Jawless vertebrates such as lamprey and hagfish lack T-cell and Bcell receptors; instead, they have unique antigen receptors known as variable lymphocyte receptors (VLRs). VLRs generate diversity by recombining highly diverse leucine-rich repeat modules and are expressed clonally on lymphocyte-like cells (LLCs). Thus far, two types of receptors, VLRA and VLRB, have been identified in lampreys and hagfish. Recent evidence indicates that VLRA and VLRB are expressed on distinct populations of LLCs that resemble T cells and B cells of jawed vertebrates, respectively. Here we identified a third VLR, designated VLRC, in the lamprey. None of the ≈100 VLRC cDNA clones subjected to sequencing had an identical sequence, indicating that VLRC can generate sufficient diversity to function as antigen receptors. Notably, the C-terminal cap of VLRC exhibits only limited diversity and has important structural differences relative to VLRA and VLRB. Single-cell PCR analysis identified LLCs that rearranged VLRC but not VLRA or VLRB, suggesting the presence of a unique population of LLCs that express only VLRC.antigen receptors | immune system evolution | jawless vertebrates | leucine-rich repeats | somatic rearrangement

FMR1 premutation (PM) alleles have 55–200 CGG·CCG-repeats in their 5′ UTR. PM carriers are at risk of fragile X–associated tremor and ataxia syndrome (FXTAS). Females are also at risk for FX primary ovarian insufficiency (FXPOI). PM pathology is generally attributed to deleterious properties of transcripts with long CGG-tracts. For FXPOI, hormone changes suggest a reduced residual follicle pool. Whether this is due to a smaller than normal original follicle pool or an increased rate of follicle depletion is unclear. A FX-PM mouse the authors generated with 130 CGG·CCG-repeats in the endogenous Fmr1 gene recapitulates features of FXTAS. Here the authors demonstrate that the gross development of the ovary and the establishment of the primordial follicle pool is normal in these mice. However, these animals show a faster loss of follicles of all follicle classes, suggesting that the problem is intrinsic to the ovary. In addition, many oocytes show aberrant nuclear accumulation of FMRP and elevated levels of ubiquitination. Furthermore, PM follicles are smaller and have fewer granulosa cells (GCs) than normal. Thus, these animals have ovarian abnormalities involving both the oocytes and GCs that may shed light on the molecular basis of FXPOI in humans.

The ubiquitin-proteasome pathway, which degrades intracellular proteins, is involved in numerous cellular processes, including the supply of immunocompetent peptides to the antigen presenting machinery. Proteolysis by proteasomes is conducted by three ␤ subunits, ␤1, ␤2, and ␤5, of the 20S proteasome. Recently, a novel ␤ subunit expressed exclusively in cortical thymic epithelial cells was discovered in mice. This subunit, designated ␤5t, is a component of the thymoproteasome, a specialized type of proteasomes implicated in thymic positive selection. In this study, we show that, like its mouse counterpart, human ␤5t is expressed exclusively in the thymic cortex. Human ␤5t was expressed in approximately 80% of cortical thymic epithelial cells and some cortical dendritic cells. Human ␤5t was incorporated into proteasomes with two other catalytically active ␤ subunits ␤1i and ␤2i, forming 20S proteasomes with subunit compositions characteristic of thymoproteasomes. The present study demonstrates, for the first time, the existence of thymoproteasomes in the human thymic cortex, indicating that thymoproteasome function is likely conserved between humans and mice. (Blood. 2009; 113:5186-5191)

Dendritic epidermal T cells (DETCs) found in mouse skin are NKG2D-positive γδ T cells involved in immune surveillance and wound repair. It is assumed that the interaction of an NKG2D receptor on DETCs and an MHC class I-like NKG2D ligand on keratinocytes activates DETCs, which then secrete cytokines promoting wound repair. However, direct evidence that DETC activation through NKG2D signaling promotes wound repair is not available. In the present study, we generated mAbs for an NKG2D ligand H60c previously suggested to be expressed specifically on skin keratinocytes. Local administration of H60c-specific mAb inhibited activation of DETCs and significantly delayed wound repair. Likewise, administration of NKG2D-specific mAb impaired wound repair to a similar extent. The delay in wound closure resulting from the blockade of the NKG2D pathway was comparable to that observed in γδ T cell-deficient mice. These results indicate that H60c/NKG2D interactions play a critical role in wound repair. Reassessment of binding affinities showed that H60c monomers bind to NKG2D with affinity (Kd = 26 ± 3.2 nM) comparable to those of other high-affinity NKG2D ligands. H60c is transcribed not only in skin but also in tissues such as tongue and female reproductive tract known to contain epithelium-resident γδ T cells expressing invariant TCRs, suggesting a more general role for H60c in the maintenance of epithelial integrity.

Background:To elucidate the incidence and mechanisms of sunitinib-induced thyroid atrophy, we investigated serial volumetric and functional changes, and evaluated histological changes of the thyroid gland in metastatic renal cell carcinoma patients who received sunitinib.Methods:Thyroid volume (by computed tomography volumetry) and thyroid function were measured at baseline, during the treatment, and at post-treatment periods. Histological evaluation of the thyroid gland was performed in four autopsied patients.Results:The median reduction rate in thyroid volume at last evaluation during sunitinib treatment was 30% in all 17 patients. The incidence of hypothyroidism during sunitinib treatment was significantly higher in the high reduction rate group (n=8; more than 50% reduction in volume) than in the low reduction rate group (n=9; less than 50% reduction in volume). Half of the patients in the high reduction rate group exhibited a transient thyroid-stimulating hormone suppression, suggesting thyrotoxicosis during sunitinib treatment. Histological evaluation demonstrated atrophy of thyroid follicles and degeneration of follicular epithelial cells without critical diminution of vascular volume in the thyroid gland.Conclusion:Thyroid atrophy is frequently observed following sunitinib treatment and may be brought about by sunitinib-induced thyrotoxicosis or the direct effects of sunitinib that lead to degeneration of thyroid follicular cells.

NKG2D is a major activating receptor of natural killer cells. Its ligands are major histocompatibility complex (MHC) class I-like molecules whose expression is induced by cellular stresses such as infections and tumorigenesis. Humans have two families of NKG2D ligands (NKG2DL): MHC class I-related chains (MIC) encoded in the MHC and UL16-binding proteins (ULBP) encoded outside the MHC. By contrast, mice have only the latter family of ligands; instead, they have non-MHC-encoded MILL molecules that are closely related to MIC, but do not function as NKG2DL. To gain insights into the origin and evolution of MIC, ULBP, and MILL gene families, we conducted comparative genomic analysis of NKG2DL family genes in five mammalian species. In the opossum MHC, we identified a ULBP-like gene adjacent to a previously described MIC-like gene, suggesting that ULBP genes were originally encoded in the MHC. The opossum genome also contained a transcribed MILL-like gene in a region syntenic to the rodent regions encoding MILL molecules. These observations indicate that MIC-, ULBP-, and MILL-like genes emerged before the divergence of placental and marsupial mammals. Comparison of the human, cattle, rat, mouse, and opossum genomes indicates that after emigration from the MHC, ULBP genes underwent extensive duplications in each species. In mice, some of the ULBP genes appear to have been translocated telomerically on the same chromosome, forming a major cluster of existent NKG2DL genes.

Objective: In patients with autoimmune diseases, blood vessels may be critically involved at the site of inflammation. For these patients, glucocorticoids (GC) are often used as therapeutics. The aim of this study is to determine the effects of GC on vascular endothelial cells which are under inflammatory conditions. Methods: We examined the molecular expressions in human umbilical vein endothelial cells (HUVEC) induced by dexamethasone (Dex) and tumor necrosis factor (TNF)-α. Live cell number of HUVEC under exposure to Dex and TNF-α was also assayed. Results: The cDNA array analysis showed that a number of genes were upregulated, but only a few were downregulated by Dex and TNF-α, respectively. Among them, thrombomodulin (TM) gene showed the least fold change when HUVEC were stimulated by TNF-α. Since TM inhibits blood coagulation, we took notice of molecules associated with coagulation and fibrinolysis. The quantitative real-time RT-PCR revealed that the expression of plasminogen activator inhibitor-1 (PAI-1) gene increased when HUVEC were exposed to Dex and TNF-α, respectively, and the corresponding augmentation of its protein expression was confirmed by immunohistochemistry. The expression of PAI-1 gene additively increased when Dex and TNF-α were added to stimulate HUVEC. Under our experimental conditions, TNF-α induced proliferation of HUVEC. On the other hand, Dex did not change the number of live cells regardless of stimulation by TNF-α. Conclusion: TNF-α can induce proliferation of vascular endothelial cells with downregulation of the anticoagulation molecule, TM, and upregulation of the anti-fibrinolysis molecule, PAI-1. Dex further increased the expression of PAI-1 gene in the cells stimulated by TNF-α, and did not reduce the effect on cell proliferation induced by TNF-α. These findings suggest that the balance of blood coagulation versus fibrinolysis may incline to coagulation when Dex and TNF-α cooperate on vascular endothelial cells.

A 57-year-old man with a permanent pacemaker implanted for complete atrioventricular block was referred to our hospital for progressive dyspnea in July 2006. Chest x-ray showed cardiac enlargement, and cardiac ultrasound exhibited diffusely reduced wall motion of the left ventricle. Ejection fraction was 29%. Chest computed tomography revealed multiple nodular lesions in both lungs, which were pathologically diagnosed as pulmonary sarcoidosis by transbronchial lung biopsy. On fasting cardiac 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET), localized uptake of FDG was noted in the anterior, septal, and inferior walls of the left ventricle ( Figure, A). With a diagnosis of cardiac sarcoidosis, oral predonisolone was started at 30 mg daily in October 2006. Two months later, however, he was transported to our hospital with cardiopulmonary arrest.An autopsy was performed, and noncaseating granuloma with Langhans-type giant cells were noted in the lung, spleen, and, more prominently, heart. Lesion activity of the cardiac sarcoid lesions varied depending on the site in the heart. Red areas (Figure, B) indicate active glanulomatous lesions with Langerhans-type giant cells and lymphocyte infiltration. Blue areas indicate lesions with less inflammatory cell infiltration along with reactive fibrosis, and black areas reveal more progressed lesions with hyalinized scar tissue. The distribution of these sarcoid lesions in the heart corresponded well with that of FDG uptake (Figure, A). FDG accumulated even in the hyalinized lesions probably because such progressed lesions were still in the active phase when FDG-PET images were obtained before steroid treatment.Studies have suggested that abnormal cardiac FDG uptake reveals the presence of active sarcoid lesions in Figure. (A) Short-axis image of fasting FDG-PET of the heart (papillary muscle level). FDG accumulation in the anterior, septal, and posterior walls of the left ventricle can be seen. (B) Gross short-axis image of the heart obtained by autopsy, corresponding to A. Active inflammatory changes with Langerhans-type cell granuloma formation were mainly distributed in the anterior, septal, and posterior walls of the left ventricle (marked changes shown in red, modest changes with reactive fibrosis shown in blue). Fibrotic and hyalinizing changes were distributed in the posteroseptal to posterior walls (black). Black bar indicates 25 m.