Cyclosporin H

Cyclosporin H is a potent, selective and competitive formyl peptide receptor (FPR) antagonist with IC50 value of 0.7 μM [1].

The formyl peptide receptor (FPR) is a G protein-coupled receptor involved in chemotaxis and mediating immune cell response to infection.

Cyclosporin H (CsH) is a potent and selective FPR antagonist. In human neutrophils, cyclosporin H inhibited FMLP-induced superoxide anion (O2-) formation. CsH inhibited the binding of FMLP (3 nM) to HL-60 membrane with IC50 and Ki values of 0.7 μM and 0.10 μM, respectively. CsH inhibited GTP hydrolysis stimulated by FMLP (100 nM) with IC50 and Ki values of 1.3 μM and 0.79 μM, respectively. CsH also inhibited the increase of [Ca2+Ii, O2- formation and β-glucuronidase release induced by FMLP with IC50 values of 0.23, 0.6 and 2.2 μM, and with Ki values of 0.08, 0.24, and 0.45 μM, respectively [1][2]. In peripheral blood basophils, CsH (8-800 nM) competitively and concentration-dependently inhibited leukotriene C4 and histamine release activated by FMLP [3]. In eosinophils isolated from bronchoalveolar lavage fluid of mice challenged with inhaled allergen, cyclosporin H increased apoptosis in the presence of 10 U/ml interleukin 5 in a concentration-dependent way. Cyclosporin H also increased apoptosis in the presence of 10 U/ml GM-CSF, but to a lesser extent [4].

References:
[1].  Wenzel-Seifert K, Seifert R. Cyclosporin H is a potent and selective formyl peptide receptor antagonist. Comparison with N-t-butoxycarbonyl-L-phenylalanyl-L-leucyl-L-phenylalanyl-L- leucyl-L-phenylalanine and cyclosporins A, B, C, D, and E. J Immunol, 1993, 150(10): 4591-4599.
[2].  Wenzel-Seifert K, Grünbaum L, Seifert R. Differential inhibition of human neutrophil activation by cyclosporins A, D, and H. Cyclosporin H is a potent and effective inhibitor of formyl peptide-induced superoxide formation. J Immunol, 1991, 147(6): 1940-1946.
[3].  de Paulis A, Ciccarelli A, de Crescenzo G, et al. Cyclosporin H is a potent and selective competitive antagonist of human basophil activation by N-formyl-methionyl-leucyl-phenylalanine. J Allergy Clin Immunol, 1996, 98(1): 152-164.
[4].  Kitagaki K, Nagai H, Hayashi S, et al. Facilitation of apoptosis by cyclosporins A and H, but not FK506 in mouse bronchial eosinophils. Eur J Pharmacol, 1997, 337(2-3): 283-289.

Cyclosporin A stimulates apical Na+/H+ exchange in LLC-PK1/PKE20 proximal tubular cells.[Pubmed:16773404]

Pediatr Nephrol. 2006 Jul;21(7):939-46.

Cyclosporin A (CyA) causes renal Na(+) retention which may lead to arterial hypertension. The apical Na(+)/H(+) exchanger (NHE3) is responsible for bulk proximal tubular Na(+) reabsorption. The aim of this study was to investigate the effects of CyA on the NHE3 of polarized proximal tubular cells to evaluate cellular mechanisms of CyA-associated arterial hypertension. The change of the intracellular pH (Delta-[pH](i)/min) was determined as a measure of the activity of the NHE in LLC-PK(1)/PKE(20) cells using 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). The NHE activity was identified as the apical NHE3 since it could be inhibited by the inhibitor S3226, but not by inhibitors of the basolateral isoform (NHE1) amiloride or HOE 694. CyA stimulated the NHE3 activity dose dependently. The mean increase stimulated by relevant CyA concentrations was 61+/-11%. A 24-h application of CyA also stimulated an increase of NHE3 activity which did not seem to be mediated by an increase of NHE3 RNA expression. The less immunosuppressive derivatives Cyclosporin H and cyclosporin G caused NHE3 activation as well. Carbachol and ATP, which both induce a Ca(2+) release from internal Ca(2+) stores, also increased the NHE3 activity. The Ca(2+) chelator 1,2-bis-(2-aminophenoxy)-ethane-N,N,-N',N'-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM) abolished the CyA-associated NHE3 stimulation, whereas low extracellular Ca(2+) had no effect. CyA-associated effects did not seem to be mediated via inhibition of protein kinase C (PKC). CyA had no additive effects on the angiotensin II-associated NHE3 stimulation. Concurrent application of losartan did not impair the CyA-induced NHE3 stimulation. In conclusion CyA stimulates the apical NHE3 in proximal tubular cells. This is mediated by Ca(2+) release from intracellular stores but is independent of the action of angiotensin II or PKC.

Advantages of cyclosporin A using 2-h levels in pediatric kidney transplantation.[Pubmed:15248059]

Pediatr Nephrol. 2004 Sep;19(9):1035-8.

Clinical trials in adult liver and heart recipients have shown that management of cyclosporine (CsA) dose with 2-h levels (C2) leads to lower rejection rates and serum creatinine levels compared with C0 monitoring. Therefore, we investigated whether C2 monitoring might also improve late graft survival after kidney transplantation in children. To date, no results in adult renal transplantation and in pediatric transplantation have been published. Forty-nine stable pediatric kidney recipients with a minimum time of 1 year after transplantation (mean=7+/-5 years) entered the study. None of the patients had experienced an acute rejection up to 6 months before entering the study. CsA dosing was based on C0 monitoring for the first 6 months and then based on C2 monitoring for the following 6 months. C0 and C2 levels were measured at 4-weekly intervals. Percentage decline in glomerular filtration rate (GFR) and mean coefficients of variation of CsA levels (C(var)) were calculated and compared during the 6-months periods. At the beginning of the study, the mean calculated GFR was 53+/-15 ml/min per 1.73 m(2). During the 6 months of C0 monitoring, the mean GFR decreased to 49+/-12 m/min per 1.73 m(2 )( P=0.001, paired t-test). Six months after switching to C2 monitoring, the mean GFR remained stable, at 49+/-15 ml/min per 1.73 m(2 )( P=0.3 paired t-test). The largest increase in GFR (3.9+/-7.9%) was found in patients with a decrease of their CsA dose of more than 5% under C2 monitoring. C(var) was significantly lower under C2 than under C0 monitoring (0.24+/-0.10 vs. 0.30+/-0.15, P=0.02, unpaired t-test). We conclude that the switch to C2 monitoring helped to identify patients with CsA overdosing as well as to reduce variation in CsA level, which resulted in a halt in GFR decline.

Cyclosporin H, Boc-MLF and Boc-FLFLF are antagonists that preferentially inhibit activity triggered through the formyl peptide receptor.[Pubmed:17687636]

Inflammation. 2007 Dec;30(6):224-9.

In order to properly interpret receptor inhibition experiments, the precise receptor specificities of the employed antagonists are of crucial importance. Lately, a great number of agonists for various formyl peptide receptors have been identified using a selection of antagonists. However, some confusion exists as to the precise receptor specificities of many of these antagonists. We have investigated the effects of formyl peptide receptor family antagonists on the neutrophil response induced by agonists for the formyl peptide receptor (FPR) and the formyl peptide receptor like 1 (FPRL1). To determine FPR- and FPRL1-specific interactions, these antagonists should not be used at used at concentrations above 10 microM. Signaling through FPR was inhibited by low concentrations of the antagonists Cyclosporin H, Boc-MLF (also termed Boc-1), and Boc-FLFLFL (also termed Boc-2), while higher concentrations also partly inhibited the signaling through FPRL1. The antagonist WRWWWW (WRW(4)) specifically inhibited the signaling through FPRL1 at low concentrations but at high concentrations also partly the signaling through FPR. Based on the difference in potency of Cyclosporin H and the two Boc-peptides, we suggest using Cyclosporin H as a specific inhibitor for FPR. To specifically inhibit the FPRL1 response the antagonist WRW(4) should be used.

Interaction Study of an Amorphous Solid Dispersion of Cyclosporin A in Poly-Alpha-Cyclodextrin with Model Membranes by (1)H-, (2)H-, (31)P-NMR and Electron Spin Resonance.[Pubmed:24883210]

J Drug Deliv. 2014;2014:575719.

The properties of an amorphous solid dispersion of cyclosporine A (ASD) prepared with the copolymer alpha cyclodextrin (POLYA) and cyclosporine A (CYSP) were investigated by (1)H-NMR in solution and its membrane interactions were studied by (1)H-NMR in small unilamellar vesicles and by (31)P (2)H NMR in phospholipidic dispersions of DMPC (dimyristoylphosphatidylcholine) in comparison with those of POLYA and CYSP alone. (1)H-NMR chemical shift variations showed that CYSP really interacts with POLYA, with possible adduct formation, dispersion in the solid matrix of the POLYA, and also complex formation. A coarse approach to the latter mechanism was tested using the continuous variations method, indicating an apparent 1 : 1 stoichiometry. Calculations gave an apparent association constant of log Ka = 4.5. A study of the interactions with phospholipidic dispersions of DMPC showed that only limited interactions occurred at the polar head group level ((31)P). Conversely, by comparison with the expected chain rigidification induced by CYSP, POLYA induced an increase in the fluidity of the layer while ASD formation led to these effects almost being overcome at 298 K. At higher temperature, while the effect of CYSP seems to vanish, a resulting global increase in chain fluidity was found in the presence of ASD.