Targeted deletion of von-Hippel-Lindau in the proximal tubule conditions the kidney against early diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease. Glomerular hyperfiltration and albuminuria subject the proximal tubule (PT) to a subsequent elevation of workload, growth, and hypoxia. Hypoxia plays an ambiguous role in the development and progression of DKD and shall be clarified in our study. PT-von-Hippel-Lindau (Vhl)-deleted mouse model in combination with streptozotocin (STZ)-induced type I diabetes mellitus (DM) was phenotyped. In contrary to PT-Vhl-deleted STZ-induced type 1 DM mice, proteinuria and glomerular hyperfiltration occurred in diabetic control mice the latter due to higher nitric oxide synthase 1 and sodium and glucose transporter expression. PT Vhl deletion and DKD share common alterations in gene expression profiles, including glomerular and tubular morphology, and tubular transport and metabolism. Compared to diabetic control mice, the most significantly altered in PT Vhl-deleted STZ-induced type 1 DM mice were Ldc-1, regulating cellular oxygen consumption rate, and Zbtb16, inhibiting autophagy. Alignment of altered genes in heat maps uncovered that Vhl deletion prior to STZ-induced DM preconditioned the kidney against DKD. HIF-1α stabilization leading to histone modification and chromatin remodeling resets most genes altered upon DKD towards the control level. These data demonstrate that PT HIF-1α stabilization is a hallmark of early DKD and that targeting hypoxia prior to the onset of type 1 DM normalizes renal cell homeostasis and prevents DKD development.

Localization Pattern of Dispatched Homolog 2 (DISP2) in the Central and Enteric Nervous System

Dispatched homolog (DISP) proteins have been implicated in the regulation of hedgehog signaling during embryologic development. Although DISP2 has recently been associated with neuronal development and control of cognitive functions, its localization pattern in the mammalian central and peripheral nervous system has not yet been investigated. In this study, the Disp2 expression profile was assessed in human tissues from publicly available transcriptomic datasets. The DISP2 localization pattern was further characterized in the human and rat central nervous system (CNS), as well as within the colonic enteric nervous system (ENS) using dual-label immunohistochemistry. Colocalization of DISP2 with neuronal and glial markers was additionally analyzed in murine primary ENS culture. At transcriptomic level, DISP2 expression was predominant in neuronal cell types of the CNS and ENS. DISP2 immunoreactivity was mainly located within PGP9.5-positive neurons rather than in S100-positive glial cells throughout the nervous system. Investigation of human and rat brain tissues, colonic specimens, and murine ENS primary cultures revealed that DISP2 was located in neuronal cell somata, as well as along neuronal processes both in the human and murine CNS and ENS. Our results indicate that DISP2 is prominently localized within neuronal cells of the CNS and ENS and support putative functions of DISP2 in these tissues.

Behind every smile there's teeth: Cathepsin B's function in health and disease with a kidney view

Cathepsin B (CatB) is a very abundant lysosomal protease with endo- and carboxydipeptidase activities and even ligase features. In this review, we will provide a general characterization of CatB and describe structure, structure-derived properties and location-dependent proteolytic actions. We depict CatB action within lysosome and its important roles in lysosomal biogenesis, lysosomal homeostasis and autophagy rendering this protease a key player in orchestrating lysosomal functions. Lysosomal leakage and subsequent escape of CatB into the cytosol lead to harmful actions, e.g. the role in activating the NLPR3 inflammasome, affecting immune responses and cell death. The second focus of this review addresses CatB functions in the kidney, i.e. the glomerulus, the proximal tubule and collecting duct with strong emphasis of its role in pathology of the respective segment. Finally, observations regarding CatB functions that need to be considered in cell culture will be discussed. In conclusion, CatB a physiologically important molecule may, upon aberrant expression in different cellular context, become a harmful player effectively showing its teeth behind its smile.

Expression Profiling of Rectal Biopsies Suggests Altered Enteric Neuropathological Traits in Parkinson's Disease Patients

Still little is known about the nature of the gastrointestinal pathological alterations occurring in Parkinson's disease (PD). Here, we used multiplexed mRNA profiling to measure the expression of a panel of 770 genes related to neuropathological processes in deep submucosal rectal biopsies of PD patients and healthy controls. Altered enteric neuropathological traits based on the expression of 22 genes related to neuroglial and mitochondrial functions, vesicle trafficking and inflammation was observed in 9 out of 12 PD patients in comparison to healthy controls. These results provide new evidences that intestinal neuropathological alterations may occur in a large proportion of PD patients.

Alpha Synuclein Connects the Gut-Brain Axis in Parkinson's Disease Patients - A View on Clinical Aspects, Cellular Pathology and Analytical Methodology

Parkinson’s disease (PD) is marked by different kinds of pathological features, one hallmark is the aggregation of α-synuclein (aSyn). The development of aSyn pathology in the substantia nigra is associated to the manifestation of motor deficits at the time of diagnosis. However, most of the patients suffer additionally from non-motor symptoms, which may occur already in the prodromal phase of the disease years before PD is diagnosed. Many of these symptoms manifest in the gastrointestinal system (GIT) and some data suggest a potential link to the occurrence of pathological aSyn forms within the GIT. These clinical and pathological findings lead to the idea of a gut-brain route of aSyn pathology in PD. The identification of pathological aSyn in the intestinal system, e.g., by GIT biopsies, is therefore of highest interest for early diagnosis and early intervention in the phase of formation and propagation of aSyn. However, reliable methods to discriminate between physiological and pathological forms of enteral aSyn on the cellular and biochemical level are still missing. Moreover, a better understanding of the physiological function of aSyn within the GIT as well as its structure and pathological aggregation pathways are crucial to understand its role within the enteric nervous system and its spreading from the gut to the brain. In this review, we summarize clinical manifestations of PD in the GIT, and discuss biochemical findings from enteral biopsies. The relevance of pathological aSyn forms, their connection to the gut-brain axis and new developments to identify pathologic forms of aSyn by structural features are critically reviewed.

Impaired Expression of Neuregulin 1 and Nicotinic Acetylcholine Receptor β4 Subunit in Diverticular Disease

Neuregulin 1 (NRG1) regulates the expression of the nicotinic acetylcholine receptor (nAChR) and is suggested to promote the survival and maintenance of the enteric nervous system (ENS), since deficiency of its corresponding receptor complex ErbB2/ErbB3 leads to postnatal colonic aganglionosis. As diverticular disease (DD) is associated with intestinal hypoganglionosis, the NRG1-ErbB2/ErbB3 system and the nAChR were studied in patients with DD and controls. Samples of tunica muscularis of the sigmoid colon from patients with DD (n = 8) and controls (n = 11) were assessed for mRNA expression of NRG1, ErbB2, and ErbB3 and the nAChR subunits α3, α5, α7, β2, and β4. Site-specific gene expression levels of the NRG1-ErbB2/3 system were determined in myenteric ganglia harvested by laser microdissection (LMD). Localization studies were performed by immunohistochemistry for the NRG1-ErbB2/3 system and nAChR subunit β4. Rat enteric nerve cell cultures were stimulated with NRG1 or glial-cell line derived neurotrophic factor (GDNF) for 6 days and mRNA expression of the aforementioned nAchR was measured. NRG1, ErbB3, and nAChR subunit β4 expression was significantly down-regulated in both the tunica muscularis and myenteric ganglia of patients with DD compared to controls, whereas mRNA expression of ErbB3 and nAChR subunits β2, α3, α5, and α7 remained unaltered. NRG1, ErbB3, and nAChR subunit β4 immunoreactive signals were reduced in neuronal somata and the neuropil of myenteric ganglia from patients with DD compared to control. nAChR subunit β4 exhibited also weaker immunoreactive signals in the tunica muscularis of patients with DD. NRG1 treatment but not GDNF treatment of enteric nerve cell cultures significantly enhanced mRNA expression of nAchR β4. The down-regulation of NRG1 and ErbB3 in myenteric ganglia of patients with DD supports the hypothesis that intestinal hypoganglionosis observed in DD may be attributed to a lack of neurotrophic factors. Regulation of nAChR subunit β4 by NRG1 and decreased nAChR β4 in patients with DD provide evidence that a lack of NRG1 may affect the composition of enteric neurotransmitter receptor subunits thus contributing to the intestinal motility disorders previously reported in DD.

Many Patients With Irritable Bowel Syndrome Have Atypical Food Allergies Not Associated With Immunoglobulin E

BACKGROUND & AIMS

Confocal laser endomicroscopy (CLE) is a technique that permits real-time detection and quantification of changes in intestinal tissues and cells, including increases in intraepithelial lymphocytes and fluid extravasation through epithelial leaks. Using CLE analysis of patients with irritable bowel syndrome (IBS), we found that more than half have responses to specific food components. Exclusion of the defined food led to long-term symptom relief. We used the results of CLE to detect reactions to food in a larger patient population and analyzed duodenal biopsy samples and fluid from patients to investigate mechanisms of these reactions.

METHODS

In a prospective study, 155 patients with IBS received 4 challenges with each of 4 common food components via the endoscope, followed by CLE, at a tertiary medical center. Classical food allergies were excluded by negative results from immunoglobulin E serology analysis and skin tests for common food antigens. Duodenal biopsy samples and fluid were collected 2 weeks before and immediately after CLE and were analyzed by histology, immunohistochemistry, reverse transcription polymerase chain reaction, and immunoblots. Results from patients who had a response to food during CLE (CLE+) were compared with results from patients who did not have a reaction during CLE (CLE-) or healthy individuals (controls).

RESULTS

Of the 108 patients who completed the study, 76 were CLE+ (70%), and 46 of these (61%) reacted to wheat. CLE+ patients had a 4-fold increase in prevalence of atopic disorders compared with controls (P = .001). Numbers of intraepithelial lymphocytes were significantly higher in duodenal biopsy samples from CLE+ vs CLE- patients or controls (P = .001). Expression of claudin-2 increased from crypt to villus tip (P < .001) and was up-regulated in CLE+ patients compared with CLE- patients or controls (P = .023). Levels of occludin were lower in duodenal biopsy samples from CLE+ patients vs controls (P = .022) and were lowest in villus tips (P < .001). Levels of messenger RNAs encoding inflammatory cytokines were unchanged in duodenal tissues after CLE challenge, but eosinophil degranulation increased, and levels of eosinophilic cationic protein were higher in duodenal fluid from CLE+ patients than controls (P = .03).

CONCLUSIONS

In a CLE analysis of patients with IBS, we found that more than 50% of patients could have nonclassical food allergy, with immediate disruption of the intestinal barrier upon exposure to food antigens. Duodenal tissues from patients with responses to food components during CLE had immediate increases in expression of claudin-2 and decreases in occludin. CLE+ patients also had increased eosinophil degranulation, indicating an atypical food allergy characterized by eosinophil activation.

Genome-wide association analysis of diverticular disease points towards neuromuscular, connective tissue and epithelial pathomechanisms

OBJECTIVE

Diverticular disease is a common complex disorder characterised by mucosal outpouchings of the colonic wall that manifests through complications such as diverticulitis, perforation and bleeding. We report the to date largest genome-wide association study (GWAS) to identify genetic risk factors for diverticular disease.

DESIGN

Discovery GWAS analysis was performed on UK Biobank imputed genotypes using 31 964 cases and 419 135 controls of European descent. Associations were replicated in a European sample of 3893 cases and 2829 diverticula-free controls and evaluated for risk contribution to diverticulitis and uncomplicated diverticulosis. Transcripts at top 20 replicating loci were analysed by real-time quatitative PCR in preparations of the mucosal, submucosal and muscular layer of colon. The localisation of expressed protein at selected loci was investigated by immunohistochemistry.

RESULTS

We discovered 48 risk loci, of which 12 are novel, with genome-wide significance and consistent OR in the replication sample. Nominal replication (p<0.05) was observed for 27 loci, and additional 8 in meta-analysis with a population-based cohort. The most significant novel risk variant rs9960286 is located near CTAGE1 with a p value of 2.3×10^-10 and 0.002 (OR_allelic=1.14 (95% CI 1.05 to 1.24)) in the replication analysis. Four loci showed stronger effects for diverticulitis, PHGR1 (OR 1.32, 95% CI 1.12 to 1.56), FAM155A-2 (OR 1.21, 95% CI 1.04 to 1.42), CALCB (OR 1.17, 95% CI 1.03 to 1.33) and S100A10 (OR 1.17, 95% CI 1.03 to 1.33).

CONCLUSION

In silico analyses point to diverticulosis primarily as a disorder of intestinal neuromuscular function and of impaired connective fibre support, while an additional diverticulitis risk might be conferred by epithelial dysfunction.

Altered enteric expression of the homeobox transcription factor Phox2b in patients with diverticular disease

Background

Diverticular disease, a major gastrointestinal disorder, is associated with modifications of the enteric nervous system, encompassing alterations of neurochemical coding and of the tyrosine receptor kinase Ret/GDNF pathway. However, molecular factors underlying these changes remain to be determined.

Objectives

We aimed to characterise the expression of Phox2b, an essential regulator of Ret and of neuronal subtype development, in the adult human enteric nervous system, and to evaluate its potential involvement in acute diverticulitis.

Methods

Site-specific gene expression of Phox2b in the adult colon was analysed by quantitative polymerase chain reaction. Colonic specimens of adult controls and patients with diverticulitis were subjected to quantitative polymerase chain reaction for Phox2b and dual-label immunochemistry for Phox2b and the neuronal markers RET and tyrosine hydroxylase or the glial marker S100β.

Results

The results indicate that Phox2b is physiologically expressed in myenteric neuronal and glial subpopulations in the adult enteric nervous system. Messenger RNA expression of Phox2b was increased in patients with diverticulitis and both neuronal, and glial protein expression of Phox2b were altered in these patients.

Conclusions

Alterations of Phox2b expression may contribute to the enteric neuropathy observed in diverticular disease. Future studies are required to characterise the functions of Phox2b in the adult enteric nervous system and to determine its potential as a therapeutic target in gastrointestinal disorders.

Internal anal sphincter nerves - a macroanatomical and microscopic description of the extrinsic autonomic nerve supply of the internal anal sphincter

AIM

The internal anal sphincter (IAS) contributes substantially to anorectal functions. While its autonomic nerve supply has been studied at the microscopic level, little information is available concerning the macroscopic topography of extrinsic nerve fibres. This study was designed to identify neural connections between the pelvic plexus and the IAS, provide a detailed topographical description, and give histological proof of autonomic nerve tissue.

METHODS

Macroscopic dissection of pelvic autonomic nerves was performed under magnification in seven (five male, two female) hemipelvises obtained from body donors (67-92 years). Candidate structures were investigated by histological and immunohistochemical staining protocols to visualize nerve tissue.

RESULTS

Nerve fibres could be traced from the anteroinferior edge of the pelvic plexus to the anorectal junction running along the neurovascular bundle anterolaterally to the rectum and posterolaterally to the prostate/vagina. Nerve fibres penetrated the longitudinal rectal muscle layer just above the fusion with the levator ani muscle (conjoint longitudinal muscle) and entered the intersphincteric space to reach the IAS. Histological and immunohistochemical findings confirmed the presence of nerve tissue.

CONCLUSIONS

Autonomic nerve fibres supplying the IAS emerge from the pelvic plexus and are distinct to nerves entering the rectum via the lateral pedicles. Thus, they should be classified as IAS nerves. The identification and precise topographical location described provides a basis for nerve-sparing rectal resection procedures and helps to prevent postoperative functional anorectal disorders.

No neuronal loss, but alterations of the GDNF system in asymptomatic diverticulosis

Background

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor known to promote the survival and maintenance of neurons not only in the developing but also in the adult enteric nervous system. As diverticular disease (DD) is associated with reduced myenteric neurons, alterations of the GDNF system were studied in asymptomatic diverticulosis (diverticulosis) and DD.

Methods

Morphometric analysis for quantifying myenteric ganglia and neurons were assessed in colonic full-thickness sections of patients with diverticulosis and controls. Samples of tunica muscularis (TM) and laser-microdissected myenteric ganglia from patients with diverticulosis, DD and controls were analyzed for mRNA expression levels of GDNF, GFRA1, and RET by RT-qPCR. Myenteric protein expression of both receptors was quantified by fluorescence-immunohistochemistry of patients with diverticulosis, DD, and controls.

Results

Although no myenteric morphometric alterations were found in patients with diverticulosis, GDNF, GFRA1 and RET mRNA expression was down-regulated in the TM of patients with diverticulosis as well as DD. Furthermore GFRA1 and RET myenteric plexus mRNA expression of patients with diverticulosis and DD was down-regulated, whereas GDNF remained unaltered. Myenteric immunoreactivity of the receptors GFRα1 and RET was decreased in both asymptomatic diverticulosis and DD patients.

Conclusion

Our data provide evidence for an impaired GDNF system at gene and protein level not only in DD but also during early stages of diverticula formation. Thus, the results strengthen the idea of a disturbed GDNF-responsiveness as contributive factor for a primary enteric neuropathy involved in the pathogenesis and disturbed intestinal motility observed in DD.

Distinct pattern of enteric phospho-alpha-synuclein aggregates and gene expression profiles in patients with Parkinson's disease

Phosphorylated alpha-synuclein (p-α-syn) containing Lewy bodies (LBs) and Lewy neurites (LNs) are neuropathological hallmarks of Parkinson’s disease (PD) in the central nervous system (CNS). Since they have been also demonstrated in the enteric nervous system (ENS) of PD patients, the aim of the study was to analyze enteric p-α-syn positive aggregates and intestinal gene expression. Submucosal rectal biopsies were obtained from patients with PD and controls and processed for dual-label-immunohistochemistry for p-α-syn and PGP 9.5. p-α-syn positive aggregates in nerve fibers and neuronal somata were subjected to a morphometric analysis. mRNA expression of α-syn and dopaminergic, serotonergic, VIP (vaso intestinal peptide) ergic, cholinergic, muscarinergic neurotransmitter systems were investigated using qPCR. Frequency of p-α-syn positive nerve fibers was comparable between PD and controls. Although neuronal p-α-syn positive aggregates were detectable in both groups, total number and area of p-α-syn positive aggregates were increased in PD patients as was the number of small and large sized aggregates. Increased expression of dopamine receptor D1, VIP and serotonin receptor 3A was observed in PD patients, while serotonin receptor 4 and muscarinic receptor 3 (M3R) were downregulated. M3R expression correlated negative with the number of small sized p-α-syn positive aggregates. The findings strengthen the hypothesis that the CNS pathology of increased p-α-syn in PD also applies to the ENS, if elaborated morphometry is applied and give further insights in altered intestinal gene expression in PD. Although the mere presence of p-α-syn positive aggregates in the ENS should not be regarded as a criterion for PD diagnosis, elaborated morphometric analysis of p-α-syn positive aggregates in gastrointestinal biopsies could serve as a suitable tool for in-vivo diagnosis of PD.

Establishment and Characterization of an SV40 Large T Antigen-Transduced Porcine Colonic Epithelial Cell Line

Continuous cell lines have become indispensable tools that have enabled investigations into cellular mechanisms by increasing experimental reproducibility and sample availability, and decreasing the use of experimental animals. To facilitate studies of epithelial barrier function of the porcine colon, we aimed to establish an epithelial cell line with an extended replicative capacity. Cells were isolated from the proximal colon of a 3-week-old piglet and transduced using a recombinant retroviral vector construct containing the simian virus 40 large T antigen (SV40 TAg). We established a clonal epithelial cell line, referred to as PoCo83-3, that stably expressed the SV40 TAg, verified at mRNA and protein levels. PoCo83-3 showed epithelial cell-specific features, such as cobblestone-like morphology, dome structure formation, the presence of apical microvilli, and the expression of keratin 18, E-cadherin and the tight junction-associated proteins zonula occludens-1, occludin, and claudin-1. To validate PoCo83-3 as an in vitro model in epithelial barrier research, proinflammatory cytokine-inducible alterations in barrier integrity were demonstrated by incubating the cells with TNF-α and IFN-γ for 48 h. These cytokine treatments promoted a decreased transepithelial electrical resistance. In summary, PoCo83-3 exhibited an extended life span and a differentiated phenotype while maintaining epithelial characteristics. Based on these results, we present this cell line as a valuable in vitro model for investigations of epithelial barrier function in the porcine colon.

Abstract 393: The Intercalated Disc Protein Myozap: A Novel Player in Cardiac Proteinopathy

Background: A growing number of cardiac muscle diseases are characterized by depositions of misfolded proteins, including cardiac amyloidosis and desmin-releated cardiomyopathy (DRM). The continued presence and chronic accumulation of misfolded or unfolded proteins can lead to aggregation and/or the formation of soluble peptides that are proteotoxic. This in turn leads to compromised protein quality control and precipitates a downward spiral of the cell’s ability to maintain homeostasis and may eventually result in cell death. We recently identified massive protein aggregates in the hearts of transgenic mice overexpressing the intercalated disc (ID) protein myozap (Myozap-tg). We now sought to investigate the precise composition of these aggregates and the role of Myozap in other proteinopathies such as DRM.

Methods and Results: We employed multi-dimensional proteomics, transcriptomics, confocal microscopy, and molecular biology approaches to decipher the underlying causes and consequences of protein aggregate formation in Myozap-tg mice. Transcriptome profiling of these mice revealed striking upregulation of autophagy, protein synthesis, and pro-inflammatory pathways, whereas protein degradation pathways were down-regulated. Surprisingly, proteomics analyses revealed Desmin and α-crystallin B (CryAB) as the major constituents of the aggregates, which was further validated by confocal microscopy. Moreover, we identified the presence of toxic preamyloid oligomers in Myozap-tg mouse hearts, a hallmark in many protein aggregation-based diseases including DRM. Most interestingly, we also observed co-localization of Myozap with protein aggregates observed in both transgenic mouse hearts overexpressing mutant Desmin (D7) and mutant CryAB (R120G), as well as in human DRM patients.

Conclusion: The present study implies a new role for Myozap, which was previously reported to affect cardiac SRF signaling: (1) Myozap accumulates in various forms of experimental and human protein aggregation cardiomyopathy, suggesting involvement in protein homoestasis. (2) The fact that Myozap is now the third ID protein (after desmin and CryAB) to cause cardiac proteinopathy points to a general role of the ID in its molecular pathogenesis.

A Tunable Scaffold of Microtubular Graphite for 3D Cell Growth

Aerographite (AG) is a novel carbon-based material that exists as a self-supportive 3D network of interconnected hollow microtubules. It can be synthesized in a variety of architectures tailored by the growth conditions. This flexibility in creating structures presents interesting bioengineering possibilities such as the generation of an artificial extracellular matrix. Here we have explored the feasibility and potential of AG as a scaffold for 3D cell growth employing cyclic RGD (cRGD) peptides coupled to poly(ethylene glycol) (PEG) conjugated phospholipids for surface functionalization to promote specific adhesion of fibroblast cells. Successful growth and invasion of the bulk material was followed over a period of 4 days.

Cardiomyocyte behavior on biodegradable polyurethane/gold nanocomposite scaffolds under electrical stimulation

Following a myocardial infarction (MI), cardiomyocytes are replaced by scar tissue, which decreases ventricular contractile function. Tissue engineering is a promising approach to regenerate such damaged cardiomyocyte tissue. Engineered cardiac patches can be fabricated by seeding a high density of cardiac cells onto a synthetic or natural porous polymer. In this study, nanocomposite scaffolds made of gold nanotubes/nanowires incorporated into biodegradable castor oil-based polyurethane were employed to make micro-porous scaffolds. H9C2 cardiomyocyte cells were cultured on the scaffolds for one day, and electrical stimulation was applied to improve cell communication and interaction in neighboring pores. Cells on scaffolds were examined by fluorescence microscopy and scanning electron microscopy, revealing that the combination of scaffold design and electrical stimulation significantly increased cell confluency of H9C2 cells on the scaffolds. Furthermore, we showed that the gene expression levels of Nkx2.5, atrial natriuretic peptide (ANF) and natriuretic peptide precursor B (NPPB), which are functional genes of the myocardium, were up-regulated by the incorporation of gold nanotubes/nanowires into the polyurethane scaffolds, in particular after electrical stimulation.

Expression and function of Neuregulin 1 and its signaling system ERBB2/3 in the enteric nervous system

Neuregulin 1 (NRG1) is suggested to promote the survival and maintenance of the enteric nervous system (ENS). As deficiency in its corresponding receptor signaling complex ERBB2/ERBB3 leads to postnatal colonic hypo/aganglionosis we assessed the distributional and expressional pattern of the NRG1-ERBB2/ERBB3 system in the human colon and explored the neurotrophic capacity of NRG1 on cultured enteric neurons. Site-specific mRNA expression of the NRG1-ERBB2/3 system was determined in microdissected samples harvested from enteric musculature and ganglia. Localization of NRG1, ERBB2 and ERBB3 was determined by dual-label-immunohistochemistry using pan-neuronal and pan-glial markers. Morphometric analysis was performed on NRG1-stimulated rat enteric nerve cultures to evaluate neurotrophic effects. mRNA expression of the NRG1-ERBB2/3 system was determined by qPCR. Co-localization of NRG1 with neuronal or synaptic markers was analyzed in enteric nerve cultures stimulated with glial cell line-derived neurotrophic factor (GDNF). The NRG1 system was expressed in both neurons and glial cells of enteric ganglia and in nerve fibers. NRG1 significantly enhanced growth parameters in enteric nerve cell cultures and ErB3 mRNA expression was down-regulated upon NRG1 stimulation. GDNF negatively regulates ErbB2 and ErbB3 mRNA expression. The NRG1-ERBB2/3 system is physiologically present in the human ENS and NRG1 acts as a neurotrophic factor for the ENS. The down-regulation of ErbB3/ErbB2 in GDNF stimulated nerve cell cultures points to an interaction of both neurotrophic factors. Thus, the data may provide a basis to assess disturbed signaling components of the NRG1 system in enteric neuropathies.

[Diverticular disease - new insights into pathogenesis]

Diverticular disease is associated with a high incidence, morbidity and burden of the healthcare system. However, the pathogenesis is not yet satisfactorily clarified and thought to be multifactorial. Non-influenceable risk factors include increasing age, genetic predisposition and rare congenital connective tissue diseases. Influenceable risk factors are low-fiber diet, increased meat consumption and obesity. Alterations of connective tissue lead to a weakening of preformed emergence sites of diverticula ("loci minoris resistentiae") and may explain the increased incidence of diverticular disease in diseases caused by a systematic connective tissue disorder. The impact of neuromuscular alterations and disturbed colonic motility on triggering diverticula formation has been previously underestimated. Moreover, intestinal innervation disorders are considered to be responsable for persisting recurrent pain symptoms in chronic diverticular disease.

Morphologic Basis for Developing Diverticular Disease, Diverticulitis, and Diverticular Bleeding

Diverticula of the colon are pseudodiverticula defined by multiple outpouchings of the mucosal and submucosal layers penetrating through weak spots of the muscle coat along intramural blood vessels. A complete prolapse consists of a diverticular opening, a narrowed neck, and a thinned diverticular dome underneath the serosal covering. The susceptibility of diverticula to inflammation is explained by local ischemia, translocation of pathogens due to retained stool, stercoral trauma by fecaliths, and microperforations. Local inflammation may lead to phlegmonous diverticulitis, paracolic/mesocolic abscess, bowel perforation, peritonitis, fistula formation, and stenotic strictures. Diverticular bleeding is due to an asymmetric rupture of distended vasa recta at the diverticular dome and not primarily linked to inflammation. Structural and functional changes of the bowel wall in diverticular disease comprise: i) Altered amount, composition, and metabolism of connective tissue; ii) Enteric myopathy with muscular thickening, deranged architecture, and altered myofilament composition; iii) Enteric neuropathy with hypoganglionosis, neurotransmitter imbalance, deficiency of neurotrophic factors and nerve fiber remodeling; and iv) Disturbed intestinal motility both in vivo (increased intraluminal pressure, motility index, high-amplitude propagated contractions) and in vitro (altered spontaneous and pharmacologically triggered contractility). Besides established etiologic factors, recent studies suggest that novel pathophysiologic concepts should be considered in the pathogenesis of diverticular disease.

Confocal endomicroscopy shows food-associated changes in the intestinal mucosa of patients with irritable bowel syndrome

BACKGROUND & AIMS

We investigated suspected food intolerances in patients with irritable bowel syndrome (IBS) using confocal laser endomicroscopy (CLE) for real-time visualization of structural/functional changes in the intestinal mucosa after food challenge. Patients with functional changes after food challenge (CLE+) were placed on personalized exclusion diets and followed up for long-term symptom relief.

METHODS

Thirty-six IBS patients with suspected food intolerance and 10 patients with Barrett's esophagus (controls) without IBS symptoms were examined by CLE at University Hospital Schleswig-Holstein (Kiel, Germany). Diluted food antigens were administered directly to the duodenal mucosa through the working channel of the endoscope. Epithelial breaks, intervillous spaces, and the number of intraepithelial lymphocytes (IEL) were measured before and after the food challenge. CLE+ patients were placed on exclusion diets, given symptom score questionnaires, and followed up for 1 year; controls resumed their previous diet.

RESULTS

CLE showed a real-time response to food antigens in 22 of 36 patients; no responses were observed in 14 of 36 patients (CLE-) or any of the controls. Baseline IELs were significantly higher in CLE+ than CLE- subjects (P = .004); numbers increased significantly after food challenge (P = .0008). Within 5 minutes of exposure of CLE+ patients to food antigens, IELs increased, epithelial leaks/gaps formed, and intervillous spaces widened. Epithelial leaks and intervillous spaces also increased significantly in CLE+ vs baseline (both P < .001). The concordance of IELs measured by CLE and conventional histology was 70.6%; they did not correlate (P = .89; r(2) = 0.027). Symptom scores improved more than 50% in CLE+ patients after a 4-week exclusion diet and increased to 74% at 12 months; symptoms continued in CLE- patients.

CONCLUSIONS

Based on CLE analysis of IBS patients with a suspected food intolerance, exposure to candidate food antigens caused immediate breaks, increased intervillous spaces, and increased IELs in the intestinal mucosa. These changes are associated with patient responses to exclusion diets. Registered at clinicaltrials.gov (registration number: NCT01692613).

Estrogen receptor beta: tissue distribution and the still largely enigmatic physiological function

In 1996, the molecular biology of E2 had to be reevaluated: in an effort to identify novel nuclear receptors or unknown isoforms of existing receptors Kuiper and colleague described the expression of a novel subtype of the estrogen receptor (ER) in rat prostate and ovary. Upon this pioneering discovery the already known ER was renamed ERα while the newly described ER was termed ERβ. In this review an attempt is made to summarize the current knowledge regarding the expression and function of ERβ in selected reproductive and non-reproductive organs under physiological conditions. The data suggest that ERβ may be considered as a dominant-negative regulator of ERα modulating transcriptional responses to estrogens. The ratio of ER α vs. β. within a cell may determine the cell sensitivity to estrogens and its biological responses to the hormone.

CONCLUSION

It is not the ligand, it is the multiplicity of receptors which determines the plethora of estrogen actions. This article is part of a Special Issue entitled 'Phytoestrogens'.

The enteric serotonergic system is altered in patients with diverticular disease

OBJECTIVE

Disturbances of the enteric serotonergic system have been implicated in several intestinal motility disorders. Patients with diverticular disease (DD) have been reported to exhibit abnormal intestinal motility and innervation patterns. Gene expression profiles of the serotonergic system and distribution of the serotonin type 4 receptor (5HT-4R) were thus studied in patients with DD.

DESIGN

Colonic specimens from patients with DD and controls were subjected to quantitative PCR for serotonin receptors 2B, 3A, 4, serotonin transporter and synthesising enzyme tryptophan hydroxylase. Localisation of 5HT-4R was determined by dual-label immunocytochemistry using smooth muscle actin (α-SMA) and pan-neuronal markers (PGP 9.5) and quantitative analysis was carried out. Site-specific gene expression analysis of 5HT-4R was assessed within myenteric ganglia and muscle layers. Correlation of 5HT-4R with muscarinic receptors 2 and 3 (M2R, M3R) messenger RNA expression was determined.

RESULTS

5HT-4R mRNA expression was downregulated in the tunica muscularis and upregulated in the mucosa of patients with DD, whereas the other components of the serotonergic system remained unchanged. 5HT-4R was detected in ganglia and muscle layers, but was decreased in the circular muscle layer and myenteric ganglia of patients with DD. 5HT-4R mRNA expression correlated with M2R/M3R mRNA expression in controls, but not in patients with DD.

CONCLUSIONS

The serotonergic system is compromised in DD. Altered expression of 5HT-4R at mRNA and protein levels may contribute to intestinal motor disturbances reported in patients with DD. The findings support the hypothesis that DD is associated and possibly promoted by an enteric neuromuscular pathology.

Expression and function of the Transforming Growth Factor-b system in the human and rat enteric nervous system

BACKGROUND

Transforming growth factor-betas (TGF-bs) are pleiotropic growth factors exerting neurotrophic functions upon various neuronal populations of the central nervous system. In contrast, the role of TGF-b isoforms in the enteric nervous system (ENS) is largely unknown. We therefore analyzed the gene expression pattern of the TGF-b system in the human colon and in rat myenteric plexus, and smooth muscle cell cultures and determined the effect of TGF-b isoforms on neuronal differentiation.

METHODS

Human colonic samples as well as cultured rat myenteric plexus, and smooth muscle cells were assessed for mRNA expression levels of the TGF-b system (TGF-b1-3, TbR-1-3) by qPCR. The colonic wall was separated into mucosa and tunica muscularis and enteric ganglia were isolated by laser microdissection (LMD) to allow site-specific gene expression analysis. Effects of TGF-b isoforms on neurite outgrowth and branching pattern of cultured myenteric neurons were monitored.

KEY RESULTS

mRNA expression of the TGF-b system was detected in all compartments of the human colonic wall as well as in LMD-isolated myenteric ganglia. Cultured myenteric neurons and smooth muscle cells of rat intestine also showed mRNA expression of all ligands and receptors. Transforming growth factor-b2 treatment increased neurite length and branching pattern in cultured myenteric neurons.

CONCLUSIONS & INFERENCES

The TGF-b system is abundantly expressed in the human and rat ENS arguing for an auto-/paracrine function of this system on enteric neurons. Transforming growth factor-b2 promotes neuronal differentiation and plasticity characterizing this molecule as a relevant neurotrophic factor for the ENS.

The GDNF System Is Altered in Diverticular Disease - Implications for Pathogenesis

Background & Aims

Absence of glial cell line-derived neurotrophic factor (GDNF) leads to intestinal aganglionosis. We recently demonstrated that patients with diverticular disease (DD) exhibit hypoganglionosis suggesting neurotrophic factor deprivation. Thus, we screened mRNA expression pattern of the GDNF system in DD and examined the effects of GDNF on cultured enteric neurons.

Methods

Colonic specimens obtained from patients with DD (n = 21) and controls (n = 20) were assessed for mRNA expression levels of the GDNF system (GDNF, GDNF receptors GFRα1 and RET). To identify the tissue source of GDNF and its receptors, laser-microdissected (LMD) samples of human myenteric ganglia and intestinal muscle layers were analyzed separately by qPCR. Furthermore, the effects of GDNF treatment on cultured enteric neurons (receptor expression, neuronal differentiation and plasticity) were monitored.

Results

mRNA expression of GDNF and its receptors was significantly down-regulated in the muscularis propria of patients with DD. LMD samples revealed high expression of GDNF in circular and longitudinal muscle layers, whereas GDNF receptors were also expressed in myenteric ganglia. GDNF treatment of cultured enteric neurons increased mRNA expression of its receptors and promoted neuronal differentiation and plasticity revealed by synaptophysin mRNA and protein expression.

Conclusions

Our results suggest that the GDNF system is compromised in DD. In vitro studies demonstrate that GDNF enhances expression of its receptors and promotes enteric neuronal differentiation and plasticity. Since patients with DD exhibit hypoganglionosis, we propose that the observed enteric neuronal loss in DD may be due to lacking neurotrophic support mediated by the GDNF system.

Oral glutamine supplementation improves intestinal permeability dysfunction in a murine acute graft-vs.-host disease model

Although a profound barrier dysfunction has been reported, little is known about the pathophysiological mechanism evoking gastrointestinal graft-vs.-host disease (GI-GvHD) and apparent therapeutic options. The aim of this study was to evaluate the influence of oral glutamine on the course of GI-GvHD in an acute semiallogenic graft-vs.-host disease (GvHD) in irradiated B6D2F1 mice. An acute semiallogenic GvHD was induced by intraperitoneal injection of lymphocytes from C57BL/6 mice to irradiated B6D2F1 mice. Half of the GvHD animals received oral glutamine supplementation for 6 days started at the time of lymphocyte transfer. Six days after induction of the semiallogenic GvHD, jejunum specimens were prepared. The expression of the proinflammatory cytokine TNF-α and the tight junction protein occludin was investigated by PCR. Histological changes along with the apoptotic response were evaluated and intestinal permeability was assessed. Animals with GvHD showed a strong increase in paracellular permeability as a sign of the disturbed barrier function. TNF-α expression was significantly increased and the expression of the tight junction protein occludin decreased. GvHD led to mucosal atrophy, crypt hyperplasia, crypt apoptosis, and a disintegration of the tight junctions. Glutamine-treated mice showed reduced expression of TNF-α, increased occludin expression, fewer histological changes in the jejunum, smaller number of apoptotic cells in the crypt, and reduced gastrointestinal permeability. In conclusion, oral glutamine seems to have beneficial effects on the severity of inflammatory changes in the course of GvHD and might be a therapeutic option.

A novel endoscopic prototype device for gastric full-thickness biopsy for the histopathologic diagnosis of GI neuromuscular pathology: in vivo porcine long-term survival study (with videos)

BACKGROUND

Many GI motility disorders are associated with underlying GI neuromuscular pathology, which requires full-thickness biopsies (FTB) for histopathologic diagnosis. Currently, none of the endoscopy-based attempts to obtain FTB specimens have proven suitable for routine use. This study evaluated a novel endoscopic prototype device (ED) for this purpose.

OBJECTIVE

To determine (1) the ability of the ED to obtain suitable FTB specimens, (2) associated complications, (3) feasibility of reliable defect closure, and (4) ability to evaluate intramural neuromuscular components.

DESIGN

Preclinical proof-of-concept study in 30 pigs.

SETTING

Animal laboratory.

INTERVENTION

Gastric FTB specimens were obtained with a circular cutter and anchor. The defect was closed by over-the-scope clips/T-tags. The resection site was inspected via laparoscopy. After 2 to 4 weeks, necropsy was carried out to evaluate late complications.

MAIN OUTCOME MEASUREMENTS

Feasibility, safety, and closure rate of the procedure. FTB specimens were assessed by histology/immunohistochemistry to visualize enteric neuromusculature.

RESULTS

A total of 29 of 30 procedures were successfully performed; one hemorrhage required endoscopic treatment. A total of 29 of 30 FTB specimens (mean diameter 9.1 mm) were retrieved in 7.1 ± 0.4 minutes (range 3.0-12.5 minutes), displaying optimal tissue quality. Defect closure took 10.8 ± 0.9 minutes (range 7.2-32 minutes). Laparoscopy did not reveal damage to adjacent organs. Necropsy showed well-healed scars at the resection site and no complications, peritonitis, or abscess formation. Histology showed smooth muscle layers and submucosal and myenteric ganglia.

LIMITATIONS

Survival animal pilot study, no patients.

CONCLUSION

The novel ED enabled safe harvesting of well-preserved FTB specimens. Defect closure proved to be reliable. All neuromuscular structures relevant for histopathologic evaluation of GI neuromuscular pathology were demonstrated. Further studies are needed to verify the efficacy of this prototype device in the entire gut and in humans.

Expression pattern and localization of alpha-synuclein in the human enteric nervous system

BACKGROUND

Alpha-synuclein (α-syn) is abundantly expressed in the central nervous system and involved in the regulation of neurotransmission. Insoluble fibrils of phosphorylated α-synuclein (p-α-syn) have been implicated in several neurodegenerative diseases (e.g. Parkinson's disease, Alzheimer's disease). The aim of the study was to determine the gene expression pattern and localization of α-syn/p-α-syn in the human enteric nervous system (ENS).

METHODS

Human colonic specimens (n=13, 15-83 years) were processed for α-syn and p-α-syn immunohistochemistry. Colocalization of α-syn was assessed by dual-labeling with pan-neuronal markers (PGP 9.5, HuC/D). For qPCR studies, tissue was obtained from full-thickness sections, tunica muscularis, submucosa, mucosa, and laser-microdissected (LMD) enteric ganglia.

RESULTS

Highest α-syn levels were detectable within the tunica muscularis and submucosa. Ganglia isolated by LMD showed high expression of α-syn mRNA. All myenteric and submucosal ganglia and nerve fibers were immunoreactive for α-syn. Dual-labeling revealed colocalization of α-syn with both pan-neuronal markers. p-α-syn immunoreactivity was consistently observed in specimens from adults with increasing age.

CONCLUSIONS

α-syn is abundantly expressed in all nerve plexus of the human ENS including both neuronal somata and processes. The presence of p-α-syn within the ENS is a regular finding in adults with increasing age and may not be regarded as pathological correlate. The data provide a basis to unravel the functions of α-syn and to evaluate altered α-syn in enteric neuropathies and α-synucleinopathies of the CNS with gastrointestinal manifestations.

Abnormalities of neuromuscular anatomy in diverticular disease

The pathogenesis of diverticular disease is still poorly understood and considered to be multifactorial. Whereas classical pathogenetic concepts have focused on risk factors including increasing age, low-fiber diet and connective tissue disorders, novel concepts take into account that patients with diverticular disease exhibit disturbed intestinal motility patterns (that may result in functional obstruction and painful sensations) therefore postulating an underlying enteric neuro-/myopathy. Recent studies including quantitative evaluations of the enteric nervous system (ENS) in diverticular disease yielded hypoganglionic conditions of both myenteric and submucosal plexus as well as a nerve tissue remodeling in chronic diverticular disease. The disturbed neuromuscular communication was proven by demonstrating alterations in several enteric neurotransmitter systems, exemplified for the cholinergic, serotonergic, nitrergic system as well as for vasointestinal peptide, galanin and tachykinins. Novel lines of evidence have added the involvement of neurotrophic factors such as glial cell line-derived neurotrophic factor which is supposed to regulate ENS development and maintenance and which is downregulated in patients with diverticular disease. Consistent with the hypothesis of an enteric myopathy, deficits in smooth muscle integrity and composition such as hypertrophy, fibrotic transformation and gene expression deficits could be delineated. Taken together, the structural and functional findings on alterations of the ENS and the enteric musculature in diverticular disease provide evidence to strengthen the hypothesis that an enteric neuro-/myopathy may contribute to the development of colonic diverticula and the generation of symptoms in the course of the disease.

IL-1β and ADAM17 are central regulators of β-defensin expression in Candida esophagitis

Candida albicans resides on epithelial surfaces as part of the physiological microflora. However, under certain conditions, it may cause life-threatening infections, including Candida sepsis. We have recently shown that human β-defensins (hBDs) hBD-2 and hBD-3 are upregulated in Candida esophagitis and that this antifungal host response is distinctly regulated by NF-κB and MAPK/activator protein-1 (AP-1) pathways. Here, we show that C. albicans induces hBD-2 through an autocrine IL-1β loop and that activation of the epidermal growth factor receptor (EGFR) by endogenous transforming growth factor-α (TGF-α) is a crucial event in the induction of hBD-3. To further dissect upstream signaling events, we investigated expression of the central sheddases for EGFR ligands ADAM10 and ADAM17 in the healthy and infected esophagus. Next, we used pharmaceutical inhibitors and small-interfering RNA-mediated knock down of ADAM10 and ADAM17 to reveal that ADAM17-induced shedding of TGF-α is a crucial step in the induction of hBD-3 expression in response to Candida infection. In conclusion, we describe for the first time an autocrine IL-1β loop responsible for the induction of hBD-2 expression and an ADAM17-TGF-α-EGFR-MAPK/AP-1 pathway leading to hBD-3 upregulation in the course of a Candida infection of the esophagus.

Establishment and characterization of porcine colonic epithelial cells grown in primary culture

BACKGROUND

Primary cultures of epithelial cells are suitable models for studying epithelial function and, in particular, the regulation of epithelial tightness in vitro. The aim of our study was to develop a protocol for the isolation and culture of porcine colonic epithelial cells and to establish transepithelial electrical resistance (TEER) as a functional parameter for epithelial tightness.

METHODS

Epithelial cells were obtained from the proximal colon of piglets by enzymatic dispase digestion. Cells were cultured on collagen-coated membrane supports for 21 days. The epithelial origin of the cells was shown by immunohistochemical detection of cytokeratin and zonula occludens protein 1 (ZO-1). Scanning electron microscopy, transmission electron microscopy and confocal microscopy were used for further morphological characterization. The integrity and tightness of the artificial epithelium were determined by measuring TEER.

RESULTS

The cultured epithelial cells were immunoreactive for cytokeratin and ZO-1. They showed dense microvilli on their apical membranes and expression of Na(+)/K(+)-ATPase on their basolateral membranes. Adjacent cells were connected by tight junctions. We observed TEER to continuously increase up to 870 ± 38 Ω·cm(2) during the culture period. TEER correlated with the amount of epithelial cells expressing ZO-1.

CONCLUSIONS

The properties of primary cultured epithelial cells resemble the structural properties of polarized colonic epithelium in vivo. Measurement of TEER seems to be suitable for studying epithelial tightness in vitro. We suggest that these primary epithelial cultures be used to investigate the regulation of the epithelial barrier function.

Diverticular disease is associated with an enteric neuropathy as revealed by morphometric analysis

BACKGROUND

The pathogenesis of diverticular disease (DD) is attributed to several aetiological factors (e.g. age, diet, connective tissue disorders) but also includes distinct intestinal motor abnormalities. Although the enteric nervous system (ENS) is the key-regulator of intestinal motility, data on neuropathological alterations are limited. The study aimed to investigate the ENS by a systematic morphometric analysis.

METHODS

Full-thickness sigmoid specimens obtained from patients with symptomatic DD (n = 27) and controls (n = 27) were processed for conventional histology and immunohistochemistry using anti-HuC/D as pan-neuronal marker. Enteric ganglia, nerve and glial cells were quantified separately in the myenteric, external and internal submucosal plexus compartments.

KEY RESULTS

Compared to controls, patients with DD showed significantly (P < 0.05) (i) reduced neuronal density in all enteric nerve plexus, (ii) decrease of ganglionic nerve cell content in the myenteric plexus, (iii) decreased ganglionic density in the internal submucosal plexus, (iv) reduced glial cell density in the myenteric plexus, (v) decrease of ganglionic glial cell content in the myenteric plexus and increase in submucosal plexus compartments, (vi) increased glia index in all enteric nerve plexus. About 44.4% of patients with DD exhibited myenteric ganglia displaying enteric gliosis.

CONCLUSIONS & INFERENCES

Patients with DD show substantial structural alterations of the ENS mainly characterized by myenteric and submucosal oligo-neuronal hypoganglionosis which may account for intestinal motor abnormalities reported in DD. The morphometric data give evidence that DD is associated with structural alterations of the ENS which may complement established pathogenetic concepts.

Laser microdissection as a new tool to investigate site-specific gene expression in enteric ganglia of the human intestine

BACKGROUND

Myenteric ganglia are key-structures for the control of intestinal motility and their mRNA expression profiles might be altered under pathological conditions. A drawback of conventional RT-PCR from full-thickness specimens is that gene expression analysis is based on heterogeneously composed tissues. To overcome this problem, laser microdissection combined with real-time RT-PCR can be used to detect and quantify low levels of gene expression in isolated enteric ganglia.

METHODS

Fresh unfixed full-thickness specimens of sigmoid colon were obtained from patients (n = 8) with diseases unrelated to intestinal motility disorders. 10 microm cryo-sections were mounted on membrane-coated slides and ultra-rapidly stained with toluidine blue. Myenteric ganglia were isolated by laser microdissection and catapulting for mRNA isolation. Real-time RT-PCR was performed for selected growth factors, neurotransmitter receptors and specific cell type markers.

KEY RESULTS

Collection of 0.5 mm(2) of ganglionic tissue was sufficient to obtain positive RT-PCR results. Collection of 4 mm(2) resulted in ct-values allowing a reliable quantitative comparison of gene expression levels. mRNA analysis revealed that neurotrophic growth factor, neurotrophin-3, serotonin receptor 3A, PGP 9.5 and S100 beta are specifically expressed in myenteric ganglia of the human colon.

CONCLUSIONS & INFERENCES

Laser microdissection combined with real-time RT-PCR is a novel technique to reliably detect and quantify site-specific expression of low-abundance mRNAs (e.g. growth factors, neurotransmitter receptors) related to the human enteric nervous system. This technical approach expands the spectrum of available tools to characterize enteric neuropathologies underlying human gastrointestinal motility disorders at the molecular biological level.

Specific Lactobacillus/Mutans Streptococcus co-aggregation

Selective interaction of mutans streptococci with benign bacteria could present an opportunity for their removal from the mouth without disruption of other oral flora. This study was conducted to find probiotic lactobacilli that could specifically co-aggregate in vitro with mutans streptococci, but not with other plaque commensals. A search of 624 lactobacilli among a large culture library revealed 6 strains, all classifiable as L. paracasei or L. rhamnosus, which met this criterion. Such novel, specific co-aggregation, however, was not a general characteristic of these species or the genus Lactobacillus. The co-aggregation by these specific lactobacilli was characterized as heat treatment (autoclaving)- and protease-resistant, lectin-independent, not inactivated by sugar substitutes, operational over a wide pH range, unaffected by whole saliva, but calcium-dependent. It is thus seen to present a potential strategy for in vivo alteration of plaque biofilm and caries.

Expression of estrogen receptors in the hypothalamo-pituitary-ovarian axis in middle-aged rats after re-instatement of estrus cyclicity

During reproductive aging female rats enter an anovulatory state of persistent estrus (PE). In an animal model of re-instatement of estrus cyclicity in middle-aged PE rats we injected the animals with progesterone (0.5 mg progesterone/kg body weight) at 12:00 for 4 days whereas control animals received corn oil injections. After the last injection animals were analyzed at 13:00 and 17:00. Young regular cycling rats served as positive controls and were assessed at 13:00 and 17:00 on proestrus. Progesterone treatment of middle-aged PE rats led to occurrence of luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin surges in a subset of animals that were denoted as responders. Responding middle-aged rats displayed a reduction of ER-β mRNA in the preoptic area which was similar to the effect in young rats. Within the mediobasal hypothalamus, only young rats showed a decline of ER-α mRNA expression. A decrease of ER-α mRNA levels in the pituitary was observed in progesterone-responsive rats and in young animals. ER-β mRNA expression was reduced in young regular cycling rats. ER-β mRNA levels in the ovary were reduced following progesterone treatment in PE rats and in young rats. Taken together our data show that cyclic administration of progesterone reinstates ovulatory cycles in intact aging females which have already lost their ability to display spontaneous cyclicity. This treatment leads to the occurrence of preovulatory LH, FSH and prolactin surges which are accompanied by differential modulation of ERs in the hypothalamus, the pituitary and the ovary.

Cell-free supernatants of Escherichia coli Nissle 1917 modulate human colonic motility: evidence from an in vitro organ bath study

Abstract Clinical studies have shown that probiotics influence gastrointestinal motility, e.g. Escherichia coli Nissle 1917 (EcN) (Mutaflor) proved to be at least as efficacious as lactulose and more potent than placebo in constipated patients. As the underlying mechanisms are not clarified, the effects of EcN culture supernatants on human colonic motility were assessed in vitro. Human colonic circular smooth muscle strips (n = 94, 17 patients) were isometrically examined in an organ bath and exposed to different concentrations of EcN supernatants. Contractility responses were recorded under (i) native conditions, (ii) electrical field stimulation (EFS), (iii) non-adrenergic non-cholinergic conditions, and (iv) enteric nerve blockade by tetrodotoxin (TTX). As concentrations of acetic acid were increased in EcN supernatants, contractility responses to acetic acid were additionally tested. EcN supernatants significantly increased the maximal tension forces both at low and high concentrations. Neither blockade of both adrenergic and cholinergic nerves nor application of TTX abolished these effects. EFS-induced contractility responses were not altered after exposure to EcN supernatants. Acetic acid elicited effects comparable to EcN supernatants only under TTX conditions. EcN supernatants modulate in vitro contractility of the human colon. As neither partial nor TTX blockade of enteric nerves abolished these effects, EcN supernatants appear to enhance colonic contractility by direct stimulation of smooth muscle cells. Active metabolites may include other substances than acetic acid, as acetic acid only partially resembled the effects elicited by EcN supernatants. The data provide a rationale for therapeutical application of probiotics in gastrointestinal motility disorders.

Effects of long-term treatment with 8-prenylnaringenin and oral estradiol on the GH-IGF-1 axis and lipid metabolism in rats

After the heart and estrogen/progestin replacement study and the women's health initiative study, the prospect of hormone replacement therapy (HRT) on cardiovascular diseases (CVD) has changed dramatically. These findings led to various attempts to search for alternatives for classical HRT, e.g. phytoestrogens. The flavanone 8-prenylnaringenin (8-PN) was identified as a phytoestrogen with strong estrogen receptor-alpha activity. As the pituitary and the liver are targets for estrogen action, we assessed the effect of ovariectomy (OVX) and long-term treatment (3 months) with 17-beta estradiol benzoate (E(2)B) and 8-PN on pituitary and liver functions in adult OVX rats. Tested doses were 6.8 and 68.4 mg/kg body weight (BW) of 8-PN and 0.17 and 0.7 mg/kg BW of E(2)B. Our results demonstrate that 8-PN and E(2)B decreased BW and increased uterus weight. The high doses of E(2)B and 8-PN increased serum GH and decreased serum IGF-1 levels. E(2)B dose dependently decreased cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) concentrations in OVX rats. The high dose of 8-PN showed an estrogenic activity regarding cholesterol and LDL regulation but had no effect on HDL concentrations. By contrast, the low dose of 8-PN augmented HDL levels compared with intact rats. Triglyceride levels were raised in response to the high E(2)B dose but unaffected by 8-PN treatment. Taken together, 8-PN displays an anti-atherosclerotic profile that appears to be even more beneficial than the one displayed by E(2)B, and thus might demonstrate a remarkable potential for the prevention of CVD associated with estrogen deficiency.

[The enteric nervous system and interstitial cells of Cajal. Changes in chronic constipation in adults]

Intestinal innervation disorders are part of the broad etiological spectrum of chronic constipation and need to be specifically addressed in differential diagnosis. The enteric nervous system constitutes the largest peripheral nervous system of its own ("brain in the gut"), and is involved in the mediation of intestinal motility. Morphologically different nerve cell types aggregate into intramural plexus layers and release a multitude of neurotransmitters. Malformations or lesions of the enteric nervous system may lead to a severely prolonged intestinal transit time resulting in chronic constipation resistant to conservative treatment. In contrast to the early manifestation of aganglionosis, non-aganglionic or acquired alterations to the intramural nerve plexus often remain unrecognised up to adulthood. Histopathological diagnosis is carried out by enzyme or immunohistochemical staining, either on sections or whole mount preparations, allowing an optimal visualization of the nerve plexus architecture. To diagnose hypoganglionosis, enteric ganglionitis or alterations in interstitial cells of Cajal, full-thickness biopsies are required. Interstitial cells of Cajal contribute significantly to the mediation of intestinal motility by generating "slow wave" activity. In adult patients with slow-transit constipation and megacolon, the intramuscular networks of the interstitial cells of Cajal show a significantly reduced density.

Changes of expression of genes related to the activity of the gonadotrophin-releasing hormone pulse generator in young versus middle-aged male rats

In females, it is well established that changes in the expression of neurotransmitters and peptides regulating the activity of the gonadotrophin-releasing hormone (GnRH) pulse generator are altered during ageing. By contrast, little is known about whether those age-related changes also occur in males. Therefore, we designed an animal study with orchidectomised young and middle-aged male rats to investigate changes in luteinising hormone (LH) secretion profiles and changes in the mRNA expression of genes regulating the activity of the GnRH pulse generator. Our results demonstrate that middle-aged rats exhibit lower serum LH levels and relatively fewer LH pulses with attenuated amplitude compared to young animals. Furthermore, upon ageing, GnRH mRNA expression is up-regulated in the preoptic area and the septum where GnRH neurones reside. Analysis of mRNA levels of glutamate decarboxylase (GAD) enzymes revealed that GAD(65) and GAD(67) mRNA expression increased in the mediobasal hypothalamus (MBH) and that GAD(67) mRNA levels decreased in the suprachiasmatic nucleus. In addition, we observed an age-related increase of oestrogen receptor (ER)alpha mRNA in the MBH, and both ERalpha and ERbeta mRNA expression was up-regulated in the pituitary of middle-aged rats compared to young animals. Taken together, our data support the existence of a male 'andropause' that is, like the menopause in females, accompanied by changes in neurotransmitter and hormone receptor expression that are involved in regulating the function of the GnRH pulse generator.

Intestinal gas retention in patients with idiopathic slow-transit constipation

Patients with slow-transit constipation (STC) have delayed colonic transit for solid und liquid bowel contents but intestinal gas handling has not been studied so far. Different nutrients influence motor and sensory gut function. We hypothesized that, in patients with STC, alteration of regulatory mechanisms may result in impaired intestinal gas dynamics. On 3 separate days, validated gas challenge was performed in 10 STC patients and 10 volunteers during duodenal saline, lipids, or intravenous glucose. During saline only 60% +/- 8% of gas was cleared by STC patients after 60-min gas infusion, vs. 91% +/- 2% by controls (P < 0.001). Acute hyperglycemia or lipids did not change intestinal gas dynamics in these patients (saline infusion), but compared to healthy subjects, significant intestinal gas retention occurred. In STC, disturbances of intestinal gas dynamics include basal intestinal gas retention, and this is virtually not affected by acute hyperglycemia or duodenal lipids.

Oestrogen synthesis in the hippocampus: role in axon outgrowth

Ovarian oestrogens have been postulated to be neuroprotective. It has also been shown that considerable amounts of oestrogens are synthesised in hippocampal neurones. In the present study, we focused on a potential role of hippocampus-derived oestradiol compared to gonad-derived oestradiol on axon outgrowth of hippocampal neurones. To address the role of hippocampus-derived oestradiol, we inhibited oestrogen synthesis by treatment of neonatal hippocampal cell cultures with letrozole, a specific aromatase inhibitor. As an alternative, we used siRNA against steroidogenic acute regulatory protein (StAR). Axon outgrowth and GAP-43 expression were significantly down-regulated in response to letrozole and in siRNA-StAR transfected cells. The effects after inhibition of oestrogen synthesis in response to letrozole and in siRNA-StAR transfected cells were reversed by oestrogen supplementation. No difference was found between ovariectomised animals, cycling animals at pro-oestrus and ovariectomised and subsequently oestradiol-treated animals. However, high pharmacological doses of oestradiol promoted axon outgrowth, which was possible to abolish by the oestrogen receptor antagonist ICI 182,780. Our results show that oestradiol-induced neurite outgrowth is very likely mediated by genomic oestrogen receptors and requires higher doses of oestradiol than physiological serum concentrations derived from the gonads.

Effects of long-term treatment with resveratrol and subcutaneous and oral estradiol administration on the pituitary-thyroid-axis

The lack of estrogen during menopause is associated with various symptoms including osteoporosis, cardiovascular diseases, and menopausal symptoms. For many years, conventional hormone replacement therapy has been successfully used to treat these conditions. However, in light of recent studies that draw attention to potential hazards of conventional HRT, various attempts were undertaken to search for alternatives of classical HRT. Phytoestrogens are supposed to ameliorate various discomforts associated with menopause. Resveratrol (RES) is present in red wine, grapes and peanuts and has been implicated in cardioprotection and prevention of adverse side effects observed after regular HRT. As the pituitary-thyroid axis is a target of estrogen action, we first assessed the effects of E2 administration on thyroid hormone stimulating hormone releasing hormone (TRH)-induced thyroid stimulating hormone (TSH) secretion from pituitary cell cultures in vitro. Our data reveal that E2 treatment augments the TRH-induced TSH secretion. We furthermore designed a long-term study of three months to assess the effects of subcutaneous and oral administration of 17beta-estradiol (E2), as well as the actions of RES on the pituitary-thyroid axis in ovariectomized (OVX) female rats. Our results demonstrate that serum levels of 1.0 and 8.1 microM RES lead to a significant increase in total serum triiodthyronine (T3) levels. OVX induces TSHbeta mRNA in the adenohypohysis and E2 treatment attenuates this effect. Treatment of rats with subcutaneous implants of E2 does not affect the pituitary-thyroid axis, whereas orally applied E2 benzoate (E2B) increases plasma TSH and total thyroxine (T4) in OVX rats. In all animals, we could not detect changes in thyroid morphology as assessed by hematoxylin-eosin (HE) and Perjod-Acid Schiff's (PAS) staining.

Chronic treatment with low doses of estradiol affects pituitary and thyroid function in young and middle-aged ovariectomized rats

Menopause marks the end of the reproductive life span of women and is characterized by a dramatic drop of circulating estrogen. Hormone replacement therapy (HRT) has been successfully used to treat the symptoms of menopause because estrogen has strong suppressive effects on climacteric complaints. As the hypothalamo-pituitary-thyroid axis is a target for estrogen action we assessed the effect of ovariectomy (OVX) and long-term (3 months) estradiol (E2) treatment by means of subcutaneously (s.c.) implanted silastic capsules on pituitary and thyroid function in middle-aged female rats. Our results demonstrate that s.c. administration of E2 resulted in physiological serum concentrations of E2. Upon OVX, ERbeta mRNA in the pituitary was induced and amounts of transcripts decreased after E2 administration. Implanted E2 capsules led to a reduction of ERalpha mRNA in the pituitary. E2 treatment attenuated the OVX-induced increases in TSHbeta and TSHalpha mRNA. Chronic E2 treatment reduced total T4 levels in OVX animals. TSH and total T3 serum levels were not altered upon E2 treatment. Taken together, our results clearly demonstrate that both, the pituitary and the thyroid of middle-aged rats remain susceptible to the influence of OVX and E2 treatment.

Chronic Treatment with Physiological Doses of Estradiol Affects the GH-IGF-1 Axis and Fat Metabolism in Young and Middle-aged Ovariectomized Rats

Estrogen deficiency may be partly responsible for the metabolic syndrome and the condition may be reversible with hormone replacement therapy. However, after the heart and estrogen/progestin replacement study and the women's health initiative study the prospect of HRT on CVD has changed dramatically. As the pituitary and the liver are targets for estrogen action we assessed the effect of ovariectomy (OVX) and long-term (3 months) estradiol (E2) treatment by means of subcutaneously (s.c.) implanted silastic capsules on pituitary and liver function in young and middle-aged female rats. Our results demonstrate that triglyceride serum levels increased, whereas insulin-like growth factor-1 (IGF-1), high density lipoprotein cholesterol (HDL), and glucose levels decreased during the transition from young to middle-age. E2 treatment increased dose-independently growth hormone (GH) secretion. IGF-1 levels were increased upon OVX in middle-aged rats and the high dose of E2 decreased IGF-1 concentrations in both age groups. Cholesterol concentrations increased after OVX and were attenuated by E2 administration in middle-aged rats. Both, low density lipoprotein cholesterol (LDL) and HDL levels raised after castration and both parameters decreased in response to E2 in young and middle-aged rats. Glucose serum concentrations decreased after E2 treatment in all animals. Taken together, our results clearly demonstrate that the pituitary and the liver metabolism of middle-aged rats remain susceptible to the influence of OVX and E2 treatment.

Effects of long-term treatment with resveratrol and subcutaneous and oral estradiol administration on pituitary function in rats

Hormone replacement therapy (HRT) has been used for several decades to treat menopausal discomforts. However, in the light of recent studies that draw attention to the potential hazards of conventional HRT, various attempts have been undertaken to search for alternatives to classical HRT. Phytoestrogens are claimed to be capable of positively influencing menopausal symptoms, including hot flushes. We designed a long-term study of 3 months to assess the effects of subcutaneous and orally fed 17beta-estradiol (E2), as well as the actions of resveratrol (RES) on pituitary function in female rats. Our results have demonstrated that RES binds with a 10-fold lower affinity to estrogen receptor (ER)-alpha than to ERbeta. The data from the in vivo study revealed that a dosage of 5 microg and 50 microg RES/kg bodyweight per day given to ovariectomized (OVX) rats achieved serum levels of 1.0 and 8.1 microM respectively. Long-term treatment of OVX rats with RES revealed no estrogenic potential on pituitary function in vivo as assessed by LH and prolactin secretion and by regulation of mRNAs for LHalpha, LHbeta, and GnRH receptor. Subcutaneous treatment with E2 in silastic capsules exerted stronger effects on LH and prolactin secretion, as well as on LHbeta, LHalpha, GnRH receptor, and ERbeta mRNA regulation compared with orally applied estradiol benzoate despite comparable serum levels. Levels of aryl hydrocarbon receptor (AhR) mRNA in the pituitary were increased following OVX and attenuated by long-term E2 treatment, whereas RES did not modulate AhR mRNA expression.

Proliferation and apoptosis of hippocampal granule cells require local oestrogen synthesis

Ovarian oestrogens have been demonstrated to influence neurogenesis in the dentate gyrus. As considerable amounts of oestrogens are synthesized in hippocampal neurones, we focused on the role of hippocampus-derived estradiol on proliferation and apoptosis of granule cells in vitro. We used hippocampal dispersion cultures, which allowed for cultivation of the cells under steroid- and serum-free conditions and monitoring of oestrogen synthesis. To address the influence of hippocampus-derived estradiol on neurogenesis, we inhibited oestrogen synthesis by treatment of hippocampal cell cultures with letrozole, a specific aromatase inhibitor. Alternatively, we used siRNA against steroidogenic acute regulatory protein (StAR). The number of proliferative cells decreased whereas the number of apoptotic cells increased dose-dependently, in response to reduced estradiol release into the medium after treatment with letrozole. This also held true for siRNA against StAR transfected cell cultures. Application of estradiol to the medium had no effect on proliferation and apoptosis whereas the anti-proliferative and pro-apoptotic effects of StAR knock-down and letrozole treatment were restored by treatment of the cultures with estradiol. Our findings suggest that neurogenesis and apoptosis in the hippocampus require a defined range of estradiol concentrations that is physiologically provided by hippocampal cells but not by gonads.