Inhibition of the renal apical sodium dependent bile acid transporter prevents cholemic nephropathy in mice with obstructive cholestasis.

BACKGROUND & AIMS: Cholemic nephropathy (CN) is a severe complication of cholestatic liver diseases for which there is no specific treatment. We revisited its pathophysiology with the aim of identifying novel therapeutic strategies. METHODS: Cholestasis was induced by bile duct ligation (BDL) in mice. Bile flux in kidneys and livers was visualized by intravital imaging, supported by MALDI mass spectrometry imaging and liquid chromatography-tandem mass spectrometry. The effect of AS0369, a systemically bioavailable apical sodium-dependent bile acid transporter (ASBT) inhibitor, was evaluated by intravital imaging, RNA-sequencing, histological, blood, and urine analyses. Translational relevance was assessed in kidney biopsies from patients with CN, mice with a humanized bile acid (BA) spectrum, and via analysis of serum BAs and KIM-1 (kidney injury molecule 1) in patients with liver disease and hyperbilirubinemia. RESULTS: Proximal tubular epithelial cells (TECs) reabsorbed and enriched BAs, leading to oxidative stress and death of proximal TECs, casts in distal tubules and collecting ducts, peritubular capillary leakiness, and glomerular cysts. Renal ASBT inhibition by AS0369 blocked BA uptake into TECs and prevented kidney injury up to 6 weeks after BDL. Similar results were obtained in mice with humanized BA composition. In patients with advanced liver disease, serum BAs were the main determinant of KIM-1 levels. ASBT expression in TECs was preserved in biopsies from patients with CN, further highlighting the translational potential of targeting ASBT to treat CN. CONCLUSIONS: BA enrichment in proximal TECs followed by oxidative stress and cell death is a key early event in CN. Inhibiting renal ASBT and consequently BA enrichment in TECs prevents CN and systemically decreases BA concentrations. IMPACT AND IMPLICATIONS: Cholemic nephropathy (CN) is a severe complication of cholestasis and an unmet clinical need. We demonstrate that CN is triggered by the renal accumulation of bile acids (BAs) that are considerably increased in the systemic blood. Specifically, the proximal tubular epithelial cells of the kidney take up BAs via the apical sodium-dependent bile acid transporter (ASBT). We developed a therapeutic compound that blocks ASBT in the kidneys, prevents BA overload in tubular epithelial cells, and almost completely abolished all disease hallmarks in a CN mouse model. Renal ASBT inhibition represents a potential therapeutic strategy for patients with CN.

Compromised blood-bile barrier after acetaminophen overdose.

N-acetylcysteine (NAC) is the only approved drug for the treatment of acetaminophen (APAP) intoxication. A limitation of NAC is the short therapeutic time-window as it is only effective within approximately eight hours after APAP ingestion, which is critical since patients seek medical attention often after the onset of symptoms approximately 24 h after overdose. Recently, a so far unknown mechanism was identified by which APAP causes an increase of intracellular bile acid concentrations in hepatocytes to concentrations that exceed cytotoxic thresholds. APAP compromises the tight junctions of bile canaliculi that leads to the leakage of highly concentrated bile acids into the sinusoids. From the sinusoidal blood, a high fraction of the released bile acids is transported back into hepatocytes by basolateral uptake carriers and secreted into bile canaliculi. Repeated leakage from the canaliculi followed by hepatocellular reuptake and canalicular secretion causes an increase of intracellular bile acid concentrations and finally hepatocyte death. Importantly, inhibition of bile acid uptake carriers reduced intracellular bile acid concentrations and strongly ameliorated APAP hepatotoxicity, a finding that could result in a new therapeutic option for APAP-intoxicated patients.

Anatomical, Histological, and Electron Microscopic Structures of Syrinx in Male Budgerigars (Melopsittacus undulatus).

The syrinx is the main source for phonation in birds, its function is analogous to the mammalian larynx. Birds have both a larynx and a syrinx, but they use only the latter to vocalize. The objective of this work to give a detailed description of the anatomical, histological, and ultrastructural of syrinx in male budgerigars as a model of a passerine bird. The syrinx in the current study was to be found as a tracheobronchial type, it consists of cranial (tympanum) part and caudal (bronchosyringeal) part and, additionally, there are lateral vibrating membranes. The tympanum is formed of the last six tracheal rings, histologically its lamina epithelialis is a pseudostratified ciliated columnar epithelium with goblet cells and interrupted by intraepithelial glands. The secretory acini appear oval and lined by pyramidal secretory cells. The lamina propria­submucosa contain numerous blood capillaries, immune cells, and telocytes (TCs). The electron microscopic examination revealed numerous blood capillaries surrounded by fibroblasts and numerous immune cells, including mast cells and wandering leukocytes, within the tympanum mucosa. Hence, this study provides a detailed knowledge about the syrinx in male budgerigars.

Comparative Morphological Features of Syrinx in Male Domestic Fowl Gallus gallus domesticus and Male Domestic Pigeon Columba livia domestica: A Histochemical, Ultrastructural, Scanning Electron Microscopic and Morphometrical Study.

Many studies have been carried out to investigate the morphological structure of the syrinx in many bird species. However, the cellular organization of the syrinx in the fowls and pigeons is still unclear. The current study revealed that in fowl and pigeon, the syrinx is formed of three main parts including tympanum (cranial) part, intermediate syringeal part, and bronchosyringeal (caudal) part, in addition to pessulus and tympaniform membranes. A great variation in the structural characteristics of syrinx of fowl and pigeon was recorded. In fowl, the tympaniform membranes showed a characteristic distribution of elastic and collagen fibers which increase the elasticity of tympaniform membranes. Moreover, the bony pessulus helps the medial tympaniform membranes to be stiffer, vibrate more strongly so that louder sound will be generated. In pigeon, the lateral tympaniform membrane is of greater thickness so that the oscillation of this membrane is reduced and the amplitude is lower. Moreover, the pessulus is smaller in size and is formed mainly of connective tissue core (devoid of cartilaginous or bony plates), resulting in the failure of stretching and vibrating of the medial tympaniform membranes, that leads to the generation of deeper sound. Electron microscopic examination of the syringes of fowls and pigeons revealed numerous immune cells including dendritic cells, plasma cells, mast cells, and lymphocytes distributed within syringeal mucosa and invading the syringeal epithelium. Telocytes were first recorded in the syrinx of fowls and pigeons in this study. They presented two long telopodes that made up frequent close contacts with other neighboring telocytes, immune cells, and blood capillaries.

Early changes in longitudinal deformation indices in young asymptomatic patients with type 1 diabetes mellitus: assessment by speckle-tracking echocardiography.

BACKGROUND: We explored early changes in regional left ventricular systolic and diastolic function assessed by speckle-tracking echocardiography (STE) in young asymptomatic patients with type 1 diabetes mellitus (DM), compared with healthy controls. METHODS: We enrolled 30 normotensive asymptomatic patients with type 1 DM, age ≤40 years, DM duration >5 years, and left ventricular ejection fraction ≥50%; and thirty matched controls. They underwent conventional echocardiography, and tissue Doppler imaging (TDI). Myocardial deformation indices were measured by STE. We measured global longitudinal systolic strain, global longitudinal systolic strain rate, and global longitudinal early diastolic strain rate, as an average of 18 myocardial segments. RESULTS: The mean age was 27.7±4.5 years, (41.7% males). The mean duration of diabetes was 14.3±5.8 years. The 2-D ejection fraction was lower in diabetic patients versus controls (P=0.03). The trans-mitral A peak was higher, and isovolumetric relaxation time longer in diabetics (P<0.05 for both). Both lateral and septal É values were lower, and E/É ratio higher in diabetics (P<0.05 for all). The global longitudinal systolic strain and strain rate were decreased in diabetics (-17.7±2.5% versus -21.2±1.7%, and -1.1±0.2 versus -1.3±0.2 s-1, P<0.001 and P=0.003, respectively). The global longitudinal early diastolic strain rate was comparable to controls (1.5±0.4 versus 1.6±0.3 s-1, respectively, P=0.33). CONCLUSIONS: In asymptomatic patients with type 1 DM, global longitudinal systolic function measured by STE was impaired versus controls; diastolic function was impaired by conventional echocardiography and TDI.