Masashi Miyao

Pivotal role of liver sinusoidal endothelial cells in NAFLD/NASH progression.

Liver sinusoidal endothelial cells (LSECs) are involved in the transport of nutrients, lipids, and lipoproteins, and LSEC injury occurs in various liver diseases including nonalcoholic fatty liver disease (NAFLD). However, the association between LSEC injury and NAFLD progression remains elusive. Accordingly, in this study, we aimed to elucidate the precise role of LSEC in the pathophysiology of NAFLD using two different mouse models, namely the choline-deficient, L-amino acid-defined and high-fat diet models. Administration of these diets resulted in liver metabolic dysregulation mimicking human NAFLD, such as steatosis, ballooning, lobular inflammation, and fibrosis, as well as central obesity, insulin resistance, and hyperlipidemia. LSEC injury appeared during the simple steatosis phase, and preceded the appearance of activated Kupffer cells and hepatic stellate cells (HSCs). These results indicate that LSEC injury may have a ‘gatekeeper’ role in the progression from simple steatosis to the early nonalcoholic steatohepatitis (NASH) stage, and LSEC injury may be necessary for the activation of Kupffer cells and HSCs, which in turn results in the development and perpetuation of chronic liver injuries. Taken together, our data provide new insights into the role of LSEC injury in NAFLD/NASH pathogenesis.

Circulating Extracellular Histones Are Clinically Relevant Mediators of Multiple Organ Injury

Extracellular histones are a damage-associated molecular pattern (DAMP) involved in the pathogenesis of various diseases. The mechanisms of histone-mediated injury in certain organs have been extensively studied, but an understanding of the pathophysiological role of histone-mediated injury in multiple organ injury remains elusive. To elucidate this role, we systemically subjected C57BL/6 mice to various doses of histones and performed a chronological evaluation of the morphological and functional changes in the lungs, liver, and kidneys. Notably, histone administration ultimately led to death after a dose-dependent aggravation of multiple organ injury. In chronological studies, pulmonary and hepatic injuries occurred within 15 minutes, whereas renal injuries presented at a later phase, suggesting that susceptibility to extracellular histones varies among organs. Histones bound to pulmonary and hepatic endothelial cells immediately after administration, leading to endothelial damage, which could be ameliorated by pretreatment with heparin. Furthermore, release of another DAMP, high-mobility group protein box 1, followed the histone-induced tissue damage, and an antibody against the molecule ameliorated hepatic and renal failure in a late phase. These findings indicate that extracellular histones induce multiple organ injury in two progressive stages-direct injury to endothelial cells and the subsequent release of other DAMPs-and that combination therapies against extracellular histones and high-mobility group protein box 1 may be a promising strategy for treating multiple organ injury.

Ectopic cervical thymus associated with infant death: 2 case reports and literature review

An ectopic cervical thymus is a rare congenital anomaly that can be located anywhere along the developmental pathway of thymic descent. Most lesions manifest as a cystic mass and have an indolent course. Two fatal cases associated with ectopic cervical thymus in the form of a solid mass are presented in conjunction with a review of the clinicopathological characteristics of the solid form. This report emphasizes the importance of considering a diagnosis of ectopic cervical thymus in infants with neck masses, with or without obstructive symptoms, to prevent possibly fatal outcomes.

The effectiveness and limitations of triphenyltetrazolium chloride to detect acute myocardial infarction at forensic autopsy.

AbstractTriphenyltetrazolium chloride (TTC) is one of the most conventional stains to detect infarcted area of the heart in animal experiments. However, its availability and limitations have not been thoroughly discussed in the forensic field. Here, authors stained human hearts with TTC soon after the harvest. Photographs of the samples were analyzed using image analysis software, which evaluated the occupying ratio of the stained area on the surface of each slice. The results showed that the stainability of TTC declines with the length of the postmortem interval (PMI). Specimens reacted well to TTC within 1.5 days after death and then decreased the stainability logarithmically with PMI (y = − 0.294 In (x) + 1.0441; x = PMI, y = TTC-stained area / total myocardial area, R2 = 0.5673). Samples with old myocardial infarction produced clear TTC contrast; normal tissue is vivid red, and fibrotic myocardium is white discoloration. In acute myocardial infarction cases where death occurred within 9 hours after the attack, however, the detection of infarcted area was very difficult even when PMI was less than 1.5 days. In summary, the TTC method may be useful within 1.5 days after death, but short suffering period before death disturbs its staining efficiency.

Histology of intestinal allografts: lymphocyte apoptosis and phagocytosis of lymphocytic apoptotic bodies are diagnostic findings of acute rejection in addition to crypt apoptosis.

Acute rejection of a small-bowel transplant is often difficult to diagnose due to complicated immune responses. The present study aimed to elucidate the specific immune responses involved in intestinal transplant rejection. We correlated immunohistologic findings with an increase in crypt apoptosis, which has been commonly accepted as a criterion for the diagnosis of acute cellular rejection (ACR). Of 8 patients who received an intestinal allograft at Kyoto University Hospital, biopsy specimens from 7 patients were assessed immunohistologically with antibodies against 20 types of lymphocytic antigens including CD3, CD4, CD8, CD79a, CD20, IgG, and T-cell receptor, along with assessment of the patients’ clinical courses. It was revealed that, in addition to apoptotic crypts, T-lymphocyte apoptosis and phagocytosis of apoptotic bodies in the lamina propria of villi were findings of ACR; both were observed in all cases. Immunostaining of the Fas ligand, one of the apoptosis-inducing molecules, was useful for the identification of the apoptotic bodies in the lamina propria of villi. Apoptotic body phagocytosis may be a surrogate diagnostic finding of grafts undergoing ACR.

Bile canalicular abnormalities in the early phase of a mouse model of sclerosing cholangitis.

BACKGROUND The bile canaliculus is the smallest and first biliary channel and is formed by two or three adjacent hepatocytes. Previous studies of chronic cholangiopathies such as primary sclerosing cholangitis have focused on the bile ductules. However, little is known about the pathological alterations in bile canaliculi in the early phase of cholangiopathies. AIM To characterize the bile canalicular morphology in the early phase of sclerosing cholangitis we used 3,5-diethoxycarbonyl-1,4-dihydrocollidine-induced mouse model of sclerosing cholangitis. METHODS Mice were fed a diet with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (0.1%). Serum biochemical, histological, immunohistochemical, and electron microscopic analyses were performed 1, 2, 4, and 7 days after feeding. RESULTS All experimental groups showed significantly increased serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels. From day 1, bile canalicular abnormalities such as dilatation and meandering and loss of microvilli were observed. After bile canalicular abnormalities had appeared, substantial infiltration of inflammatory cells was observed amongst the necrotic cells and periductal region. After these inflammatory changes, cholangiocytes proliferated in the portal area and formed ductular reactions. Finally, periductal fibrosis appeared. CONCLUSION This study provides novel evidence of the occurrence of bile canalicular abnormalities during the early phase of sclerosing cholangitis.

Invariant natural killer T cells infiltrate intestinal allografts undergoing acute cellular rejection

Immunological responses in human intestinal allografts are poorly understood and accurate diagnosis of acute cellular rejection remains difficult. Here, human intestinal allografts were analyzed by multi‐color quantitative fluorescent immunohistochemical morphometry in order to monitor the clinical course of rejection. Morphometry gave two‐dimensional plots based on size and circularity, and identified phenotypes of individual cells infiltrating the allograft by fluorescent staining. Using this method, invariant TCRVα24+ NKT (iNKT) cells were observed in the intestinal allograft during rejection. Because these were not identified in the normal donor intestine before surgery, this finding was considered to be a signature of acute cellular rejection of the intestinal allograft. Infiltrating iNKT cells released IL‐4 and IL‐5, Th2‐related cytokines that antagonize the Th1 responses that induce acute cellular rejection. Histological observation suggested eosinophilic enteritis in the mucosa with elevation of IL‐4 and IL‐5. In conclusion, iNKT cells were recruited to the intestine; however, because higher levels of IL‐4 and IL‐5 may contribute to eosinophilic enteritis, timely steroid administration is recommended for allograft injury due to enteritis, as well as acute cellular rejection.

Subdural hemorrhage: A unique case involving secondary vitamin K deficiency bleeding due to biliary atresia

Extrahepatic biliary atresia (EHBA) is a rare disease characterized by progressive and obliterative cholangiopathy in infants and is one of the major causes of secondary vitamin K deficiency bleeding (VKDB) due to cholestasis-induced fat malabsorption. Breast feeding increases the tendency of bleeding in EHBA patients because breast milk contains low amounts of vitamin K. A 2-month-old female infant unexpectedly died, with symptoms of vomiting and jaundice prior to death. She had been born by uncomplicated vaginal delivery and exhibited normal growth and development with breastfeeding. There was no history of trauma. She received vitamin K prophylaxis orally. In an emergency hospital, a CT scan showed a right intracranial hematoma and mass effect with midline shift to the left. In the postmortem examination, severe atresia was observed in the whole extrahepatic bile duct. Histologically, cholestasis, periductal fibrosis, and distorted bile ductules were noted. The gallbladder was not identified. A subdural hematoma and cerebellar tonsillar herniation were found; however, no traumatic injury in any part of the body was observed. Together, these findings suggest that the subdural hemorrhage was caused by secondary vitamin K deficiency resulting from a combination of cholestasis-induced fat malabsorption and breastfeeding. Subdural hemorrhage by secondary VKDB sometimes occurs even when vitamin K prophylaxis is continued. This case demonstrated that intrinsic factors, such as secondary VKDB (e.g., EHBA, neonatal hepatitis, chronic diarrhea), should also be considered in infant autopsy cases presenting with subdural hemorrhage.

Ectopic cervical thymus: A clinicopathological study of consecutive, unselected infant autopsies

OBJECTIVES An ectopic cervical thymus (ECT) is regarded as a rare congenital anomaly; therefore, the optimal diagnostic and therapeutic strategy remains a debatable matter. We designed a study to elucidate the clinicopathological characteristics of ECTs in consecutive, unselected infant autopsies, to help guide case management. METHODS We searched for ECTs in all of the 21 consecutive, unselected infant autopsy cases performed at our institution over a period of 3 years, and all ECT consensus diagnoses were confirmed by histological examination. The following clinical characteristics were evaluated in cases with ECTs: age, gender, birth week and weight, clinical symptoms due to the ECT(s), position on discovery of death, cause of death, ECT contribution to the cause of death, and concomitant congenital disorders. The anatomical features evaluated included the location, number, size, color, shape, and margins of the ECTs, and the presence of a mediastinal thymus. Histological findings of the ECT(s) and the mediastinal thymus were compared within each individual. Fusion of the parathyroid and the ECT was also investigated histologically. Spearmans rank correlation coefficient (ρ) and the corresponding P value were calculated to determine if there was an association between ECT diameter and age. RESULTS We detected 10 ECT lesions in seven cases (33%) among the 21 infant autopsy cases. The ECT cases involved five boys and two girls, with ages ranging from 1 day to 4 months. There were no reports of a positive family history of sudden death or antemortem clinical symptoms due to ECT in any of the cases. The ECTs were considered incidental regarding the cause of death, with the exception of one case that was extremely rare. Most ECTs were localized to the inferior thyroid, ranging from 0.4 to 1.9 cm in size. Size demonstrated a significant negative correlation with age (ρ=-0.75 and P=0.034). CONCLUSIONS This study revealed that ECT is an essentially benign anomaly that occurs frequently during the development of the thymus, and may disappear over the first few years of life. These results suggest a conservative approach to the management of ECTs would be appropriate.

Pituitary abscess presenting a very rapid progression: report of a fatal case.

Pituitary abscess is a rare disease presenting with nonspecific clinical symptoms, and diagnosis is often difficult. This disease is potentially life-threatening, but most cases have a chronic and indolent course. We report a case of a 60-year-old man with a pituitary abscess associated with pituitary adenoma who died 5 days after the onset of clinical symptoms without a definitive diagnosis. Postmortem computed tomography and autopsy findings revealed a sellar mass with cystic change and extension toward the optic chiasm. Histopathology of the lesion demonstrated an abscess with suppurative meningitis and encephalitis. The disturbance of the cardiac autonomic nervous system because of hypothalamus involvement was suggested as the cause of rapid progression and death. This case provides useful information for clinicians to avoid a lethal outcome.