Outlining the skin-homing and circulating CLA+NK cells in patients with severe atopic dermatitis.

Atopic dermatitis (AD) is a complex, multifactorial skin disease, characterized by pruritus and predominant Th2 inflammation. Innate immune cells may play a role in AD development and are composed of granulocytes, macrophages, innate-like T cells, and innate lymphoid cells. This study investigates the phenotypic and functional profile of circulating CLA+ natural killer (NK) cells and its role in the skin-homing to NK cells infiltrated in adults' skin with AD. We selected 44 AD patients and 27 non-AD volunteers for the study. The results showed increased frequencies of both CLA+CD56bright and CLA+CD56dim NK cell populations in the peripheral blood, mainly in severe AD patients. Upon SEB stimulation, we observed an augmented percentage of CLA+CD56dim NK cells expressing CD107a, IFN-γ, IL-10, and TNF, reinforcing the role of staphylococcal enterotoxins in AD pathogenesis. Additionally, we demonstrated increased dermal expression of both NK cell markers NCAM-1/CD56 and pan-granzyme, corroborating the skin-homing, mostly in severe AD. Further studies are necessary to elucidate the potential role of NK cells in the chronification of the inflammatory process in AD skin, as well as their possible relationship with staphylococcal enterotoxins, and as practicable therapeutic targets.

Proinflammatory and regulatory mechanisms in allergic contact dermatitis caused by methylchloroisothiazolinone and methylisothiazolinone.

BACKGROUND: Methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) are the cause of an increasing number of contact allergies. Understanding the mechanisms by which MCI/MI induces proinflammatory and regulatory factors production is necessary to understand the outcome of allergic contact dermatitis (ACD). OBJECTIVES: To evaluate the dysfunction of proinflammatory cytokines and regulatory factors in the positive MCI/MI patch test at the transcriptional and protein expression levels. Moreover, to analyse the cytokines production induced by MI in peripheral blood mononuclear cells (PBMCs). MATERIALS AND METHODS: The selected patients had positive MCI/MI patch test results. The expression of proinflammatory factors was evaluated by q-PCR and immunochemistry at 48 hours of positive MCI/MI patch test. The MCI/MI- or MI- induced secretion of IL-1ß, TNF and IL-6 by PBMC was analysed by flow cytometry. RESULTS: The results showed a decreased TLR4 expression with upregulated IL6, FOXP3, IL10 and TGFß mRNA expression as assessed by q-PCR at the site of the MCI/MI skin reaction. We detected increased protein levels of TLR4, FOXP3 and IL-10 in the dermis layer in the ACD reaction by immunocitochemistry. Moreover, MCI/MI induced proinflammatory cytokine production by PBMC through the NF-κB signalling pathway. CONCLUSION: Considering the altered innate immune response triggered by MCI/MI sensitization, these findings indicate that the regulatory process at the induction phase of ACD is a crucial mechanism. Given the increase in occupational and domestic exposure to MCI/MI, the underlying immunological mechanisms should be understood.

RAGE and CCR7 mediate the transmigration of Zika-infected monocytes through the blood-brain barrier.

Details of the "Trojan Horse" mechanism by which Zika virus (ZIKV) crosses the blood-brain barrier (BBB) remain unclear. However, the migration of ZIKV-infected monocytes to the brain is thought to be dependent on both pattern-recognition and chemokine receptors. In this study, we investigated whether the migration of ZIKV-infected MonoMac-1 (MM-1) cells through the BBB is dependent on chemokine receptor 7 (CCR7) and receptor for advanced glycation end (RAGE); we also determined whether high mobility group box protein 1 (HMGB1) could facilitate the permeabilization of endothelial cells. We demonstrated that ZIKV infects MM-1 cells, leading to milieu accumulation of HMGB1. Our results suggest that HMGB1 is involved in the dysregulation of primary human brain microvascular endothelial cell junction markers. Our results also indicate that the migration of ZIKV-infected monocytes is dependent on chemokine ligand 19 (CCL19), the natural ligand of CCR7, in conditions recapitulating inflammation. RAGE-dependent migration of ZIKV-infected cells declined during transmigration assays in the presence of RAGE receptor antagonist FPS-ZM1. Understanding the molecular role of monocyte trafficking during ZIKV infections could facilitate the development of new therapeutic strategies to prevent the deleterious consequences of ZIKV neuroinfection.

Up-regulation of HMGB1 and TLR4 in skin lesions of lichen planus.

Lichen planus (LP) is a chronic, mucocutaneous inflammatory disease of an unknown aetiology. The disease has been associated with certain viruses, and the factors such as DAMPs (damage-associated molecular patterns) and PAMPs (pathogen-associated molecular patterns) may also contribute to the inflammatory response in LP. HMGB1 (high mobility group box 1 protein) is one of the major DAMPs that induces inflammation and could trigger LP disease. The present study was aimed to examine TLR4, RAGE and HMGB1 production in epidermis or dermis by immunohistochemistry and the respective expression of these targets in the skin lesions of patients with LP. Moreover, we measured HMGB1 serum levels by ELISA. The results showed similar profile of expression by HMGB1 and TLR4, which are decreased at epidermis and up-regulated at dermis of skin lesions of LP patients that was sustained by intense cellular infiltration. RAGE expression was also increased in dermis of LP. Although there is increased RAGE protein levels, a decreased RAGE transcript levels was detected. Similar HMGB1 serum levels were detected in the LP and control groups. This study demonstrates that HMGB1 and TLR4 could contribute to the inflammatory LP process in skin.

Staphylococcus aureus enterotoxins modulate IL-22-secreting cells in adults with atopic dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory immune-mediated skin disease characterized by skin colonization by Staphylococcus aureus. Interleukin (IL)-22, in cooperation with IL-17, triggers antimicrobial peptide elaboration and enhances certain immunological responses. In AD, IL-22 is related to epidermal hyperplasia, keratinocyte apoptosis, and inhibition of antimicrobial peptide (AMP) production. We aimed to evaluate the impact of staphylococcal enterotoxins on the Tc22/Th22 induction in the peripheral blood of AD patients and on CD4+/CD8+ T cells expressing IL-22 in AD skin. Our study showed inhibition of the staphylococcal enterotoxins A and B (SEA and SEB) response by Th22 (CD4+IL-22+IL-17A-IFN-γ-) cells in AD patients. In contrast, Tc22 (CD8+IL-22+IL-17A-IFN-γ-) cells were less susceptible to the inhibitory effects of staphylococcal enterotoxins and exhibited an enhanced response to the bacterial stimuli. In AD skin, we detected increased IL-22 transcript expression and T lymphocytes expressing IL-22. Together, our results provide two major findings in response to staphylococcal enterotoxins in adults with AD: dysfunctional CD4+ IL-22 secreting T cells and increased Tc22 cells. Our hypothesis reinforces the relevance of CD8 T cells modulated by staphylococcal enterotoxins as a potential source of IL-22 in adults with AD, which is relevant for the maintenance of immunological imbalance.

Activation of myeloid dendritic cells, effector cells and regulatory T cells in lichen planus.

BACKGROUND: Lichen planus (LP) is a chronic mucocutaneous inflammatory disease. Evaluating the balance between regulatory T cells and effector T cells could be useful for monitoring the proinflammatory profile of LP. Therefore, this study aimed to assess populations of dendritic cells (DCs) and regulatory and effector T cells in peripheral blood samples collected from patients with LP to evaluate the polyfunctionality of T cells upon toll-like receptor (TLR) activation. METHODS: Peripheral blood mononuclear cells collected from 18 patients with LP and 22 healthy control subjects were stimulated with agonists of TLR4, TLR7, TLR7/TLR8 or TLR9. Frequencies of circulating IFN-α(+) plasmacytoid DCs (pDCs); TNF-α(+) myeloid DCs (mDCs); regulatory T cells (Tregs); and IL-17-, IL-10-, IL-22-, TNF-, and IFN-γ-secreting T cells were assessed via flow cytometry. RESULTS: The frequencies of regulatory CD4(+) and CD8(+)CD25(+)Foxp3(+)CD127(low/-) T cells and TNF-α(+) mDCs were induced following activation with TLR4, TLR7 and TLR8 agonists in the LP group. Moreover, increased baseline frequencies of CD4(+)IL-10(+) T cells and CD8(+)IL-22(+) or IFN-γ(+)T cells were found. In the LP group, TLR4 activation induced an increased frequency of CD4(+)IFN-γ(+) T cells, while TLR7/8 and staphylococcal enterotoxin B (SEB) activation induced an increased frequency of CD8(+) IL-22(+) T cells. An increased frequency of polyfunctional CD4(+) T cells that simultaneously secreted 3 of the evaluated cytokines (not including IL-10) was verified upon TLR7/8/9 activation, while polyfunctional CD8(+) T cells were already detectable at baseline. CONCLUSIONS: TLR-mediated activation of the innate immune response induced the production of proinflammatory mDCs, Tregs and polyfunctional T cells in patients with LP. Therefore, TLR activation has an adjuvant role in inducing both innate and adaptive immune responses.

Up-regulation of Proinflammatory Genes and Cytokines Induced by S100A8 in CD8+ T Cells in Lichen Planus.

Lichen planus (LP) is a chronic inflammatory mucocutaneous disease. The inflammatory status of LP may be related to S100A8 (myeloid-related protein 8; MRP8) activation of cytotoxic cells. The aims of this study were to evaluate S100A8 expression in skin lesions and the in vitro effects of S100A8 on CD8+ T cells and natural killer (NK) cells in LP. Increased levels of S100A8/S100A9 were detected in the skin lesions as well as in the sera of subjects with LP. S100A8 expression induced an increased cytotoxic response by peripheral blood CD8+CD107a+ T cells as well as by NK CD56bright cells in patients with LP. Increased expression of interleukin (IL)-1ß, tumour necrosis factor (TNF) and IL-6 in the CD8+ T cells of patients with LP was induced by S100A8, in contrast to the control group that produced IL- 10 and interferon (IFN) type I genes. These data suggest that, in individuals with LP, S100A8 may exert distinct immunomodulatory and cytotoxicity functions.

Human endogenous retrovirus expression is inversely related with the up-regulation of interferon-inducible genes in the skin of patients with lichen planus.

Lichen planus (LP) is a common inflammatory skin disease of unknown etiology. Reports of a common transactivation of quiescent human endogenous retroviruses (HERVs) support the connection of viruses to the disease. HERVs are ancient retroviral sequences in the human genome and their transcription is often deregulated in cancer and autoimmune diseases. We explored the transcriptional activity of HERV sequences as well as the antiviral restriction factor and interferon-inducible genes in the skin from LP patients and healthy control (HC) donors. The study included 13 skin biopsies from patients with LP and 12 controls. Real-time PCR assay identified significant decrease in the HERV-K gag and env mRNA expression levels in LP subjects, when compared to control group. The expressions of HERV-K18 and HERV-W env were also inhibited in the skin of LP patients. We observed a strong correlation between HERV-K gag with other HERV sequences, regardless the down-modulation of transcripts levels in LP group. In contrast, a significant up-regulation of the cytidine deaminase APOBEC 3G (apolipoprotein B mRNA-editing), and the GTPase MxA (Myxovirus resistance A) mRNA expression level was identified in the LP skin specimens. Other transcript expressions, such as the master regulator of type I interferon-dependent immune responses, STING (stimulator of interferon genes) and IRF-7 (interferon regulatory factor 7), IFN-ß and the inflammassome NALP3, had increased levels in LP, when compared to HC group. Our study suggests that interferon-inducible factors, in addition to their role in innate immunity against exogenous pathogens, contribute to the immune control of HERVs. Evaluation of the balance between HERV and interferon-inducible factor expression could possibly contribute to surveillance of inflammatory/malignant status of skin diseases.