慢性肝疾患モデルマウスにみられたsublethal tubular cell injuryを伴う腎障害

京都大学0048新制・課程博士博士(医学)甲第19599号医博第4106号新制||医||1014(附属図書館)32635京都大学大学院医学研究科医学専攻(主査)教授 柳田 素子, 教授 妹尾 浩, 教授 浅野 雅秀学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

Renal impairment with sublethal tubular cell injury in a chronic liver disease mouse model

The pathogenesis of renal impairment in chronic liver diseases (CLDs) has been primarily studied in the advanced stages of hepatic injury. Meanwhile, the pathology of renal impairment in the early phase of CLDs is poorly understood, and animal models to elucidate its mechanisms are needed. Thus, we investigated whether an existing mouse model of CLD induced by 3, 5-diethoxycarbonyl-1, 4-dihydrocollidine (DDC) shows renal impairment in the early phase. Renal injury markers, renal histology (including immunohistochemistry for tubular injury markers and transmission electron microscopy), autophagy, and oxidative stress were studied longitudinally in DDC- and standard diet-fed BALB/c mice. Slight but significant renal dysfunction was evident in DDC-fed mice from the early phase. Meanwhile, histological examinations of the kidneys with routine light microscopy did not show definitive morphological findings, and electron microscopic analyses were required to detect limited injuries such as loss of brush border microvilli and mitochondrial deformities. Limited injuries have been recently designated as sublethal tubular cell injury. As humans with renal impairment, either with or without CLD, often show almost normal tubules, sublethal injury has been of particular interest. In this study, the injuries were associated with mitochondrial aberrations and oxidative stress, a possible mechanism for sublethal injury. Intriguingly, two defense mechanisms were associated with this injury that prevent it from progressing to apparent cell death: autophagy and single-cell extrusion with regeneration. Furthermore, the renal impairment of this model progressed to chronic kidney disease with interstitial fibrosis after long-term DDC feeding. These findings indicated that DDC induces renal impairment with sublethal tubular cell injury from the early phase, leading to chronic kidney disease. Importantly, this CLD mouse model could be useful for studying the pathophysiological mechanisms of sublethal tubular cell 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

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. Spearman's 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

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

Advance online publication 27 July 2015Liver 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

Single-cell extrusion with subsequent regeneration in the kidney of 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed mice.

<p>(<b>A</b>) A representative photograph of a single tubular cell extrusion (<i>triangles</i>) from the epithelial layer of proximal tubules at day 3. Scale bar = 10 μm. (<b>B</b>) Counts of mitotic cells per field on proximal tubules of control (<i>white bar</i>) and DDC-fed mice (<i>black bar</i>) at days 1, 3, and 7. (<b>C</b>) Counts of Ki-67-positive cells per field on proximal tubules of control (<i>white bar</i>) and DDC-fed mice (<i>black bar</i>) at days 1, 3, and 7. Data are presented as means ± SEM. *<i>P</i> < 0.05 compared with control mice. (<b>D</b>) Immunohistochemical staining for Ki-67 in the proximal tubules of control and DDC-fed mice at days 1, 3, and 7. Scale bar = 100 μm.</p

Sublethal injury leads to interstitial fibrosis and fibroblast activation after long-term 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding.

<p>(<b>A</b>) Plasma creatinine levels and urinary albumin/creatinine ratio in control (<i>white bar</i>) and DDC-fed mice (<i>black bar</i>) at days 7, 14, and 56. Data are presented as means ± SEM. *<i>P</i> < 0.05 compared with the control mice. Control and 7 days of DDC-fed mice samples were reproduced from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146871#pone.0146871.g001" target="_blank">Fig 1</a>; data were acquired using n ≥ 3 mice/group for the albumin/creatinine ratio. (<b>B</b>) Light and electron microscopic images of kidneys of control and DDC-fed mice at days 7, 14, and 56; top row, reticulin staining; middle row, Azan staining; bottom row, transmission electron microscopy (TEM); <i>red arrowheads</i>, accumulation of immature collagen fibers; <i>black asterisks</i>, accumulation of mature collagen fibers (blue staining); <i>arrows</i>, peritubular collagen fibers; <i>white asterisk</i>, myofibroblast with released collagen fibers. Scale bars = 25 μm (top row), 100 μm (middle row), and 2 μm (bottom row).</p

Renal dysfunction with tubular injuries in 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed mice.

<p>Plasma creatinine levels, plasma blood urea nitrogen (BUN) levels, urinary neutrophil gelatinase-associated lipocalin (urinary NGAL) levels, urinary albumin/creatinine ratio, arterial blood bicarbonate, and arterial blood pH in control (<i>white bar</i>) and DDC-fed mice (<i>black bar</i>) at days 1, 3, and 7. Data are presented as means ± SEM. *<i>P</i> < 0.05 compared with control mice. NS, not significant.</p

Sublethal tubular cell injuries in the kidney of 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed mice.

<p>(<b>A</b>) Semi-thin sections with toluidine blue staining (top row) and transmission electron microscopic (TEM) (bottom row) images of proximal tubules in control and DDC-fed mice at days 1, 3, and 7; <i>red arrowheads</i>, loss of brush border microvilli. Scale bars = 25 μm (top row), 10 μm (bottom row). (<b>B</b>) The proportion of injured cells to total tubular cells is presented as percentage; control (<i>white bar</i>) and DDC-fed mice (<i>black bar</i>) at days 1, 3, and 7. (<b>C</b>) TEM images of intracellular organelles (top row) and immunofluorescent analysis for KIM-1 (bottom row) in proximal tubules of control and DDC-fed mice at days 1, 3, and 7; <i>asterisks</i>, mitochondria with abnormal features; <i>arrowheads</i>, intact endoplasmic reticula; <i>green</i>, immunofluorescence labeling for KIM-1; <i>red</i>, phalloidin; <i>blue</i>, 4,6-diamidino-2-phenylindole (DAPI). Scale bars = 500 nm (top row), 50 μm (bottom row). (<b>D</b>) KIM-1 staining on renal tubules of the control and DDC-fed mice was digitally analyzed and presented as percentage positive staining area per field; control (<i>white bar</i>) and DDC-fed mice (<i>black bar</i>) at days 1, 3, and 7. Data are presented as means ± SEM. *<i>P</i> < 0.05 compared with control mice.</p