Ute Laggner

Identification of a Novel Proinflammatory Human Skin-Homing Vγ9Vδ2 T Cell Subset with a Potential Role in Psoriasis

γδ T cells mediate rapid tissue responses in murine skin and participate in cutaneous immune regulation including protection against cancer. The role of human γδ cells in cutaneous homeostasis and pathology is characterized poorly. In this study, we show in vivo evidence that human blood contains a distinct subset of proinflammatory cutaneous lymphocyte Ag and CCR6-positive Vγ9Vδ2 T cells, which is rapidly recruited into perturbed human skin. Vγ9Vδ2 T cells produced an array of proinflammatory mediators including IL-17A and activated keratinocytes in a TNF-α– and IFN-γ–dependent manner. Examination of the common inflammatory skin disease psoriasis revealed a striking reduction of circulating Vγ9Vδ2 T cells in psoriasis patients compared with healthy controls and atopic dermatitis patients. Decreased numbers of circulating Vγ9Vδ2 T cells normalized after successful treatment with psoriasis-targeted therapy. Taken together with the increased presence of Vγ9Vδ2 T cells in psoriatic skin, these data indicate redistribution of Vγ9Vδ2 T cells from the blood to the skin compartment in psoriasis. In summary, we report a novel human proinflammatory γδ T cell involved in skin immune surveillance with immediate response characteristics and with potential clinical relevance in inflammatory skin disease.

|[alpha]|1|[beta]|1 integrin is crucial for accumulation of epidermal T cells and the development of psoriasis

Psoriasis is a common T cell–mediated autoimmune inflammatory disease. We show that blocking the interaction of α1β1 integrin (VLA-1) with collagen prevented accumulation of epidermal T cells and immunopathology of psoriasis. α1β1 integrin, a major collagen-binding surface receptor, was exclusively expressed by epidermal but not dermal T cells. α1β1-positive T cells showed characteristic surface markers of effector memory cells and contained high levels of interferon-γ but not interleukin-4. Blockade of α1β1 inhibited migration of T cells into the epidermis in a clinically relevant xenotransplantation model. This was paralleled by a complete inhibition of psoriasis development, comparable to that caused by tumor necrosis factor-α blockers. These results define a crucial role for α1β1 in controlling the accumulation of epidermal type 1 polarized effector memory T cells in a common human immunopathology and provide the basis for new strategies in psoriasis treatment focusing on T cell–extracellular matrix interactions.

The IL23R R381Q Gene Variant Protects against Immune-Mediated Diseases by Impairing IL-23-Induced Th17 Effector Response in Humans

IL-23 and Th17 cells are key players in tissue immunosurveillance and are implicated in human immune-mediated diseases. Genome-wide association studies have shown that the IL23R R381Q gene variant protects against psoriasis, Crohns disease and ankylosing spondylitis. We investigated the immunological consequences of the protective IL23R R381Q gene variant in healthy donors. The IL23R R381Q gene variant had no major effect on Th17 cell differentiation as the frequency of circulating Th17 cells was similar in carriers of the IL23R protective (A) and common (G) allele. Accordingly, Th17 cells generated from A and G donors produced similar amounts of Th17 cytokines. However, IL-23-mediated Th17 cell effector function was impaired, as Th17 cells from A allele carriers had significantly reduced IL-23-induced IL-17A production and STAT3 phosphorylation compared to G allele carriers. Our functional analysis of a human disease-associated gene variant demonstrates that IL23R R381Q exerts its protective effects through selective attenuation of IL-23-induced Th17 cell effector function without interfering with Th17 differentiation, and highlights its importance in the protection against IL-23-induced tissue pathologies.

Cutting Edge: A Critical Functional Role for IL-23 in Psoriasis

Interleukin-23 is a key cytokine involved in the generation of Th17 effector cells. Clinical efficacy of an anti-p40 mAb blocking both IL-12 and IL-23 and disease association with single nucleotide polymorphisms in the IL23R gene raise the question of a functional role of IL-23 in psoriasis. In this study, we provide a comprehensive analysis of IL-23 and its receptor in psoriasis and demonstrate its functional importance in a disease-relevant model system. The expression of IL-23 and its receptor was increased in the tissues of patients with psoriasis. Injection of a mAb specifically neutralizing human IL-23 showed IL-23–dependent inhibition of psoriasis development comparable to the use of anti-TNF blockers in a clinically relevant xenotransplant mouse model of psoriasis. Together, our results identify a critical functional role for IL-23 in psoriasis and provide the rationale for new treatment strategies in chronic epithelial inflammatory disorders.

Regression of melanoma metastases following treatment with the n-bisphosphonate zoledronate and localised radiotherapy

We report a case of regression of pulmonary and bony metastases in a patient with malignant melanoma following palliative treatment with systemic zoledronate and localised radiotherapy to the bone. Zoledronate is a potent new bisphosphonate used for the treatment of metabolic bone diseases including bone metastases due to its inhibitory effect on osteoclasts. In the context of metastatic cancer zoledronate is routinely used to improve bone pain and reduce the frequency of skeletal events. There is also an increasing body of evidence suggesting that bisphosphonates exhibit anti-tumour properties. Bisphosphonates are able to activate Vgamma9Vdelta2 gamma-delta T cells which can be key players in the immune defence against malignant cells. Furthermore bisphosphonates have direct anti-proliferative, anti-metastatic and pro-apoptotic effects on tumour cells. These actions, together with their low side effect profile, may prove to be useful therapeutic tools in the treatment of cancer even in the absence of bone metastases. On the basis of this case report we here review the current literature on present preclinical and clinical studies using bisphosphonates for the treatment of cancer.

Allele-Specific Cytokine Responses at the HLA-C Locus: Implications for Psoriasis

Psoriasis is an inflammatory skin disorder that is inherited as a complex trait. Genetic studies have repeatedly highlighted HLA-C as the major determinant for psoriasis susceptibility, with the Cw*0602 allele conferring significant disease risk in a wide-range of populations. Despite the potential importance of HLA-C variation in psoriasis, either via an effect on peptide presentation or immuno-inhibitory activity, allele-specific expression patterns have not been investigated. Here, we used reporter assays to characterize two regulatory variants, which virtually abolished the response to TNF-α (rs2524094) and IFN-γ (rs10657191) in HLA-Cw*0602 and a cluster of related alleles. We validated these findings through the analysis of HLA-Cw*0602 expression in primary keratinocytes treated with TNF-α and IFN-γ. Finally, we showed that HLA-Cw*0602 transcripts are not increased in psoriatic skin lesions, despite highly elevated TNF-α levels. Thus, our findings demonstrate the presence of allele-specific differences in HLA-C expression and indicate that HLA-Cw*0602 is unresponsive to up-regulation by key pro-inflammatory cytokines in psoriasis. These data pave the way for functional studies into the pathogenic role of the major psoriasis susceptibility allele.