ß-Cyclodextrin counteracts obesity in Western diet-fed mice but elicits a nephrotoxic effect.

Obesity has become a worldwide health crisis and is associated with a plethora of comorbidities. The multi-organ effects of obesity have been linked to ectopic lipid accumulation. Thus, there is an urgent need to tackle the obesity crisis by developing effective lipid-lowering therapies. 2-hydroxypropyl-ß-Cyclodextrin (2HP-ß-CD) has been previously shown to reduce lysosomal cholesterol accumulation in a murine model of Niemann Pick Type C (NPC) disease. Using a murine model of Western diet-induced obesity (DIO), we report the effects of 2HP-ß-CD in counteracting weight gain, expansion of adipose tissue mass and ectopic lipid accumulation. Interestingly, DIO caused intracellular storage of neutral lipids in hepatic tissues and of phospholipids in kidneys, both of which were prevented by 2HP-ß-CD. Importantly, this report brings attention to the nephrotoxic effects of 2HP-ß-CD: renal tubular damage, inflammation and fibrosis. These effects may be overlooked, as they are best appreciated upon assessment of renal histology.

Liver disease predominates in a mouse model for mild human Zellweger spectrum disorder.

Zellweger spectrum disorders (ZSDs) are autosomal recessive diseases caused by defective peroxisome assembly. They constitute a clinical continuum from severe early lethal to relatively milder presentations in adulthood. Liver disease is a prevalent symptom in ZSD patients. The underlying pathogenesis for the liver disease, however, is not fully understood. We report a hypomorphic ZSD mouse model, which is homozygous for Pex1-c.2531G>A (p.G844D), the equivalent of the most common pathogenic variant found in ZSD, and which predominantly presents with liver disease. After introducing the Pex1-G844D allele by knock-in, we characterized homozygous Pex1-G844D mice for survival, biochemical parameters, including peroxisomal and mitochondrial functions, organ histology, and developmental parameters. The first 20 post-natal days (P20) were critical for survival of homozygous Pex1-G844D mice (~20% survival rate). Lethality was likely due to a combination of cholestatic liver problems, liver dysfunction and caloric deficit, probably as a consequence of defective bile acid biosynthesis. Survival beyond P20 was nearly 100%, but surviving mice showed a marked delay in growth. Surviving mice showed similar hepatic problems as described for mild ZSD patients, including hepatomegaly, bile duct proliferation, liver fibrosis and mitochondrial alterations. Biochemical analyses of various tissues showed the absence of functional peroxisomes accompanied with aberrant levels of peroxisomal metabolites predominantly in the liver, while other tissues were relatively spared. ur findings show that homozygous Pex1-G844D mice have a predominant liver disease phenotype, mimicking the hepatic pathology of ZSD patients, and thus constitute a good model to study pathogenesis and treatment of liver disease in ZSD patients.

Excessive dietary lipid intake provokes an acquired form of lysosomal lipid storage disease in the kidney.

Obesity and dyslipidaemia are features of the metabolic syndrome and risk factors for chronic kidney disease. The cellular mechanisms connecting metabolic syndrome with chronic kidney disease onset and progression remain largely unclear. We show that proximal tubular epithelium is a target site for lipid deposition upon overnutrition with a cholesterol-rich Western-type diet. Affected proximal tubule epithelial cells displayed giant vacuoles of lysosomal or autophagosomal origin, harbouring oxidised lipoproteins and concentric membrane layer structures (multilamellar bodies), reminiscent of lysosomal storage diseases. Additionally, lipidomic analysis revealed renal deposition of cholesterol and phospholipids, including lysosomal phospholipids. Proteomic profiles of renal multilamellar bodies were distinct from those of epidermis or lung multilamellar bodies and of cytoplasmic lipid droplets. Tubular multilamellar bodies were observed in kidney biopsies of obese hypercholesterolaemic patients, and the concentration of the phospholipidosis marker di-docosahexaenoyl (22:6)-bis(monoacylglycerol) phosphate was doubled in urine from individuals with metabolic syndrome and chronic kidney disease. The enrichment of proximal tubule epithelial cells with phospholipids and multilamellar bodies was accompanied by enhanced inflammation, fibrosis, tubular damage markers, and higher urinary electrolyte content. Concomitantly to the intralysosomal lipid storage, a renal transcriptional response was initiated to enhance lysosomal degradation and lipid synthesis. In cultured proximal tubule epithelial cells, inhibition of cholesterol efflux transport or oxysterol treatment induced effects very similar to the in vivo situation, such as multilamellar body and phospholipid amassing, and induction of damage, inflammatory, fibrotic, and lipogenic molecules. The onset of phospholipidosis in proximal tubule epithelial cells is a novel pathological trait in metabolic syndrome-related chronic kidney disease, and emphasises the importance of healthy lysosomes and nutrition for kidney well-being. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Metabolic injury-induced NLRP3 inflammasome activation dampens phospholipid degradation.

The collateral effects of obesity/metabolic syndrome include inflammation and renal function decline. As renal disease in obesity can occur independently of hypertension and diabetes, other yet undefined causal pathological pathways must be present. Our study elucidate novel pathological pathways of metabolic renal injury through LDL-induced lipotoxicity and metainflammation. Our in vitro and in vivo analysis revealed a direct lipotoxic effect of metabolic overloading on tubular renal cells through a multifaceted mechanism that includes intralysosomal lipid amassing, lysosomal dysfunction, oxidative stress, and tubular dysfunction. The combination of these endogenous metabolic injuries culminated in the activation of the innate immune NLRP3 inflammasome complex. By inhibiting the sirtuin-1/LKB1/AMPK pathway, NLRP3 inflammasome dampened lipid breakdown, thereby worsening the LDL-induced intratubular phospholipid accumulation. Consequently, the presence of NLRP3 exacerbated tubular oxidative stress, mitochondrial damage and malabsorption during overnutrition. Altogether, our data demonstrate a causal link between LDL and tubular damage and the creation of a vicious cycle of excessive nutrients-NLRP3 activation-catabolism inhibition during metabolic kidney injury. Hence, this study strongly highlights the importance of renal epithelium in lipid handling and recognizes the role of NLRP3 as a central hub in metainflammation and immunometabolism in parenchymal non-immune cells.

NLRX1 dampens oxidative stress and apoptosis in tissue injury via control of mitochondrial activity.

Mitochondrial dysfunction is the most prominent source of oxidative stress in acute and chronic kidney disease. NLRX1 is a receptor of the innate immune system that is ubiquitously expressed and localized in mitochondria. We investigated whether NLRX1 may act at the interface of metabolism and innate immunity in a model of oxidative stress. Using a chimeric mouse model for renal ischemia-reperfusion injury, we found that NLRX1 protects against mortality, mitochondrial damage, and epithelial cell apoptosis in an oxidative stress-dependent fashion. We found that NLRX1 regulates oxidative phosphorylation and cell integrity, whereas loss of NLRX1 results in increased oxygen consumption, oxidative stress, and subsequently apoptosis in epithelial cells during ischemia-reperfusion injury. In line, we found that NLRX1 expression in human kidneys decreased during acute renal ischemic injury and acute cellular rejection. Although first implicated in immune regulation, we propose that NLRX1 function extends to the control of mitochondrial activity and prevention of oxidative stress and apoptosis in tissue injury.

Mucosal integrity and sensitivity to acid in the proximal esophagus in patients with gastroesophageal reflux disease.

Acid reflux episodes that extend to the proximal esophagus are more likely to be perceived. This suggests that the proximal esophagus is more sensitive to acid than the distal esophagus, which could be caused by impaired mucosal integrity in the proximal esophagus. Our aim was to explore sensitivity to acid and mucosal integrity in different segments of the esophagus. We used a prospective observational study, including 12 patients with gastroesophageal reflux disease (GERD). After stopping acid secretion-inhibiting medication, two procedures were performed: an acid perfusion test and an upper endoscopy with electrical tissue impedance spectroscopy and esophageal biopsies. Proximal and distal sensitivity to acid and tissue impedance were measured in vivo, and mucosal permeability and epithelial intercellular spaces at different esophageal levels were measured in vitro. Mean lag time to heartburn perception was much shorter after proximal acid perfusion (0.8 min) than after distal acid perfusion (3.9 min) (P = 0.02). Median in vivo tissue impedance was significantly lower in the distal esophagus (4,563 Ω·m) compared with the proximal esophagus (8,170 Ω·m) (P = 0.002). Transepithelial permeability, as measured by the median fluorescein flux was significantly higher in the distal (2,051 nmol·cm(-2)·h(-1)) than in the proximal segment (368 nmol·cm(-2)·h(-1)) (P = 0.033). Intercellular space ratio and maximum heartburn intensity were not significantly different between the proximal and distal esophagus. In GERD patients off acid secretion-inhibiting medication, acid exposure in the proximal segment of the esophagus provokes symptoms earlier than acid exposure in the distal esophagus, whereas mucosal integrity is impaired more in the distal esophagus. These findings indicate that the enhanced sensitivity to proximal reflux episodes is not explained by increased mucosal permeability.

Unique Renal Manifestation of Type I Cryoglobulinemia, With Massive Crystalloid Deposits in Glomerular Histiocytes, Podocytes, and Endothelial Cells.

OBJECTIVES: We describe a 62-year-old woman with a 15-year history of a plasma cell dyscrasia (monoclonal IgGκ), manifested by type I cryoglobulinemia and dermal vasculitis. METHODS: In addition to the clinical examinations, light microscopy with immunohistochemistry, sequential multicolor immunohistochemistry, and electron microscopy were used to characterize the crystalline deposits. RESULTS: At initial presentation and for a later flare, she was treated with cyclophosphamide and prednisolone with good clinical response. She had renal function decline, microscopic hematuria, and proteinuria. A renal biopsy specimen revealed the presence of glomerular macrophages and duplication of the capillary walls with cellular interposition. Glomerular cells contained abundant needle-shaped eosinophilic crystalline inclusions positive for κ light chain. Electron microscopy confirmed the presence of intracytoplasmatic crystalline structures in endothelial cells, podocytes, and macrophages but not in the tubular epithelium. Rituximab treatment was started. At follow-up (now up to 6 months), renal function remained stable. CONCLUSIONS: This patient displays a unique renal manifestation of type I cryoglobulinemia related to a plasma cell dyscrasia.

Histological Response to Fluticasone Propionate in Patients With Eosinophilic Esophagitis Is Associated With Improved Functional Esophageal Mucosal Integrity.

OBJECTIVES: The esophageal mucosal integrity is impaired in patients with eosinophilic esophagitis (EoE). We aimed to evaluate the effect of fluticasone propionate on inflammation and functional and structural markers of esophageal mucosal barrier integrity in adult patients with EoE. METHODS: In this prospective study, we included 15 EoE patients (median age (IQR), 43 (30-45) years). Patients underwent upper endoscopy before and after an 8-week course of swallowed fluticasone propionate 500 µg BID. Several parameters of esophageal mucosal barrier integrity were evaluated: esophageal electrical tissue impedance in vivo during endoscopy, transepithelial electrical resistance (TER) and transepithelial molecule flux in Ussing chambers using esophageal biopsy specimens, and intercellular spaces as a structural marker of permeability using electron microscopy. Esophageal eosinophils and mast cells were counted, and expression of inflammatory cytokines and barrier integrity proteins was investigated using qPCR. Esophageal symptoms and signs were also assessed. RESULTS: Peak eosinophil and mast cell counts decreased significantly after fluticasone propionate treatment. The esophageal mucosal integrity increased substantially during treatment, as shown by increased extracellular impedance and TER (both P<0.01) and decreased transepithelial molecule flux in Ussing chambers (P<0.05). Whereas expression of genes encoding for inflammatory cytokines (IL5, IL13, eotaxin-3, periostin, TSLP) decreased after treatment, expression of genes encoding for barrier integrity proteins (filaggrin and desmoglein-1) increased. CONCLUSIONS: Fluticasone propionate treatment decreases eosinophilic inflammation and improves the esophageal mucosal barrier integrity in adult EoE patients. Improvement of the mucosal barrier integrity correlates with normalization of expression of desmoglein-1 and filaggrin marker genes.

Chronic kidney disease and an uncertain diagnosis of Fabry disease: approach to a correct diagnosis.

BACKGROUND AND OBJECTIVES: Screening for Fabry disease (FD), an X-linked lysosomal storage disorder, reveals a significant number of individuals with a genetic variant of unknown significance without classical FD manifestations; these variants in the α-galactosidase A gene often result in a high residual leukocyte α-galactosidase A and it is unclear whether these individuals suffer from FD. Therefore, a structured diagnostic approach is warranted. We present a diagnostic algorithm on how to approach adults with chronic kidney disease and an uncertain diagnosis of FD nephropathy. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: A modified Delphi procedure was conducted to reach consensus among 11 FD experts. A systematic review was performed to identify possible criteria that could confirm or exclude FD nephropathy. RESULTS: The gold standard for FD nephropathy was defined as characteristic storage on electron microscopy (EM) in a kidney biopsy in the absence of medication that may induce similar storage. The suggested criteria to confirm FD nephropathy are as follows: 'renal cysts', 'Maltese cross sign', 'immunohistochemical staining of Gb3 in urine' and 'high urinary Gb3'; and to exclude FD nephropathy: 'absence of renal cysts', 'small kidneys' and 'high protein excretion' were rejected because of low or uncertain specificity. Urinary Gb3 may be increased in other kidney diseases and there was no agreement on this criterion, although a third of the panel indicated that it is sufficient to diagnose FD nephropathy. The 'Maltese cross sign' and 'high urinary Gb3' were selected as red flags to suggest the possibility of FD nephropathy, but are not sufficient for a definite diagnosis of FD nephropathy. CONCLUSIONS: In adults with chronic kidney disease, an α-galactosidase A gene variant and an uncertain diagnosis of FD, a kidney biopsy with EM analysis should be performed to confirm or reject the diagnosis of FD nephropathy. Other criteria currently cannot substitute for a biopsy in these cases.

Genetic analysis of intracapillary glomerular lipoprotein deposits in aging mice.

BACKGROUND: Renal aging is characterized by functional and structural changes like decreased glomerular filtration rate, and glomerular, tubular and interstitial damage. To gain insight in pathways involved in renal aging, we studied aged mouse strains and used genetic analysis to identify genes associated with aging phenotypes. METHODS: Upon morphological screening in kidneys from 20-month-old mice from 26 inbred strains we noted intracapillary PAS-positive deposits. The severity of these deposits was quantified by scoring of a total of 50 glomeruli per section (grade 0-4). Electron microscopy and immunohistochemical staining for apoE, apoB, apoA-IV and perilipin-2 was performed to further characterize the lesions. To identify loci associated with these PAS-positive intracapillary glomerular deposits, we performed haplotype association mapping. RESULTS: Six out of 26 mouse strains showed glomerular PAS-positive deposits. The severity of these deposits varied: NOD(0.97), NZW(0.41), NON(0.30), B10(0.21), C3 H(0.9) and C57BR(0.7). The intracapillary deposits were strongly positive for apoE and weakly positive for apoB and apoA-IV. Haplotype association mapping showed a strong association with a 30-Kb haplotype block on Chr 1 within the Esrrg gene. We investigated 1 Mb on each site of this region, which includes the genes Spata17, Gpatch2, Esrrg, Ush2a and Kctd3. CONCLUSIONS: By analyzing 26 aged mouse strains we found that some strains developed an intracapillary PAS and apoE-positive lesion and identified a small haplotype block on Chr 1 within the Esrrg gene to be associated with these lipoprotein deposits. The region spanning this haplotype block contains the genes Spata17, Gpatch2, Esrrg, Ush2a and Kctd3, which are all highly expressed in the kidney. Esrrg might be involved in the evolvement of these glomerular deposits by influencing lipid metabolism and possibly immune reponses.

Proton pump inhibitors partially restore mucosal integrity in patients with proton pump inhibitor-responsive esophageal eosinophilia but not eosinophilic esophagitis.

BACKGROUND & AIMS: Histologic analysis is used to distinguish patients with proton pump inhibitor-responsive eosinophilia (PPI-REE) from those with eosinophilic esophagitis (EoE). It is not clear whether these entities have different etiologies. Exposure to acid reflux can impair the integrity of the esophageal mucosal. We proposed that patients with EoE and PPI-REE might have reflux-induced esophageal mucosal damage that promotes transepithelial flux of allergens. We therefore assessed the integrity of the esophageal mucosal in these patients at baseline and after PPI. METHODS: We performed a prospective study of 16 patients with suspected EoE and 11 controls. Patients had dysphagia, endoscopic signs of EoE, and esophageal eosinophilia (>15 eosinophils/high-power field [eos/hpf]). All subjects underwent endoscopy at baseline; endoscopy was performed again on patients after 8 weeks of treatment with high-dose esomeprazole. After PPI treatment, patients were diagnosed with EoE (>10 eos/hpf; n = 8) or PPI-REE (≤10 eos/hpf; n = 8). We evaluated the structure (intercellular spaces) and function (electrical tissue impedance, transepithelial electrical resistance, transepithelial molecule flux) of the esophageal mucosal barrier. RESULTS: Compared with controls, electrical tissue impedance and transepithelial electrical resistance were reduced in patients with EoE (P < .001 and P < .001, respectively) and PPI-REE (P = .01 and P = .06, respectively), enabling transepithelial small-molecule flux. PPI therapy partially restored these changes in integrity and inflammation in patients with PPI-REE, but not in those with EoE. CONCLUSIONS: The integrity of the esophageal mucosa is impaired in patients with EoE and PPI-REE, allowing transepithelial transport of small molecules. PPI therapy partially restores mucosal integrity in patients with PPI-REE, but not in those with EoE. Acid reflux might contribute to transepithelial allergen flux in patients with PPI-REE. Trialregister.nl number: NTR3480.

Cyclosporine versus everolimus: effects on the glomerulus.

Inhibitors of the mammalian target of rapamycin (mTOR) have been associated with proteinuria. We studied the development of proteinuria in renal transplant recipients (RTR) treated with the mTOR inhibitor everolimus in comparison with a calcineurin inhibitor. We related the presence of proteinuria to histopathological glomerular findings in two-yr protocol biopsies. In a single-center study, nested in a multicenter randomized controlled trial, we determined eGFR, proteinuria, and renal biopsy data (light- and electron microscopy) of RTR receiving prednisolone/everolimus (P/EVL) (n = 16) in comparison with patients treated with prednisolone/cyclosporine A (P/CsA) (n = 7). All patients had been on the above-described maintenance immunosuppression for 18 months. Renal function at two yr after transplantation did not differ between patients receiving P/EVL or P/CsA (eGFR 45.5 vs. 45.7 mL/min/1.73 m(2)). Proteinuria was slightly increased in P/EVL vs. P/CsA group (0.29 vs. 0.14 g/24 h, p = 0.06). There were no differences in light- or electron microscopic findings. We could not demonstrate increased podocyte effacement or changes in glomerular basement membrane (GBM) thickness in P/EVL-treated patients. In conclusion, long-term treatment with everolimus leaves the GBM and podocytes unaffected.

Hedgehog signalling stimulates precursor cell accumulation and impairs epithelial maturation in the murine oesophagus.

OBJECTIVE: In the intestine Hedgehog (Hh) signalling is directed from epithelium to mesenchyme and negatively regulates epithelial precursor cell fate. The role of Hh signalling in the oesophagus has not been studied in vivo. Here the authors examined the role of Hh signalling in epithelial homeostasis of oesophagus. DESIGN: The authors used transgenic mice in which the Hh receptor Patched1 (Ptch1) could be conditionally inactivated in a body-wide manner and mice in which Gli1 could be induced specifically in the epithelium of the skin and oesophagus. Effects on epithelial homeostasis of the oesophagus were examined using immunohistochemistry, in situ hybridisation, transmission electron microscopy and real-time PCR. Hh signalling was examined in patients with oesophageal squamous cell carcinoma (SCC) by quantitative real-time PCR. RESULTS: Sonic Hh is signalled in an autocrine manner in the basal layer of the oesophagus. Activation of Hh signalling resulted in an expansion of the epithelial precursor cell compartment and failure of epithelial maturation and migration. Levels of Hh targets GLI1, HHIP and PTCH1 were increased in SCC compared with normal tissue from the same patients. CONCLUSION: Here the authors find that Hh signalling positively regulates the precursor cell compartment in the oesophageal epithelium in an autocrine manner. Since Hh signalling targets precursor cells in the oesophageal epithelium and signalling is increased in SCCs, Hh signalling may be involved in oesophageal SCC formation.

Blimp1 regulates the transition of neonatal to adult intestinal epithelium.

In many mammalian species, the intestinal epithelium undergoes major changes that allow a dietary transition from mother's milk to the adult diet at the end of the suckling period. These complex developmental changes are the result of a genetic programme intrinsic to the gut tube, but its regulators have not been identified. Here we show that transcriptional repressor B lymphocyte-induced maturation protein 1 (Blimp1) is highly expressed in the developing and postnatal intestinal epithelium until the suckling to weaning transition. Intestine-specific deletion of Blimp1 results in growth retardation and excessive neonatal mortality. Mutant mice lack all of the typical epithelial features of the suckling period and are born with features of an adult-like intestine. We conclude that the suckling to weaning transition is regulated by a single transcriptional repressor that delays epithelial maturation.

Loss of Indian Hedgehog activates multiple aspects of a wound healing response in the mouse intestine.

BACKGROUND & AIMS: Indian Hedgehog (Ihh) is expressed by the differentiated epithelial cells of the small intestine and signals to the mesenchyme where it induces unidentified factors that negatively regulate intestinal epithelial precursor cell fate. Recently, genetic variants in the Hh pathway have been linked to the development of inflammatory bowel disease. METHODS: We deleted Ihh from the small intestinal epithelium in adult mice using Cyp1a1-CreIhh(fl/fl) conditional Ihh mutant mice. Intestines were examined by immunohistochemistry, in situ hybridization, and real-time polymerase chain reaction. RESULTS: Deletion of Ihh from the intestinal epithelium initially resulted in a proliferative response of the intestinal epithelium with lengthening and fissioning of crypts and increased Wnt signaling. The epithelial proliferative response was associated with loss of bone morphogenetic protein and Activin signaling from the epithelium of the villus and crypts, respectively. At the same stage we observed a substantial influx of fibroblasts and macrophages into the villus core with increased mesenchymal transforming growth factor-ß signaling and deposition of extracellular matrix proteins. Prolonged loss of Ihh resulted in progressive leukocyte infiltration of the crypt area, blunting and loss of villi, and the development of intestinal fibrosis. CONCLUSIONS: Loss of Ihh initiates several events that are characteristic of an intestinal wound repair response. Prolonged loss resulted in progressive inflammation, mucosal damage, and the development of intestinal fibrosis. Ihh is a signal derived from the superficial epithelial cells that may act as a critical indicator of epithelial integrity.

Ultrastructural analysis of dermal fibroblasts in mucopolysaccharidosis type I: Effects of enzyme replacement therapy and hematopoietic cell transplantation.

In mucopolysaccharidosis type I (MPS I; alpha-L-iduronidase deficiency), glycosaminoglycans (GAGs) accumulate in different cell types, causing characteristic vacuolization. Hematopoietic cell transplantation (HCT) and enzyme replacement therapy (ERT) both aim to restore tissue morphology by delivering alpha-L-iduronidase to the deficient cells. The authors investigated the efficacy of both therapies on dermal fibroblast morphology in 12 patients by electron microscopy of repeated skin biopsies before and during 2 years of ERT as well as before and 6 months after HCT. Cell vacuolization was rated according to a semi-quantitative scoring system. At baseline all patients showed an increased vacuolization score as compared to controls. In addition the vacuolization score was significantly higher in patients with the severe phenotype of the disease (n = 7) compared to patients with attenuated phenotypes (n = 5) (p = .009). After initiation of ERT a significant decrease in cell vacuolization was observed (p = .012). However, the response rate varied among patients, as the vacuolization score remained high during the first year of ERT in 3 patients with the severe phenotype. In all patients who received a successful HCT (n = 3) only minimal disturbances in cell morphology were observed afterward. In conclusion, both ERT and HCT are capable of restoring, at least partially, dermal fibroblast morphology in MPS I.

Depletion of the colonic epithelial precursor cell compartment upon conditional activation of the hedgehog pathway.

BACKGROUND & AIMS: The intestinal epithelium is a homeostatic system in which differentiated cells are in dynamic equilibrium with rapidly cycling precursor cells. Wnt signaling regulates intestinal epithelial precursor cell fate and proliferation. Homeostatic systems exist by virtue of negative feedback loops, and we have previously identified the Hedgehog (Hh) pathway as a potential negative feedback signal in the colonic epithelium. Indian hedgehog (Ihh) is produced by the differentiated enterocytes and negatively regulates Wnt signaling in intestinal precursor cells. We studied the role of members of the Hh signaling family in the intestine using a conditional genetic approach. METHODS: We inactivated the Hh receptor Patched1 (Ptch1) in adult mice, resulting in constitutive activation of the Hh signaling pathway. Effects on colonic mucosal homeostasis were examined. Colon tissues were examined by immunohistochemistry, in situ hybridization, transmission electron microscopy, and real-time polymerase chain reaction. RESULTS: Ihh but not Sonic hedgehog (Shh) was expressed in colonic epithelium. Expression of Ptch1 and Gli1 was restricted to the mesenchyme. Constitutive activation of Hh signaling resulted in accumulation of myofibroblasts and colonic crypt hypoplasia. A reduction in the number of epithelial precursor cells was observed with premature development into the enterocyte lineage and inhibition of Wnt signaling. Activation of Hh signaling resulted in induction of the expression of bone morphogenetic proteins (Bmp) and increased Bmp signaling in the epithelium. CONCLUSIONS: Hh signaling acts in a negative feedback loop from differentiated cells via the mesenchyme to the colonic epithelial precursor cell compartment in the adult mouse.

Improved preservation and microcirculation with POLYSOL after transplantation in a porcine kidney autotransplantation model.

BACKGROUND: The most widely used preservation method for kidney grafts is cold static storage (CS) using the University of Wisconsin (UW) solution. To date, new preservation solutions have not been able to significantly improve preservation quality of grafts. The aim of this study was to compare POLYSOL, a recently developed low viscosity preservation solution, and the UW solution for CS of porcine kidney grafts. METHODS: In a porcine autotransplantation model, real-time parameters of the renal microcirculation were evaluated using the novel oxygen-to-see (O2C) combined laser Doppler and flowmetry system. Thereafter, kidneys were retrieved and washed out with POLYSOL or UW followed by 20-h CS. After the preservation period, the contralateral kidneys were removed and the preserved kidneys autotransplanted. The microcirculation was re-assessed at 10 min after reperfusion and at 7 days posttransplant, prior to removal of the grafts for histological evaluation. RESULTS: POLYSOL was able to better preserve the microcirculation compared to UW as expressed by higher values of capillary blood flow, blood flow velocity and tissue oxygen saturation values. In addition, CS using POLYSOL resulted in improved functional recovery demonstrated by lower posttransplant serum creatinine and blood urea values in comparison to the UW group. Also, structural integrity was better preserved in the POLYSOL group, compared to UW. CONCLUSIONS: This study in a clinically relevant large animal model showed that a new preservation solution, POLYSOL, resulted in improved preservation quality of kidney grafts compared to the UW solution.

Analysis of apoptosis in peripheral blood and synovial tissue very early after initiation of infliximab treatment in rheumatoid arthritis patients.

OBJECTIVE: Infliximab treatment results in a decrease in synovial cellularity as early as 48 hours after initiation of therapy in patients with rheumatoid arthritis (RA). This study was undertaken to investigate whether infliximab induces apoptosis within the first 24 hours after infusion. METHODS: The percentage of apoptotic cells was determined by flow cytometry in blood drawn from 21 patients directly before, 1 hour after, and 24 hours after infliximab infusion. Synovial tissue samples obtained before, 1 hour after (n = 5), or 24 hours after (n = 5) initiation of therapy were subjected to immunohistochemistry to detect active caspase 3 and to TUNEL assay and electron microscopy to detect apoptosis. In addition, plasma levels of nucleosomes (generated during apoptosis) and C4b/c (an indicator of complement activation) were measured. RESULTS: There were no signs of apoptosis induction in peripheral blood monocytes or lymphocytes after infliximab treatment. Circulating lymphocyte counts were increased within 1 hour after infusion (P < 0.05). There was no definite evidence of apoptosis induction in the synovium, except in 1 patient 24 hours after the infliximab infusion. Consistent with these results, there was no increase in nucleosome levels nor were there signs of complement activation. CONCLUSION: Our findings indicate that the rapid decrease in synovial cellularity observed after initiation of anti-tumor necrosis factor antibody therapy cannot be explained by apoptosis induction at the site of inflammation. It is tempting to speculate that the striking effects on synovial inflammation may be explained by other mechanisms, such as decreased migration toward the synovial compartment and reduced retention in the inflamed synovium.

Tubuloreticular structures in different types of myositis: implications for pathogenesis.

In dermatomyositis (DM) there is strong histopathological evidence of a microvascular pathogenesis, including endothelial microtubular inclusions. In nonspecific myositis, perimysial and perivascular infiltrates in the muscle biopsy similar to DM are found. Microtubular inclusions in endothelial cells were systematically searched for and found in 4 of the 20 muscle biopsies of nonspecific myositis patients (20%). Three had a CTD (SLE, scleroderma, and Sjogren syndrome). Ten patients with DM and 5 patients with sporadic inclusion body myositis served as positive and negative controls, respectively.