Differential effect of three commercial heparins on Na+/H+ exchange and growth of PASMC

1996 ◽  
Vol 270 (2) ◽  
pp. L260-L265 ◽  
Author(s):  
C. G. Dahlberg ◽  
B. T. Thompson ◽  
P. M. Joseph ◽  
H. G. Garg ◽  
C. R. Spence ◽  
...  
Keyword(s):  
Amino Acid ◽  
Antiproliferative Activity ◽  
Fluorescent Microscopy ◽  
Variable Effect ◽  
Chemical Content ◽  
Acid Load ◽  
Pulmonary Artery Smooth Muscle ◽  
Intracellular Alkalinization ◽  
Heparin Preparation ◽  
Stimulation Of

Heparin preparations vary in chemical content and in antiproliferative activity for pulmonary artery smooth muscle cells (PASMC). Intracellular alkalinization via stimulation of the Na+/H+ antiporter appears to be a permissive event for proliferation of PASMC. We wondered whether the variable effect of heparin preparations on PASMC growth might be due to different degrees of inhibition of the Na+/H+ antiporter and whether variations in chemical formulation might correlate with the inhibition. Fluorescent microscopy of bovine PASMC was done using a dye with which fluorescence varies directly with intracellular pH (pHi). Bovine PASMC were preincubated with three heparin preparations previously shown to vary in antiproliferative activity, at 1.0 microgram/ml for 24 h. Platelet-derived growth factor (PDGF; 60 ng/ml) on PASMC without heparin resulted in a rise in pHi of 0.27 +/- 0.02 pH units. The rise in pH units in heparin-treated PASMC was 0.34 +/- 0.03 with Choay, 0.21 +/- 0.02 with Elkins-Sinn, and 0.07 +/- 0.02 with Upjohn (+/-SE; all P < 0.05; n = 5). Upjohn heparin incubation for as little as 15 min still impeded the rise in pH induced by PDGF. Heparin did not block the Na+/H+ exchanger directly, as it still restored pHi in response to an acid load. Compared with PASMC proliferation induced by 60 ng/ml PDGF, 1 microgram/ml of Choay, Elkins-Sinn, and Upjohn heparin produced -4 +/- 7.4, 1.4 +/- 4.8, and 48 +/- 2.2% inhibition of PDGF control, respectively (P < 0.05 for Upjohn compared with PDGF and Choay). The heparins varied in protein content and amino acid composition. However, amino acid and glucosamine composition, total sulfation, and extent of 3-O-sulfation did not predict their activity. Thus inhibition of PDGF activation of the Na+/H+ antiporter by a given heparin preparation correlated well with its ability to inhibit PASMC proliferation.

scholarly journals Insulin Stimulation of Amino Acid Uptake in Rat Diaphragm

1968 ◽  
Vol 243 (8) ◽  
pp. 1846-1853 ◽  
Author(s):  
L J Elsas ◽  
I Albrecht ◽  
L E Rosenberg
Keyword(s):  
Amino Acid ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Rat Diaphragm ◽  
Insulin Stimulation ◽  
Stimulation Of

Effect of chronic inflammation on electrolyte transport in rabbit ileal villus and crypt cells

1997 ◽  
Vol 272 (4) ◽  
pp. G732-G741 ◽  
Author(s):  
U. Sundaram ◽  
A. B. West
Keyword(s):  
Chronic Inflammation ◽  
Inflammatory Mediators ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Basolateral Membrane ◽  
Rabbit Model ◽  
Electrolyte Transport ◽  
Acid Load ◽  
Crypt Cells ◽  
Stimulation Of

The effect of chronic inflammation on electrolyte transport in rabbit ileal villus and crypt cells was determined with the use of a rabbit model of chronic ileitis. In both cells, Na+/H+ exchange was monitored by following recovery from an acid load, and Cl-/HCO3- exchange was monitored by following recovery from an alkaline load. In villus cells, recovery from an acid load was not affected; however, recovery from an alkaline load was slowed. These data suggest that chronic inflammation inhibits Cl-/HCO3- exchange in villus cells. In contrast, in crypt cells, recovery from an alkaline load was unaffected, whereas recovery from an acid load was accelerated. These data suggest that chronic inflammation stimulates Na+/H+ exchange in crypt cells. Inhibition of Cl-/HCO3- exchange in villus cells would be expected to inhibit coupled NaCl absorption, which occurs by the coupling of brush-border membrane (BBM) Na+/H+ and Cl-/HCO3- exchange. Stimulation of Na+/H+ exchange in crypt cells, known to be present only on the basolateral membrane, alkalinizes the cell. This alkalinization may stimulate BBM Cl-/HCO3- exchange, resulting in HCO3- secretion. Thus these unique alterations in transporter activity suggest that different endogenous immune-inflammatory mediators may have differing effects on specific transporters in villus and crypt cells in the chronically inflamed ileum.

scholarly journals 15 A novel CD28 humanized mouse model for efficacy assessment of CD28-targeting therapies

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A15-A15
Author(s):  
Fabiane Sônego ◽  
Gaelle Martin ◽  
Chloé Beuraud ◽  
Audrey Beringer ◽  
Yacine Cherifi ◽  
...  
Keyword(s):  
T Cells ◽  
Amino Acid ◽  
Mouse Model ◽  
Cytokine Production ◽  
List Type ◽  
Humanized Mouse ◽  
Humanized Mouse Model ◽  
Efficacy Assessment ◽  
Human And Mouse ◽  
Stimulation Of

BackgroundImmuno-intervention through targeting of activating and inhibitory immune checkpoints (ICP), has shown promising results in the clinic over the last years. To facilitate these researches, mouse models expressing humanized ICP instead of their mouse counterparts were developed. Herein, we describe a novel CD28 humanized mouse model (hCD28 model), designed to test compounds targeting human CD28 (hCD28).MethodsHuman and mouse CD28 (mCD28) have different signalling responses, with hCD28 being known for inducing higher levels of pro-inflammatory cytokines upon stimulation with ligands/superagonists. This can be explained by the expression of CD28i, a hCD28 amplifier isoform which is not found in mouse. Additionally, evidences suggested that the different signalling between human and mCD28 relies on one amino acid change in the intracellular domain (ICD).1 Because the hCD28 model was developed to assess hCD28-targeting therapeutics, we decided to keep the expression of both canonical and CD28i isoforms to avoid undermining the biological effects of the testing antibodies. Although keeping the human ICD could favour the evaluation of cytokine production and therefore the safety of the test therapeutics, we decided to keep the mouse ICD to enable a proper interaction of CD28 with its signalling partners, allowing a physiological stimulation of CD28 in efficacy studies.Results hCD28 mice express hCD28 on T cells and the frequency of CD3 T cells is comparable in both WT and hCD28 mice. Stimulation of hCD28 mice-isolated T cells with hCD28 ligands and agonist antibodies resulted in T cell proliferation and cytokine production, suggesting that hCD28 is functional in mouse cells. MC38 uptake rate and kinetic of growth were comparable in WT and hCD28 mice, suggesting no major defect in the immune response in the hCD28 mice. Importantly, splenocytes and tumor draining lymph nodes cells isolated from tumor-bearing hCD28 mice showed higher production of IL-2 and IFN-gamma upon in vitro re-challenged with MC38 when compared to WT cells. Since the frequency of CD3 cells (Treg, CD4+ and CD8+) is comparable to WT mice, this could be explained by the expression of the amplifier CD28i isoform, which is absent in WT mice.ConclusionsThe hCD28 model described here supports the efficacy assessment of hCD28-targeting biologics, enabling PK/PD studies as hCD28 expression levels and pattern are physiological. However, after careful consideration of the CD28 biology, we decided to keep the mouse ICD, although it triggers lower pro-inflammatory cytokine production than CD28 human ICD. As such, this model is not suitable for toxicology/safety studies.ReferencePorciello N, Grazioli P, Campese AF, et al. A non-conserved amino acid variant regulates differential signalling between human and mouse CD28. Nat Commun 2018; 9:1–16.

The disposal of an intravenously administered amino acid load across the human forearm

Metabolism ◽  
1982 ◽  
Vol 31 (5) ◽  
pp. 463-470 ◽  
Author(s):  
Naji N. Abumrad ◽  
David Rabin ◽  
Kendall L. Wise ◽  
W.W. Lacy
Keyword(s):  
Amino Acid ◽  
Amino Acid Load ◽  
Human Forearm ◽  
Acid Load
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