Roles of tumor necrosis factor-like ligand 1A in γδT-cell activation and psoriasis pathogenesis.

Background: Interleukin (IL)-17-producing γδT (γδT17) cells mediate inflammatory responses in barrier tissues. Dysregulated γδT17 cell activation can lead to the overproduction of IL-17 and IL-22 and the development of inflammatory diseases, including psoriasis. IL-23 and IL-1ß are known to synergistically activate γδT17 cells, but the regulatory mechanisms of γδT17 cells have not been fully elucidated. This study aimed to reveal the contribution of the inflammatory cytokine tumor necrosis factor-like ligand 1A (TL1A) to γδT17 cell activation and psoriasis development. Methods: Anti-TL1A antibody was injected into an imiquimod (IMQ)-induced murine psoriasis model. TL1A receptor expression was analyzed in splenic and dermal γδT cells. γδT cells were tested for cytokine production in vitro and in vivo under stimulation with IL-23, IL-1ß, and TL1A. TL1A was applied to a psoriasis model induced by intradermal IL-23 injection. Mice deficient in γδT cells were intradermally injected with IL-23 plus TL1A to verify the contribution of TL1A-dependent γδT-cell activation to psoriasis development. Results: Neutralization of TL1A attenuated γδT17 cell activation in IMQ-treated skin. TL1A induced cytokine production by splenic γδT17 cells in synergy with IL-23. Dermal γδT17 cells constitutively expressed a TL1A receptor at high levels and vigorously produced IL-22 upon intradermal IL-23 and TL1A injection but not IL-23 alone. TL1A exacerbated the dermal symptoms induced by IL-23 injection in wild-type but not in γδT cell-deficient mice. Conclusion: These findings suggest a novel regulatory mechanism of γδT cells through TL1A and its involvement in psoriasis pathogenesis as a possible therapeutic target.

Factors related to white thrombi in acute ischemic stroke in cancer patients.

OBJECTIVES: Thrombi in cerebral large vessel occlusion associated with active cancer are often fibrin and platelet-rich white thrombi. However, evaluating the thrombus composition in a short time before thrombectomy is often ineffective. We sought to determine factors related to white thrombi in acute ischemic stroke due to large vessel occlusion in cancer patients. METHODS: Consecutive cancer patients undergoing thrombectomy for acute ischemic stroke due to large vessel occlusion between January 2018 and May 2022 were retrospectively reviewed. The patients were classified into white thrombus and red thrombus groups on the basis of the pathological findings of retrieved thrombi. Patient characteristics and laboratory findings were compared between the two groups. RESULTS: There were 12 patients in the white thrombus group and 11 patients in the red thrombus group. Active cancer was significantly more in the white thrombus group than in the red thrombus group (91.7% vs. 36.3%, p = 0.0094). Internal carotid artery occlusion was significantly less in the white thrombus group than in the red thrombus group (0% vs. 36.4%, p = 0.037). Among laboratory findings, D-dimer levels were an independent factor associated with white thrombi (odds ratio 8.97 [95% confidence interval 1.71-368.99], p < 0.0001). The cutoff value of D-dimer levels for predicting white thrombi was 3.5 µg/mL (83.3% sensitivity and 100% specificity). CONCLUSIONS: In acute ischemic stroke in cancer patients, active cancer, no internal carotid artery occlusion, and higher D-dimer levels (≥3.5 µg/mL) may be associated with occlusion with fibrin and platelet-rich white thrombi.

Membrane skeleton hyperstability due to a novel alternatively spliced 4.1R can account for ellipsoidal camelid red cells with decreased deformability.

The red blood cells (RBCs) of vertebrates have evolved into two basic shapes, with nucleated nonmammalian RBCs having a biconvex ellipsoidal shape and anuclear mammalian RBCs having a biconcave disk shape. In contrast, camelid RBCs are flat ellipsoids with reduced membrane deformability, suggesting altered membrane skeletal organization. However, the mechanisms responsible for their elliptocytic shape and reduced deformability have not been determined. We here showed that in alpaca RBCs, protein 4.1R, a major component of the membrane skeleton, contains an alternatively spliced exon 14-derived cassette (e14) not observed in the highly conserved 80 kDa 4.1R of other highly deformable biconcave mammalian RBCs. The inclusion of this exon, along with the preceding unordered proline- and glutamic acid-rich peptide (PE), results in a larger and unique 90 kDa camelid 4.1R. Human 4.1R containing e14 and PE, but not PE alone, showed markedly increased ability to form a spectrin-actin-4.1R ternary complex in viscosity assays. A similar facilitated ternary complex was formed by human 4.1R possessing a duplication of the spectrin-actin-binding domain, one of the mutations known to cause human hereditary elliptocytosis. The e14- and PE-containing mutant also exhibited an increased binding affinity to ß-spectrin compared with WT 4.1R. Taken together, these findings indicate that 4.1R protein with the e14 cassette results in the formation and maintenance of a hyperstable membrane skeleton, resulting in rigid red ellipsoidal cells in camelid species, and suggest that membrane structure is evolutionarily regulated by alternative splicing of exons in the 4.1R gene.

Endoscope-assisted microsurgical repair in trigeminal meningocele: case report.

Trigeminal meningocele is a rare disease that results in rhinorrhea. Treatments with endoscopic approaches and open craniotomies have high recurrence rates, and controversy regarding the most effective surgical strategy for trigeminal meningocele is ongoing. The authors report a case of a 13-year-old female patient with a diagnosis of trigeminal meningocele determined after she presented with a history of intermittent headaches, suspected rhinorrhea, and recurrent meningitis. In addition to the conventional method of covering the efflux point of CSF and filling the inside of the meningocele with fascial tissues, the authors selectively closed the influx point of CSF from the prepontine cistern to the meningocele using an anterior transpetrosal approach. On the basis of the preoperative images, the authors hypothesized that the influx point of CSF could not be observed under the microscopic direct view and instead used a flexible endoscope. A check valve-like structure with one-way communication of CSF from the prepontine cistern into the cystic cavity was identified and was closed. At the time of this report, 36 months postoperatively, the patient had no indications of recurrence. Although cases of trigeminal meningoceles are infrequently encountered and require a tailored approach, the results in this case thus far indicate that the use of an endoscope and open craniotomy is an effective strategy for surgical treatment.

The thymoproteasome hardwires the TCR repertoire of CD8+ T cells in the cortex independent of negative selection.

The thymoproteasome expressed specifically in thymic cortical epithelium optimizes the generation of CD8+ T cells; however, how the thymoproteasome contributes to CD8+ T cell development is unclear. Here, we show that the thymoproteasome shapes the TCR repertoire directly in cortical thymocytes before migration to the thymic medulla. We further show that the thymoproteasome optimizes CD8+ T cell production independent of the thymic medulla; independent of additional antigen-presenting cells, including medullary thymic epithelial cells and dendritic cells; and independent of apoptosis-mediated negative selection. These results indicate that the thymoproteasome hardwires the TCR repertoire of CD8+ T cells with cortical positive selection independent of negative selection in the thymus.

Enhanced Immunotherapeutic Efficacy of Anti-PD-L1 Antibody in Combination with an EP4 Antagonist.

Combination treatment approaches are increasingly considered to overcome resistance to immunotherapy targeting immunoinhibitory molecules such as programmed death (PD)-1 and PD-ligand 1 (PD-L1). Previous studies have demonstrated that the therapeutic efficacy of anti-PD-L1 Abs is enhanced by combination treatment with cyclooxygenase-2 inhibitors, through downregulation of the immunosuppressive eicosanoid PGE2, although the underlying mechanism remains unclear. In this study, we show that serum PGE2 levels are upregulated after anti-PD-L1 Ab administration in a bovine model of immunotherapy and that PGE2 directly inhibits T cell activation via its receptor E prostanoid (EP) 4. Additionally, anti-PD-L1 Ab induces TNF-α production and TNF-α blockade reduces PGE2 production in the presence of anti-PD-L1 Ab, suggesting that anti-PD-L1 Ab-induced TNF-α impairs T cell activation by PGE2 upregulation. Our studies examining the therapeutic potential of the dual blockade of PD-L1 and EP4 in bovine and murine immune cells reveal that the dual blockade of PD-L1 and EP4 significantly enhances Th1 cytokine production in vitro. Finally, we show that the dual blockade decreases tumor volume and prolongs survival in mice inoculated with the murine lymphoma cell line EG7. Altogether, these results suggest that TNF-α induced by anti-PD-L1 Ab treatment is associated with T cell dysfunction via PGE2/EP4 pathway and that the dual blockade of PD-L1 and EP4 should be considered as a novel immunotherapy for cancer.

A Rare Case of Giant Solid Hemangioblastoma Accompanied with Hemophilia Type A.

The surgical removal of giant solid hemangioblastoma involves a high risk of perioperative bleeding and requires attentive hemostasis. Here, we present a case of a giant solid hemangioblastoma accompanied with hemophilia which was previously undiagnosed. A 35-year-old man without any past medical history was admitted with diplopia and ocular motility disorder. computed tomography (CT) and magnetic resonance imaging (MRI) revealed obstructive hydrocephalus and a solid giant tumor of more than 4.0 cm in diameter in the right cerebellopontine angle (CPA). Hemangioblastoma was suspected on cerebral angiography. After ventriculoperitoneal shunt for obstructive hydrocephalus, oozing from the skin incision continued for several days. Hemophilia type A was diagnosed based on the result of laboratory blood coagulability examination. Supplemental administration of factor VIII and coil embolization of the feeding arteries of the lesion on the CPA were performed, and the tumor was subtotally resected without hemorrhagic complications. The histopathological diagnosis was hemangioblastoma. We report this case to emphasize the importance not to overlook previously undiagnosed coagulopathy before surgical excision of hemangioblastoma. And, with appropriate perioperative management for coagulopathy, surgical treatment involving a high risk of perioperative bleeding can be safely undertaken.

Histopathological Correlations between Mediastinal Fat-Associated Lymphoid Clusters and the Development of Lung Inflammation and Fibrosis following Bleomycin Administration in Mice.

Bleomycin (BLM) has been reported to induce lung inflammation and fibrosis in human and mice and showed genetic susceptibility. Interestingly, the C57BL/6 (B6) mice had prominent mediastinal fat-associated lymphoid cluster (MFALCs) under healthy condition, and showed susceptibility to development of lung fibrosis following BLM administration. However, the pathogenesis of lung lesion progression, and their correlation with MFALC morphologies, remain to be clarified. To investigate the correlations between MFALC structures and lung injuries in B6 mice, histopathological examination of mediastinal fat tissues and lungs was examined at 7 and 21 days (d) following a single 50 µL intranasal (i.n.) instillation of either BLM sulfate (5 mg/kg) (BLM group) or phosphate-buffered saline (control group). The lung fibrosis was examined by Masson's trichrome (MT) stain of paraffin sections and mRNA expression levels of Col1a1, Col3a1, and Acta2 in different frozen lung samples. Furthermore, immunohistochemistry for CD3, B220, Iba1, Gr1, BrdU, LYVE-1, and peripheral node addressin (PNAd) was performed to detect T- and B-cells, macrophages, granulocytes, proliferating cells, lymph vessels (LVs), and high endothelial venules (HEVs). We found that MFALCs were more abundant in the BLM group as compared to the control group. The lung of BLM group developed pneumonitis with severe cellular infiltrations at 7 days and significant collagen deposition (MT) and higher expression of Col1a1, and Col3a1 at 21 days post-administration. Numerous immune cells, proliferating cells, HEVs, and LVs were observed in both MFALCs and lungs of the BLM group. Interestingly, PNAd + HEVs were observed in the lungs of the BLM group, but not the control group. Moreover, numerous Gr1 + polymorphonuclear and mononuclear-like ring cells were found in the MFALCs and lungs of the BLM group. Interestingly, flow cytometric analysis revealed a significant increase of B-cell populations within the MFALCs of BLM group suggesting a potential proliferative induction of B-cells following inflammation. Furthermore, significant positive correlations were observed between quantitative parameters of these immune cells in both the lungs and MFALCs. Thus, we suggest a potentially important role for MFALCs and HEVs in the progression of lung disease, especially in inflammatory lung disease.

Antigen processing and presentation in the thymus: implications for T cell repertoire selection.

The processing and presentation of major histocompatibility complex (MHC)-associated antigens depend on the intracellular digestion of self- and nonself-proteins, the loading of digested peptides onto MHC molecules, and the traffic of peptide-MHC complexes to plasma membrane surface for display to interacting T cells. Recent studies have revealed unique machineries for antigen processing and presentation in thymic antigen-presenting cells that display self-antigens to developing thymocytes for the formation of functionally competent yet self-tolerant T cell repertoire. Here, we briefly summarize those machineries, focusing on the biology of cortical and medullary thymic epithelial cells.

TCR affinity for thymoproteasome-dependent positively selecting peptides conditions antigen responsiveness in CD8(+) T cells.

In the thymus, low-affinity T cell antigen receptor (TCR) engagement facilitates positive selection of a useful T cell repertoire. Here we report that TCR responsiveness of mature CD8(+) T cells is fine tuned by their affinity for positively selecting peptides in the thymus and that optimal TCR responsiveness requires positive selection on major histocompatibility complex class I-associated peptides produced by the thymoproteasome, which is specifically expressed in the thymic cortical epithelium. Thymoproteasome-independent positive selection of monoclonal CD8(+) T cells results in aberrant TCR responsiveness, homeostatic maintenance and immune responses to infection. These results demonstrate a novel aspect of positive selection, in which TCR affinity for positively selecting peptides produced by thymic epithelium determines the subsequent antigen responsiveness of mature CD8(+) T cells in the periphery.

Thymoproteasomes produce unique peptide motifs for positive selection of CD8(+) T cells.

Positive selection in the thymus provides low-affinity T-cell receptor (TCR) engagement to support the development of potentially useful self-major histocompatibility complex class I (MHC-I)-restricted T cells. Optimal positive selection of CD8(+) T cells requires cortical thymic epithelial cells that express ß5t-containing thymoproteasomes (tCPs). However, how tCPs govern positive selection is unclear. Here we show that the tCPs produce unique cleavage motifs in digested peptides and in MHC-I-associated peptides. Interestingly, MHC-I-associated peptides carrying these tCP-dependent motifs are enriched with low-affinity TCR ligands that efficiently induce the positive selection of functionally competent CD8(+) T cells in antigen-specific TCR-transgenic models. These results suggest that tCPs contribute to the positive selection of CD8(+) T cells by preferentially producing low-affinity TCR ligand peptides.

Positive-selection-inducing self-peptides displayed by cortical thymic epithelial cells.

A repertoire of antigen recognition specificities in mature T cell pool is formed by the selection during T cell development in the thymus. Positive selection is an essential process for the development of functionally competent T cells and is dependent on the interaction between T cell antigen receptors (TCRs) that newly generated thymocytes express and self-peptide-associated major histocompatibility complex (pMHC) molecules that cortical thymic epithelial cells (cTECs) express. Characterization of positive-selection-inducing peptides has revealed that the low-affinity TCR engagement by the positive-selection-inducing pMHC complexes initiates intracellular signals that induce the survival of immature thymocytes and their differentiation into mature T cells. Recent studies suggest unique mechanisms of antigen processing in cTECs for the production of positively selecting MHC-bound self-peptides.

Alpha-smooth muscle actin expression identifies subpopulations of mouse lymph node non-hematopoietic cells.

Significant attention has been given to the role played by non-hematopoietic cells in the immune organs, including the lymph nodes, in hopes of understanding the development, maintenance, and regulation of the immune system. However, the molecular and cellular characterization of non-hematopoietic cells is still in its infancy. Here we show that non-hematopoietic cells in mouse lymph nodes can be fractionated into previously unidentified subpopulations according to the transgenic reporter expression of alpha-smooth muscle actin (αSMA). αSMA(+) non-hematopoietic cells were predominantly detected in gp38(+)CD31(-) and gp38(-)CD31(-) cells. Molecular expression profiles suggest similarities between αSMA(+)gp38(+)CD31(-) and αSMA(-)gp38(+)CD31(-) subpopulations and dissimilarities between αSMA(+)gp38(-)CD31(-) and αSMA(-)gp38(-)CD31(-) subpopulations. The results indicate that αSMA is a useful marker for further understanding the molecular and cellular characteristics of non-hematopoietic cells in the lymph nodes.

Gimap3 and Gimap5 cooperate to maintain T-cell numbers in the mouse.

Gimap3 (IAN4) and Gimap5 (IAN5) are highly homologous GTP-binding proteins of the Gimap family. Gimap3 and Gimap5, whose transcripts are abundant in mature lymphocytes, can associate with antiapoptotic Bcl-2 family proteins. While it is established that Gimap5 regulates T-cell survival, the in vivo role of Gimap3 is unclear. Here we report the preparation and characteristics of mouse strains lacking Gimap3 and/or Gimap5. We found that the number of T cells was markedly reduced in mice deficient in both Gimap3 and Gimap5. The defects in T-cell cellularity were more severe in mice lacking both Gimap3 and Gimap5 than in mice lacking only Gimap5. No defects in the cellularity of T cells were detected in mice lacking only Gimap3, whereas bone marrow cells from Gimap3-deficient mice showed reduced T-cell production in a competitive hematopoietic environment. Moreover, retroviral overexpression and short hairpin RNAs-mediated silencing of Gimap3 in bone marrow cells elevated and reduced, respectively, the number of T cells produced in irradiated mice. These results suggest that Gimap3 is a regulator of T-cell numbers in the mouse and that multiple Gimap family proteins cooperate to maintain T-cell survival.

Development and function of cortical thymic epithelial cells.

The thymic cortex provides a microenvironment that supports the generation and T cell antigen receptor (TCR)-mediated selection of CD4(+)CD8(+)TCRαß(+) thymocytes. Cortical thymic epithelial cells (cTECs) are the essential component that forms the architecture of the thymic cortex and induces the generation as well as the selection of newly generated T cells. Here we summarize current knowledge on the development, function, and heterogeneity of cTECs, focusing on the expression and function of ß5t, a cTEC-specific subunit of the thymoproteasome.

ß5t-containing thymoproteasome: specific expression in thymic cortical epithelial cells and role in positive selection of CD8+ T cells.

Proteasomes are multisubunit proteolytic complexes that degrade cytoplasmic and nuclear proteins in eukaryotes. Proteasome-dependent proteolysis contributes to various cellular processes, including misfolded protein degradation, signal transduction, and antigen presentation. The thymoproteasome is a form of proteasome that contains the vertebrate-specific catalytic subunit ß5t specifically expressed by cortical epithelial cells in the thymus. The thymoproteasome is essential for the positive selection of CD8+ T cells that carry an immunocompetent repertoire of antigen recognition specificity. Here we summarize the structure and expression of the thymoproteasome and discuss how it regulates the positive selection of CD8+ T cells.

Positive selection optimizes the number and function of MHCII-restricted CD4+ T cell clones in the naive polyclonal repertoire.

T cell receptors (TCRs) on T lymphocytes in an individual bind foreign peptides bound to major histocompatibility complex (MHC) molecules expressed in that individual (designated MHC(A)). Results from radiation bone marrow chimeras and TCR transgenic mice indicate that this complex form of antigen recognition is the result of positive selection of clones with low affinity for self peptide:MHC(A) complexes during development. Here we used a sensitive peptide:MHC tetramer enrichment method to quantify the role of positive selection in the generation of the preimmune polyclonal T cell repertoire in normal individuals. We made the surprising observation that mouse and human naive T cells capable of binding to foreign peptide:MHC(A) were present at the same frequency in hosts that expressed MHC(A) or a different MHC isoform (MHC(B)). However, most of the clones in MHC(B) hosts also recognized self peptide:MHC(A) complexes. When these "alloreactive" T cells were removed from the MHC(B) repertoire via negative selection in an MHC(A) host, the number of foreign peptide:MHC(A)-binding T cells was reduced to one fifth and many of the remaining cells did not respond to the peptide. Therefore, although positive selection on MHC(A) was not required to produce foreign peptide:MHC(A)-binding clones, it had a large effect on selecting responsive clones.

Identification of a quantitative trait locus regulating B cell-dominant infiltration into autoimmune sialitis lesions of the IQI mouse model of primary Sjögren's syndrome.

Sjögren's syndrome (SS) is caused by an autoimmune sialodacryoadenitis, and up to 5% of patients with SS develop malignant B cell growth. The IQI mouse is a spontaneous model of primary SS in which B cells are the dominant cellular subpopulation among mononuclear infiltrates in sialitis lesions. Understanding the genetic control of aberrant B cell growth in IQI mice may help elucidate the genetic mechanisms involved in B-lineage hyperplasia leading to malignant transformation in human SS. B cell-dominant infiltration in the submandibular glands of 6-month-old IQI and C57BL/6 (B6) mice and their F1 and F2 progenies was quantified as B-lymphocytic sialitis score, and a genome-wide scan of 179 (IQI x B6) F2 females was performed to identify a quantitative trait locus (QTL) controlling this phenotype. A QTL significantly associated with variance in B-lymphocytic sialitis score was mapped to the D6Mit138 marker (position of 0.68cM) on proximal chromosome 6, with a logarithm of odds score of 4.3 (p = 0.00005). This QTL, named autoimmune sialitis in IQI mice, associated locus 1 (Asq1), colocalized with Islet cell autoantigen 1 (Ica1), which encodes a target protein of the immune processes that define the pathogenesis of primary SS in humans and in the nonobese diabetic mouse model.

Autoimmunity against a tissue kallikrein in IQI/Jic Mice: a model for Sjogren's syndrome.

We have recently characterized IQI/Jic mice as a model for Sjogren's syndrome (SS), a chronic autoimmune disease in humans. In SS, local lymphocytic infiltrations into salivary and lacrimal glands frequently develop to the involvement of systemic exocrine and nonexocrine organs, and the mechanism for progression of this disease remains obscure. Herein, we report identification of an autoantigen shared by various target organs in IQI/Jic mice. Polypeptides identified based on immunorecognition by autoantibodies in sera from IQI/Jic mice affected with autoimmune disease (>12 weeks of age) were tissue kallikrein (Klk)-1 and -13 and were cross-reactive to the autoantibodies. Interestingly, Klk-13, but not Klk-1, caused a proliferative response of splenic T cells from IQI/Jic mice from the age of 4 weeks onward. In addition, remarkably enhanced expression of Klk-13 was observed in the salivary glands of the mice in accordance with the development of inflammatory lesions. These results indicate that Klk-13 acts as an autoantigen and may increase T cells responsive to organs commonly expressing Klk-13, playing a pivotal role in the etiology of progression of disease in IQI/Jic mice. Our findings provide insights into the contributions of autoantigens shared by multiple organs in the progress of SS from an organ-specific to a systemic disorder.