A modeling framework for contact, adhesion and mechano-transduction between excitable deformable cells

Cardiac myocytes are the fundamental cells composing the heart muscle. The propagation of electric signals and chemical quantities through them is responsible for their nonlinear contraction and dilatation. In this study, a theoretical model and a finite element formulation are proposed for the simulation of adhesive contact interactions between myocytes across the so-called gap junctions. A multi-field interface constitutive law is proposed for their description, integrating the adhesive and contact mechanical response with their electrophysiological behavior. From the computational point of view, the initial and boundary value problem is formulated as a structure-structure interaction problem, which leads to a straightforward implementation amenable for parallel computations. Numerical tests are conducted on different couples of myocytes, characterized by different shapes related to their stages of growth, capturing the experimental response. The proposed framework is expected to have impact on the understanding how imperfect mechano-transduction could lead to emergent pathological responses.Comment: 31 pages, 17 figure

Phase field modelling and simulation of damage occurring in human vertebra after screws fixation procedure

The present endeavor numerically exploits the use of a phase-field model to simulate and investigate fracture patterns, deformation mechanisms, damage, and mechanical responses in a human vertebra after the incision of pedicle screws under compressive regimes. Moreover, the proposed phase field framework can elucidate scenarios where different damage patterns, such as crack nucleation sites and crack trajectories, play a role after the spine fusion procedure, considering several simulated physiological movements of the vertebral body. A convergence analysis has been conducted for the vertebra-screws model, considering several mesh refinements, which has demonstrated good agreement with the existing literature on this topic. Consequently, by assuming different angles for the insertion of the pedicle screws and taking into account a few vertebral motion loading regimes, a plethora of numerical results characterizing the damage occurring within the vertebral model has been derived. Overall, the phase field results may shed more light on the medical community, which will be useful in enhancing clinical interventions and reducing post-surgery bone failure and screw loosening.Comment: 23 pages, 9 figures. arXiv admin note: text overlap with arXiv:2207.0936

Modulatory Effect of Gliadin Peptide 10-mer on Epithelial Intestinal CACO-2 Cell Inflammatory Response.

Celiac Disease (CD) is a chronic inflammatory enteropathy, triggered in genetically susceptible individuals by dietary gluten. Gluten is able to elicit proliferation of specific T cells and secretion of inflammatory cytokines in the small intestine. In this study we investigated the possibility that p10-mer, a decapeptide from durum wheat (QQPQDAVQPF), which was previously shown to prevent the activation of celiac peripheral lymphocytes, may exert an inhibitory effect on peptic-tryptic digested gliadin (PT-Gly)-stimulated intestinal carcinoma CACO-2 cells. In these cells, incubated with PT-Gly or p31-43 α-gliadin derived peptide in the presence or in the absence of p10-mer, IRAK1 activation and NF-kB, ERK1/2 and p38 MAPK phosphorylation were measured by immunoblotting, Cyclooxigenase 2 (COX-2) activity by PGE-2 release assay, and production of cytokines in the cell supernatants by ELISA. Our results showed that pre-treatment of CACO-2 cells with p10-mer significantly inhibited IRAK1 activation and NF-kB, ERK1/2 and p38 MAPK phosphorylation, as well as COX-2 activity (i.e. PGE-2 release) and production of the IL-6 and IL-8 pro-inflammatory cytokines, induced by gliadin peptides. These findings demonstrate the inhibitory effect of the p10-mer peptide on inflammatory response in CACO-2 cells. The results of the present study show that this p10-mer peptide can modulate "in vitro" the inflammatory response induced by gliadin peptides, allowing to move towards new therapeutic strategies. Turning off the inflammatory response, may in fact represent a key target in the immunotherapy of celiac disease

Adherence of uremic erythrocytes to vascular endothelium decreases endothelial nitric oxide synthase expression

Adherence of uremic erythrocytes to vascular endothelium decreases endothelial nitric oxide synthase expression.BackgroundHigh prevalence of atherosclerotic cardiovascular events accounts for much of the mortality among patients suffering from end-stage renal disease (ESRD). Endothelial dysfunction as a pathogenic mechanism might contribute to increasing the cardiovascular risk of ESRD. Reduced endothelium-dependent vasodilation has consistently been observed in chronic renal failure patients. Since nitric oxide (NO) is the principal endothelium-derived vasodilator, a reduction in the NO bioavailability may be envisaged in ESRD patients.MethodsTo clarify whether exposure to erythrocytes from ESRD patients might modulate NO release by the endothelium, we evaluated endothelial NO synthase (eNOS) protein levels (Western blot), eNOS mRNA quantity (real-time PCR), and NOS activity (conversion of L-[3H] arginine in L-[3H] citruline) in endothelial cultures stimulated by erythrocytes from healthy subjects and ESRD patients.ResultsA time-dependent decrease in eNOS protein levels was evident in cultures treated with erythrocytes from ESRD patients. This observation was consistent with the decreased eNOS mRNA quantities induced by erythrocytes from such patients. Moreover, compared to controls, NOS activity exhibited a significant reduction after incubation with erythrocytes from ESRD patients. The observed eNOS reduction induced by erytrocytes from ESRD patients was totally abolished by annexin V, able to mask red blood cell (RBC) surface-exposed phosphatidylserine.ConclusionThese findings suggest that adhesion of erythrocytes from ESRD patients to vascular endothelium may cause a decrease in the levels of eNOS mRNA and protein, and inhibition of NOS activity. This might contribute to endothelial dysfunction, and may play a role in the pathogenesis of cardiovascular disease in ESRD patients

Modulatory Effect of Gliadin Peptide 10-mer on Epithelial Intestinal CACO-2 Cell Inflammatory Response

Celiac Disease (CD) is a chronic inflammatory enteropathy, triggered in genetically susceptible individuals by dietary gluten. Gluten is able to elicit proliferation of specific T cells and secretion of inflammatory cytokines in the small intestine. In this study we investigated the possibility that p10-mer, a decapeptide from durum wheat (QQPQDAVQPF), which was previously shown to prevent the activation of celiac peripheral lymphocytes, may exert an inhibitory effect on peptic-tryptic digested gliadin (PT-Gly)-stimulated intestinal carcinoma CACO-2 cells. In these cells, incubated with PT-Gly or p31-43 α-gliadin derived peptide in the presence or in the absence of p10-mer, IRAK1 activation and NF-kB, ERK1/2 and p38 MAPK phosphorylation were measured by immunoblotting, Cyclooxigenase 2 (COX-2) activity by PGE-2 release assay, and production of cytokines in the cell supernatants by ELISA. Our results showed that pre-treatment of CACO-2 cells with p10-mer significantly inhibited IRAK1 activation and NF-kB, ERK1/2 and p38 MAPK phosphorylation, as well as COX-2 activity (i.e. PGE-2 release) and production of the IL-6 and IL-8 pro-inflammatory cytokines, induced by gliadin peptides. These findings demonstrate the inhibitory effect of the p10-mer peptide on inflammatory response in CACO-2 cells. The results of the present study show that this p10-mer peptide can modulate "in vitro" the inflammatory response induced by gliadin peptides, allowing to move towards new therapeutic strategies. Turning off the inflammatory response, may in fact represent a key target in the immunotherapy of celiac disease

Inhibitory effect of gliadin peptide 10-mer on cytokine production.

<p>CACO-2/TC7 cells either unstimulated or stimulated with PT-Gly (1mg/ml), p10-mer (50 µg/ml), p10-mer (50 µg/ml) + PT-Gly (1mg/ml) were analyzed for cytokine production. Cell supernatants were analyzed for pro-inflammatory cytokines IL-6 (<b>A</b>) and IL-8 (<b>B</b>) release by an ELISA kit. Statistical analysis: *P<0.01 <i>versus</i> control; §P<0.05 <i>versus</i> PT-Gly. Results are expressed as mean ± SD; n = 3.</p

Effect of gliadin peptide 10-mer on p31–43 activity and entrance in CACO-2 cells.

<p>(<b>A</b>) CACO-2/TC7 cells, either unstimulated or stimulated with p31–43 (50 µg/ml), p10-mer (50 µg/ml) + p31–43 (50 µg/ml), were analyzed by Western blot for ERK phosphorylation and NF-kB activation. (<b>i</b>) Phosphorylated levels of ERK were analyzed in whole cell extracts by Western blot with anti-phospho-ERK1/2 antibodies; for control, the blotted membranes were stripped and reprobed with anti-ERK1/2 antibodies. Bound antibodies were visualized with HRP-conjugated IgG and immunoreactivity was assessed by ECL. (<b>ii</b>) NF-kB activation was analyzed in whole cell extracts by Western blot with anti-phospho-NF-kB p65 Ser antibodies; for control, the blotted membranes were stripped and reprobed with anti-NF-kB p65 antibodies. Bound antibodies were visualized with HRP-conjugated IgG and immunoreactivity was assessed by ECL. Densitometric analysis was performed using ImageJ version 1.46 software, peaks were reproduced by reading the Western Blot bands. One example representative of 3 experiments. (<b>B</b>) CACO-2/TC7 cells, either unstimulated or stimulated with biotinylated p31–43 (50 µg/ml), p10-mer (50 µg/ml) + biotinylated p31–43 (50 µg/ml), were immunostained with streptavidin-AlexaFluor and analyzed by a BD FACSCalibur flow cytometer. (<b>C</b>) CACO-2/TC7 cells, either unstimulated or stimulated with biotinylated p31–43 (50 µg/ml), p10-mer (50 µg/ml) + biotinylated p31–43 (50 µg/ml), were immunostained with streptavidin-AlexaFluor. The images were acquired using an Olympus U RFL fluorescence microscope.</p

Inhibitory effect of gliadin peptide 10-mer on IRAK1 phosphorylation and NF-kB activation.

<p>CACO-2/TC7 cells, either unstimulated or stimulated with PT-Gly (1mg/ml), p10-mer (50 µg/ml), p10-mer (50 µg/ml) + PT-Gly (1mg/ml), were analyzed by Western blot for IRAK1 phosphorylation and NF-kB activation. (<b>A</b>) Phosphorylated levels of IRAK1 (p-IRAK1) were analyzed in whole cell extracts by Western blot with anti-phospho-IRAK1 antibodies; for control, the blotted membranes were stripped and reprobed with anti-IRAK-1 antibodies. Bound antibodies were visualized with HRP-conjugated IgG and immunoreactivity was assessed by ECL. (<b>B</b>) NF-kB activation was analyzed in whole cell extracts by Western blot with anti-phospho-NF-kB p65 Ser antibodies; for control, the blotted membranes were stripped and reprobed with anti-NF-kB p65 antibodies. Bound antibodies were visualized with HRP-conjugated IgG and immunoreactivity was assessed by ECL. Densitometric analysis was performed using ImageJ version 1.46 software and peaks were reproduced by reading the Western Blot bands. One example representative of 3 experiments.</p

Inhibitory effect of gliadin peptide 10-mer on ERK and p38 MAPK phosphorylation.

<p>CACO-2/TC7 cells either unstimulated or stimulated with PT-Gly (1mg/ml), p10-mer (50 µg/ml), p10-mer (50 µg/ml) + PT-Gly (1mg/ml), were analyzed by Western blot for ERK and p38 phosphorylation. Phosphorylated levels of ERK were analyzed in whole cell extracts by Western blot with anti-phospho-ERK1/2 antibodies; for control, the blotted membranes were stripped and reprobed with anti-ERK1/2 antibodies. Bound antibodies were visualized with HRP-conjugated IgG and immunoreactivity was assessed by ECL. (<b>B</b>) Phosphorylated levels of p38 MAPK were analyzed in whole cell extracts by Western blot with anti-phospho-p38 MAPK antibodies; for control, the blotted membranes were stripped and reprobed with anti-p38 MAPK antibodies. Bound antibodies were visualized with HRP-conjugated IgG and immunoreactivity was assessed by ECL. Densitometric analysis was performed using ImageJ version 1.46 software and peaks were reproduced by reading the Western Blot bands. One example representative of 3 experiments.</p