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.

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 S100ß. 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.

Persistent Increased Enteric Glial Expression of S100ß is Associated With Low-grade Inflammation in Patients With Diverticular Disease.

BACKGROUND: Diverticular disease (DD) is a common gastrointestinal inflammatory disorder associated with an enteric neuropathy. Although enteric glial cells (EGCs) are essential regulators of intestinal inflammation and motility functions, their contribution to the pathophysiology of DD remains unclear. Therefore, we analyzed the expression of specific EGC markers in patients with DD. MATERIALS AND METHODS: Expression of the glial markers S100ß, GFAP, Sox10, and Connexin 43 was analyzed by real-time quantitative PCR in colonic specimens of patients with DD and in that of controls. Protein expression levels of S100ß, GFAP, and Connexin 43 were further analyzed using immunohistochemistry in the submucosal and myenteric plexus of patients with DD and in that of controls. Expression of the inflammatory cytokines tumor necrosis factor-α and interleukin-6 was quantified using qPCR, and infiltration of CD3+ lymphocytes was determined using immunohistochemistry. RESULTS: Expression of S100ß was increased in the submucosal and myenteric plexus of patients with DD compared with that in controls, whereas expression of other glial factors remained unchanged. This increased expression of S100ß was correlated to CD3+ lymphocytic infiltrates in patients with DD, whereas no correlation was observed in controls. CONCLUSIONS: DD is associated with limited but significant alterations of the enteric glial network. The increased expression of S100ß is associated with a persistent low-grade inflammation reported in patients with DD, further emphasizing the role of EGCs in intestinal inflammation.

Impaired Expression of Neuregulin 1 and Nicotinic Acetylcholine Receptor ß4 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, ß2, and ß4. 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 ß4. 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 ß4 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 ß2, α3, α5, and α7 remained unaltered. NRG1, ErbB3, and nAChR subunit ß4 immunoreactive signals were reduced in neuronal somata and the neuropil of myenteric ganglia from patients with DD compared to control. nAChR subunit ß4 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 ß4. 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 ß4 by NRG1 and decreased nAChR ß4 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.

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.

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]. / Divertikelkrankheit - Neues zur Pathogenese.

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.

Alpha-synuclein is associated with the synaptic vesicle apparatus in the human and rat enteric nervous system.

BACKGROUND AND AIMS: Aggregation of alpha-synuclein (a-syn) has been implicated in the development of neurodegenerative diseases including its spread from the enteric nervous system (ENS) to the brain. Physiologically, a-syn is located at the presynapse and might be involved in regulating of neurotransmission. Therefore, the aim of the study was to characterize the physiological ontogenetic and locoregional expression pattern of a-syn in the ENS and its association with the synaptic vesicle apparatus. MATERIAL AND METHODS: Ontogenetic mRNA expression of a-syn and synaptophysin was determined in the rat intestine. Myenteric plexus cultures treated with glial cell line-derived neurotrophic factor (GDNF) were assessed for mRNA expression of a-syn, co-localization of a-syn with the pan-neuronal marker PGP 9.5 and the synaptic vesicle marker synaptophysin and studied by scanning electron microscopy (SEM). Human colonic specimens were subjected to co-localization studies of a-syn with synaptophysin. RESULTS: a-syn and synaptophysin intestinal gene expression levels were highest during early postnatal life and also detectable at adult age. a-syn was co-localized with PGP 9.5 and synaptophysin in myenteric plexus cultures and up-regulated after GDNF treatment. SEM confirmed the presence of neuronal varicosities to which a-syn was associated. Consistently, a-syn and synaptophysin showed partial co-localization in the human ENS. CONCLUSIONS: The ontogenetic and cellular expression pattern as well as the regulation by GNDF give evidence that a-syn is physiologically associated to the synaptic vesicle apparatus. The data suggest that a-syn is involved in the regulation of synaptic plasticity in the ENS during early postnatal life and adult age.

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.

Expression and regulation of reelin and its receptors in the enteric nervous system.

BACKGROUND & AIMS: In the central nervous system (CNS), reelin coordinates migration and lamination of neurons and regulates synaptic plasticity, whereas its role in the enteric nervous system (ENS) remains enigmatic. Thus we determined the expression pattern and localization of reelin in the human ENS and monitored the time course of mRNA expression of the reelin signaling system in the rat intestine as well as in GDNF treated ENS cultures. RESULTS: Reelin, its receptors and Dab1 were expressed in all intestinal layers as well as in isolated myenteric ganglia. Enteric ganglia and nerve fibers were immunoreactive for reelin which co-localized with PGP 9.5 and synaptophysin. In the rat small intestine, highest expression levels of reelin were detected at early postnatal stages. Enteric nerve cell cultures treated with GDNF showed marked up-regulation of reelin and its receptors. CONCLUSIONS: Reelin and its receptors are strongly expressed in the human ENS. Reelin is specifically localized in enteric neurons with highest expression levels during early postnatal life as well as in neuronal network forming enteric nerve cell cultures pointing to putative functions in the differentiation and maintenance of the ENS. EXPERIMENTAL METHODS: Gene expression of reelin, its receptors and Dab1 were analyzed in the human colon and isolated enteric ganglia. Co-localization of reelin with the pan-neuronal marker PGP 9.5 and the synaptic vesicle marker synaptophysin was studied by dual-label-immunocytochemistry. The time course of reelin expression was monitored in an ontogenetic study of rat intestines as well as in GDNF-treated cultures of enteric neurons.

Alterations of the enteric smooth musculature in diverticular disease.

BACKGROUND: The pathogenesis of diverticular disease (DD) is considered to be multifactorial and involves intestinal motor disturbances and an underlying enteric neuromuscular pathology. While an enteric neuropathy has been well documented, actual studies on concomitant alterations of the enteric musculature are limited. This study is aimed at reassessing the smooth muscle tissue by histological, ultrastructural and molecular-biological approaches. METHODS: Full-thickness sigmoid specimens were obtained from patients with DD (n = 20) and controls (n = 19). Morphometric analysis was performed to evaluate the thickness and connective tissue index of the circular and longitudinal muscle layers as well as the myenteric plexus. Structural alterations were determined by light and transmission electron microscopy. mRNA profiles of components of the contractile smooth muscle apparatus including smooth muscle α-actin, smoothelin, histone deacetylase 8, and smooth muscle myosin heavy chain (SMMHC) were assessed by qPCR. Altered gene expression levels were confirmed at protein level by immunohistochemistry. RESULTS: Compared to controls, patients with DD showed (1) increased thickness of the circular and longitudinal muscle layers, (2) architectural alterations of smooth muscle cells, (3) increased connective tissue index of the longitudinal muscle layer, (4) focally reduced density of myofilaments at ultrastructural level, (5) specific down-regulation of SMMHC mRNA levels, (6) decreased immunoreactivity of SMMHC, (7) oligo-neuronal hypoganglionosis. CONCLUSIONS: DD is associated with distinct structural and functional alterations of the enteric musculature. The enteric myopathy is characterized by disturbed muscular architecture, connective tissue replacement and loss of specific myofilaments and thus may contribute to the pathogenesis and progression of DD.

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.

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 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.

Effects of the TLR2 agonists MALP-2 and Pam3Cys in isolated mouse lungs.

BACKGROUND: Gram-positive and Gram-negative bacteria are main causes of pneumonia or acute lung injury. They are recognized by the innate immune system via toll-like receptor-2 (TLR2) or TLR4, respectively. Among all organs, the lungs have the highest expression of TLR2 receptors, but little is known about the pulmonary consequences of their activation. Here we studied the effects of the TLR2/6 agonist MALP-2, the TLR2/1 agonist Pam(3)Cys and the TLR4 agonist lipopolysaccharide (LPS) on pro-inflammatory responses in isolated lungs. METHODOLOGY/PRINCIPAL FINDINGS: Isolated perfused mouse lungs were perfused for 60 min or 180 min with MALP-2 (25 ng/mL), Pam(3)Cys (160 ng/mL) or LPS (1 µg/mL). We studied mediator release by enzyme linked immunosorbent assay (ELISA), the activation of mitogen activated protein kinase (MAPK) and AKT/protein kinase B by immunoblotting, and gene induction by quantitative polymerase chain reaction. All agonists activated the MAPK ERK1/2 and p38, but neither JNK or AKT kinase. The TLR ligands upregulated the inflammation related genes Tnf, Il1ß, Il6, Il10, Il12, Ifng, Cxcl2 (MIP-2α) and Ptgs2. MALP-2 was more potent than Pam(3)Cys in inducing Slpi, Cxcl10 (IP10) and Parg. Remarkable was the strong induction of Tnc by MALP2, which was not seen with Pam(3)Cys or LPS. The growth factor related genes Areg and Hbegf were not affected. In addition, all three TLR agonists stimulated the release of IL-6, TNF, CXCL2 and CXCL10 protein from the lungs. CONCLUSIONS/SIGNIFICANCE: TLR2 and TLR4 activation leads to similar reactions in the lungs regarding MAPK activation, gene induction and mediator release. Several genes studied here have not yet been appreciated as targets of TLR2-activation in the lungs before, i.e., Slpi, tenascin C, Parg and Traf1. In addition, the MALP-2 dependent induction of Tnc may indicate the existence of TLR2/6-specific pathways.

Conserved responses to trichostatin A in rodent lungs exposed to endotoxin or stretch.

Histone deacetylase (HDAC) isoenzymes have been suggested as possible drug targets in pulmonary cancer and in inflammatory lung diseases such as asthma and COPD. Whether HDAC inhibition is pro- or anti-inflammatory is under debate. To further examine this clinically relevant paradigm, we analyzed 8 genes that are upregulated by two pro-inflammatory stimuli, i.e. endotoxin and mechanical stress (overventilation), in isolated rat and mouse lungs, respectively. We studied the effect of the HDAC inhibitor trichostatin A (TSA) under control conditions, in response to endotoxin and overventilation, and on the effects of the steroid dexamethasone. TSA affected gene expression largely independent of the stimulus (endotoxin, overventilation) and the species (rat, mouse) leading to upregulation of some genes (Tnf, Cxcl2) and downregulation of others (Cxcl10, Timp1, Selp, Il6). At the protein level, TSA reduced the stimulated release of TNF, MIP-2alpha and IL-6, indicating that TSA may affect protein translation independent from gene transcription. In general, the anti-inflammatory effects of TSA on gene expression and protein release were additive to that of dexamethasone, suggesting that both drugs employ different mechanisms. We conclude that pro-inflammatory stimuli induce distinct sets of genes that are regulated by HDAC in a diverse, but consistent manner across two rodent species. The present findings together with previous in vivo studies suggest that the effect of HDAC inhibition in the intact lung is in part anti-inflammatory.

Variable tidal volumes improve lung protective ventilation strategies in experimental lung injury.

RATIONALE: Noisy ventilation with variable Vt may improve respiratory function in acute lung injury. OBJECTIVES: To determine the impact of noisy ventilation on respiratory function and its biological effects on lung parenchyma compared with conventional protective mechanical ventilation strategies. METHODS: In a porcine surfactant depletion model of lung injury, we randomly combined noisy ventilation with the ARDS Network protocol or the open lung approach (n = 9 per group). MEASUREMENTS AND MAIN RESULTS: Respiratory mechanics, gas exchange, and distribution of pulmonary blood flow were measured at intervals over a 6-hour period. Postmortem, lung tissue was analyzed to determine histological damage, mechanical stress, and inflammation. We found that, at comparable minute ventilation, noisy ventilation (1) improved arterial oxygenation and reduced mean inspiratory peak airway pressure and elastance of the respiratory system compared with the ARDS Network protocol and the open lung approach, (2) redistributed pulmonary blood flow to caudal zones compared with the ARDS Network protocol and to peripheral ones compared with the open lung approach, (3) reduced histological damage in comparison to both protective ventilation strategies, and (4) did not increase lung inflammation or mechanical stress. CONCLUSIONS: Noisy ventilation with variable Vt and fixed respiratory frequency improves respiratory function and reduces histological damage compared with standard protective ventilation strategies.