Masato Kakeda

Calcineurin Inhibitors Suppress Cytokine Production from Memory T Cells and Differentiation of Naïve T Cells into Cytokine-Producing Mature T Cells

T cells have been classified as belonging to the Th1 or Th2 subsets according to the production of defining cytokines such as IFN-γ and IL-4. The discovery of the Th17 lineage and regulatory T cells shifted the simple concept of the Th1/Th2 balance into a 4-way mechanistic pathway of local and systemic immunological activity. Clinically, the blockage of cytokine signals or non-specific suppression of cytokine predominance by immunosuppressants is the first-line treatment for inflammatory T cell-mediated disorders. Cyclosporine A (CsA) and Tacrolimus (Tac) are commonly used immunosuppressants for the treatment of autoimmune disease, psoriasis, and atopic disorders. Many studies have shown that these compounds suppress the activation of the calcium-dependent phosphatase calcineurin, thereby inhibiting T-cell activation. Although CsA and Tac are frequently utilized, their pharmacological mechanisms have not yet been fully elucidated.In the present study, we focused on the effects of CsA and Tac on cytokine secretion from purified human memory CD4(+)T cells and the differentiation of naïve T cells into cytokine-producing memory T cells. CsA or Tac significantly inhibited IFN-γ, IL-4, and IL-17 production from memory T cells. These compounds also inhibited T cell differentiation into the Th1, Th2, and Th17 subsets, even when used at a low concentration. This study provided critical information regarding the clinical efficacies of CsA and Tac as immunosuppressants.

Granzyme B is a novel interleukin-18 converting enzyme

BACKGROUND Granzyme B (GrB) is recognized to induce apoptosis; however, little is known about its possible role in other biological events. IL-18, a potent inflammatory cytokine, is produced as an inactive precursor (proIL-18). Several cells, including monocytes/macrophage lineage and non-hematopoietic cells such as keratinocytes, produce proIL-18. ProIL-18 requires appropriate processing to become active. Caspase-1 is the authentic IL-18 processing enzyme and is essential for IL-18 release from monocyte/macrophage lineage cells. However, caspase-1 is absent in non-hematopoietic cells, suggesting that there is another candidate to cleave proIL-18 except for caspase-1. OBJECTIVE GrB can invade and be active in cytoplasm of non-hematopoietic cells via perforin, therefore we investigated whether GrB converts proIL-18 into the biologically active form. METHODS Recombinant proIL-18 (rproIL-18) was produced and purified for protease reaction with GrB; this incubate was evaluated by immunoblotting. Biological activity of the proteolytic fragment cleaved by GrB was determined by IFN-gamma assay using KG-1 cells. IFN-gamma induction was also analyzed between extracts from GrB(+)/caspase-1(-) human CD8+ T cells and proIL-18 from normal human keratinocytes (NHK). RESULTS The proteolytic fragment that GrB cleaved proIL-18 had the same sequence and biological activity compared with mature IL-18 cleaved by caspase-1. Culture extracts from CD8+ T cells was able to cleave proIL-18 into authentic mature IL-18. IFN-gamma induction was also detected in NHK treated with CD8+ T cells. CONCLUSION GrB is a potent IL-18 converting enzyme and suggest that GrB secreted by CTLs and/or NK cells may initiate IL-18 release from target cells, leading to the development of inflammation.

Increased interferon-γ, interleukin-12p40 and IL-8 production in Propionibacterium acnes-treated peripheral blood mononuclear cells from patient with acne vulgaris: host response but not bacterial species is the determinant factor of the disease.

BACKGROUND Acne vulgaris is a multifactorial inflammatory disease of the sebaceous follicles of the face and torso that frequently occurs in adolescence. Initially, acne starts as a non-inflammatory comedo. Subsequently, inflammatory reactions evolve to pustules, granulomas and cystic lesions. Many pathogenic mechanisms have been proposed including sebum excretion, obstruction of hair follicles, impaired keratinization of hair epithelium, bacterial overgrowth and immunological mechanisms; the role of Propionibacterium acnes (P. acnes) is particularly important. Facultative anaerobic gram-positive rods have been implicated in acne pathogenesis. However, the host immune response to P. acnes has not been as yet elucidated. OBJECTIVES The aim of the present study is to evaluate the importance of the immune response to P. acnes and the bacteriological factor in the pathogenesis of acne. METHODS P. acnes isolated from acne lesions and healthy volunteers skin were cultured. The peripheral blood mononuclear cells (PBMC) from acne patients or healthy volunteers were stimulated with viable P. acnes, and cytokine production was evaluated using RT-PCR and ELISA. RESULTS IFN-gamma, IL-12p40, and IL-8 mRNA and protein production were significantly increased in PBMC from acne patients compared to that from normal donors. However, different P. acnes species isolated from acne lesions or normal subjects showed no difference in cytokines production from acne patients and normal subjects PBMC. CONCLUSIONS The inflammatory response of acne appears to be attributable to P. acnes-induced host immune response rather than P. acnes strains from normal skin or acne lesions.

Cytokines and Chemokines in Irritant Contact Dermatitis

Irritant contact dermatitis is a result of activated innate immune response to various external stimuli and consists of complex interplay which involves skin barrier disruption, cellular changes, and release of proinflammatory mediators. In this review, we will focus on key cytokines and chemokines involved in the pathogenesis of irritant contact dermatitis and also contrast the differences between allergic contact dermatitis and irritant contact dermatitis.

Persistent Release of IL-1s from Skin Is Associated with Systemic Cardio-Vascular Disease, Emaciation and Systemic Amyloidosis: The Potential of Anti-IL-1 Therapy for Systemic Inflammatory Diseases

The skin is an immune organ that contains innate and acquired immune systems and thus is able to respond to exogenous stimuli producing large amount of proinflammatory cytokines including IL-1 and IL-1 family members. The role of the epidermal IL-1 is not limited to initiation of local inflammatory responses, but also to induction of systemic inflammation. However, association of persistent release of IL-1 family members from severe skin inflammatory diseases such as psoriasis, epidermolysis bullosa, atopic dermatitis, blistering diseases and desmoglein-1 deficiency syndrome with diseases in systemic organs have not been so far assessed. Here, we showed the occurrence of severe systemic cardiovascular diseases and metabolic abnormalities including aberrant vascular wall remodeling with aortic stenosis, cardiomegaly, impaired limb and tail circulation, fatty tissue loss and systemic amyloid deposition in multiple organs with liver and kidney dysfunction in mouse models with severe dermatitis caused by persistent release of IL-1s from the skin. These morbid conditions were ameliorated by simultaneous administration of anti-IL-1α and IL-1β antibodies. These findings may explain the morbid association of arteriosclerosis, heart involvement, amyloidosis and cachexia in severe systemic skin diseases and systemic autoinflammatory diseases, and support the value of anti-IL-1 therapy for systemic inflammatory diseases.

IL-4/IL-13 antagonist DNA vaccination successfully suppresses Th2 type chronic dermatitis

Background  Atopic dermatitis (AD) is a chronic disease with a Th2‐type‐cytokine dominant profile. Several cytokines and related peptides have been used for the treatment of AD but they were ineffective because of their limited biological half‐life. We have recently developed a highly efficient mouse dominant negative interleukin (IL)‐4/IL‐13 antagonist (IL‐4DM), which blocks both IL‐4 and IL‐13 signal transductions.

Intratumoral Injection of Propionibacterium acnes Suppresses Malignant Melanoma by Enhancing Th1 Immune Responses

Malignant melanoma (MM) is an aggressive cutaneous malignancy associated with poor prognosis; many putatively therapeutic agents have been administered, but with mostly unsuccessful results. Propionibacterium acnes (P. acnes) is an aerotolerant anaerobic gram-positive bacteria that causes acne and inflammation. After being engulfed and processed by phagocytes, P. acnes induces a strong Th1-type cytokine immune response by producing cytokines such as IL-12, IFN-γ and TNF-α. The characteristic Th2-mediated allergic response can be counteracted by Th1 cytokines induced by P. acnes injection. This inflammatory response induced by P. acnes has been suggested to have antitumor activity, but its effect on MM has not been fully evaluated. We analyzed the anti-tumor activity of P. acnes vaccination in a mouse model of MM. Intratumoral administration of P. acnes successfully protected the host against melanoma progression in vivo by inducing both cutaneous and systemic Th1 type cytokine expression, including TNF-α and IFN-γ, which are associated with subcutaneous granuloma formation. P. acnes-treated tumor lesions were infiltrated with TNF-α and IFN-γ positive T cells. In the spleen, TNF-α as well as IFN-γ producing CD8+T cells were increased, and interestingly, the number of monocytes was also increased following P. acnes administration. These observations suggest that P. acnes vaccination induces both systemic and local antitumor responses. In conclusion, this study shows that P. acnes vaccination may be a potent therapeutic alternative in MM.

Propionibacterium acnes vaccination induces regulatory T cells and Th1 immune responses and improves mouse atopic dermatitis

Abstract:  Atopic dermatitis (AD) is a chronic disease characterized by a polarized Th2 immune response. Propionibacterium acnes (P. acnes) has been shown to elicit strong Th1 immune responses. We hypothesized that the host immune response to P. acnes will prevent the development of AD. To demonstrate this hypothesis, we investigated the effect of P. acnes vaccination on AD that occurs in keratin 14/driven caspase‐1 transgenic mouse. Vaccination with low dose of P. acnes successfully prevented clinical manifestations in the skin of AD mice associated with systemic and cutaneous increased expression of Th1‐type cytokines but without suppression of Th2 cytokines. Interestingly, the numbers of IFN‐γ+T cells, FoxP3+CD4+CD25+T cells (nTreg) and IL‐10+T cells (Tr1) were significantly increased in the spleen. P. acnes vaccination has effects to alter the cytokine milieu and may be useful for the improvement of atopic symptom.

1,24-Dihydroxyvitamin D3 (tacalcitol) prevents skin T-cell infiltration

Background  1,24‐Dihydroxyvitamin D3 (tacalcitol), a vitamin D3 compound, has been used to treat T cell‐mediated inflammatory skin diseases such as psoriasis, prurigo and vitiligo. The best‐known mechanism of action of this compound is inhibition of the abnormal proliferation of keratinocytes and subsequent maturation; however, its effects on skin T‐cell recruitment have not yet been evaluated. Cutaneous lymphocyte‐associated antigen (CLA), a surface glycoprotein expressed on T cells, plays a critical role in skin T‐cell infiltration. We recently reported that 1,25‐dihydroxyvitamin D3 inhibits skin infiltration of CD4+ T cells by suppressing CLA expression on T cells.

Innate immune cells express IL-17A/F in acute generalized exanthematous pustulosis and generalized pustular psoriasis

Acute generalized exanthematous pustulosis (AGEP) and generalized pustular psoriasis (GPP) are rare pustular skin disorders with systemic involvement. IL-17A/F is a proinflammatory cytokine involved in various neutrophilic inflammatory disorders. Here we show that IL-17A/F is highly expressed by innate immune cells such as neutrophils and mast cells in both AGEP and GPP.