Takashi Tomiyama

Mst1 regulates integrin-dependent thymocyte trafficking and antigen recognition in the thymus.

Thymocyte trafficking has an important role in thymic selection. Here we show that the Hippo homologue Mst1 is required for thymocyte migration and antigen recognition by LFA-1 and ICAM-1 within the medulla. Using two-photon imaging of thymic tissues, we found that highly motile mature thymocytes arrest and are activated in the vicinity of rare populations of Aire(+) ICAM-1(hi) medullary thymic epithelia in a negatively selecting environment. Notably, Mst1 deficiency or blocking the cell adhesion molecules LFA-1 and ICAM-1 results in inefficient migration and antigen recognition of CD4(+) thymocytes within the medulla. Consistent with these defects, thymocyte selection is impaired in Mst1(-/-) mice, which display T cell-dependent inflammatory infiltrates in multiple organs and develop autoantibodies. Our results suggest that Mst1 has a key role in regulating thymocyte self-antigen recognition in the medulla.

Antigen-Specific Suppression and Immunological Synapse Formation by Regulatory T Cells Require the Mst1 Kinase

Although the cell-to-cell contact between CD4+Foxp3+ regulatory T (Treg) and their target cells is important for the suppressor function of Treg cells, the regulation of this process is not well understood. Here we show that the Mst1 kinase plays a critical role in the suppressor function of Treg cells through regulation of cell contact dependent processes. Mst1 -/- Treg cells failed to prevent the development of experimental colitis and antigen-specific suppression of naïve T cells proliferation in vitro. Mst1 -/- Treg cells exhibited defective interactions with antigen-presenting dendritic cells (DCs), resulting in reduced down-regulation of costimulatory molecules. While wild-type CD4+ Foxp3+ Treg cells formed mobile immunological synapses on supported planar membrane, Mst1 -/- Treg cells did not exhibit ICAM-1 ring or central peptide-MHC clustering. Using two-photon imaging we showed that antigen-specific wild-type Treg cells exhibited dynamic mobile contacts with antigen-pulsed DCs bearing stably associated naïve T cells. In contrast, Mst1 -/- Treg had impairments in their interactions with DCs. Thus, Mst1 is required for Treg cells to mediate contact-dependent suppressor functions.

Diagnosis and classification of autoimmune pancreatitis.

Recent studies suggested the existence of two subtypes of autoimmune pancreatitis (AIP): type 1 related with IgG4 as the pancreatic manifestation of IgG4-related disease (IgG4-RD), and type 2 related with a granulocytic epithelial lesion. Apart from type 2 AIP, the characteristic features of type 1 AIP are increased serum IgG4 levels, lymphoplasmacytic sclerosing pancreatitis (abundant infiltration of IgG4+ plasmacytes and lymphocytes, storiform fibrosis, and obliterative phlebitis), extra-pancreatic manifestations of IgG4-RD (e.g. sclerosing cholangitis, sclerosing sialadenitis, retroperitoneal fibrosis), and steroid responsiveness. Although the way how to diagnose IgG4-RD has not been established yet, the Comprehensive Diagnostic Criteria (CDC) for IgG4-RD for general use, and several organ specific criteria for AIP have been proposed; the International Consensus Diagnostic Criteria (ICDC) and the revised clinical diagnostic criteria in 2011 by Japan Pancreas Society (JPS-2011) for type1 AIP. In cases of probable or possible IgG4-RD diagnosed by the CDC, organ specific diagnostic criteria should be concurrently used according to an algorithm of diagnosis for IgG4-RD with reference to the specialist.

NDR1-Dependent Regulation of Kindlin-3 Controls High-Affinity LFA-1 Binding and Immune Synapse Organization

ABSTRACT Antigen-specific adhesion between T cells and antigen-presenting cells (APC) during the formation of the immunological synapse (IS) is mediated by LFA-1 and ICAM-1. Here, LFA-1–ICAM-1 interactions were measured at the single-molecule level on supported lipid bilayers. High-affinity binding was detected at low frequencies in the inner peripheral supramolecular activation cluster (SMAC) zone that contained high levels of activated Rap1 and kindlin-3. Rap1 was essential for T cell attachment, whereas deficiencies of ste20-like kinases, Mst1/Mst2, diminished high-affinity binding and abrogated central SMAC (cSMAC) formation with mislocalized kindlin-3 and vesicle transport regulators involved in T cell receptor recycling/releasing machineries, resulting in impaired T cell-APC interactions. We found that NDR1 kinase, activated by the Rap1 signaling cascade through RAPL and Mst1/Mst2, associated with and recruited kindlin-3 to the IS, which was required for high-affinity LFA-1/ICAM-1 binding and cSMAC formation. Our findings reveal crucial roles for Rap1 signaling via NDR1 for recruitment of kindlin-3 and IS organization.

Sema3e/Plexin D1 Modulates Immunological Synapse and Migration of Thymocytes by Rap1 Inhibition

Regulation of thymocyte trafficking plays an important role during thymic selection, but our understanding of the molecular mechanisms underlying these processes is limited. In this study, we demonstrated that class III semaphorin E (sema3e), a guidance molecule during neural and vascular development, directly inhibited Rap1 activation and LFA-1–dependent adhesion through the GTPase-activating protein activity of plexin D1. Sema3e inhibited Rap1 activation of thymocytes in response to chemokines and TCR stimulation, LFA-mediated adhesion, and T cell–APC interactions. Immunological synapse (IS) formation in mature thymocytes on supported lipid bilayers was also attenuated by sema3e. Impaired IS formation was associated with reduced Rap1 activation on the contact surface and cell periphery. Moreover, a significant increase of CD4+ thymocytes was detected in the medulla of mice with T cell lineage–specific deletion of plexin D1. Two-photon live imaging of thymic explants and slices revealed enhanced Rap1 activation and migration of CD69+ double-positive and single-positive cells with plexin D1 deficiency. Our results demonstrate that sema3e/plexin D1 modulates IS formation and Ag-scanning activities of thymocytes within thymic tissues.

Esophageal Large-Cell Neuroendocrine Carcinoma with Inconsistent Response to Treatment in the Primary and Metastatic Lesions

Esophageal large-cell neuroendocrine carcinoma (NEC) is a rare malignant tumor that is characterized by high-grade malignancy and a poor prognosis. However, the rarity of esophageal NEC has prevented the development of an established treatment, and no reports have described a discrepancy in the effectiveness of cisplatin plus irinotecan between primary and metastatic lesions. A 43-year-old Japanese man was referred to our hospital with refractory epigastralgia. A previous gastrointestinal endoscopy had revealed a 50-mm type 2 tumor in the abdominal esophagus. The pathological findings indicated poorly differentiated squamous cell carcinoma. Contrast-enhanced computed tomography revealed a metastatic liver tumor. One cycle of fluorouracil and cisplatin was not effective, and endoscopy was repeatedly performed. The pathological findings indicated a large-cell malignant tumor with tumor cells that were positive for CD56, synaptophysin, and Ki-67 (> 80%). Based on a diagnosis of esophageal large-cell NEC with a metastatic liver tumor, the patient received cisplatin plus irinotecan biweekly. After 4 months, computed tomography revealed marked shrinkage of the metastatic tumor, but the patient complained of dysphagia. Endoscopy revealed enlargement of the primary tumor, which was then treated using radiotherapy plus fluorouracil and cisplatin. The primary tumor subsequently shrank, and the patient’s symptoms were relieved, but the metastatic tumor grew. Thus, chemoradiotherapy could be an option for managing a primary esophageal large-cell NEC that does not respond to chemotherapy alone. However, the possibility of an inconsistent response to therapy in primary and metastatic lesions should be considered.

Morphological and immunohistochemical comparison of intrapancreatic nerves between chronic pancreatitis and type 1 autoimmune pancreatitis

OBJECTIVES The abdominal pain associated with chronic pancreatitis (CP) may be related to the increased number and size of intrapancreatic nerves. On the other hand, patients with type 1 autoimmune pancreatitis (AIP) rarely suffer from the pain syndrome, and there are no previous studies concerning the histopathological findings of intrapancreatic nerves in patients with type 1 AIP. The current study is aimed at investigating the differences in the histopathological and immunohistochemical findings of intrapancreatic nerves in patients with CP and type 1 AIP. METHODS Neuroanatomical differences between CP and type 1 AIP were assessed by immunostaining with a pan-neuronal marker, protein gene product 9.5 (PGP9.5). The number (neural density) and area (neural hypertrophy) of PGP9.5-immunopositive nerves were quantitatively analyzed. Furthermore, the expression of nerve growth factor (NGF), and a high affinity receptor for NGF, tyrosine kinase receptor A (TrkA), was assessed by immunohistochemistry. RESULTS Both neural density and hypertrophy were significantly greater in pancreatic tissue samples from patients with CP than those with normal pancreas or type 1 AIP. NGF expression was stronger in type 1 AIP than in CP, whereas TrkA expression in type 1 AIP was poorer than in CP. CONCLUSIONS Although CP and type 1 AIP are both characterized by the presence of sustained pancreatic inflammation, they are different in terms of the density and hypertrophy of intrapancreatic nerve fibers. It is possible that this may be related to the difference in the activity of the NGF/TrkA-pathway between the two types of pancreatitis.

Multifocal Colonic Wall Abscesses during Anti-Tumor Necrosis Factor (TNF)-α Therapy for a Patient with Ulcerative Colitis: A Very Rare Manifestation of Infectious Complications.

A 24-year-old woman was transferred to our hospital under suspicion of an exacerbation of her known ulcerative colitis. Colonoscopy revealed an edematous swelling and multifocal discharge of pus throughout the descending colon, concurrent with active ulcerative colitis findings in the rectum and sigmoid colon. Computed tomography showed a thickened wall and multifocal abscesses within the wall of the descending colon. Two weeks after starting antimicrobial therapy, she was discharged home. This is the first case report of multifocal colonic wall abscesses. In order not to increase the risk of serious infection associated with anti-TNF-α therapy, proper qualification and strict monitoring are essential.

Reply to the letter by A. Eshraghian et al. regarding “Oral steroid versus steroid pulse therapy for autoimmune pancreatitis”

Thank you for your interest in our article. Most autoimmune pancreatitis (AIP) reported in Japan is lymphoplasmacytic sclerosing pancreatitis (LPSP), and the pathogenesis of this entity is not clear. We previously reported, in our study with mouse models, that a reaction with a self-antigen, such as lactoferrin or carbonic anhydrase II, was an important trigger of AIP, occurring via a Th1-type immune reaction [1]. It has also been reported that inducible T-cell co-stimulator (ICOS)-positive regulatory T cells are important for the production of IgG4 through interleukin (IL)-10 [2]. The clinical course of LPSP is also unclear; however, it is known that there are many relapses [3]. The recurrence that happens after the ending of steroid therapy is a big problem in the treatment of AIP. New treatments using agents such as anti-tumor necrosis factor (TNF)-alpha and antagonists of IL-2 receptors might have the possibility of solving this problem. We agree with the necessity for performing experiments using these drugs. However, many problems about the safety of these drugs, such as their side effects, should be resolved. At present, it is thought that treatment with steroids is safest for AIP. In the Asian diagnostic criteria, the use of steroids as diagnostic treatment was allowed only when the imaging findings were compatible with AIP and only after there was a negative result for malignancy work-up [4]. After the publication of new international diagnostic criteria [5], it is thought that the need for diagnostic therapy with steroids will increase. Even if a negative work-up for pancreatic cancer has been done, the possibility of pancreatic cancer cannot be completely ruled out. The major advantages of steroid pulse therapy are that nonresponder patients can immediately stop the steroid after the pulse therapy and have an early surgical operation in a steroid-free condition if necessary. In our retrospective study, we did not find any significant differences between the group with conventional oral steroid therapy and the group with pulse steroid therapy, except for hepatic enzymes (alanine aminotransferase [ALT] and c-guanosine triphosphate [c-GTP]). We found that some patients with biliary lesions who did not respond well to oral steroid responded well to the pulse therapy [6]. A prospective study should be necessary to determine a new treatment for AIP.