Induction of skin-pathogenic Th22 cells by epicutaneous allergen exposure.

BACKGROUND: Atopic dermatitis (AD) is a common inflammatory skin disease with dysfunction of the skin barrier, an abnormal immune response and frequent allergies to environmental antigens like food antigens. Clinical observations suggest that certain diets can influence the course of AD. OBJECTIVE: Here we compared the phenotype of food allergen-specific T cells activated through skin or gut allergen exposure to transfer skin inflammation into naïve recipients upon epicutaenous allergen challenge. METHODS: Ovalbumin (OVA) TCR-transgenic mice were treated epicutaneously with OVA or were fed OVA. CD4+ T cells from skin lymph nodes or mesenteric lymph nodes were transferred into naïve BALB/c mice, which were challenged with OVA epicutaneously. Skin inflammation was determined by histological parameters. In addition, we analyzed the phenotype of the immune response in lymphoid tissues and in skin tissue. RESULTS: TCR-transgenic T cells activated through epicutaneous or oral OVA exposure both migrate to skin lymph nodes after adoptive transfer and epicutaenous OVA exposure. AD-like skin inflammation could only be induced by the transfer of epicutaneously primed OVA T cells. Analysis of the immune phenotype demonstrated an IL-22/IL-17A-dominated immune phenotype of skin-pathogenic T cells. CONCLUSION: IL-22 seems to be the critical cytokine for the development of AD and is induced in this model by epicutaneous sensitization with OVA.

Nutritional control of IL-23/Th17-mediated autoimmune disease through HO-1/STAT3 activation.

The nutritional curcumin (CUR) is beneficial in cell-mediated autoimmune diseases. The molecular mechanisms underlying this food-mediated silencing of inflammatory immune responses are poorly understood. By investigating antigen-specific immune responses we found that dietary CUR impairs the differentiation of Th1/Th17 cells in vivo during encephalomyelitis and instead promoted Th2 cells. In contrast, feeding CUR had no inhibitory effect on ovalbumin-induced airway inflammation. Mechanistically, we found that CUR induces an anti-inflammatory phenotype in dendritic cells (DC) with enhanced STAT3 phosphorylation and suppressed expression of Il12b and Il23a. On the molecular level CUR readily induced NRF2-sensitive heme oxygenase 1 (HO-1) mRNA and protein in LPS-activated DC. HO-1 enhanced STAT3 phosphorylation, which enriched to Il12b and Il23a loci and negatively regulated their transcription. These findings demonstrate the underlying mechanism through which a nutritional can interfere with the immune response. CUR silences IL-23/Th17-mediated pathology by enhancing HO-1/STAT3 interaction in DC.

Reduced Insulin/IGF-1 Signaling Restores the Dynamic Properties of Key Stress Granule Proteins during Aging.

Low-complexity "prion-like" domains in key RNA-binding proteins (RBPs) mediate the reversible assembly of RNA granules. Individual RBPs harboring these domains have been linked to specific neurodegenerative diseases. Although their aggregation in neurodegeneration has been extensively characterized, it remains unknown how the process of aging disturbs RBP dynamics. We show that a wide variety of RNA granule components, including stress granule proteins, become highly insoluble with age in C. elegans and that reduced insulin/insulin-like growth factor 1 (IGF-1) daf-2 receptor signaling efficiently prevents their aggregation. Importantly, stress-granule-related RBP aggregates are associated with reduced fitness. We show that heat shock transcription factor 1 (HSF-1) is a main regulator of stress-granule-related RBP aggregation in both young and aged animals. During aging, increasing DAF-16 activity restores dynamic stress-granule-related RBPs, partly by decreasing the buildup of other misfolded proteins that seed RBP aggregation. Longevity-associated mechanisms found to maintain dynamic RBPs during aging could be relevant for neurodegenerative diseases.