Role of a histamine 4 receptor as an anti-inflammatory target in carrageenan-induced pleurisy in mice

Histamine H4 Receptor Agonist, 4-Methylhistamine, Aggravates Disease Progression and Promotes Pro-Inflammatory Signaling in B Cells in an Experimental Autoimmune Encephalomyelitis Mouse Model

We sought to assess the impact of 4-Methylhistamine (4-MeH), a specific agonist targeting the Histamine H4 Receptor (H4R), on the progression of experimental autoimmune encephalomyelitis (EAE) and gain insight into the underlying mechanism. EAE is a chronic autoimmune, inflammatory, and neurodegenerative disease of the central nervous system (CNS) characterized by demyelination, axonal damage, and neurodegeneration. Over the past decade, pharmacological research into the H4R has gained significance in immune and inflammatory disorders. For this study, Swiss Jim Lambert EAE mice were treated with 4-MeH (30 mg/kg/day) via intraperitoneal administration from days 14 to 42, and the control group was treated with a vehicle. Subsequently, we evaluated the clinical scores. In addition, flow cytometry was employed to estimate the impact of 4-Methylhistamine (4-MeH) on NF-κB p65, GM-CSF, MCP-1, IL-6, and TNF-α within CD19+ and CXCR5+ spleen B cells. Additionally, we investigated the effect of 4-MeH on the mRNA expression levels of Nf-κB p65, Gmcsf, Mcp1, Il6, and Tnfα in the brain of mice using RT-PCR. Notably, the clinical scores of EAE mice treated with 4-MeH showed a significant increase compared with those treated with the vehicle. The percentage of cells expressing CD19+NF-κB p65+, CXCR5+NF-κB p65+, CD19+GM-CSF+, CXCR5+GM-CSF+, CD19+MCP-1+, CXCR5+MCP-1+, CD19+IL-6+, CXCR5+IL-6+, CD19+TNF-α+, and CXCR5+TNF-α+ exhibited was more pronounced in 4-MeH-treated EAE mice when compared to vehicle-treated EAE mice. Moreover, the administration of 4-MeH led to increased expression of NfκB p65, Gmcsf, Mcp1, Il6, and Tnfα mRNA in the brains of EAE mice. This means that the H4R agonist promotes pro-inflammatory mediators aggravating EAE symptoms. Our results indicate the harmful role of H4R agonists in the pathogenesis of MS in an EAE mouse model.

Extracellular vesicles produced by bone marrow mesenchymal stem cells overexpressing programmed death-ligand 1 ameliorate dextran sodium sulfate-induced ulcerative colitis in rats by regulating Th17/Treg cell balance through PTEN/PI3K/AKT/mTOR axis

BACKGROUND AND AIM

Programmed death-ligand 1 (PD-L1) was involved in regulating Th17/Treg cell balance in ulcerative colitis (UC). Extracellular vesicles (EVs) from genetically modified bone marrow mesenchymal stem cells (BMSCs) can serve as a stable delivery system to overexpress PD-L1. The study was designed to evaluate the therapeutic mechanism of BMSC-EVs overexpressing PD-L1 (PD-L1-EVs) on ulcerative colitis.

METHODS

Experimental model of UC was established in rats by drinking 5% dextran sulfate sodium (DSS). Apoptosis-related proteins, inflammatory response-related factors and oxidative stress related mediators were detected. Westernblot was used to detecte key proteins in the PI3K/AKT signaling pathway and its downstream effectors. The CD4⁺ Foxp3⁺ Treg cells and CD4⁺ IL-17A⁺ Th17 cells in spleen and mesenteric lymph nodes (MLNs) was detected by flow cytometry.

RESULTS

PD-L1-EVs significantly alleviated the manifestations and pathological damage of UC rats by inhibiting the expression of IFN-γ, IL-1β, IL-8, IL-6, IL-2, BAX, NF-κB, TNF-α, MPO, and MDA, and up-regulating the expression of IL-4, BCL-2, SOD, and GSH. Furthermore, the proportions of Th17 cells were decreased and that of Treg cells were upregulated by PD-L1-EVs treatment. PTEN inhibitors (bpv) partially abolished the inhibitory effect of PD-L1-EVs on PI3K-AKT signaling and impaired the therapeutic efficacy of PD-L1-EVs.

CONCLUSIONS

PD-L1-EVs mitigated colonal inflammation, apoptosis and oxidative stress through blocking the activation of PI3K/Akt/mTOR pathway and regulating the balance of Th17/Treg cells.

Chimarrão, terere and mate-tea in legitimate technology modes of preparation and consume: A comparative study of chemical composition, antioxidant, anti-inflammatory and anti-anxiety properties of the mostly consumed beverages of Ilex paraguariensis St. Hil

ETHNOPHARMACOLOGICAL RELEVANCE

Ilex paraguariensis St. Hil. (Aquifoliaceae) is a medicinal plant widely used by South American populations for centuries and is popularly attributed to stimulating and detoxifying properties. Nowadays, their consume traditionally occurs through three different beverages: chimarrão, terere and mate-tea.

AIM OF THE STUDY

Although its composition and properties are well studied, literature lacks work comparing the potential of their extracts obtained by a legitimate preparation mode of their popular beverages. Therefore, the purpose of this research is to investigate changes in chemical composition, antioxidant activity, anti-inflammatory efficacy and anxiolytic effect from lyophilized aqueous extracts obtained simulating the legitimate popular preparation mode of chimarrão, terere and mate-tea.

MATERIALS AND METHODS

In this work, were investigated differences related to preparation technology and dry material used through chemical composition analysis, with the lyophilized aqueous extracts obtained simulating the chimarrão, terere and mate-tea preparation. The chemical composition analysis comprises the total soluble phenolics content, chemical profiles by HPLC-ESI-MS/MS, and quantitative component detection by HPLC-UV/DAD. Moreover, evaluations of comparative antioxidant activity of the extracts (DPPH and ORAC_FL assays), anti-inflammatory efficacy and anxiolytic effect were performed in vivo.

RESULTS

Our results showed that chimarrão extracts presented a richer composition in terms of phenolic compounds and purine alkaloids, and better antioxidant activity when compared to the other extracts. In pleurisy test, all products showed anti-inflammatory properties in the dose of 60 mg/kg. In the anxiolytic evaluation, although all extracts presented some effect, chimarrão and terere were better than mate-tea in general. No sign of toxicity was observed.

CONCLUSIONS

Our findings support that the beverage made as chimarrão has the best composition and the most promising properties overall.

Molecular Modeling of Histamine Receptors-Recent Advances in Drug Discovery

The recent developments of fast reliable docking, virtual screening and other algorithms gave rise to discovery of many novel ligands of histamine receptors that could be used for treatment of allergic inflammatory disorders, central nervous system pathologies, pain, cancer and obesity. Furthermore, the pharmacological profiles of ligands clearly indicate that these receptors may be considered as targets not only for selective but also for multi-target drugs that could be used for treatment of complex disorders such as Alzheimer's disease. Therefore, analysis of protein-ligand recognition in the binding site of histamine receptors and also other molecular targets has become a valuable tool in drug design toolkit. This review covers the period 2014-2020 in the field of theoretical investigations of histamine receptors mostly based on molecular modeling as well as the experimental characterization of novel ligands of these receptors.

Assessment of DNA repair efficiency in the inbred BTBR T+tf/J autism spectrum disorder mouse model exposed to gamma rays and treated with JNJ7777120

Information regarding DNA repair in autism is limited to a few studies, which have reported inconsistent results. Therefore, we designed a study to determine whether DNA repair efficiency is altered in autism and to investigate whether the H₄ ligand JNJ7777120 can enhance DNA repair efficiency in BTBR T⁺tf/J (BTBR) mice; we also attempted to elucidate the mechanism(s) underlying this amelioration. Evaluation of DNA damage using the comet assay on bone marrow cells showed increased levels of DNA damage in BTBR mice compared with age-matched control C57BL/6J mice. Conversely, BTBR animals pretreated with 20 mg/kg JNJ7777120 for five days exhibited significant decreases in DNA damage compared with that of control BTBR mice. Our results also indicated higher sensitivity of BTBR mice exposed to gamma rays to DNA damage generation. A marked difference was observed between BTBR and C57BL/6J mice at different sampling times after irradiation, with BTBR mice showing a higher percentage of DNA damage and slower repair rate than that of C57BL/6J mice. JNJ7777120 led to enhanced repair of the DNA damage induced by radiation when administered to BTBR mice five days prior to radiation. Additionally, oxidative stress in BTBR mice was significantly elevated with a reduced GSH/GSSG ratio; significant amelioration was subsequently observed in JNJ7777120-pretreated BTBR mice. Furthermore, repetitive behaviors were also attenuated in BTBR mice by JNJ7777120 treatment without altering locomotor activity. Our results suggest that JNJ7777120 can be developed for use as a therapeutic agent to enhance DNA repair efficiency in autism spectrum disorder.

Sequestration of artemin reduces inflammation-induced activation and sensitization of bone marrow nociceptors in a rodent model of carrageenan-induced inflammatory bone pain

BACKGROUND

Pathologies that affect the bone marrow have a significant inflammatory component; however, it is not clear how inflammatory mediators affect nociceptive nerve terminals within the marrow cavity.

METHODS

In this study, an in vivo bone-nerve preparation was used to directly record the physiological response properties of bone marrow nociceptors innervating the tibial marrow cavity of rats, before and after application of the inflammatory agent carrageenan. In addition, endogenous artemin was sequestered by application of an artemin neutralizing antibody to determine if this could prevent the inflammation-induced physiological changes observed.

RESULTS

A single injection of carrageenan administered into the tibial marrow cavity produced rapid changes in weight bearing (pain-like behaviour) in conscious animals. Carrageenan, but not saline, activated bone marrow nociceptors in whole-nerve recordings and sensitized a subtype of Aδ-bone marrow nociceptors to mechanical stimulation. The activation and sensitization had a rapid time course that matched that of pain-like behaviours. Sequestration of endogenous artemin significantly reduced carrageenan-induced increases in ongoing activity and completely abolished sensitization of bone marrow nociceptors to mechanical stimulation.

CONCLUSIONS

These observations indicate that inflammation affects the activity and sensitivity of bone marrow nociceptors; that artemin plays a role in these changes; and that artemin might be a promising target for pharmacological manipulations in the treatment of inflammatory bone pain.

SIGNIFICANCE

Most pathologies that affect the bone marrow have an inflammatory component. We have used a model of carrageenan-induced inflammation to show that sequestration of artemin reduces inflammation-induced activation and sensitization of bone marrow nociceptors. Our findings suggest that artemin signalling is a target for the treatment of inflammatory bone pain.

P-FN12, an H4R-Based Epitope Vaccine Screened by Phage Display, Regulates the Th1/Th2 Balance in Rat Allergic Rhinitis

Allergic rhinitis (AR) involves antigen-specific immune-inflammation of the nasal mucosa. Classical therapy for AR targets the histamine pathway, e.g., histamine receptor blockers. Histamine H4 receptor (H4R) was suggested as a novel therapeutic target due to its wide expression on almost all immune-related cells. A 12-mer random peptide library was used to select the specific epitope of the H4R. The phage clone showing the highest degree of activation was verified and translated to the corresponding peptide. The peptide FNKWMDCLSVTH, designated as P-FN12, was bound by H4R monoclonal antibody (mcAb) with high affinity. Moreover, the P-FN12 + CTB@Lipo-formulated vaccine, used as nasal drops, decreased allergic symptoms such as sneezing and nasal rubbing in a rat model. The level of ovalbumin (OVA)-specific immunoglobulin E (IgE) decreased significantly after vaccine administration. It also elicited increased levels of interferon (IFN)-γ and interleukin-2 (IL-2) but a decreased level of IL-4, and it elevated the T helper type 1 (Th1):T helper type 2 (Th2) cell ratio in peripheral blood mononuclear cell cultures. Our results indicated that the reduction of allergic inflammation by P-FN12-based vaccine was related to a decrease in production of OVA-specific IgE, Th2 immunity, and tissue eosinophilia. P-FN12 + CTB@Lipo is a promising vaccine that could suppress Th2 response and enhance the induction of Th1 cells in an AR model.

Antiinflammatory properties of betulinic acid and xylopic acid in the carrageenan-induced pleurisy model of lung inflammation in mice

This study investigated the antiinflammatory properties of betulinic acid (BA) and xylopic acid (XA) extracted from Margaritaria discoidea and Xylopia aethiopica, respectively. M. discoidea and X. aethiopica are plants native in Ghana and the West-African region and used traditionally to treat different pathologies including inflammatory conditions. The antiinflammatory effect of BA and XA was established by an in vivo assay using the carrageenan-induced pleural inflammation model in mice. Also, the ability of BA and XA to increase catalase, superoxide dismutase, glutathione levels and decrease lipid peroxidation level in reactive oxidative assays was assessed. In addition, the ability of XA and BA to prevent potential lung tissue damage was quantified. Pretreatment with BA and XA reduced significantly, signs of inflammation: neutrophil infiltration, oedema, and alveoli septal thickening in carrageenan-treated lung tissue. Additionally, BA or XA pretreatment lowered the degree of lipid peroxidation in the lung tissue while increasing the levels of catalase, superoxide dismutase, and glutathione in vivo. Comparatively, XA was more efficacious than BA in the prevention of lung tissue damage. BA and XA derived from X. aethiopica and M. discoidea possess antiinflammatory and in vivo antioxidant activities in mice pleurisy model. The effect of these compounds gives credence to the traditional use in the management of inflammatory conditions of the airway.

Clinical Development of Histamine H4 Receptor Antagonists

The discovery of the histamine H₄ receptor (H₄R) provided a new avenue for the exploration of the physiological role of histamine, as well as providing a new drug target for the development of novel antihistamines. The first step in this process was the identification of selective antagonists to help unravel the pharmacology of the H₄R relative to other histamine receptors. The discovery of the selective H₄R antagonist JNJ 7777120 was vital for showing a role for the H₄R in inflammation and pruritus. While this compound has been very successful as a tool for understanding the function of the receptor, it has drawbacks, including a short in vivo half-life and hypoadrenocorticism toxicity in rats and dogs, that prevented advancing it into clinical studies. Further research let to the discovery of JNJ 39758979, which, similar to JNJ 7777120, was a potent and selective H₄R antagonist and showed anti-inflammatory and anti-pruritic activity preclinically. JNJ 39758979 advanced into human clinical studies and showed efficacy in reducing experimental pruritus and in patients with atopic dermatitis. However, development of this compound was terminated due to the occurrence of drug-induced agranulocytosis. This was overcome by developing another H₄R antagonist with a different chemical structure, toreforant, that does not appear to have this side effect. Toreforant has been tested in clinical studies in patients with rheumatoid arthritis, asthma, or psoriasis. In conclusions there have been many H₄R antagonists reported in the literature, but only a few have been studied in humans underscoring the difficulty in finding ligands with all of the properties necessary for testing in the clinic. Nevertheless, the clinical data to date suggests that H₄R antagonists can be beneficial in treating atopic dermatitis and pruritus.

Pharmacological targeting of allergen-specific T lymphocytes

Allergic disorders are the result of a complex pathophysiology, involving major cellular lineages and a multitude of humoral factors of the innate and adaptive immune system, and have the tendency to involve multiple organs. Consequently, even standard pharmacological treatment of allergies is rarely specific but usually targets more than one pathway/cellular system at a time. Accordingly, many of the classic anti-allergic drugs have a critical impact also on T helper cells, which are pivotal not only during the sensitization but also the maintenance phase of allergic diseases. Recent years have seen a dramatic increase of novel drugs with the potency to interfere, more or less specifically, with T lymphocyte function, which might, possibly together with classic anti-allergic drugs, help harnessing one of the central cellular players in allergic responses. A major theme in the years to come will be a thoughtful combination of previously established with recently developed treatment modalities.

International Union of Basic and Clinical Pharmacology. XCVIII. Histamine Receptors

Histamine is a developmentally highly conserved autacoid found in most vertebrate tissues. Its physiological functions are mediated by four 7-transmembrane G protein-coupled receptors (H1R, H2R, H3R, H4R) that are all targets of pharmacological intervention. The receptors display molecular heterogeneity and constitutive activity. H1R antagonists are long known antiallergic and sedating drugs, whereas the H2R was identified in the 1970s and led to the development of H2R-antagonists that revolutionized stomach ulcer treatment. The crystal structure of ligand-bound H1R has rendered it possible to design new ligands with novel properties. The H3R is an autoreceptor and heteroreceptor providing negative feedback on histaminergic and inhibition on other neurons. A block of these actions promotes waking. The H4R occurs on immuncompetent cells and the development of anti-inflammatory drugs is anticipated.

Naringin attenuates the development of carrageenan-induced acute lung inflammation through inhibition of NF-κb, STAT3 and pro-inflammatory mediators and enhancement of IκBα and anti-inflammatory cytokines

Naringin has been reported to possess diverse pharmacological properties, including anti-arthritic and anti-inflammatory activities. The aim of the present study was to determine the potential anti-inflammatory effect of naringin in a mouse model of carrageenan-induced pleurisy. A single dose of naringin (40 and 80 mg/kg) was administered per oral (p.o.) 1 h before carrageenan (Cg) administration. Pro- and anti-inflammatory cytokines were analysed in pleural fluid. We also assessed the effects of naringin on the expression levels of iNOS, inducible cyclooxygenase isoform (COX-2), ICAM-1, MIP-2, PGE2, STAT3, TGF-β1, nuclear factor kappa B (NF-κB) and inhibitor of kappa B (IκBα) in lung tissue. The histological examinations revealed anti-inflammatory effect of naringin while Cg group deteriorated. Naringin downregulated Th1 and upregulated Th2 cytokines. Western blot analyses revealed increased protein expression of NF-κB, STAT3 and COX-2 and decreased IκBα in response to Cg treatment, which were reversed by the treatment with naringin. In the Cg group, mRNA expression levels of pro-inflammatory mediators upregulated and anti-inflammatory mediators downregulated. Naringin reversed these actions.

Design and Synthesis of N-Arylphthalimides as Inhibitors of Glucocorticoid-Induced TNF Receptor-Related Protein, Proinflammatory Mediators, and Cytokines in Carrageenan-Induced Lung Inflammation

N-Arylphthalimides (1-10P) derived from thalidomide by insertion of hydrophobic groups were evaluated for anti-inflammatory activity, and (4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-N'-[(4-ethoxyphenyl)methylidene]benzohydrazide 6P was identified as a promising anti-inflammatory agent. Further testing confirmed that compared with the control, 6P treatment resulted in a considerable decrease in CD4(+), NF-κB p65(+), TNF-α(+), IL-6(+), GITR(+), and IL-17(+) cell populations and an increase in the Foxp3(+), CD4(+)Foxp3(+), and IκBα(+) populations in whole blood and pleural fluid of a mouse model of lung inflammation. Moreover, treatment with compound 6P decreased the proteins associated with inflammation including TNF-α, IL-6, IL-17, GITR, NF-κB, COX-2, STAT-3, and iNOS and increased the anti-inflammatory mediators such as IL-10 and IL-4. Further, histopathological examination confirmed the potent anti-inflammatory effects of compound 6P. Thus, the N-arylphthalimide derivative 6P acts as a potent anti-inflammatory agent in the carrageenan-induced lung inflammation model, suggesting that this compound may be useful for the treatment of inflammation in a clinical setting.

Histamine 4 receptor promotes expression of costimulatory B7.1/B7.2 molecules, CD28 signaling and cytokine production in stress-induced immune responses

Recently, the expression of histamine 4 receptor (H4R) on neurons was reported, however its function in cells within the central nervous system (CNS) remains poorly understood. To this end, we used the H4R agonist, 4-methylhistamine (4-MeH), and the H4R antagonist, JNJ77777120 (JNJ), to investigate the function of H4R signaling in immune cells in a murine model of chronic stress. Treatment of stressed mice with 4-MeH resulted in an increase in the proportion of lymphocyte subsets (CD3(+), CD8(+), CD28(+), and CD4(+)CD28(+)) and cells expressing the co-stimulatory molecules CD80(+) (B7.1) and CD86(+) (B7.2) in heparinized blood as compared to normal control (NC) and stressed control (SC) groups. We also observed that as compared to NC and SC mice, 4-MeH-treated mice showed greater production of IL-2(+), IL-6(+), IL-9(+), IL-21(+), and IL-27(+) cytokines in the spleen and by splenic CD4(+) T cells. Furthermore, 4-MeH treatment of stressed mice led to an increase in the levels of serum Th1/Th17 cytokines and corticosterone, and a decrease in Th2 cytokines. Treatment of chronically-stressed mice with 4-MeH also augmented expression of IL-6, IL-21, NF-κB p65, and STAT3 mRNA. Moreover, Western blot analyses confirmed increased protein expression of NF-κB, iNOS, and STAT3 expression following 4-MeH treatment of chronically-stressed mice as compared to controls. These proteins provide a novel relevant targets for the manipulation of chronic stress induced immune regulation. In striking contrast, treatment of stressed mice with the H4R antagonist, JNJ, resulted in a substantial reduction in all of the aforementioned effects upon immune cell percentages and cytokine production.

Anti-nociceptive and anti-inflammatory activities of 4-[(1-phenyl-1H-pyrazol-4-yl) methyl] 1-piperazine carboxylic acid ethyl ester: A new piperazine derivative

Piperazine compounds possess anti-infective, anti-carcinogenic, anxiolytic, hypotensive, anti-hypertensive and vasorelaxant properties and are attractive candidates for the development of new analgesic and anti-inflammatory drugs. This study investigates the anti-nociceptive and anti-inflammatory effects of piperazine derivative 4-[(1-phenyl-1H-pyrazol-4-yl) methyl]1-piperazine carboxylic acid ethyl ester (LQFM-008) and the involvement of the serotonergic pathway. In the formalin test, treatments with LQFM-008 (15 and 30mg/kg p.o.) reduced the licking time in both neurogenic and inflammatory phases of this test. In the tail flick and hot plate tests, LQFM008 treatment (15 and 30mg/kg p.o.) increased latency to thermal stimulus, suggesting the involvement of central mechanisms in the anti-nociceptive effect of LQFM-008. In the carrageenan-induced paw edema test, LQFM-008 (p.o.) at the doses of 15 and 30mg/kg reduced the edema at all tested time points, while the dose of 7.5mg/kg reduced the edema only for the first hour. LQFM-008 (30mg/kg p.o.) reduced both cell migration and protein exudation in the carrageenan-induced pleurisy test. Furthermore, pre-treatment with NAN-190 (0.6mg/kgi.p.) and PCPA (100mg/kgi.p.) antagonized the anti-nociceptive effect of LQFM-008 in both phases of the formalin test. Our data suggest that LQFM-008 possesses anti-inflammatory and anti-nociceptive effects mediated through the serotonergic pathway.

Stimulation of the histamine 4 receptor with 4-methylhistamine modulates the effects of chronic stress on the Th1/Th2 cytokine balance

Alterations to the immune system caused by stress have been considered to markedly increase the risk for immune-related diseases such as cancer and autoimmune disorders. We investigated the potential anti-stress effects of the histamine 4 receptor (H4R) agonist, 4-methylhistamine (4-MeH), in a murine stress model. Mice were placed in 50ml conical centrifuge tubes for 12h followed by a 12h rest. The effects of treatment with 4-MeH (30mg/kg, i.p., twice daily) for 2 days were assessed. At 2 days after physical restraint, mice were sacrificed and tissues harvested. We evaluated the effects of 4-MeH treatment on CD4(+) T cell production, and intracellular IFN-γ and IL-4 expression in these cells. We also assessed IL-1β, IFN-γ, TNF-α, and IL-4 mRNA expression as well as IFN-γ, TNF-α, GITR, Ox40 and IL-4 protein expression in the spleen. The results showed that 4-MeH treatment of stressed mice results in a substantial increase in the CD4(+) T cells as well as in IFN-γ production by these cells. Compared to both untreated and stressed controls. In contrast, IL-4 expression decreased significantly following 4-MeH treatment of mice. Moreover, stimulation of the H4R resulted in up-regulated expression of IL-1β, IFN-γ and TNF-α mRNAs and decreased the expression of IL-4. Western blot analysis confirmed decreased protein expression of IFN-γ, TNF-α, GITR, Ox40 and increased IL-4 in the SC group and treatment of mice with 4-MeH reversed these effects. Our results confirm the significant impact of chronic stress on T cell function and production of Th1/Th2 mediators H4R.

The role of poly(ADP-ribose) polymerase-1 inhibitor in carrageenan-induced lung inflammation in mice

Increasing indication is unveiling a role for poly(ADP-ribose) polymerase (PARP)-1 in the regulation of inflammatory/immune responses. The aim of the present study was to determine the potential anti-inflammatory effects of PARP-1 inhibitor 5-aminoisoquinolinone (5-AIQ) to explore the role of PARP-1 inhibitor in a mouse model of carrageenan-induced lung inflammation. A single dose of 5-AIQ (1.5mg/kg) was administered intraperitoneally (i.p.) 1h before λ-carrageenan (Cg) administration. We assessed the effects of 5-AIQ treatment on CD25(+), GITR(+), CD25(+)GITR(+), IL-17(+) and Foxp3(+) cells which were investigated using flowcytometry in pleural exudates and heparinized blood. We also evaluated mRNA expressions of IL-6, TNF-α, IL-1β, IL-10, CD11a, l-selectin (CD62L), ICAM-1, MCP-1, iNOS and COX-2 in the lung tissue. We further examined the effects of 5-AIQ on the key mediators of inflammation, namely COX-2, STAT-3, NF-kB p65, PARP-1, IkB-α and IL-4 protein expression in the lung tissue using western blotting. The results illustrated that the numbers of T cell subsets, IL-17(+) cytokine levels were markedly increased and Foxp3(+) production decreased in the Cg group. Furthermore, Cg-induced up-regulation of adhesion molecules, pro-inflammatory mediators and chemokine expressions. Western blot analysis revealed an increased protein expressions of COX-2, STAT-3 NF-kB p65 and PARP-1 and decreased IkB-α and IL-4 in the Cg group. PARP-1 inhibitor via 5-AIQ treatment reverses the action significantly of all the previously mentioned effects. Moreover, histological examinations revealed anti-inflammatory effects of 5-AIQ, whereas Cg-group aggravated Cg-induced inflammation. Present findings demonstrate the potent anti-inflammatory action of the PARP-1 inhibitor in acute lung injury induced by carrageenan.