TYK2 is a JAK family protein tyrosine kinase activated in response to multiple cytokines, including type I IFNs, IL-6, IL-10, IL-12, and IL-23. Extensive studies of mice that lack TYK2 expression indicate that the IFN-α, IL-12, and IL-23 pathways, but not the IL-6 or IL-10 pathways, are compromised. In contrast, there have been few studies of the role of TYK2 in primary human cells. A genetic mutation at the tyk2 locus that results in a lack of TYK2 protein in a single human patient has been linked to defects in the IFN-α, IL-6, IL-10, IL-12, and IL-23 pathways, suggesting a broad role for TYK2 protein in human cytokine responses. In this article, we have used a panel of novel potent TYK2 small-molecule inhibitors with varying degrees of selectivity against other JAK kinases to address the requirement for TYK2 catalytic activity in cytokine pathways in primary human cells. Our results indicate that the biological processes that require TYK2 catalytic function in humans are restricted to the IL-12 and IL-23 pathways, and suggest that inhibition of TYK2 catalytic activity may be an efficacious approach for the treatment of select autoimmune diseases without broad immunosuppression.

The use of murine systems to model pathogen-induced human diseases presumes that general immune mechanisms between these species are conserved. One important immunoregulatory mechanism involves linkage of innate and adaptive immunity to direct the development of T helper subsets, for example toward subset 1 (TH1) development through STAT4 activation. In analyzing type I interferon signaling, we uncovered a difference between murine and human cells which may affect how these two species control linkage between innate and adaptive immunity. We show that in humans, type I interferons induce TH1 development and can activate STAT4 by recruitment to the IFN-alpha receptor complex specifically via the carboxy-terminus of STAT2. However, the mouse Stat2 gene harbors a minisatellite insertion that has altered the carboxy-terminus and selectively disrupted its capacity to activate STAT4, but not other STATs. This defect in murine Stat2 suggests that the signals leading to STAT4 activation and TH1 development in CD4+ T cells are different between mice and humans.

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Quantitative bone ultrasound (QUS) has a significant heritable component. Because estrogen is required for attainment of peak bone mass, we studied alleles of two genes, estrogen receptor ␣ (ER1) and amplified in

Inconsistent use of oral contraceptives (OCs) exposes women to risks of unintended pregnancy. This study explored women's self-described reasons for missed OC pills. Data from diary cards completed by 141 women were studied to see how reasons for missing pills were related to patterns of pill use. The findings suggest that practitioners might improve OC use by focusing on the reasons that women miss pills, thus providing a more tailored approach that addresses individual risks based on women's personal experiences.