T cell activation is controlled by incompletely defined opposing stimulation and suppression signals that together sustain the balance between optimal host defense against infection and peripheral tolerance. Herein, we explored the impacts of Foxp3+ regulatory T cell (Treg) suppression in priming antigen-specific T cell activation under non-infection and infection conditions. We find the transient ablation of Foxp3+ Tregs unleashes the robust expansion and activation of peptide stimulated CD8+ T cells that provide protection against Listeria monocytogenes (Lm) infection in an antigen-specific fashion. By contrast, Treg-ablation had non-significant impacts on the CD8+ T cell response primed by infection with recombinant Lm. Similarly, non-recombinant Lm administered with peptide stimulated the expansion and activation of CD8+ T cells that paralleled the response primed by Treg-ablation. Interestingly, these adjuvant properties of Lm did not require CD8+ T cell stimulation by IL-12 produced in response to infection, but instead were associated with sharp reductions in Foxp3+ Treg suppressive potency. Therefore, Foxp3+ Tregs impose critical barriers that when overcome naturally during infection or artificially with ablation allows the priming of protective antigen-specific CD8+ T cells.

Melanocyte-stimulating hormone (MSH) reduces UV-induced DNA damage through the induction of pigmentation. In this study, we provide evidence that MSH also enhances DNA repair in skin keratinocytes by modulating the function of DNA repair molecules. Intracutaneous injection of MSH prevented UV-induced DNA damage in human and mouse skin independent of its effects on melanogenesis. In keratinocytes, MSH bound to the melanocyte melanocortin receptor type 1 and activated adenylate cyclase activity, which in turn activated Xeroderma pigmentosum group A (XPA)-binding protein 1 and induced nuclear translocation of XPA, a critical factor controlling nucleotide excision repair signaling pathways. Together, our findings reveal a novel pigmentation-independent mechanism that underlies MSH-mediated DNA repair following UVB irradiation. Cancer Res; 70(9); 3547-56. ©2010 AACR.

Summary Typhoid fever is a persistent infection caused by host‐adapted Salmonella strains adept at circumventing immune‐mediated host defences. Given the importance of T cells in protection, the culling of activated CD4+ T cells after primary infection has been proposed as a potential immune evasion strategy used by this pathogen. We demonstrate that the purging of activated antigen‐specific CD4+ T cells after virulent Salmonella infection requires SPI‐2 encoded virulence determinants, and is not restricted only to cells with specificity to Salmonella‐expressed antigens, but extends to CD4+ T cells primed to expand by co‐infection with recombinant Listeria monocytogenes. Unexpectedly, however, the loss of activated CD4+ T cells during Salmonella infection demonstrated using a monoclonal population of adoptively transferred CD4+ T cells was not reproduced among the endogenous repertoire of antigen‐specific CD4+ T cells identified with MHC class II tetramer. Analysis of T‐cell receptor variable segment usage revealed the selective loss and reciprocal enrichment of defined CD4+ T‐cell subsets after Salmonella co‐infection that is associated with the purging of antigen‐specific cells with the highest intensity of tetramer staining. Hence, virulent Salmonella triggers the selective culling of high avidity activated CD4+ T‐cell subsets, which re‐shapes the repertoire of antigen‐specific T cells that persist later after infection.

Objective: Recent studies have reported associations between dietary intake and mental health. Dietary fiber is one nutrient that may modulate mental health, specifically depression risk, through the gut microbiome. We prospectively examined the association between dietary fiber intake and mental health-related quality of life (QOL) scores, a proxy for depressive symptoms, in a cohort of 14,129 post-menopausal women in the Iowa Women's Health Study. Methods: Dietary intake was assessed at baseline [1986] using a 127-item food frequency questionnaire. Mental health-related QOL scores were assessed at the follow-up questionnaire [2004] using the Mental Health (MH) component and Mental Health Composite (MCS) scales derived from the SF-36 Health Survey. The association between dietary fiber intake and mean QOL scores was examined using linear regression, with adjustment for age, alcohol intake, energy intake, waist-to-hip ratio, physical activity, smoking status, and education. Results: The median dietary fiber intake was 19.0 g/day, ranging from 1.1 to 89.4 g/day. Multivariable-adjusted mean MH scores were higher among those with higher fiber intake (P for trend = 0.02). For MCS score, the association with fiber intake observed in a model adjusted for age and energy intake became insignificant after multivariable adjustment. Conclusions: Our study is one of the first prospective analyses of the association between higher dietary fiber intake and increased MH QOL scores later in life. Given a plausible biological mechanism underlying the association between fiber intake and mental health, additional studies are warranted. (A. Prizment).Maturitas 131 (2020) 1-7 0378-5122/

Acute respiratory distress syndrome (ARDS) is a severe, lifethreatening form of respiratory failure characterized by pulmonary edema, inflammation, and hypoxemia due to reduced alveolar fluid clearance (AFC). Alveolar fluid clearance is required for recovery and effective gas exchange, and higher rates of AFC are associated with reduced mortality. Thyroid hormones play multiple roles in lung function, and L-3,5,39-triiodothyronine (T3) has multiple effects on lung alveolar type II cells. T3 enhances AFC in normal adult rat lungs when administered intramuscularly and in normal or hypoxia-injured lungs when given intratracheally. The safety of a commercially available formulation of liothyronine sodium (synthetic T3) administered intratracheally was assessed in an Investigational New Drug Application-enabling toxicology study in healthy rats. Instillation of the commercial formulation of T3 without modification rapidly caused tracheal injury and often mortality. Intratracheal instillation of T3 that was reformulated and brought to a neutral pH at the maximum feasible dose of 2.73 mg T3 in 300 ml for 5 consecutive days had no clinically relevant T3related adverse clinical, histopathologic, or clinical pathology findings. There were no unscheduled deaths that could be attributed to the reformulated T3 or control articles, no differences in the lung weights, and no macroscopic or microscopic findings considered to be related to treatment with T3. This preclinical safety study has paved the way for a phase I/II study to determine the safety and tolerability of a T3 formulation delivered into the lungs of patients with ARDS, including coronavirus disease 2019-associated ARDS, and to measure the effect on extravascular lung water in these patients. SIGNIFICANCE STATEMENTThere is growing interest in treating lung disease with thyroid hormone [triiodothyronine (T3)] in pulmonary edema and acute respiratory distress syndrome (ARDS). However, there is not any published experience on the impact of direct administration of T3 into the lung. An essential step is to determine the safety of multiple doses of T3 administered in a relevant animal species. This study enabled Food and Drug Administration approval of a phase I/II clinical trial of T3 instillation in patients with ARDS, including coronavirus disease 2019-associated ARDS (T3-ARDS ClinicalTrials.gov Identifier NCT04115514).

Supplementary Figure 4 from Melanocyte-Stimulating Hormone Directly Enhances UV-Induced DNA Repair in Keratinocytes by a Xeroderma Pigmentosum Group A–Dependent Mechanism

Supplementary Figure 7 from Melanocyte-Stimulating Hormone Directly Enhances UV-Induced DNA Repair in Keratinocytes by a Xeroderma Pigmentosum Group A–Dependent Mechanism

Supplementary Figure 3 from Melanocyte-Stimulating Hormone Directly Enhances UV-Induced DNA Repair in Keratinocytes by a Xeroderma Pigmentosum Group A–Dependent Mechanism