The role of superantigens in skin disease

Current knowledge on psoriasis and autoimmune diseases

Psoriasis is a prevalent, chronic inflammatory disease of the skin, mediated by crosstalk between epidermal keratinocytes, dermal vascular cells, and immunocytes such as antigen presenting cells (APCs) and T cells. Exclusive cellular “responsibility” for the induction and maintenance of psoriatic plaques has not been clearly defined. Increased proliferation of keratinocytes and endothelial cells in conjunction with APC/T cell/monocyte/macrophage inflammation leads to the distinct epidermal and vascular hyperplasia that is characteristic of lesional psoriatic skin. Despite the identification of numerous susceptibility loci, no single genetic determinant has been identified as responsible for the induction of psoriasis. Thus, numerous other triggers of disease, such as environmental, microbial and complex cellular interactions must also be considered as participants in the development of this multifactorial disease. Recent advances in therapeutics, especially systemic so-called “biologics” have provided new hope for identifying the critical cellular targets that drive psoriasis pathogenesis. Recent recognition of the numerous co-morbidities and other autoimmune disorders associated with psoriasis, including inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus suggest common signaling elements and cellular mediators may direct disease pathogenesis. In this review, we discuss common cellular pathways and participants that mediate psoriasis and other autoimmune disorders that share these cellular signaling pathways.

Epicutaneous exposure to staphylococcal superantigen enterotoxin B enhances allergic lung inflammation via an IL-17A dependent mechanism

Atopic dermatitis (AD) is the initial step of the atopic march: the progression from AD to allergic rhinitis and asthma. There is a close association between skin barrier abnormalities and the development of AD and the atopic march. One of cardinal features of AD is that the lesional skin of the majority of AD patients is chronically colonized with Staphylococcus aureus with half isolates producing superantigen enterotoxin B (SEB). Although diverse roles of SEB in the pathogenesis and severity of AD have been recognized, whether SEB contributes to the dermal inflammation that drives lung inflammation and airway hyperresponsiveness (AHR) has not been examined. Here we show a novel role of S. aureus superantigen SEB in augmenting allergen ovalbumin (Ova) induced atopic march through an IL-17A dependent mechanism. When mice epicutaneously (EC) sensitized with allergen Ova, addition of topical SEB led to not only augmented systemic Th2 responses but also a markedly exaggerated systemic Th17/IL-17 immune environment. The ability of SEB in enhancing Th17/IL-17 was mediated through stimulating lymphocytes in spleen and draining lymph nodes to promote IL-6 production. Epicutaneous sensitization of mice with a combination of Ova and SEB significantly enhanced Ova-induced AHR and granulocytic lung inflammation than Ova allergen alone. When IL-17A was deleted genetically, the effects of SEB on augmenting lung inflammation and AHR were markedly diminished. These findings suggest that chronic heavy colonization of enterotoxin producing S. aureus in the skin of patients with atopic dermatitis may have an important role in the development of atopic march via an IL-17A dependent mechanism.

A study of the efficacy, safety and tolerance of cosmetic products for basic care and hygiene in a combined therapy of patients suffering from atopic dermatitis in the mild to moderate forms

The article is considering contemporary views on the role and significance of microorganisms in pathogenesis of atopic dermatitis. One can also find here efficiency analysis of cosmetics Emolium P «Triaktivnyj cream» and «Triaktivnaja bath emulsion» as treatments for low and middle severity atopic dermatitis, as well as research results of skin microbiota (before study initiation and on 14 day).

Inhalation of Staphylococcus aureus enterotoxin A induces IFN-gamma and CD8 T cell-dependent airway and interstitial lung pathology in mice

Staphylococcus aureus, a primary source of bacterial superantigen (SAg), is known to colonize the human respiratory tract and has been implicated in airway inflammation. Studies have documented a role for SAgs in respiratory disorders, such as nasal polyps, chronic obstructive pulmonary disease, chronic rhinosinusitis, and asthma. However, cellular and molecular mediators involved in SAg-mediated pulmonary disease have not been clearly identified. In this study, we investigated the effect of intranasal staphylococcal enterotoxin A (SEA) exposure on murine lung. The pathological features in the lung resulting from SEA exposure had characteristics of both obstructive and restrictive pulmonary disorders. There was also an increase in bronchoalveolar lavage protein concentration and cellularity following SEA challenge. Massive CD8(+)Vbeta3(+) T cell accumulation observed in the lung was dependent on CD4 T cell help, both for recruitment and for IFN-gamma synthesis. The primary source of IFN-gamma synthesis was CD8 T cells, and depletion of these cells abrogated disease. IFN-gamma deficiency also prevented SEA-mediated disease, and this was by enhancing early recruitment of neutrophils as detected in the bronchoalveolar lavage. Thus, IFN-gamma appeared to selectively aid the recruitment of T cells to the lungs while preventing the neutrophil accumulation. Therefore, our results show that IFN-gamma-producing CD8 T cells mediated pulmonary alveolitis and inflammation, which were dependent upon CD4 T cells for their recruitment to the lung.

Psoriasiform and palmoplanter pustular lesions induced after Kawasaki disease

A 7-month-old boy was referred to us because of psoriatic lesions on the bilateral cheeks and on the extensor region of the left upper arm at the same site of his vaccination for tuberculosis 4 months previously (Fig. 1a,b). He also presented with small pustules scattered on the palms and soles (Fig. 1c).

Atopic dermatitis in young children is associated with impaired interleukin-10 and interferon-gamma responses to allergens, vaccines and colonizing skin and gut bacteria

BACKGROUND

A significant proportion of children with food allergy and more severe forms of atopic dermatis (AD) go on to develop persistent forms of allergic disease such asthma. Defining immune dysregulation in these children will be of great value in understanding disease pathogenesis.

OBJECTIVE

In this study we characterized the immune responses of young infants (6-18 months of age) with moderate-to-severe AD (a modified SCORAD>or=25) and compared these (n=53) with responses of non-allergic children with no history of dermatitis or sensitization of the same age (n=20).

METHODS

Mononuclear cell cytokine responses to allergens (egg ovalbumin (OVA), beta-lactoglobulin (BLG), house dust mite (HDM)), vaccines (tetanus toxoid (TT), diphtheria toxoid (DT)), intestinal flora (heat-killed Lactobacillus species (HKLB)), heat-killed Staphylococcus aureus (HKSA), S. aureus enterotoxin B (SEB) and mitogen (phytohaemaglutinin (PHA)) were compared in children with AD with unaffected children.

RESULTS

Children with AD had significantly lower spontaneous (unstimulated) production of regulatory cytokine IL-10 (P<0.001), as well as IFN-gamma (P<0.001) and TNF-alpha (P<0.001) compared with the unaffected children. After allowing for differences in baseline levels IL-10 responses to virtually all stimuli (food allergens (P=0.003), vaccines P=0.01, intestinal flora (heat-killed Lactobacillus species (HKLB), P=0.005) and skin flora (heat-killed Staphylococcus aureus (HKSA), P=0.003)) were also significantly attenuated in children with AD. The only exception was HDM, to which responses were stronger in children with AD [P=0.05]. Although there were no significant correlations between HDM IgE and HDM cytokine responses at this age, T-helper type 2 (Th2) IL-5 (P=0.014) and IL-13 (P=0.004) responses to HDM were significantly more frequent in the children with AD. However, while children with AD showed significantly attenuated Th1 IFN-gamma responses to food allergens (OVA, P=0.007 and BLG, P<0.001) and vaccines (DT, P=0.008 and TT, P<0.001), these children showed no difference in Th1 IFN-gamma responses to HDM or microbial agents (HKSA and HKLB).

CONCLUSION

A increase in propensity for Th2 responses to aeroallergens in children with AD is associated with early impaired production of IL-10 regulatory cytokine to a broad range of environmental stimuli including foods, intestinal flora, S. aureus, and vaccines.

Lessons from murine models of atopic dermatitis

Atopic dermatitis (AD) is a complex disease that manifests immunologic abnormalities in the skin. The immunologic changes of AD are characterized by a T helper cell type 2 (Th2)-dominated immune response in its acute phase and a Th1/Th2 mixed immune response in its chronic phase. Although the clinical presentation and pathologic changes are initially in the skin, AD may be, in part, a systemic disorder. In fact, AD is often considered to be the initial manifestation of the "atopic march" that progresses from AD to allergic rhinitis and asthma. In the past several years, a number of murine models of AD have been developed or discovered, and studies on these models have contributed greatly to our understanding of the immunopathogenesis of this disease. This review is focused on these recent, illuminating advances in animal models of AD.

Effects of the macrolide antibiotic, midecamycin, on Staphylococcus aureus product-induced Th2 cytokine response in patients with atopic dermatitis

In the present study, the effects of the macrolide antibiotic, midecamycin (MDM), on the Th2 cytokine response induced by the Staphylococcus aureus products, staphylococcal enterotoxin B (SEB), lipoteichoic acid (LTA), and peptidoglycan (PEG), was investigated in human peripheral blood mononuclear cells (PBMCs) from patients with atopic dermatitis (AD). MDM inhibited SEB-induced mRNA expression of the Th2 cytokines interleukin-4 (IL-4) and IL-5 in PBMCs from patients with AD. Furthermore, MDM also suppressed LTA-induced or PEG-induced IL-5 mRNA expression in these patients. Inhibition of mRNA expression by MDM correlated with the synthesis of cytokines in PBMCs, indicating that MDM controls Th2 cytokine production. In addition, S. aureus strains isolated from skin lesions of patients with AD were particularly susceptible to MDM compared with gentamicin, which is used widely in Japan as an antibiotic ointment combined with steroid for topical application in AD. These results suggest that topical administration of MDM might be beneficial in AD lesions infected with S. aureus.

Epicutaneous sensitization with superantigen induces allergic skin inflammation

BACKGROUND

Atopic dermatitis (AD) is characterized by skin infiltration with eosinophils and lymphocytes and expression of Th2 cytokines in acute skin lesions. The skin of patients with AD is frequently colonized with enterotoxin-secreting strains of Staphylococcus aureus. Staphylococcal enterotoxins have been implicated in the exacerbations of the inflammatory skin lesions in patients with AD.

OBJECTIVE

We sought to determine whether epicutaneous (EC) sensitization of mice with staphylococcal enterotoxin B (SEB) results in allergic skin inflammation.

METHODS

BALB/c mice were EC-sensitized with SEB. Their skin was examined for allergic inflammation and cytokine expression, and their splenocytes were examined for cytokine secretion in response to SEB.

RESULTS

EC sensitization with SEB elicited a local, cutaneous, inflammatory response characterized by dermal infiltration with eosinophils and mononuclear cells and increased mRNA expression of the Th2 cytokine IL-4 but not of the Th1 cytokine IFN-gamma. EC-sensitized mice mounted a systemic Th2 response to SEB evidenced by elevated total and SEB-specific IgG1 and IgE. Although EC sensitization with SEB resulted in selective depletion of SEB-specific T-cell receptor Vbeta8+ cells from the spleen and sensitized skin, splenocytes from SEB-sensitized mice secreted relatively more IL-4 and less IFN-gamma than did saline-sensitized controls, consistent with Th2 skewing of the systemic immune response to the superantigen.

CONCLUSION

These results suggest that EC exposure to superantigens skews the immune response toward Th2 cells, leading to allergic skin inflammation and increased IgE synthesis that are characteristic of AD.

Atopic dermatitis and fungi

Atopic dermatitis (AD) is a chronic, itching, inflammatory skin disease which is associated with asthma and/or hay fever and a familial occurrence of these conditions. Genetic factors are important in the development of AD, but the exact hereditary pathway is still unknown. Dry skin and the weakened barrier function in patients with AD is very important for the patient's reactions to irritants and other external trigger factors including microorganisms. The standard treatments are topical corticosteroids, topical immunomodulating agents, and emollients. If AD cannot be controlled by this type of treatment, systemic immunomodulating agents may be used. UVB, UVA, or psoralen-UVA may also be used for widespread severe lesions. However, some patients do not respond to these standard treatment, and then it is important to consider the role of microorganisms, house dust mites or food. The role of the Malassezia yeasts in AD, especially AD located to the head and neck region, is now documented in several papers. There are also several papers indicating the role of Candida as an aggravating factor in AD. Patients with AD also develop chronic dermatophyte infections more easily, and patients with AD and chronic dermatophyte infections may show improvement in their AD when treated with antifungal drugs.

Cell wall components of Staphylococcus aureus induce interleukin-5 production in patients with atopic dermatitis

Lipoteichoic acid (LTA) and peptidoglycan (PEG) from Staphylococcus aureus induced interleukin-5 (IL-5) production in human peripheral blood mononuclear cells (PBMC) from patients with atopic dermatitis (AD) but not in PBMC from healthy donors. The production of IL-5 induced by LTA or PEG was correlated with the expression of IL-5 mRNA in PBMC. Furthermore, the level of IL-5 production induced by treatment with both LTA and PEG from S. aureus was higher than that induced by the addition of each alone. These results suggest that LTA and PEG have an additive effect on IL-5 production in PBMC from AD patients and may explain the role of colonization with nontoxin-producing strains of S. aureus in these patients.

Management and morbidity of cellulitis of the leg

Ascending cellulitis of the leg is a common emergency. An audit was conducted in two district general hospitals to determine how it is managed and the long-term morbidity, and to formulate a treatment strategy. Case notes were reviewed for 92 patients admitted to hospital under adult specialties. Mean duration of inpatient therapy was 10 days. A likely portal of entry was identified in 51/92 cases, of which the commonest were minor injuries and tinea pedis. Pathogens were rarely identified, group G streptococci being the single most frequent organism. Benzylpenicillin was administered in only 43 cases. Long-term morbidity, identified in 8 of 70 patients with over six months' follow-up, included persistent oedema (6) and leg ulceration (2); an additional 19 patients had either suffered previous episodes or experienced a further episode subsequently. Ascending cellulitis of the leg has substantial short-term and long-term morbidity. Important but often neglected therapeutic suggestions are the inclusion of benzylpenicillin in all cases without a contraindication, assessment and treatment of tinea pedis, use of support hosiery, and serological testing for streptococci to confirm the diagnosis in retrospect. The high frequency of recurrent episodes suggests that longer courses of penicillin, or penicillin prophylaxis, might be useful.

Immunological study on CD3 defective cutaneous T cell lymphoma cells from a patient with Sézary syndrome

Here we investigated the nature of cutaneous T cell lymphoma (CTCL) cells lacking surface CD3. A large number of CD3- CD4 T cells were found in the peripheral blood and lesional skin of a patient with Sézary syndrome, which is a variant of CTCL. Southern blot analysis revealed that a clonal rearrangement of T cell receptor (TCR) genes was detected in the separated CD3- CD4 cells, whereas CD3+ CD4 cells showed no clonal rearrangement, indicating that the CD3- CD4 cells represented CTCL cells. However, the CTCL cells expressed TCR with a particular Vbeta apart from CD3. The CTCL cells showed significant responses to staphylococcal enterotoxins (SEs) in vitro, although they hardly responded to phytohaemagglutinin, Mycobacterium tuberculosis antigen, and alloantigen. They required antigen-presenting cells (APC) to respond to SEB. Blocking analyses with MoAbs revealed that they recognized SEB through TCR depending on HLA-DR and intercellular adhesion molecule-1 (ICAM-1). Taken collectively, these results indicate that the CTCL cells lacking surface CD3 could proliferate in response to bacterial superantigens, whereas the responses to conventional antigens were generally suppressed. These results also implied that CTCL could be exacerbated by bacterial infection.

Immunotherapy with Mycobacterium vaccae in the treatment of psoriasis

A placebo-controlled study of immunotherapy with Mycobacterium vaccae for chronic plaque psoriasis showed improvement in the psoriasis area severity index in 19 of 21 immunotherapy recipients (P<0.005). Minor improvement, not reaching statistical significance for the group, occurred in nine of 14 placebo recipients. There were losses to follow-up and the placebo used, tetanus toxoid, was not ideal. Clinical improvement after immunotherapy persisted for 6 months and another injection of the immunotherapeutic given to a few volunteers from either group resulted in benefits lasting a year. Lymphoproliferative tests were carried out at each clinic visit, and on 50 matched controls. Starting with reduced responses to mycobacterial antigens and concanavalin A, both treatment groups showed a fall after 3 months, and diverged at 6 months with M. vaccae recipients rising to values similar to those of healthy controls, whereas placebo recipients continued to fall. Conclusions reached were that immunotherapy with M. vaccae gave long-lasting clinical benefit to most patients, with minimal side effects. This accompanied a return towards normal cellular immune responsiveness to mycobacterial antigens, which did not follow the use of the placebo.

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

The strong association of acute guttate psoriasis and streptococcal throat infection, together with the preferential use of T cells expressing a particular T-cell receptor, has suggested a role for bacterial superantigens in the pathogenesis of psoriasis. We examined the proliferative responses of peripheral blood lymphocytes (PBLs), obtained from patients with psoriasis and from healthy controls, to streptococcal superantigens, cytoplasmic membrane-associated protein (CAP) and secretion-type CAP (SCAP), isolated from group A, beta-haemolytic streptococci. PBLs from patients with psoriasis showed significantly less response to SCAP and CAP than those from healthy controls. Because there was no difference between psoriatic patients and controls in the proliferative response of PBLs to staphylococcal enterotoxin A or E (SEA, SEE) or the mitogen phytohaemagglutinin (PHA), these findings strongly suggest that the reduced reactivity to the streptococcal superantigens seems to reflect anergy of a population of PBLs to the superantigens. As the CAP used in the present study stimulates V beta 8 T cells selectively, we further examined the proliferation of V beta 8 T cells after such stimulation using flow cytometry. V beta 8 T cells obtained from three of four psoriatic patients failed to proliferate in the presence of CAP, whereas they proliferated vigorously in the presence of SEE, which activates V beta 8 T cells, confirming the specific hyporesponsiveness of PBLs from psoriatic patients to streptococcal superantigens. We then determined the effects of serum factors on the suppressed response of PBLs to the streptococcal superantigens with SCAP or CAP. It was partially restored when PBLs were cultured with sera obtained from healthy subjects, although the responses were still significantly lower than those of the healthy controls. In contrast, psoriatic sera markedly suppressed the proliferative response of PBLs from healthy controls to CAP or SCAP, but showed no suppression of the proliferative response of PBLs to SEA. Because these findings suggest the presence of specific inhibitory factors in psoriatic sera, we examined whether the inhibitory effect was caused by antisuperantigen antibody. However, no significant increase was detected in antibody titre to CAP in psoriatic sera, as has been noted in sera from patients with poststreptococcal glomerulonephritis. The present results show for the first time the hyporesponsiveness of PBLs to streptococcal superantigens and the presence of serum inhibitors that specifically inhibit T-cell response to the superantigens in psoriatic patients. These findings suggest a pathological role for streptococcal infections in the pathogenesis of psoriasis.