TFH cells progressively differentiate to regulate the germinal center response.

Germinal center (GC) B cells undergo affinity selection, which depends on interactions with CD4(+) follicular helper T cells (TFH cells). We found that TFH cells progressed through transcriptionally and functionally distinct stages and provided differential signals for GC regulation. They initially localized proximally to mutating B cells, secreted interleukin 21 (IL-21), induced expression of the transcription factor Bcl-6 and selected high-affinity B cell clones. As the GC response evolved, TFH cells extinguished IL-21 production and switched to IL-4 production, showed robust expression of the co-stimulatory molecule CD40L, and promoted the development of antibody-secreting B cells via upregulation of the transcription factor Blimp-1. Thus, TFH cells in the B cell follicle progressively differentiate through stages of localization, cytokine production and surface ligand expression to 'fine tune' the GC reaction.

Absence of CNTNAP2 leads to epilepsy, neuronal migration abnormalities, and core autism-related deficits.

Although many genes predisposing to autism spectrum disorders (ASD) have been identified, the biological mechanism(s) remain unclear. Mouse models based on human disease-causing mutations provide the potential for understanding gene function and novel treatment development. Here, we characterize a mouse knockout of the Cntnap2 gene, which is strongly associated with ASD and allied neurodevelopmental disorders. Cntnap2(-/-) mice show deficits in the three core ASD behavioral domains, as well as hyperactivity and epileptic seizures, as have been reported in humans with CNTNAP2 mutations. Neuropathological and physiological analyses of these mice before the onset of seizures reveal neuronal migration abnormalities, reduced number of interneurons, and abnormal neuronal network activity. In addition, treatment with the FDA-approved drug risperidone ameliorates the targeted repetitive behaviors in the mutant mice. These data demonstrate a functional role for CNTNAP2 in brain development and provide a new tool for mechanistic and therapeutic research in ASD.

A rare case report for dermatomyofibroma in nasion.

Dermatomyofibroma is a benign and rare proliferation of myofibroblasts and fibroblasts of the skin. Dermatomyofibroma commonly locates at the shoulder and neck of young adults and adolescents. Other frequently affected anatomic sites are upper arms, thigh, chest wall, back, axillary region and abdomen. Herein, we reported a case of dermatomyofibroma occurred in the nasion. The asymptomatic firm nodule and histopathological features were consistent with dermatomyofibroma. Immunohistochemically, the tumor cells expressed vimentin, HHF35 and α-smooth muscle actin (α-SMA). The patient was followed up for 2 years after excision of the tumors and recurrences were not observed.

Common genetic variants on 5p14.1 associate with autism spectrum disorders.

Autism spectrum disorders (ASDs) represent a group of childhood neurodevelopmental and neuropsychiatric disorders characterized by deficits in verbal communication, impairment of social interaction, and restricted and repetitive patterns of interests and behaviour. To identify common genetic risk factors underlying ASDs, here we present the results of genome-wide association studies on a cohort of 780 families (3,101 subjects) with affected children, and a second cohort of 1,204 affected subjects and 6,491 control subjects, all of whom were of European ancestry. Six single nucleotide polymorphisms between cadherin 10 (CDH10) and cadherin 9 (CDH9)-two genes encoding neuronal cell-adhesion molecules-revealed strong association signals, with the most significant SNP being rs4307059 (P = 3.4 x 10(-8), odds ratio = 1.19). These signals were replicated in two independent cohorts, with combined P values ranging from 7.4 x 10(-8) to 2.1 x 10(-10). Our results implicate neuronal cell-adhesion molecules in the pathogenesis of ASDs, and represent, to our knowledge, the first demonstration of genome-wide significant association of common variants with susceptibility to ASDs.

Genome-wide analyses of exonic copy number variants in a family-based study point to novel autism susceptibility genes.

The genetics underlying the autism spectrum disorders (ASDs) is complex and remains poorly understood. Previous work has demonstrated an important role for structural variation in a subset of cases, but has lacked the resolution necessary to move beyond detection of large regions of potential interest to identification of individual genes. To pinpoint genes likely to contribute to ASD etiology, we performed high density genotyping in 912 multiplex families from the Autism Genetics Resource Exchange (AGRE) collection and contrasted results to those obtained for 1,488 healthy controls. Through prioritization of exonic deletions (eDels), exonic duplications (eDups), and whole gene duplication events (gDups), we identified more than 150 loci harboring rare variants in multiple unrelated probands, but no controls. Importantly, 27 of these were confirmed on examination of an independent replication cohort comprised of 859 cases and an additional 1,051 controls. Rare variants at known loci, including exonic deletions at NRXN1 and whole gene duplications encompassing UBE3A and several other genes in the 15q11-q13 region, were observed in the course of these analyses. Strong support was likewise observed for previously unreported genes such as BZRAP1, an adaptor molecule known to regulate synaptic transmission, with eDels or eDups observed in twelve unrelated cases but no controls (p = 2.3x10(-5)). Less is known about MDGA2, likewise observed to be case-specific (p = 1.3x10(-4)). But, it is notable that the encoded protein shows an unexpectedly high similarity to Contactin 4 (BLAST E-value = 3x10(-39)), which has also been linked to disease. That hundreds of distinct rare variants were each seen only once further highlights complexity in the ASDs and points to the continued need for larger cohorts.

Plasmacytoid dendritic cells take up opsonized antigen leading to CD4+ and CD8+ T cell activation in vivo.

Plasmacytoid dendritic cells (pDC) are the body's main source of IFN-alpha, but, unlike classical myeloid DC (myDC), they lack phagocytic activity and are generally perceived as playing only a minor role in Ag processing and presentation. We show that murine pDC, as well as myDC, express Fcgamma receptors (CD16/CD32) and can use these receptors to acquire Ag from immune complexes (IC), resulting in the induction of robust Ag-specific CD4(+) and CD8(+) T cell responses. IC-loaded pDC stimulate CD4(+) T cells to proliferate and secrete a mixture of IL-4 and IFN-gamma, and they induce CD8(+) T cells to secrete IL-10 as well as IFN-gamma. In contrast, IC-loaded myDC induce both CD4(+) and CD8(+) T cells to secrete mainly IFN-gamma. These results indicate that pDC can shape an immune response by acquiring and processing opsonized Ag, leading to a predominantly Th2 response.

STAT4 and T-bet control follicular helper T cell development in viral infections.

Follicular helper T (Tfh) cells promote germinal center (GC) B cell survival and proliferation and guide their differentiation and immunoglobulin isotype switching by delivering contact-dependent and soluble factors, including IL-21, IL-4, IL-9, and IFN-γ. IL-21 and IFN-γ are coexpressed by Tfh cells during viral infections, but transcriptional regulation of these cytokines is not completely understood. In this study, we show that the T helper type 1 cell (Th1 cell) transcriptional regulators T-bet and STAT4 are coexpressed with Bcl6 in Tfh cells after acute viral infection, with a temporal decline in T-bet in the waning response. T-bet is important for Tfh cell production of IFN-γ, but not IL-21, and for a robust GC reaction. STAT4, phosphorylated in Tfh cells upon infection, is required for expression of T-bet and Bcl6 and for IFN-γ and IL-21. These data indicate that T-bet is expressed with Bcl6 in Tfh cells and is required alongside STAT4 to coordinate Tfh cell IL-21 and IFN-γ production and for promotion of the GC response after acute viral challenge.

Prevention of acute graft-versus-host disease by blocking T-cell entry to secondary lymphoid organs.

In acute graft-versus-host disease (aGVHD), donor T cells attack the recipient's gastrointestinal tract, liver, and skin. We hypothesized that blocking access to distinct lymphoid priming sites may alter the specific organ tropism and prevent aGVHD development. In support of this initial hypothesis, we found that different secondary lymphoid organs (SLOs) imprint distinct homing receptor phenotypes on evolving alloreactive effector T cells in vivo. Yet preventing T-cell entry to specific SLOs through blocking monoclonal antibodies, or SLO ablation, did not alter aGVHD pathophysiology. Moreover, transfer of alloreactive effector T cells into conditioned secondary recipients targeted the intestines and liver, irrespective of their initial priming site. Thus, we demonstrate redundancy of SLOs at different anatomical sites in aGVHD initiation. Only prevention of T-cell entry to all SLOs could completely abrogate the onset of aGVHD.

In vivo analyses of early events in acute graft-versus-host disease reveal sequential infiltration of T-cell subsets.

Graft-versus-host disease (GVHD) is a major obstacle in allogeneic hematopoietic cell transplantation. Given the dynamic changes in immune cell subsets and tissue organization, which occur in GVHD, localization and timing of critical immunological events in vivo may reveal basic pathogenic mechanisms. To this end, we transplanted luciferase-labeled allogeneic splenocytes and monitored tissue distribution by in vivo bioluminescence imaging. High-resolution analyses showed initial proliferation of donor CD4+ T cells followed by CD8+ T cells in secondary lymphoid organs with subsequent homing to the intestines, liver, and skin. Transplantation of purified naive T cells caused GVHD that was initiated in secondary lymphoid organs followed by target organ manifestation in gut, liver, and skin. In contrast, transplanted CD4+ effector memory T (T(EM)) cells did not proliferate in secondary lymphoid organs in vivo and despite their in vitro alloreactivity in mixed leukocyte reaction (MLR) assays did not cause acute GVHD. These findings underline the potential of T-cell subsets with defined trafficking patterns for immune reconstitution without the risk of GVHD.