10, and IFN-gamma, by PBMCs between psoriatic patients and healthy controls after stimulation with CAP or two different staphylococcal superantigens, staphylococcal enterotoxin A (SEA) or E (SEE). When PBMCs were stimulated with CAP, the production of IL-10 was significantly lower by psoriatic PBMCs than by those from healthy controls, whereas those of IL-4, IL-5, or IFN-gamma were not different between the two groups. Such a significant decrease in IL-10 production by psoriatic PBMCs was not observed when they were stimulated with staphylococcal superantigens. Flow cytometric analysis of intracytoplasmic IL-10 demonstrated defective IL-10 production by psoriatic PBMCs in both CD3+ T cells and CD14+ monocytes. There was a significant positive correlation between IFN-gamma production by PBMCs and the proliferation of Vbeta8+ T cells preferentially stimulated by CAP. These data demonstrating the defective IL-10 production by psoriatic PBMCs stimulated with streptococcal superantigen seem to explain why only psoriatic patients evolve sustained and Th-1 deviated skin lesions after streptococcal upper respiratory infection.

Family history of psoriasis, stressful life events, and recent infectious disease are risk factors for a first episode of acute guttate psoriasis: results of a case-control study

BACKGROUND

The association of guttate psoriasis with streptococcal pharyngitis is well accepted. The association of other risk factors is less well defined.

OBJECTIVE

We attempted to provide an estimate of the risk for guttate psoriasis associated with a recent infectious disease and to explore other potential risk factors, including family history of psoriasis and psychologic stress.

METHODS

This was a case-control study. Cases were patients with a first diagnosis ever of acute guttate psoriasis, made by a dermatologist. Controls were patients newly diagnosed as having dermatologic conditions other than psoriasis and seen in the same outpatient services as the cases. Inclusion of cases and controls was restricted to patients older than 16 years. The Holmes and Rahe Social Readjustment Rating Scale was used to assess stressful life events during the 6 months before diagnosis. A total of 73 cases (median age, 26 years) and 430 controls (median age, 28 years) were included in the analysis.

RESULTS

A family history of psoriasis was strongly associated with guttate psoriasis, the multivariate odds ratio being 7.0 (95% confidence interval, 3.7-13.5) for subjects who reported a history of the disease in parents or siblings. Stressful life events were also associated with guttate psoriasis. The multivariate odds ratio was 1.7 (95% confidence interval, 0.8-3.6) for subjects scoring 41 to 100 and 2.6 (95% confidence interval, 1.3-5.2) for those scoring more than 100 on the Holmes and Rahe Scale. The risk increased with the reported history of any infectious disease. The analysis of specific diagnoses documented a high and significant association with acute pharyngitis, the adjusted odds ratio being 7.8 (95% confidence interval, 1.8-32.5).

CONCLUSION

The study confirmed that recent pharyngeal infection is a risk factor for guttate psoriasis. It also documented the strong association between guttate psoriasis and a family history of psoriasis. Finally, the study added evidence to the belief that stressful life events may represent risk factors for the onset of psoriasis. By relying on the clinical diagnosis we possibly underestimate the association of guttate psoriasis with infection.

Normal proliferative responses of peripheral blood mononuclear cells to streptococcal preparation OK-432 in patients with pustulosis palmaris et plantaris constitute a distinct feature from the reduced responses observed in those with psoriasis vulgaris, pustular psoriasis, and acrodermatitis continua of Hallopeau

It was previously reported that peripheral blood mononuclear cells (PBMC) from the patients with psoriasis vulgaris (PV) showed a reduced proliferative response in vitro to the stimulation of a lyophilized preparation of penicillin-treated low virulence Su-strain of Streptococcus pyogenes group 3, OK-432. In this study, at first it was examined whether OK-432 acts as a superantigen. By analyzing the usage of Vbeta T-cell receptor (TCR) of proliferating T cells stimulated with OK-432, it was found that OK-432 stimulated preferentially Vbeta2 TCR-bearing T cells. Next, to find differences in in vitro responses of PBMC among various types of sterile pustular dermatoses such as pustulosis palmaris et plantaris (PPP), acrodermatitis continua of Hallopeau (AC), and generalized pustular psoriasis (GPP), the proliferative responses of PBMC obtained from these patients under the stimulation of OK-432 were compared. When the PBMC was stimulated with interleukin (IL)-2, no significant difference was found in their proliferative responses among those obtained from the patients with these sterile pustular dermatoses, PV or healthy controls. However, like those from PV patients, PBMC from AC and GPP patients showed significantly smaller responses to OK-432 than those from the healthy controls. In contrast, the proliferative responses of PBMC from the patients with PPP to OK-432 was comparable to those from healthy controls. These results, in addition to its unique clinical and histopathological characteristics, suggest that PPP has a different pathogenetic background from that underlying PV, AC, or GPP.

Guttate psoriasis triggered by perianal streptococcal dermatitis in a four-year-old boy

Perianal streptococcal dermatitis (PSD) is a superficial bacterial infection usually with group A beta-hemolytic streptococci. PSD is often misdiagnosed for long periods and patients are subjected to treatments for a variety of differential diagnoses without success. We report a 4-year-old boy with PSD who presented to our clinic with guttate psoriasis for 2 reasons: first, to make dermatologists aware of PSD and second, to emphasize the necessity to examine patients, particularly pediatric patients, with guttate psoriasis very thoroughly and swab both the pharynx and perianal and/or perigenital areas even when they are, or seem to be, asymptomatic for bacterial infections. Once PSD has been diagnosed, systemic antibiotic therapy with penicillin, erythromycin, roxithromycin, or azithromycin (probably augmented by topical mupirocin ointment) should be the treatment of choice. Therapy should be monitored by posttreatment perianal and throat swabs as well as a urine analysis to monitor for poststreptococcal glomerulonephritis.

Lipopolysaccharide-dependent down-regulation of CD27 expression on T cells activated with superantigen

To investigate the mechanisms underlying T-cell responses during superantigen (SAg) stimulation, we analysed the effects of SAg on CD27 expression with or without lipopolysaccharide (LPS) as a novel regulator of T-cell function. CD27 is expressed on the majority of resting peripheral blood T cells (CD27low). Activation of T cells by SAg induces high levels of CD27 surface expression (CD27high) accompanied with simultaneous CD30 receptor expression. After prolonged activation in vitro, the level of CD27 expression became intermediate. The effects of LPS on down-regulation of CD27high expression on CD30+ T cells were dose-dependent. Separating LPS-stimulated monocytes from T cells by mechanical dispersion abolished its inhibitory effect, indicating the requirement for direct interactions between monocytes and T cells. We also found that SAg up-regulated CD80 expression on CD14+ monocytes and LPS inhibited SAg-induced CD80 expression after 24 hr of stimulation. Up-regulation of CD152 (CTLA-4) was selective, since it was found to be preferentially expressed on the CD30+ population. Competitive experiments using soluble blocking peptides showed that addition of CD28 or CD80 peptide recovered LPS-induced down-regulation of CD27high expression on CD30+ T cells. These observations suggested that the presence of low levels of CD80 on monocytes may partially inhibit CD27 expression due to inefficient delivery of positive signals via CD28/CD80 interaction, and that the increased levels of CD80 enhance the inhibition through interactions with CD152 which is expressed at the highest levels after 48 hr of activation.