Biogenesis and function of fibrillin assemblies

Fibrillin-1 and fibrillin-2 are large cysteine-rich glycoproteins that serve two key physiological functions: as supporting structures that impart tissue integrity and as regulators of signaling events that instruct cell performance. The structural role of fibrillins is exerted through the temporal and hierarchical assembly of microfibrils and elastic fibers, whereas the instructive role reflects the ability of fibrillins to sequester transforming growth factor β (TGFβ) and bone morphogenetic protein (BMP) complexes in the extracellular matrix. Characterization of fibrillin mutations in human patients and in genetically engineered mice has demonstrated that perturbation of either function manifests in disease. More generally, these studies have indicated that fibrillins are integral components of a broader biological network of extracellular, cell surface, and signaling molecules that orchestrate morphogenetic and homeostatic programs in multiple organ systems. They have also suggested that the relative composition of fibrillin-rich microfibrils imparts contextual specificity to TGFβ and BMP signaling by concentrating the ligands locally so as to regulate cell differentiation within a spatial context during organ formation (positive regulation) and by restricting their bioavailability so as to modulate cell performance in a timely fashion during tissue remodeling/repair (negative regulation). Correlative evidence suggests functional coupling of the cell-directed assembly of microfibrils and targeting of TGFβ and BMP complexes to fibrillins. Hence, the emerging view is that fibrillin-rich microfibrils are molecular integrators of structural and instructive signals, with TGFβ and BMPs as the nodal points that convert extracellular inputs into discrete and context-dependent cellular responses.     

Extragastric manifestations of Helicobacter pylori infection

The possible role of Helicobacter pylori as a trigger for some extragastric diseases has been largely investigated in the last year. There are, in fact, several studies concerning cardiovascular diseases, neurological disorders, diabetes mellitus, ear and eyes diseases, immunological and hematological disorders, liver and bile tract diseases, gynecological and respiratory tract pathologies. Among them, idiopathic sideropenic anemia and idiopathic thrombocytopenic purpura still remain the extragastric diseases showing the most convincing results. Concerning ischemic heart disease, there are new interesting data playing in favor of the association, even though there are still some open issues to be clarified. For the other diseases, more studies are needed to clarify the reality of the proposed association.     

Short-term therapy with celecoxib and lansoprazole modulates Th1/ Th2 immune response in human gastric mucosa

Background: Selective cyclooxygenase‐2 (COX‐2) inhibitors and proton pump inhibitors may exert immune‐mediated effects in human gastric mucosa. T‐cell immune response plays a role in Helicobacter pylori‐induced pathogenesis. This study evaluated effects of celecoxib and lansoprazole on T‐helper (Th) 1 and Th2 immune response in human gastric mucosa. Methods: Dyspeptic patients with or without osteoarticular pain were given one of the following 4‐week therapies: celecoxib 200 mg, celecoxib 200 mg plus lansoprazole 30 mg, and lansoprazole 30 mg daily. Expression of COX‐2, T‐bet, and pSTAT6 and production of prostaglandin E₂ (PGE₂), interferon (IFN)‐γ, and interleukin (IL)‐4 were determined in gastric biopsies before and after therapy. Histology was evaluated. Results: Cyclooxygenase‐2 expression and PGE₂ production was higher, and Th1 signaling pathway was predominant in H. pylori‐infected vs. uninfected patients. T‐bet expression and IFN‐γ production increased, while STAT6 activation and IL‐4 production decreased following therapy with celecoxib and celecoxib plus lansoprazole, respectively. Th1 and Th2 signaling pathways down‐regulated after therapy with lansoprazole, and this was associated with an improvement of gastritis. Effect of therapy was not affected by H. pylori status. Conclusion: Celecoxib and lansoprazole modulate Th1/Th2 immune response in human gastric mucosa. The use of these drugs may interfere with long‐term course of gastritis.     

pH dependence of the enzymatic processing of collagen I by MMP-1 (fibroblast collagenase), MMP-2 (gelatinase A), and MMP-14 ectodomain

The proteolytic processing of collagen I by three matrix metalloproteinases (MMPs), a collagenase (MMP-1), a gelatinase (MMP-2), and the ectodomain of a membrane-type metalloproteinase (MMP-14), has been investigated at 37 °C between pH 6.0 and 9.2, a pH range reflecting conditions found in different body compartments under various physiopathological processes. In the proteolytic degradation the native collagen triple helix must be partially unwound to allow the binding of α chains to the protease’s active-site cleft. We have found that MMP-1 interacts with the two types of collagen I α chains in a similar fashion, whereas both MMP-2 and MMP-14 bind the two α chains in a different way. The overall enzymatic activity is higher on the α-2 chain for both MMP-1 and MMP-2, whereas the MMP-14 ectodomain preferentially cleaves the α-1 chain. In MMP-2 a marked difference for substrate affinity (higher for the α-1 chain) is overwhelmed by an even more marked propensity to cleave the α-2 chain. As a whole, the three classes of MMPs investigated appear to process collagen I in a significantly different fashion, so various MMPs play different roles in the collagen homeostasis in various compartments (such as bloodstream, synovial fluid, normal and tumoral tissues), where different pH values are observed.     

Synthesis and molecular modelling studies of prenylated pyrazolines as MAO-B inhibitors

A series of N-substituted-3-[(2'-hydroxy-4'-prenyloxy)-phenyl]-5-phenyl-4,5-dihydro-(1H)-pyrazolines were synthesized and tested on human monoamine oxidase-A and -B isoforms. Structure-activity relationships and molecular modelling showed that some substitutions, such as benzyloxy or chlorine atom, improve the best interaction with active site of hMAO-B.     

Comparative 5-doxylstearoyllecithin and 3-doxylcholestane EPR spin labeling study of phospholipid bilayer perturbation by different oxidized lecithin species

A 3-doxylcholestane spin label was employed in addition to 5-doxylstearoyl lecithin for a more detailed study of the different effects exerted by variously oxidized lecithins on fatty acid alignment in phospholipid planar bilayers. Either spin label was enclosed in oriented PLPC planar samples also containing in turn a variety of conjugated-dienes lecithins and cleaved chain lecithins, in order to monitor EPR spectral angular dependence loss. Data obtained by use of arachidonoyl-hydroxystearoyl-PC and palmitoyl-hydroxylinoleoyl-PC confirm that the 5-DSPC nitroxide ring almost completely retains its orientation in CD-PCs-containing planar membranes, in contrast with angular dependence loss observed in the presence of the CC-PC molecular species palmitoyl-oxononanoyl-PC and palmitoyl-oxovaleroyl-PC, already seen with cleaved-chain palmitoyl-glutaroyl-PC and palmitoyl-azelaoyl-PC. However, the 3-DC nitroxide ring also loses its orientation with CD-PCs, in addition to being disoriented by cleaved chain-lecithins, similarly to 5DSPC. Joint information from the two spin labels will help to clarify whether OXPC-related disordering involved the whole bilayer structure or only the hydrophobic core. In addition, the propensity of different OXPCs to form bilayer vesicles in water suspension was also determined by Sepharose 4B gel-chromatography. The results suggest that CD-PCs might yield SPB bilayer structures with a disordered hydrophobic core, while pure CC-PC more probably forms non-bilayer disordered structures, possibly micelles or mixed micelle/bilayers.     

Design, synthesis, biophysical and biological studies of trisubstituted naphthalimides as G-quadruplex ligands

A series of trisubstituted naphthalimides have been synthesized and evaluated as telomeric G-quadruplex ligands by biophysical methods. Affinity for telomeric G-quadruplex AGGG(TTAGGG)(3) binding was first screened by fluorescence titrations. Subsequently, the interaction of the telomeric G-quadruplex with compounds showing the best affinity has been studied by isothermal titration calorimetry and UV-melting experiments. The two best compounds of the series tightly bind the telomeric quadruplex with a 2:1 drug/DNA stoichiometry. These derivatives have been further evaluated for their ability to inhibit telomerase by a TRAP assay and their pharmacological properties by treating melanoma (M14) and human lung cancer (A549) cell lines with increasing drug concentrations. A dose-dependent inhibition of cell proliferation was observed for all cellular lines during short-term treatment.     

“Glycans and Glycosylation in SARS-COV2 Infection” session at the XVII Advanced School in Carbohydrate Chemistry,Italian Chemical Society. July 4th -7th 2021, Pontignano (Si), Italy

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