Oxazolone-induced Delayed Type Hypersensitivity Research Articles

Manipulation of tissue factor-mediated basal PAR-2 signalling on macrophages determines sensitivity for IFNγ responsiveness and significantly modifies the phenotype of murine DTH.

BackgroundTissue factor (TF) generates proteases that can signal through PAR-1 and PAR-2. We have previously demonstrated PAR-1 signalling primes innate myeloid cells to be exquisitely sensitive to interferon-gamma (IFNγ). In this work we explored how TF mediated PAR-2 signalling modulated responsiveness to IFNγ and investigated the interplay between PAR-1/-2 signalling on macrophages.MethodologyWe characterised how TF through PAR-2 influenced IFNγ sensitivity in vitro using PCR and flow cytometry. and how it influenced oxazolone-induced delayed type hypersensitivity (DTH) responses in vivo. We investigated how basal signalling through PAR-2 influenced PAR-1 signalling using a combination of TF-inhibitors and PAR-1 &-2 agonists and antagonists. Finally, we investigated whether this system could be targeted therapeutically using 3-mercaptopropionyl-F-Cha-Cha-RKPNDK (3-MP), which has actions on both PAR-1 and -2.ResultsTF delivered a basal signal through PAR-2 that upregulated SOCS3 expression and blunted M1 polarisation after IFNγ stimulation, opposing the priming achieved by signalling through PAR-1. PAR-1 and -2 agonists or antagonists could be used in combination to modify this basal signal in vitro and in vivo. 3-MP, by virtue of its PAR-2 agonist properties was superior to agents with only PAR-1 antagonist properties at reducing M1 polarisation induced by IFNγ and suppressing DTH. Tethering a myristoyl electrostatic switch almost completely abolished the DTH response.ConclusionsTF-mediated signalling through PARs-1 and -2 act in a homeostatic way to determine how myeloid cells respond to IFNγ. 3-MP, an agent that simultaneously inhibits PAR-1 whilst delivering a PAR-2 signal, can almost completely abolish immune responses dependent on M1 polarisation, particularly if potency is enhanced by targeting to cell membranes; this has potential therapeutic potential in multiple diseases.

Inhibition of thrombin signalling on the surface of monocytes reduces inflammation in oxazolone-induced delayed type hypersensitivity

Abstract Thrombin can directly signal to innate immune cells via protease activating receptor-1 (PAR-1) but the functional consequence of receptor activation has yet to be fully defined. This study aims to assess the outcome of signalling through PAR-1 on monocytes in vivo. In a model of oxazolone-induced delayed type hypersensitivity (DTH)-contact dermatitis; inhibiting thrombin signalling via transgenic expression of hirudin on murine CD31 cells (Hir-Tg) significantly reduced ear swelling (ES) vs. wild type (WT) at 24 and 48 hours. The Hir-Tg mice had reduced CD68 cell recruitment and the recruited cells had a phenotype more polarised towards anti-inflammatory M2, with reduced iNOS, IFNγ & CCR2 expression, and increased expression of IL-10 and ABCA1. This phenotype was shown to be due to inhibition of thrombin signalling on the monocytes, as WT recipients of Hir-Tg bone marrow had a reduced ES, CD68 infiltration, granuloma and iNOS expression. Whereas Hir-Tg recipients (who would still express hirudin on the surface of endothelial cells) of WT bone marrow did not show a reduction in ES and behaved phenotypically akin to WT mice. Mice receiving IP-PAR1 antagonist prior to re-challenge had a similar reduction in ES and similar CD68 infiltration. This data shows that inhibiting thrombin signalling on the surface of innate immune cells both reduces recruitment in models of DTH and alters the behaviour of the cells to a more anti-inflammatory phenotype.

VX-509 (Decernotinib) Is a Potent and Selective Janus Kinase 3 Inhibitor That Attenuates Inflammation in Animal Models of Autoimmune Disease

Cytokines, growth factors, and other chemical messengers rely on a class of intracellular nonreceptor tyrosine kinases known as Janus kinases (JAKs) to rapidly transduce intracellular signals. A number of these cytokines are critical for lymphocyte development and mediating immune responses. JAK3 is of particular interest due to its importance in immune function and its expression, which is largely confined to lymphocytes, thus limiting the potential impact of JAK3 inhibition on nonimmune physiology. The aim of this study was to evaluate the potency and selectivity of the investigational JAK3 inhibitor VX-509 (decernotinib) [(R)-2-((2-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyrimidin-4-yl)amino)-2-methyl-N-(2,2,2-trifluoroethyl)butanamide] against JAK3 kinase activity and inhibition of JAK3-mediated signaling in vitro and JAK3-dependent physiologic processes in vivo. These results demonstrate that VX-509 potently inhibits JAK3 in enzyme assays (Ki = 2.5 nM + 0.7 nM) and cellular assays dependent on JAK3 activity (IC50 range, 50-170 nM), with limited or no measurable potency against other JAK isotypes or non-JAK kinases. VX-509 also showed activity in two animal models of aberrant immune function. VX-509 treatment resulted in dose-dependent reduction in ankle swelling and paw weight and improved paw histopathology scores in the rat collagen-induced arthritis model. In a mouse model of oxazolone-induced delayed-type hypersensitivity, VX-509 reduced the T cell-mediated inflammatory response in skin. These findings demonstrate that VX-509 is a selective and potent inhibitor of JAK3 in vitro and modulates proinflammatory response in models of immune-mediated diseases, such as collagen-induced arthritis and delayed-type hypersensitivity. The data support evaluation of VX-509 for treatment of patients with autoimmune and inflammatory diseases such as rheumatoid arthritis.

Targeting Interleukin-2-inducible T-cell Kinase (ITK) and Resting Lymphocyte Kinase (RLK) Using a Novel Covalent Inhibitor PRN694

Interleukin-2-inducible T-cell kinase (ITK) and resting lymphocyte kinase (RLK or TXK) are essential mediators of intracellular signaling in both normal and neoplastic T-cells and natural killer (NK) cells. Thus, ITK and RLK inhibitors have therapeutic potential in a number of human autoimmune, inflammatory, and malignant diseases. Here we describe a novel ITK/RLK inhibitor, PRN694, which covalently binds to cysteine residues 442 of ITK and 350 of RLK and blocks kinase activity. Molecular modeling was utilized to design molecules that interact with cysteine while binding to the ATP binding site in the kinase domain. PRN694 exhibits extended target residence time on ITK and RLK and is highly selective for a subset of the TEC kinase family. In vitro cellular assays confirm that PRN694 prevents T-cell receptor- and Fc receptor-induced cellular and molecular activation, inhibits T-cell receptor-induced T-cell proliferation, and blocks proinflammatory cytokine release as well as activation of Th17 cells. Ex vivo assays demonstrate inhibitory activity against T-cell prolymphocytic leukemia cells, and in vivo assays demonstrate durable pharmacodynamic effects on ITK, which reduces an oxazolone-induced delayed type hypersensitivity reaction. These data indicate that PRN694 is a highly selective and potent covalent inhibitor of ITK and RLK, and its extended target residence time enables durable attenuation of effector cells in vitro and in vivo. The results from this study highlight potential applications of this dual inhibitor for the treatment of T-cell- or NK cell-mediated inflammatory, autoimmune, and malignant diseases.

Inhibition of Toll-Like Receptor-Mediated Inflammation In Vitro and In Vivo by a Novel Benzoxaborole

Pro-inflammatory cytokines play a critical role in the development of autoimmune and inflammatory diseases. Targeting the cytokine environment has proven efficient for averting inflammation. In this study, we reported that 6-[4-(aminomethyl)-2-chlorophenoxyl]benzo[c][1,2]oxaborol-1(3H)-ol (AN3485), a benzoxaborole analog, inhibited TLR2-, TLR3-, TLR4-, and TLR5-mediated TNF-α, IL-1β, and IL-6 release from human PBMCs and isolated monocytes with IC(50) values ranging from 18 to 580 nM, and the inhibition was mediated at the transcriptional level. Topical administration of AN3485 significantly reduced PMA-induced contact dermatitis and oxazolone-induced delayed-type hypersensitivity in mice, indicating its capability of penetrating skin and potential topical application in skin inflammation. Oral administration of AN3485 showed dose-dependent suppression of LPS-induced TNF-α and IL-6 production in mice with an ED(90) of 30 mg/kg. Oral AN3485, 35 mg/kg, twice a day, suppressed collagen-induced arthritis in mice over a 20-day period. The potent anti-inflammatory activity in in vitro and in vivo disease models makes AN3485 an attractive therapeutic lead for a variety of cutaneous and systemic inflammatory diseases.

An important role of lymphatic vessel activation in limiting acute inflammation

AbstractIn contrast to the established role of blood vessel remodeling in inflammation, the biologic function of the lymphatic vasculature in acute inflammation has remained less explored. We studied 2 established models of acute cutaneous inflammation, namely, oxazolone-induced delayed-type hypersensitivity reactions and ultraviolet B irradiation, in keratin 14-vascular endothelial growth factor (VEGF)-C and keratin 14-VEGF-D transgenic mice. These mice have an expanded network of cutaneous lymphatic vessels. Transgenic delivery of the lymphangiogenic factors VEGF-C and the VEGFR-3 specific ligand mouse VEGF-D significantly limited acute skin inflammation in both experimental models, with a strong reduction of dermal edema. Expression of VEGFR-3 by lymphatic endothelium was strongly down-regulated at the mRNA and protein level in acutely inflamed skin, and no VEGFR-3 expression was detectable on inflamed blood vessels and dermal macrophages. There was no major change of the inflammatory cell infiltrate or the composition of the inflammatory cytokine milieu in the inflamed skin of VEGF-C or VEGF-D transgenic mice. However, the increased network of lymphatic vessels in these mice significantly enhanced lymphatic drainage from the ear skin. These results provide evidence that specific lymphatic vessel activation limits acute skin inflammation via promotion of lymph flow from the skin and reduction of edema formation.

Pituitary Adenylate Cyclase-Activating Polypeptide Deficiency Enhances Oxazolone-Induced Allergic Contact Dermatitis in Mice

Pituitary adenylate cyclase-activating polypeptide (PACAP) is present in capsaicin-sensitive sensory neurons and inflammatory/immune cells, therefore it is suggested to play a role in neuro-immune interactions. Our aim was to investigate the role of PACAP in oxazolone-induced delayed-type hypersensitivity reaction in the skin using deficient mice (PACAP(-/-)). Sensitization was induced by 2% oxazolone application on the shaved abdomen on two consecutive days; inflammation was elicited by oxazolone smearing on the ears 6days later. Ear thickness was measured by micrometry. Histological examination, cytokine profile [IL-2, IL-4, IL-5, and monocyte chemoattractant protein-1: MCP-1, IFN-γ, tumor necrosis factor alpha (TNF-α)] and myeloperoxidase activity correlating with the number of neutrophils/macrophages were determined 24 and 48h later. Oxazolone induced a 110-130% swelling after 24-48h in wild-type mice, which was significantly greater in PACAP-deficient mice. Histological analysis confirmed markedly increased edema in PACAP(-/-) mice, but the moderately enhanced inflammatory cell accumulation was not statistically significant compared with the wild-types. There was no difference in myeloperoxidase activity of the ear homogenates. Elevation of MCP-1, but not the levels of the other cytokines, was significantly higher in the samples of the PACAP-deficient mice. These results suggest that PACAP exerts anti-inflammatory, particularly edema-inhibiting effects in allergic contact dermatitis.

Oxazolone-Induced Delayed Type Hypersensitivity Reaction in the Adult Yucatan Pigs. A Useful Model for Drug Development and Validation

The purpose of this study was to establish a model of delayed type hypersensitivity (DTH) reaction in the ear skin of large animals such as adult Yucatan pigs, which may aid in evaluating the efficacy of therapeutic modalities of newly developed anti-inflammatory drugs. The pigs were sensitized with oxazolone, re-challenged with the same irritant six days later, and dosed with either vehicle or with cyclosporine A (CsA) before and after challenge. CsA reduced the redness, inhibited the accumulation of ear fluid and inflammatory cells, as well as the release of the inflammatory mediators. Further, CsA inhibited the proliferation of T cells collected from the spleens or PBMCs of CsA-treated pigs when these cells were stimulated in vitro with PMA plus Ionomycin. These results indicate that pig skin can be used to evaluate modalities for the purpose of developing drugs that may be used to treat DTH in humans.

Impaired defense mechanism against inflammation, hyperalgesia, and airway hyperreactivity in somatostatin 4 receptor gene-deleted mice

We have shown that somatostatin released from activated capsaicin-sensitive nociceptive nerve endings during inflammatory processes elicits systemic anti-inflammatory and analgesic effects. With the help of somatostatin receptor subtype 4 gene-deleted mice (sst(4)(-/-)), we provide here several lines of evidence that this receptor has a protective role in a variety of inflammatory disease models; several symptoms are more severe in the sst(4) knockout animals than in their wild-type counterparts. Acute carrageenan-induced paw edema and mechanical hyperalgesia, inflammatory pain in the early phase of adjuvant-evoked chronic arthritis, and oxazolone-induced delayed-type hypersensitivity reaction in the skin are much greater in mice lacking the sst(4) receptor. Airway inflammation and consequent bronchial hyperreactivity elicited by intranasal lipopolysaccharide administration are also markedly enhanced in sst(4) knockouts, including increased perivascular/peribronchial edema, neutrophil/macrophage infiltration, mucus-producing goblet cell hyperplasia, myeloperoxidase activity, and IL-1beta, TNF-alpha, and IFN-gamma expression in the inflamed lung. It is concluded that during these inflammatory conditions the released somatostatin has pronounced counterregulatory effects through sst(4) receptor activation. Thus, this receptor is a promising novel target for developing anti-inflammatory, analgesic, and anti-asthmatic drugs.

Oxazolone-Induced Delayed Type Hypersensitivity (DTH) Reaction in Adult Yucatan pigs: Validation of the Model with Cyclosporine A (CsA) (137.39)

Abstract DTH reactions are an important arm of the immune system and their deregulation results in several auto-immune and inflammatory diseases. Although rodents are widely used for the validation of novel anti-inflammatory drugs, it represents a challenge since their immune system is much less diverse and complex then the human immune system. We describe here and validate the first DTH swine model induced by Oxazolone using CsA. The results show a dramatic decrease in the ear inflammation in CsA treated pigs. In particular, this drug reduced the redness, inhibited the accumulation of ear fluid and inflammatory cells, as well as the accumulation and/or the release of the inflammatory mediators, CRP, IL-2 and IL-8 in the inflamed ears. Additionally, dosing with CsA significantly inhibited the levels of CRP, IL-2 and IL-8 in the sera of sensitized pigs, and also inhibited the in vitro proliferation of T cells collected from their spleens or PBMCs, particularly when these cells were stimulated in vitro with PMA plus ionomycin. Furthermore, CsA also inhibited the in vitro IL-2 released from PBMCs or splenocytes with or without stimulation with PMA plus ionomycin. Although CsA tended to reduce the ear thickness developed in mice and rats, this reduction did not reach significance, suggesting that pigs represent a better and more suitable model for screening the anti-inflammatory activity of compounds.

Coptis chinensisExtract Inhibits the Production of Inflammatory Mediators and Delayed Type Hypersensitivity in Mice

Coptis chinensis rhizome has been used as a medicinal herb in traditional Oriental medicine. We investigated the effects of Coptis chinensis extract on inflammatory mediators and delayed type hypersensitivity in mice. Methods: The inhibitory effect of ethanolic extract of Coptis chinensis (CCE) on cell proliferation was evaluated using MTS assay. The lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and the Con A-activated mouse splenocytes were cultured with various concentrations of CCE. Total nitric oxide (NO) production was determined by Griess reaction. The amounts of secreted prostaglandine E2 (PGE 2 ), interleukin (IL)-2 and IFN-γ were measured by ELISA. To investigate the in vivo anti-inflammatory effect of CCE, oxazolone-induced delayed type hypersensitivity (DTH) model was used. Results: The CCE at 100μg/ml significantly blocked the LPS-induced production of pro-inflammatory mediators (NO and PGE) in RAW264.7 macrophages. Also, it significantly inhibited cell proliferation and cytokine (IL-2 and IFN-γ) production in splenocytes. Furthermore, when splenocytes from CCE fed mice (200 mg/kg for 2 weeks) were activated with Con A, cell proliferation and cytokine production were significantly inhibited. In addition, CCE decreased in vivo inflammation in oxazolone-induced DTH model mice. Conclusion: We suggest that Coptis chinensis can be used as an anti-inflammatory drug by exerting an inhibitory effect in inflammatory mediator- and cell-mediated inflammation.

Anti-inflammatory effects of an ethanolic extract from Clematis mandshurica Rupr

Clematis mandshurica Rupr (Ranunculaceae) roots are used in traditional Korean medicine to treat inflammation-related diseases. Therefore, we undertook to investigate their inhibitory effect on inflammation under non-cytotoxic conditions. The ethanolic extract of Clematis mandshurica at 100 μg/ml was found to significantly block the production of the pro-inflammatory mediators, nitric oxide (NO) and prostaglandin E 2 (PGE 2), in lipopolysaccharide (LPS)/interferon(IFN)-γ-stimulated mouse peritoneal macrophages, by up to 77% and 59%, respectively. In addition, it significantly inhibited cell proliferation and cytokine production (interleukin (IL)-2 and IFN-γ) in splenocytes stimulated with Con A (concanavalin A; 5 μg/ml). Furthermore, when splenocytes from extract fed mice (200 mg/kg for 2 weeks) were activated with Con A, cell proliferation and the production of IL-2 and IFN-γ were significantly inhibited. In addition, the extract reduced in vivo inflammation in oxazolone-induced delayed type hypersensitivity (DTH) model mice. Taken together, these data suggest that Clematis mandshurica is able to ameliorate inflammatory disease by exerting an anti-inflammatory effect in cases of proinflammatory and cell-mediated inflammation.

Heparin's anti-inflammatory effects require glucosamine 6-O-sulfation and are mediated by blockade of L- and P-selectins.

Heparin has been used clinically as an anticoagulant and antithrombotic agent for over 60 years. Here we show that the potent anti-inflammatory property of heparin results primarily from blockade of P-selectin and L-selectin. Unfractionated heparin and chemically modified analogs were tested as inhibitors of selectin binding to immobilized sialyl Lewis(X) and of cell adhesion to immobilized selectins or thrombin-activated endothelial cells. Compared with unfractionated heparin, the modified heparinoids had inhibitory activity in this general order: over-O-sulfated heparin > heparin > 2-O,3-O-desulfated > or = N-desulfated/N-acetylated heparin > or = carboxyl-reduced heparin > or= N-,2-O,3-O-desulfated heparin >> 6-O-desulfated heparin. The heparinoids also showed similar differences in their ability to inhibit thioglycollate-induced peritonitis and oxazolone-induced delayed-type hypersensitivity. Mice deficient in P- or L-selectins showed impaired inflammation, which could be further reduced by heparin. However, heparin had no additional effect in mice deficient in both P- and L-selectins. We conclude that (a) heparin's anti-inflammatory effects are mainly mediated by blocking P- and L-selectin-initiated cell adhesion; (b) the sulfate groups at C6 on the glucosamine residues play a critical role in selectin inhibition; and (c) some non-anticoagulant forms of heparin retain anti-inflammatory activity. Such analogs may prove useful as therapeutically effective inhibitors of inflammation.

Heparin’s anti-inflammatory effects require glucosamine 6-O-sulfation and are mediated by blockade of L- and P-selectins

Heparin has been used clinically as an anticoagulant and antithrombotic agent for over 60 years. Here we show that the potent anti-inflammatory property of heparin results primarily from blockade of P-selectin and L-selectin. Unfractionated heparin and chemically modified analogs were tested as inhibitors of selectin binding to immobilized sialyl LewisX and of cell adhesion to immobilized selectins or thrombin-activated endothelial cells. Compared with unfractionated heparin, the modified heparinoids had inhibitory activity in this general order: over–O-sulfated heparin > heparin > 2-O,3-O-desulfated ≥ N-desulfated/N-acetylated heparin ≥ carboxyl-reduced heparin ≥ N-,2-O,3-O-desulfated heparin >> 6-O-desulfated heparin. The heparinoids also showed similar differences in their ability to inhibit thioglycollate-induced peritonitis and oxazolone-induced delayed-type hypersensitivity. Mice deficient in P- or L-selectins showed impaired inflammation, which could be further reduced by heparin. However, heparin had no additional effect in mice deficient in both P- and L-selectins. We conclude that (a) heparin’s anti-inflammatory effects are mainly mediated by blocking P- and L-selectin–initiated cell adhesion; (b) the sulfate groups at C6 on the glucosamine residues play a critical role in selectin inhibition; and (c) some non-anticoagulant forms of heparin retain anti-inflammatory activity. Such analogs may prove useful as therapeutically effective inhibitors of inflammation.

In vivo activity of pseudoguaianolide sesquiterpene lactones in acute and chronic inflammation

The pseudoguaianolide sesquiterpene lactones 4-α-O-acetyl-pseudoguaian-6β-olide (1), hymenin (2), ambrosanolide (3), tetraneurin A (4), parthenin (5), hysterin (6) and confertdiolide (7) were evaluated for their ability to affect the inflammation responses induced by different agents. All the compounds showed activity against the 12- O-tetradecanoylphorbol 13-acetate (TPA)-induced mouse ear edema. The ethyl phenylpropiolate (EPP)-induced mouse ear edema was inhibited by compounds 3, 5 and 7. However, when sesquiterpene lactones were assayed on the arachidonic acid (AA)-induced mouse ear edema, none of them were active. The only sesquiterpene lactone orally active against the paw mouse edema induced by carrageenan was 7, which gave a 46% edema inhibition after 3 h. On the other hand, compounds 3, 5 and 7 reduced the serotonin-induced paw edema in mice, although compound 7 was inactive in presence of cycloheximide. In addition, the sesquiterpene lactones were assayed against the chronic inflammation induced by repeated application of TPA on mouse ear. Confertdiolide was the most active compound; it reduced the edema by 87% and had a more moderate effect against the leukocyte recruitment (36% reduction in myeloperoxidase (MPO) levels). A histological study of ear the samples treated with 7 presented no detectable morphological lesions such as those treated with dexamethasone. On the oxazolone-induced delayed type hypersensitivity (DTH) only compounds 4 and 5 were active 24 h after the challenge. Compound 5 affected polymorphonuclear leukocyte infiltration (69% reduction in MPO levels). The results suggest that the especial chemical structure and spatial conformation of confertdiolide may facilitate its anti-inflammatory effect.

Screening of antiinflammatory medicinal plants used in traditional medicine against skin diseases

The antiinflammatory activity of twelve medicinal plants used against skin disorders were tested in different experimental models of topical inflammation and one in vitro inhibitory test against phospholipase A2 (PLA2) from Naja naja venom. Forsythia suspensa was the most active species on the arachidonic acid (AA) topical test. This last species together with Astragalus membranaceus and Ranunculus sceleratus were the most active on the 12-O-tetradecanoylphorbol-13-acetate (TPA) acute ear oedema test. Scrophularia auriculata was the most active on multiple topical applications of TPA and on the oxazolone-induced delayed type hypersensitivity (DTH). Santolina chamaecyparissus was the only species that inhibited PLA2in vitro. © 1998 John Wiley & Sons, Ltd.