Kiyotaka Nagahama

Differential requirement for CARMA1 in agonist-selected T-cell development

Caspase recruitment domain‐containing membrane‐associated guanylate kinase protein‐1 (CARMA1) is a critical component of the NF‐κB signaling cascade mediated by TCR engagement. In addition to activation of naïve T cells, TCR signaling is important for the development of agonist‐selected T‐cell subsets such as Treg, NKT cells, and CD8‐αα T cells. However, little is known about the role of CARMA1 in the development of these lineages. Here we show that CARMA1‐deficient mice (CARMA1−/−) have altered populations of specific subsets of agonist‐selected T cells. Specifically, CARMA1−/− mice have impaired natural and adaptive Treg development, whereas NKT cell numbers are normal compared with wild‐type mice. Interestingly, CD8‐αα T cells, which may also be able to develop through an extrathymic selection pathway, are enriched in the gut of CARMA1−/− mice, whereas memory‐phenotype CD4+ T cells (CD62Llow/CD44high) are present at reduced numbers in the periphery. These results indicate that CARMA1 is essential for Treg development, but is not necessary for the development of other agonist‐selected T‐cell subsets. Overall, these data reveal an important but differential role for CARMA1‐mediated TCR signaling in T‐cell development.

Pulmonary cysts of Birt-Hogg-Dubé syndrome: a clinicopathologic and immunohistochemical study of 9 families.

Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant disorder characterized by fibrofolliculomas, renal tumors, and pulmonary cysts with recurrent pneumothorax. Multiple pulmonary cysts and pneumothorax are the key signs for diagnosing BHD syndrome. The pathologic features of BHD pulmonary cysts, however, are poorly understood. This disorder is caused by mutations in the gene that encodes folliculin (FLCN). FLCN is regarded as a tumor suppressor; it mediates cellular activities by interacting with the mammalian target of rapamycin (mTOR). In this study, we investigated the lungs of 11 patients from 9 BHD families. The majority of patients consulting doctors were women between 30 and 60 years of age who had pulmonary cysts and repeated pneumothoraces. Genomic DNA testing revealed 5 different mutation patterns. Histopathologic examination found that the inner surface of cysts was lined by epithelial cells, sometimes with a predominance of type II pneumocyte-like cuboidal cells. The cysts occasionally contained internal septa consisting of alveolar walls or showed an “alveoli within an alveolus” pattern. The cells constituting the cysts stained positive for phospho-S6 ribosomal protein expression, suggesting activation of the mTOR pathway. Although BHD pulmonary cysts are frequently misdiagnosed as nonspecific cystic diseases, they are distinctly different in histopathology from other bullous changes. Mechanical stress such as rupture and postrupture remodeling allows mesothelial invagination and fibrosis. Such modified BHD pulmonary cysts are virtually indistinguishable from nonspecific blebs and bullae. We propose a new insight, namely, that the BHD syndrome-associated pulmonary cyst may be considered a hamartoma-like cystic alveolar formation associated with deranged mTOR signaling.

Dependence of intestinal granuloma formation on unique myeloid DC-like cells

Granulomas represent a localized inflammatory reaction that is characteristically observed in many inflammatory conditions. However, the mechanisms of granuloma formation have not been fully defined. Herein we demonstrate, by using experimental models of intestinal inflammation, that a unique CD11c+ DC-like cell subset that exhibits phenotypic and functional features of immature myeloid DCs and is characterized by the expression of a macrophage marker (F4/80) produces large amounts of IL-23 and directly induces the development of granulomas under a Th1-predominant intestinal inflammatory condition. Importantly, both IL-4 and IgG contribute to the suppression of F4/80+ DC-like cell-mediated granuloma formation by regulating the function and differentiation of this cell subset. In addition, enteric flora is required for the F4/80+ DC-like cell-mediated granuloma formation. Collectively, our data provide what we believe are novel insights into the involvement of F4/80+ DC-like cells in intestinal granuloma formation and demonstrate the role of host (IL-4 and IgG) and environmental (enteric flora) factors that regulate this function.

Possible role of autoantibodies in the pathophysiology of GM2 gangliosidoses

Mice containing a disruption of the Hexb gene have provided a useful model system for the study of the human lysosomal storage disorder known as Sandhoff disease (SD). Hexb(-/-) mice rapidly develop a progressive neurologic disease of ganglioside GM2 and GA2 storage. Our study revealed that the disease states in this model are associated with the appearance of antiganglioside autoantibodies. Both elevation of serum antiganglioside autoantibodies and IgG deposition to CNS neurons were found in the advanced stages of the disease in Hexb(-/-) mice; serum transfer from these mice showed IgG binding to neurons. To determine the role of these autoantibodies, the Fc receptor gamma gene (FcR gamma) was additionally disrupted in Hexb(-/-) mice, as it plays a key role in immune complex-mediated autoimmune diseases. Clinical symptoms were improved and life spans were extended in the Hexb(-/-)FcR gamma(-/-) mice; the number of apoptotic cells was also decreased. The level of ganglioside accumulation, however, did not change. IgG deposition was also confirmed in the brain of an autopsied SD patient. Taken together, these findings suggest that the production of autoantibodies plays an important role in the pathogenesis of neuropathy in SD and therefore provides a target for novel therapies.

Disrupted Balance of Angiogenic and Antiangiogenic Signalings in Preeclampsia

The placenta plays a central role in governing local circulatory system that mediates maternal condition and fetal growth. In early gestational phases, the placenta exerts properties of invasion and neovascularization for successful placentation. Extravillous invasive trophoblasts replace uterine endometrial vasculature and establish local blood pathway to obtain oxygen and nutrients from the mother. In later phases, the placenta promotes villous angiogenesis and vascular maturation that are finely controlled by angiogenic and antiangiogenic molecules. Among various molecules involved in placental neovascularization, vascular endothelial growth factor receptors (VEGFRs) and angiotensin II receptor type 1 (AT1) mediate important signaling pathways for maternal circulatory system and fetal growth. VEGFR1 and VEGFR2 are functional receptors for placental growth factor (PlGF) and VEGF, respectively, and PlGF-VEGFR1 and VEGF-VEGFR2 interactions are disturbed in many preeclamptic patients by excess amount of soluble form of VEGFR1 (also named sFlt1), a natural PlGF/VEGF antagonist. Recent studies have disclosed that excessive sFlt1 production in the placenta and aberrant AT1 signaling in the mother are closely associated with the pathology of preeclampsia and intrauterine growth restriction (IUGR). In this paper, neovascularization of the placenta and pathological events associated with disrupted balance between angiogenic and antiangiogenic signaling in preeclampsia are discussed.

Differential expression patterns of CXCR3 variants and corresponding CXC chemokines in clear cell ovarian cancers and endometriosis

OBJECTIVES Carcinogenesis of the ovary is often associated with endometriosis. We previously demonstrated that antitumor chemokine receptor CXCR3 was upregulated both in endometriosis and ovarian cancers. Currently, little is known about the roles of CXCR3 variants in these ovarian diseases. In this study, we investigated the expression of CXCR3 variants and their corresponding ligands in endometriosis and ovarian cancers. METHODS The expression patterns of CXCR3 variants (CXCR3A, CXCR3B and CXCR3-alt) and their corresponding ligands were investigated by quantitative RT-PCR, Western blot and in situ hybridization in normal ovaries (n=16), endometriosis (n=12), and clear cell ovarian cancers (n=22) including endometriosis-coexisting cases (n=11). RESULTS Sequence analysis of purified RT-PCR products confirmed the presence of three CXCR3 variants in human ovaries. Quantitative RT-PCR analysis revealed differential expression patterns of these variants depending on conditions. CXCR3A was upregulated both in endometriosis and cancers. On the other hand, CXCR3-alt was upregulated and CXCR3B was downregulated in cancers compared with endometriosis. The corresponding ligand CXCL11 was upregulated only in the cancers with elevated CXCR3-alt. Another ligand CXCL4 was downregulated in the cancers with suppressed CXCR3B. In situ hybridization demonstrated preferential expression of CXCR3A in cancer cells and infiltrating lymphocytes. CXCR3B and CXCR3-alt were detectable mainly in microvessels. CONCLUSIONS Collective data suggest that differential expression patterns of CXC chemokines and CXCR3 variants are involved in specific inflammatory microenvironment of ovarian cancers. Altered balance of CXCR3 variants may become helpful information for better understanding of the pathogenesis of ovarian cancers arising from endometriosis.

Mucin‐producing gallbladder adenocarcinoma with focal small cell and large cell neuroendocrine differentiation associated with pancreaticobiliary maljunction

Herein is reported a case of mucin‐producing carcinoma of the gallbladder in a 55‐year‐old Japanese woman. Although the patients status and laboratory data initially suggested biliary pancreatitis due to gallstone, radiography and endoscopy confirmed the presence of pancreaticobiliary maljunction and a gallbladder tumor with excessive mucin, in which the duodenal papilla and the common bile duct were impacted. Following surgery, the gallbladder tumor was histopathologically diagnosed as a mixed endocrine–exocrine carcinoma. The carcinoma predominantly consisted of papillary, but also contained some tubular adenocarcinomatous components. Additionally, small foci of small cell and large cell neuroendocrine carcinomatous components were observed. There was no evidence of lymph node metastasis, distant metastasis, or direct invasion outside the gallbladder. Thus, the final classification of pT2N0M0 stage II was given to this lesion, according to the Union Internationale Contre le Cancer guidelines. The postoperative course was uneventful, and the carcinoma had not recurred in the absence of chemoradiotherapy for a period of 20 months. Mucin‐producing gallbladder carcinoma is a rare clinical condition that can occur in patients with pancreaticobiliary maljunction. Detailed investigation of this condition is important to develop and refine effective therapeutic strategies.

Possible role of autoantibodies against nephrin in an experimental model of chronic graft-versus-host disease

Nephrin, a product of the NPHS1 gene, is a component of the slit diaphragms that are found between glomerular foot processes and is a crucial element for glomerular filtration barrier. Recently, nephrin has been focused in a number of studies of proteinuria development including various types of acquired glomerular diseases including minimal change nephrotic syndrome and membranous nephropathy. However, the precise role of nephrin in such acquired glomerular diseases is still unknown. To analyse the role of nephrin further, two kinds of anti‐nephrin antibodies were raised in the rabbits and applied to an experimental mouse model of chronic graft‐versus‐host disease, in which (C57BL/10 × DBA/2) F1 mice developed clinically apparent severe proteinuria with significant glomerular lesions 7 weeks after parental DBA/2 cell transfer. Antibody‐sandwich ELISA detected anti‐nephrin antibodies during week 2 to week 6, with the peak at week 2 or week 4. Colocalization of nephrin and IgG on week 4, week 6, and week 8 was revealed by confocal microscopic analysis, suggesting that in situ immune complex formation with nephrin in glomerular lesion. Taken together, it seems to be suggested nephrin and its autoantibody have a certain role in the development of glomerular lesion in our model mice.

Splenectomy may improve the glomerulopathy of type ii mixed cryoglobulinemia

Many patients with type II mixed cryoglobulinemia have been shown to be infected with hapatitis C virus (HCV). Therefore, interferon-alfa has become the first choice of treatment for patients with HCV-associated cryoglobulinemia. However, the disease often relapses after the discontinuation of interferon therapy. The long-term effect of interferon therapy is controversial. Therefore, a more effective therapy needs to be developed. A 62-year-old Japanese woman was admitted to our hospital for the examination of abnormal liver function tests, severe edema, and purpura in her lower extremities. Glomerulopathy secondary to HCV-related cryoglobulinemia was suspected. Her serum creatinine was increased to 2.1 mg/dL. Interferon therapy was considered initially. However, because of pancytopenia caused by liver cirrhosis and splenomegaly, splenectomy was performed in February 1997, before the start of interferon therapy. Renal biopsy specimen taken at the time of the splenectomy showed typical cryoglobulinemic glomerulonephritis. Gradually, after surgery, the patients thrombocytopenia and anemia improved, her proteinuria and hematuria were decreased, her cryocrit dropped from 15% to 5%, the Ccr increased from 21.1 mL/min to 48.8 mL/min, and the purpura in her lower extremities disappeared. A repeat renal biopsy performed in May 1998 showed marked histological improvement. Splenectomy is not widely accepted as a treatment for cryoglobulinemia. Our case suggests the possibility that the monoclonal-IgM component of the type II cryoglobulin may be formed in the spleen. In conclusion, splenectomy may be an effective therapy for cryoglobulinemia in patients with HCV-positive liver cirrhosis and pancytopenia secondary to splenomegaly.

Thymic Alterations in GM2 Gangliosidoses Model Mice

Background Sandhoff disease is a lysosomal storage disorder characterized by the absence of β-hexosaminidase and storage of GM2 ganglioside and related glycolipids. We have previously found that the progressive neurologic disease induced in Hexb −/− mice, an animal model for Sandhoff disease, is associated with the production of pathogenic anti-glycolipid autoantibodies. Methodology/Principal Findings In our current study, we report on the alterations in the thymus during the development of mild to severe progressive neurologic disease. The thymus from Hexb −/− mice of greater than 15 weeks of age showed a marked decrease in the percentage of immature CD4+/CD8+ T cells and a significantly increased number of CD4+/CD8− T cells. During involution, the levels of both apoptotic thymic cells and IgG deposits to T cells were found to have increased, whilst swollen macrophages were prominently observed, particularly in the cortex. We employed cDNA microarray analysis to monitor gene expression during the involution process and found that genes associated with the immune responses were upregulated, particularly those expressed in macrophages. CXCL13 was one of these upregulated genes and is expressed specifically in the thymus. B1 cells were also found to have increased in the thy mus. It is significant that these alterations in the thymus were reduced in FcRγ additionally disrupted Hexb −/− mice. Conclusions/Significance These results suggest that the FcRγ chain may render the usually poorly immunogenic thymus into an organ prone to autoimmune responses, including the chemotaxis of B1 cells toward CXCL13.