Pharmacological studies confirm neurotoxic metabolite(s) produced by the bloom-forming Cylindrospermopsis raciborskii in Hungary.

A rapid cyanobacterial bloom of Cylindrospermopsis raciborskii (3.2 × 10(4) filaments/mL) was detected early November, 2012, in the Fancsika pond (East Hungary). The strong discoloration of water was accompanied by a substantial fish mortality (even dead cats were seen on the site), raising the possibility of some toxic metabolites in the water produced by the bloom-forming cyanobacteria (C. raciborskii). The potential neuronal targets of the toxic substances in the bloom sample were studied on identified neurons (RPas) in the central nervous system of Helix pomatia. The effects of the crude aqueous extracts of the Fancsika bloom sample (FBS) and the laboratory isolate of C. raciborskii from the pond (FLI) were compared with reference samples: C. raciborskii ACT 9505 (isolated in 1995 from Lake Balaton, Hungary), the cylindrospermopsin producer AQS, and the neurotoxin (anatoxin-a, homoanatoxin-a) producer Oscillatoria sp. (PCC 6506) strains. Electrophysiological tests showed that both FBS and FLI samples as well the ACT 9505 extracts modulate the acetylcholine receptors (AChRs) of the neurons, evoking ACh agonist effects, then inhibiting the ACh-evoked neuronal responses. Dose-response data suggested about the same range of toxicity of FBS and FLI samples (EC50 = 0.397 mg/mL and 0.917 mg/mL, respectively) and ACT 9505 extracts (EC50 = 0.734 mg/mL). The extract of the neurotoxin-producing PCC 6506 strain, however, proved to be the strongest inhibitor of the ACh responses on the same neurons (EC50 = 0.073 mg/mL). The presented results demonstrated an anatoxin-a-like cholinergic inhibitory effects of cyanobacterial extracts (both the environmental FBS sample, and the laboratory isolate, FLI) by some (yet unidentified) toxic components in the matrix of secondary metabolites. Previous pharmacological studies of cyanobacterial samples collected in other locations (Balaton, West Hungary) resulted in similar conclusions; therefore, we cannot exclude that this chemotype of C. raciborskii which produce anatoxin-a like neuroactive substances is more widely distributed in this region.

Regulation of proteolytic activity induced by inflammatory stimuli in lung epithelial cells.

A large number of chronic lung diseases such as asthma bronchiale are associated with alveolar and/or bronchial inflammation accompanied by a damage of the alveolocapillary barrier. In this process proteolytic mechanisms may play a crucial role. The aim of the present study was to assess the role of TNF-alpha on the proteolytic activity of pulmonary epithelial cells and to find possible intracellular signaling pathways which may mediate the effect of TNF-alpha. For our studies we have used the A549 human lung epithelial cell line. Plasminogen activator and metalloproteinase activity was measured using zymography. TNF-alpha induced a time and concentration dependent activation of the urokinase type plasminogen activator (u-PA) and tissue type plasminogen activator (t-PA) activity in A549 cells. This effect could be blocked completely by dexamethasone and was reduced significantly by the Rho-kinase inhibitor Y27632. Similarly, an increased activity in the culture medium of the 72 kDa MMP-2 in response to TNF-alpha could be observed as well. This could be reduced by dexamethasone and Y27632. Our results show that TNF-alpha is at least partly responsible for an increased proteolytic activity and beside corticosteroids Rho-kinase may constitute a potential target for future therapeutical approaches.

Growth factor-induced morphological, physiological and molecular characteristics in cerebral endothelial cells.

The capacity of vascular endothelial cells to modulate their phenotype in response to changes in environmental conditions is one of the most important characteristics of this cell type. Since different growth factors may play an important signalling role in this adaptive process we have investigated the effect of endothelial cell growth factor (ECGF) on morphological, physiological and molecular characteristics of cerebral endothelial cells (CECs). CECs grown in the presence of ECGF and its cofactor heparin exhibit an epithelial-like morphology (type I CECs). Upon removal of growth factors, CECs develop an elongated spindle-like shape (type II CECs) which is accompanied by the reorganization of actin filaments and the induction of alpha-actin expression. Since one of the most important functions of CECs is the creation of a selective diffusion barrier between the blood and the central nervous system (CNS), we have studied the expression of junction-related proteins in both cell types. We have found that removal of growth factors from endothelial cultures leads to the downregulation of cadherin and occludin protein levels. The loss of junctional proteins was accompanied by a significant increase in the migratory activity and an altered protease activity profile of the cells. TGF-beta1 suppressed endothelial migration in all experiments. Our data provide evidence to suggest that particular endothelial functions are largely controlled by the presence of growth factors. The differences in adhesiveness and migration may play a role in important physiological and pathological processes of endothelial cells such as vasculogenesis or tumor progression.

Adalimumab in Crohn's disease: tips and tricks after 5 years of clinical experience.

INTRODUCTION: Three anti TNF-α agents have currently been approved for the treatment of moderate-to-severe or complicated Crohn's disease (CD): infliximab, certolizumab and adalimumab. Infliximab is effective in CD, but for reasons linked to its chimeric structure, response to treatment may be lost overtime and as a result, it can sometimes be unable to provide long term durable treatment of CD. Adalimumab, a fully human anti TNF-α antibody, demonstrates similar treatment efficacy as infliximab and certolizumab, and can easily be self-administered at home. AIM AND METHODS: A literature search in the Cochrane, MEDLINE, PUBMED, Ovid MEDLINER® and EMBASE databases has been performed on the efficacy, safety and the impact adalimumab has on the quality of life and natural history of CD. Abstracts presented at the DDW, UEGW and ECCO Congresses have also been reviewed as well as references from review articles, meta-analysis studies and published RCTs. RESULTS: Adalimumab induced remission of CD in 64% of patients, and maintained remission in more than 80% of initial responders. Adalimumab did not significantly increase the risk of adverse events compared with conventional medication up to 3 years of follow-up. Adalimumab reduces more than 50% the risk for hospitalisation and surgery due to CD. It is also effective for fistula closure, for the healing of the mucosa, and improving quality of life. CONCLUSION: Adalimumab is effective in the induction and maintenance of clinical remission in CD and is generally well tolerated. It has been proved to have a positive impact by improving quality of life of patients, and reducing the need for hospitalisation and surgery due to CD. According to the European Crohn's and Colitis Organisation (ECCO), infliximab or adalimumab can be used for the treatment of fistulizing CD.

Review article: anti-fibrotic agents for the treatment of Crohn's disease - lessons learnt from other diseases.

BACKGROUND: The current therapies for Crohn's disease (CD) are mainly focused on blockade of inflammation. Fibrosis remains one of the major complications of CD often leading to surgery, affecting patients' quality-of-life. AIM: To summarize the published data regarding the potential anti-fibrotic role of drugs commonly used in CD and the most effective anti-fibrotic drugs used in other diseases evaluating their potential use to treat intestinal fibrosis in CD. METHODS: A literature search was performed in the PubMed, Medline, Cochrane and EMBASE databases, considering in vitro, animal and human studies on fibrosis in inflammatory bowel disease and other similar chronic pathologies. RESULTS: Treatment of fibrosis in CD is limited to surgery or endoscopic dilatation, although some of the drugs currently used may have anti-fibrotic activity. In other diseases, anti-fibrotic agents are already used or are in preclinical or clinical trials. ACE inhibitors, Angiotensin Receptor Blockers, and HMG-CoA inhibitors merit further investigation in CD because of their role in preventing fibrosis in cardiovascular and renal diseases. CONCLUSIONS: Anti-fibrotic drugs are under evaluation or already used in clinical practice in other chronic inflammatory diseases. In CD, there is a great need for investigation into agents that may prevent, reduce or reverse intestinal fibrosis.