Determinants of liver damage associated with intravenous methylprednisolone pulse therapy in Graves' ophthalmopathy.

BACKGROUND: Intravenous methylprednisolone pulses (IVMP) are more efficacious and better tolerated than oral prednisone in Graves' ophthalmopathy (GO) patients. However, acute and severe liver damage has been reported in sporadic cases during IVMP, resulting in fatal acute liver failure in four patients so far. The mechanism causing the liver damage is incompletely understood. DESIGN: We performed a prospective observational study in 13 patients with dysthyroid optic neuropathy (group A) and in 14 patients with moderately severe GO (group B) who were treated with high-dose (group A) or low-dose (group B) IVMP; cumulative steroid doses were 8.45 g in group A and 4.5 g in group B, and follow-up time was 24 weeks. MAIN OUTCOME: Slight increases in serum aminotransferases (in alanine aminotransferase [ALAT] more than in aspartate aminotransferase [ASAT]) were observed, in seven patients exceeding the upper normal limit of 40 U/L. These changes were more prominent in group A than in group B as was also evident from a decrease in ASAT/ALAT ratio in group A but not in group B. Changes in serum aminotransferases occurred especially in the first 6 weeks of IVMP, becoming smaller thereafter with the decrease in steroid dosage. Pretreatment liver steatosis or diabetes were not related to liver damage, but preexistent viral hepatitis was. CONCLUSION: IVMP in GO patients causes dose-dependent liver damage by a direct toxic effect of glucocorticoids on hepatocytes. Nevertheless, IVMP seems to be pretty safe if cumulative doses exceeding 8 g are avoided and liver function is checked before and at regular intervals during pulse therapy.     

Perturbation of podocyte plasma membrane domains in experimental nephrosis. A lectin-binding and freeze-fracture study

Alterations in the ultrastructural organization of podocyte plasma membrane domains were quantitatively assessed in puromycin aminonucleoside-treated rats by the use of 1) Helix pomatia lectin-gold complexes for detection of a specific glycocalyx component(s) normally associated with foot process bases and 2) freeze-fracture for detection of intramembrane particles and endocytotic invaginations on the plasma membrane. Lectin-binding sites were significantly reduced on podocyte foot process bases during the 7-day treatment period; and in freeze-fracture, the plasma membrane of the foot process base showed an increase in intramembrane particle number and size and an increased number of endocytotic invaginations, compared with the numbers in control animals. The cell body of nephrotic animals also had a significantly increased intramembrane particle density, compared with the control animals. These results provide direct evidence that the normal structure of specific plasma membrane regions is perturbed in podocytes that have lost their characteristic array of foot processes and support a role for these domains in the maintenance of normal podocyte architecture.     

Immunohistochemical localization of carbonic anhydrase in postnatal and adult rat kidney

With use of specific antibodies against human and rat erythrocyte carbonic anhydrase C and human carbonic anhydrase B, only the isozyme C could be detected by immunofluorescence in rat kidney epithelial cells. In the postnatal kidney a few cells were positive after 2 days, but the number of fluorescent cells increased during the first few weeks of life to reach the final adult levels after 3 wk in the cortex and 5 wk in the medulla. In the postnatal and adult kidney a characteristic mosaic pattern of fluorescence was seen in the late distal tubule, the connecting segment, and the collecting tubule, where the mitochondria-rich dark cells were brightly fluorescent. In addition, in later postnatal stages and in the adult, the entire epithelium of the initial portion of descending thin limbs of Henle (long loops) was labeled. Some kidney regions that had previously been shown to contain carbonic anhydrase activity by biochemical and histochemical techniques stained only weakly with the immunocytochemical method. This suggests either that the enzyme in these regions does not cross-react strongly with our antibodies or that these regions contain only low amounts of carbonic anhydrase, at the limit of the detection threshold of our techniques.     

Mammalian Sec23p homologue is restricted to the endoplasmic reticulum transitional cytoplasm.

The yeast Sec23 protein is required in vivo and in vitro for transport of proteins from the endoplasmic reticulum (ER) to the Golgi apparatus. Ultrastructural localization of the Sec23p mammalian homologue (detected by antibody cross-reaction) in exocrine and endocrine pancreatic cells shows a specific distribution to the cytoplasmic zone between the transitional ER cisternae and Golgi apparatus where it appears associated with the tubular protuberances of the transitional ER cisternae, as well as with a population of vesicles, and surrounding cytoplasm. When ER-Golgi transport is interrupted with an energy poison, protuberances and transfer vesicles markedly decrease but Sec23p immunoreactive sites remain in the transitional cytoplasm not apparently tethered by membrane attachment. This unanticipated degree of organization suggests that cytosolic proteins, such as Sec23p, may be retained in specialized areas of the cytoplasm. A structure within the transitional zone may organize the flux of transport vesicles and Sec proteins so as to ensure efficient protein traffic in this limb of the secretory pathway.     

Fecal microbiota transplantation: a promising strategy in preventing the progression of non-alcoholic steatohepatitis and improving the anti-cancer immune response

Introduction: Non-alcoholic fatty liver disease (NAFLD) has the potential to progress to hepatocellular carcinoma (HCC). However, limited therapies are currently available for the treatment of advanced HCC, and one must strive to search for novel strategies.

Areas covered: We provide insight on current knowledge related to gut microbiota and NAFLD, summarize the sequence linking obesity to HCC and highlight gut dysbiosis in obesity and its consequences on the liver. We detail the impact of the gut microbiota on immune checkpoint inhibitors, and speculate on the role of fecal microbiota transplantation (FMT) in NAFLD and in improving anti-neoplastic immune response.

Expert Opinion: Manipulation of the gut microbiota seems promising in the secondary prevention of NAFLD/NASH and/or in potentiating anti-cancer immune response, notably by a global ‘resetting’ using FMT. However, the composition of a ‘harmful’ gut microbiome in HCC still needs to be characterized, and the impact of FMT on HCC growth needs to be assessed.     

Identification of a lobe in the adult human pancreas rich in pancreatic polypeptide

Summary Systematic sampling of human necropsy pancreases has revealed that pancreatic polypeptide (PP) cells are not distributed equally in the gland. PP-cells are the most abundant cell type in the posterior part of the pancreatic head while they are scarce or absent in the remainder of the gland. The PP-rich part of the head can be separated by blunt dissection from the pancreas as a discrete lobe. This lobe probably originates from the ventral pancreatic bud during embryogenesis. A quantitative study of the immunofluorescent endocrine cell types (insulin, glucagon, somatostatin and pancreatic polypeptide cells) in PP-rich and PP-poor regions of pancreases in 8 subjects with ages ranging from 33 fetal weeks to 80 years, showed that the proportions of the cell types were different in youngs and adults.     

Hypertrophy and hyperplasia of somatostatin-containing D-cells in diabetes.

Insulin-, glucagon-, and somatostatin-contianing cells, identified by immunofluorescent staining, were quantitated morphometrically in sections of pancreas obtained from diabetic and nondiabetic humans and rats. Both the volume density and number of somatostatin- and glucagon-containing cells were significantly increased in the islets of juvenile-type human diabetics and of streptozotocin diabetic rats.     

Mammalian Erv46 localizes to the endoplasmic reticulum-Golgi intermediate compartment and to cis-Golgi cisternae

Yeast endoplasmic reticulum (ER) vesicle protein Erv46p is a novel membrane protein involved in transport through the early secretory pathway. Investigation of mammalian Erv46 (mErv46) reveals that it is broadly expressed in tissues and protein-secreting cells. By immunofluorescence microscopy, mErv46 displays a crescent-shaped perinuclear staining pattern that is characteristic of the Golgi complex. Quantitative immunoelectron microscopy indicates that mErv46 is restricted to the cis face of the Golgi apparatus and to vesicular tubular structures between the transitional ER and cis-Golgi. Minor amounts of mErv46 reside in ER membranes and later Golgi cisternae. On Brefeldin A treatment, mErv46 redistributes to punctate structures that costain for ERGIC53. Depletion of mErv46 protein by RNA interference caused no apparent structural changes in the intermediate compartment or Golgi complex. These findings place mErv46 in a group of itinerant proteins that cycle between the ER and Golgi compartments such as ERGIC53 and the p24 proteins.