Expression Of Cysteinyl Leukotriene Receptor Research Articles

Biomarkers for predicting response to long-term high dose aspirin therapy in aspirin-exacerbated respiratory disease.

IntroductionAspirin‐exacerbated respiratory disease (AERD) is a phenotype of asthma characterized by eosinophilic inflammation in the airways, mast cell activation, cysteinyl leukotriene overproduction, and acute respiratory reactions on exposure to cyclooxygenase‐1 inhibitors. Aspirin desensitization followed by daily high‐dose aspirin therapy is a safe and effective treatment option for the majority of patients with AERD. However, there is still some percentage of the population who do not derive benefits from daily aspirin use.MethodsBased on the current literature, the biomarkers, which might predict aspirin treatment outcomes in AERD patients, were evaluated.Results and conclusionsPatients with severe symptoms of chronic rhinosinusitis, type 2 asthma based on blood eosinophilia, non‐neutrophilic inflammatory phenotype based on sputum cells, as well as high plasma level of 15‐hydroxyeicosatetraenoic acid (15‐HETE) are potentially good responders to long term high‐dose aspirin therapy. Additionally, high expression of the hydroxyprostaglandin dehydrogenase gene, HPGD encoding prostaglandin‐degrading enzyme 15‐hydroxyprostaglandin dehydrogenase (15‐PGDH) and low expression of the proteoglycan 2 gene, PRG2 encoding constituent of the eosinophil granule in sputum cells might serve as a predictor of good response to aspirin therapy. Variations in the expression of cysteinyl leukotriene receptor 1 in the airways could additionally influence the response to long‐term aspirin therapy. Arachidonic acid metabolites levels via the 5‐lipoxygenase as well as via the cyclooxygenase pathways in induced sputum supernatant do not change during high dose long‐term aspirin therapy and do not influence outcomes of aspirin treatment.

Exosomes from MSCs overexpressing microRNA-223-3p attenuate cerebral ischemia through inhibiting microglial M1 polarization mediated inflammation

AimsTo explore the therapeutic effect and possible mechanism of exosomes from MSCs overexpressing miR-223 on cerebral ischemia and microglia polarization mediated inflammation. Main methodsRats after middle cerebral artery occlusion and reperfusion (MCAO/R) surgery and microglia BV-2 exposed to oxygen and glucose deprivation (OGD) and cysteinyl leukotrienes (CysLTs) stimulation were subject to exosomes from miR-223-3p transfected MSCs treatment, respectively. Behavioral tests were applied to assess the rats' neurological function. FACS was used to analyze M1/M2 microglia BV-2. production of cytokines in the ischemic hemisphere and BV-2 was detected by ELISA or qRT-PCR. Western blotting and qRT-PCR were also used to examine the expression of cysteinyl leukotriene receptor 2 (CysLT2R) in vivo and in vitro. Key findingsExosomes from MSCs over expressing miR-223-3p decreased MCAO/R induced cerebral infarct volume, improved neurological deficits, promoted learning and memorizing abilities. They suppressed pro-inflammatory factors expression and promoted anti-inflammatory factors secretion in the ischemic cortex and hippocampus. In vitro, exosomal miR-223-3p exhibited a more evident impact on modulating mRNA expression and protein production of cytokines. It promoted M2 microglia transformation of M1 microglia induced by NMLTC4 with a concentration-dependent manner. Western blot and qRT-PCR also revealed exosomal miR-223-3p decreased mRNA and protein expression of CysLT2R in vitro and in vivo. SignificanceExosomal miR-223-3p from MSCs attenuated cerebral ischemia/reperfusion injury through inhibiting microglial M1 polarization mediated pro-inflammatory response, which may be related with inhibitory effect of exosomal miR-223-3p on CysLT2R.

Abstract 4092: High mast cell density is associated with improved prognosis in colon cancer patients

Abstract Background. Inflammatory cells and inflammatory mediators play an important role in colon cancer. However, the role of mast cells (MCs) in colon cancer progression remains unclear. Pro-inflammatory cysteinyl leukotrienes (CysLTs) have been associated with colorectal cancer (CRC) development. In particular, previous studies have shown that CRC patients with increased expression of cysteinyl leukotriene receptor 1 (CysLTR1) have poorer prognoses, and Cysltr1−/− mice display fewer intestinal polyps. The aim of the present study was to investigate the clinical and prognostic significance of mast cell density (MCD) in patients with CRC and to determine the significance of CysLTR1 on MCD in a mouse model of colitis-associated colon cancer (CAC). Materials and methods. A tissue microarray (TMA) of primary colon cancers from 72 patients was stained with MC anti-tryptase and anti-chymase antibodies. Mouse colon tissue was stained with MC anti-tryptase antibody. Immunohistochemistry was used to identify MCD in cancerous and normal areas of patient tissues and in polyp/tumour, adjacent and normal areas of mouse tissues. Results. In patient samples, the mean MCD was significantly higher in normal tissue than in cancer tissue (p = 0.0009). Patients with a high MCD in cancer tissue showed better overall survival compared with those with a low MCD (hazard ratio (HR) 0.575; 95% confidence interval (CI), 0.293 - 1.130). The same result was observed in patients aged 55-75 years (HR 0.332; 95% CI 0.121 - 0.911) and among patients without distant metastasis at diagnosis (HR 0.311; 95% CI 0.118 - 0.821). In the CAC mouse model, Cysltr1−/− mice had fewer intestinal polyps and significantly higher MCD in polyp/tumour areas compared with controls. Conclusion. A high MCD in cancer tissue correlates with longer patient survival. In Cysltr1−/− CAC mice, a high polyp/tumour MCD also appears beneficial. Thus, these results indicate that a high MCD is a good prognostic factor. Citation Format: Anita Sjölander. High mast cell density is associated with improved prognosis in colon cancer patients. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4092.

High tumor mast cell density is associated with longer survival of colon cancer patients

Background: Inflammatory cells and inflammatory mediators play an important role in colorectal cancer (CRC). Previous studies have shown that CRC patients with increased expression of cysteinyl leukotriene receptor 1 (CysLTR1) have a poorer prognosis, and Cysltr1−/− mice display fewer intestinal polyps. However, the role of mast cells (MCs) in colon cancer progression remains unclear. The aim of the present study was to explore the relevance of MCs in CRC.Material and methods: A tissue microarray from 72 CRC patients was stained with MC anti-tryptase and -chymase antibodies. Mouse colon tissue was stained with MC anti-tryptase antibody. Immunohistochemistry was used to identify MCs in patients and mice.Results: Patient colon cancer tissue had in comparison with normal colon tissue a reduced number of MCs, predominantly of chymase-positive cells. Further analysis revealed that patients with a relative high MCD in their cancer tissues showed significantly longer overall survival compared to those with a low MCD [hazard ratio (HR) 0.539; 95% confidence interval (CI), 0.302–0.961]. Similar results were observed in subgroups of patients with either no distant metastasis (p = 0.004), or <75 years (p = 0.015) at time of diagnosis. Multivariate Cox analysis showed that MCD independently correlated with reduced risk of death in colon cancer patients (HR 0.380; 95% CI 0.202–0.713). Additionally, a negative correlation was found between cytoplasmic CysLTR1 expression and number of MCs. In agreement, in the CAC mouse model, Cysltr1−/− mice showed significantly higher MCs in their polyp/tumor areas compared with wild-type mice.Conclusion: A high MCD in cancer tissue correlated with longer patient survival independently from other risk factors for CRC. The concept that MCs have an anti-tumor effect in CRC is further supported by the findings of a negative correlation with CysLTR1 expression in patients and a high MCD in colon polyps/tumors from CysLTR1−/− mice.

Expression of cysteinyl leukotriene receptor 1 and 2 (CysLTR1 and CysLTR2) in the lymphocytes of hyperplastic tonsils: comparison between allergic and nonallergic snoring children.

Cysteinyl leukotriene receptor 1 and 2 (CysLTR1 and CysLTR2) are involved in allergic processes and play a role in adenotonsillar hyperplasia (AH). Clinically, only CysLTR1 may be blocked by montelukast. Our objective was to compare the expression of CysLTR1 and CysLTR2 in the B and T cells of hyperplasic tonsils of sensitized (SE) and control (NS) snoring children. Sixty children, 5 to 10 years of age, referred for adenotonsillectomy, were divided into SE and NS groups, according to their responses to the skin-prick test. Cells from the removed tissues were stained for CysLTR1, CysLTR2, CD19, and CD3 and counted via flow cytometry. messenger RNA (mRNA) expression of the CysLTRs genes was measured real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR). The SE group showed reduced expression of the small CD3+/CysLTR1+ lymphocytes (4.6 ± 2.2 vs 6.5 ± 5.0; p = 0.04). Regarding the large lymphocytes, the SE group showed lower expression of CD3+/CysLTR1+ (40.9 ± 14.5 vs 47.6 ± 11.7; p = 0.05), CD19+/CysLTR1+ (44.6 ± 16.9 vs 54.1 ± 12.4; p = 0.01), and CD19+/CysLTR2+ (55.3 ± 11.3 vs 61.5 ± 12.6; p = 0.05) lymphocytes. Considering the total number of lymphocytes, the SE group had fewer CD3+/CysLTR1+ lymphocytes (11.1 ± 5.5 vs 13.7 ± 6.2; p = 0.04). All other cell populations exhibited reduced expression in the SE group without statistical significance. The expression of CysLTR2 was significantly higher (p < 0.05) than CysLTR1 in most studied cell populations. The mRNA expression did not show significant differences between the groups. The expression of CysLTR is higher in the lymphocytes of the NS children, and CysLTR2 shows greater expression than CysLTR1 Respiratory allergies do not appear to be a stimulus for AH occurrence. Newer drugs capable of blocking both CysLTRs warrant further study.

Aggravated inflammation and increased expression of cysteinyl leukotriene receptors in the brain after focal cerebral ischemia in AQP4-deficient mice

Aquaporin-4 (AQP4), the main water channel protein in the brain, plays a critical role in water homeostasis and brain edema. Here, we investigated its role in the inflammatory responses after focal cerebral ischemia. In AQP4-knockout (KO) and wild-type mice, focal cerebral ischemia was induced by 30 min of middle cerebral arterial occlusion (MCAO). Ischemic neuronal injury and cellular inflammatory responses, as well as the expression and localization of cysteinyl leukotriene CysLT(2) and CysLT(1) receptors, were determined at 24 and 72 h after MCAO. AQP4-KO mice showed more neuronal loss, more severe microglial activation and neutrophil infiltration, but less astrocyte proliferation in the brain after MCAO than wild-type mice. In addition, the protein levels of both CysLT(1) and CysLT(2) receptors were up-regulated in the ischemic brain, and the up-regulation was more pronounced in AQP4-KO mice. The CysLT(1) and CysLT(2) receptors were primarily localized in neurons, microglia and neutrophils; those localized in microglia and neutrophils were enhanced in AQP4-KO mice. AQP4 may play an inhibitory role in postischemic inflammation.

Leukotriene D4 induces cognitive impairment through enhancement of CysLT1R-mediated amyloid-β generation in mice

Amyloid plaques in the extracellular parenchyma mainly consist of amyloid-β peptides (Aβ), one of the pathological hallmarks in Alzheimer's disease (AD). In the present study, we examined neuroinflammation, amyloidogenesis, and memory performance following intracerebral infusions of leukotriene D4 (LTD4) in mice. The results demonstrated that intracerebral infusions of LTD4 (1 ng/mouse) produced memory impairment as determined by Morris water maze test and Y-maze test in mice, and caused the accumulation of Aβ1–40 and Aβ1–42 in the hippocampus and cortex through increased activity of β- and γ-secretases accompanied with increased expression of amyloid precursor protein (APP). LTD4 also induced expression of cysteinyl leukotriene receptor 1 (CysLT1R) and NF-κB p65 in the hippocampus and cortex. Pretreatment with pranlukast (1.5 ng/mouse, intracerebroventricularly), a CysLT1R antagonist, blocked LTD4-induced amyloidogenesis, memory deficits. Pranlukast (0.6 μM) also prevented LTD4 (20 nM)-induced amyloidogenesis in the cultured neurons in vitro. Moreover, LTD4-induced increases in CysLT1R and NF-κB p65 in the brain were also attenuated by pranlukast. These results suggest that LTD4 increases Aβ peptide burden via activation of CysLT1R, which further affects APP levels and activity of β- and γ-secretases via the NF-κB pathway. Our findings identify CysLT1R signaling as a novel proinflammatory and proamyloidogenic pathway, and suggest a rationale for development of therapeutics targeting the CysLT1R in neuroinflammatory diseases such as AD.

Cysteinyl leukotriene receptors in tonsillar B- and T-lymphocytes from children with obstructive sleep apnea

Cysteinyl leukotrienes have been implicated in the pathogenesis of adenotonsillar hypertrophy in children with obstructive sleep apnea (OSA). This study aimed to quantify the expression of cysteinyl leukotriene receptors (CysLT(1), CysLT(2)) by tonsillar lymphocyte subpopulations from children with OSA and to make comparisons to lymphocyte subpopulations from control subjects with recurrent tonsillitis (RT). Tonsillar tissue from children with OSA or RT was studied for CysLT(1) and CysLT(2) expression by RT-PCR, flow cytometry (FC), and immunofluorescence. Ten children with OSA and 10 control subjects were recruited. In OSA participants, CysLT(1)+ fraction of small-size CD19+ B-lymphocytes was similar to the CysLT(1)+ CD3+ T-lymphocytes fraction (FC: 36.5 [16.5-55.4] vs. 14 [2.8-22.1]) (p>0.05) and higher than the CysLT(1)+ moderate/large-size CD19+ B-lymphocytes fraction (6.6 [1.5-14.4]) (p<0.01). Similar trends were recognized for CysLT(2). CysLT(1) and CysLT(2) immunoreactivity was detected by immunofluorescence in the tonsillar mantle zones (small B-lymphocytes) and the extrafollicular areas (T-lymphocytes). Compared to subjects with RT, children with OSA had significantly higher expression of CysLT(1) in small-size CD19+ B-lymphocytes (FC) and in CD3+ T-lymphocytes (RT-PCR and FC) (p<0.05). Increased expression of leukotriene receptors by immunologically active tonsillar areas in children with OSA is a potential therapeutic target for pediatric sleep apnea.

Reduced expression of the prostaglandin E2 receptor E-prostanoid 2 on bronchial mucosal leukocytes in patients with aspirin-sensitive asthma

Prostaglandin E(2) (PGE(2)) is thought to play a role in the pathogenesis of aspirin-sensitive asthma (ASA). We sought to extend our previous observations implicating impaired inflammatory cell responsiveness to PGE(2) as a pathogenetic mechanism in patients with aspirin-sensitive rhinosinusitis to the bronchial mucosa in patients with ASA. Immunohistochemistry was used to enumerate inflammatory cells and their expression of cysteinyl leukotriene receptors 1 and 2 (CysLT(1) and CysLT(2)) and the PGE(2) receptors E-prostanoid 1 to 4 (EP(1)-EP(4)) in bronchial biopsy specimens from patients with ASA, patients with aspirin-tolerant asthma, and control subjects (n= 15 in each group). Concentrations of PGE(2) in bronchoalveolar lavage fluid were measured by using ELISA. The effects of PGE(2) and EP receptor agonists on CD3/CD28-stimulated cytokine production by PBMCs were measured by using ELISA. Airways responsiveness to LTD(4)in vivo was measured in asthmatic patients by means of bronchial challenge. Compared with patients with aspirin-tolerant asthma, patients with ASA had increased bronchial mucosal neutrophil and eosinophil numbers but reduced percentages of T cells, macrophages, mast cells, and neutrophils expressing EP(2). Both groups showed increased bronchial sensitivity to inhaled LTD(4), but this did not correlate with mucosal expression of CysLT(1) or CysLT(2). Bronchoalveolar lavage fluid PGE(2) concentrations were comparable in all groups. In vitro PGE(2) inhibited cytokine production by PBMCs through EP(2) but not other PGE(2) receptors. Our data are consistent with the hypothesis that impaired inhibition of inflammatory leukocytes by PGE(2) acting through the EP(2) receptor has a role in the pathogenesis of ASA.

Human TH2 cells respond to cysteinyl leukotrienes through selective expression of cysteinyl leukotriene receptor 1

Allergic asthma is characterized by reversible airway obstruction and bronchial hyperresponsiveness associated with T(H)2 cell-mediated inflammation. Cysteinyl leukotrienes (CysLTs) are potent lipid mediators involved in bronchoconstriction, mucus secretion, and cell trafficking in asthmatic patients. Recent data have implicated CysLTs in the establishment and amplification of T(H)2 responses in murine models, although the precise mechanisms are unresolved. Preliminary microarray studies suggested that human T(H)2 cells might selectively express cysteinyl leukotriene receptor 1 (CYSLTR1) mRNA. We sought to establish whether human T(H)2 cells are indeed a CysLT target cell type. We examined the expression of CYSLTR1 using real-time PCR in human T(H)1 and T(H)2 cells. We functionally assessed cysteinyl leukotriene receptor 1 protein (CysLT(1)) expression using calcium flux, cyclic AMP, and chemotaxis assays. We show that human T(H)2 cells selectively express CYSLTR1 mRNA at high levels compared with T(H)1 cells after invitro differentiation from naive precursors. Human T(H)2 cells are selectively responsive to CysLTs in a calcium flux assay when compared with T(H)1 cells with a rank order of potency similar to that described for CysLT(1) (leukotriene [LT] D(4) > LTC(4) > LTE(4)). We also show that LTD(4)-induced signaling in T(H)2 cells is mediated through CysLT(1) coupled to G(α)q and G(α)i proteins, and both pathways can be completely inhibited by selective CysLT(1) antagonists. LTD(4) is also found to possess potent chemotactic activity for T(H)2 cells at low nanomolar concentrations. These findings suggest a novel mechanism of action for CysLTs in the pathogenesis of asthma and provide a potential explanation for the anti-inflammatory effects of CysLT(1) antagonists.

Novel methods to diagnose obstructive sleep apnea in children

Sleep-disordered breathing encompasses a spectrum of disorders that increase in severity from snoring to obstructive sleep apnea (OSA). OSA is a clinical disorder that requires a polysomnogram (PSG) to make the diagnosis. The PSG is the gold standard to confirm OSA. Alternative diagnostic tests are presented to supplement the clinical evaluation with objective information when evaluating the snoring child. Diagnostic tests to identify the anatomical site of obstruction are also discussed.

Functional expression of cysteinyl leukotriene receptors on human platelets

Normal peripheral blood leukocytes, such as basophils, eosinophils, B lymphocytes and monocytes/macrophages, have a cysteinyl leukotriene 1 (CysLT1) receptor, while the cysteinyl leukotriene 2 (CysLT2) receptor is expressed in cardiac Purkinje cells, endothelium, brain and leukocytes. However, it is unknown whether or not platelets express the CysLT1 or CysLT2 receptor. In this study we identify and characterize the biological function of the CysLT receptor of human platelets. We determined the CysLT1 or CysLT2 receptor mRNA expression in normal human platelets by RT-PCR and determined protein expression by Western blotting and flow cytometry. Moreover, we examined the effect of cysteinyl leukotrienes (CysLTs) in platelets on the induction of RANTES (Regulated on Activation, Normal T Expressed, and presumably Secreted). We also investigated whether the CysLT1 receptor antagonist pranlukast inhibits CysLT-induced RANTES release. In conclusion, we showed the functional expression of CysLT receptors on human platelets and demonstrated that CysLTs induced the release of significant amounts of RANTES, which suggests a novel role for human platelets in CysLT-mediated allergic inflammation.

Modification of Cysteinyl Leukotriene Receptors Expression in Capsular Contracture

Periprosthetic capsular contracture represents a specific iatrogenic phenomenon with different side effects. Recently, interesting data have disclosed a potential role of leukotrienes as important mediators of inflammation in the reactivation process of capsular contracture. Some preliminary studies have assessed the efficacy of leukotriene antagonists in the prevention and treatment of capsular contracture. These clinical data are still lacking of a potential biomolecular basis. The aim of our present study was to evaluate the expression of the protein receptor cysteinyl leukotriene receptors (CysLTR). We included 50 patients with severe capsular contracture (Baker III-IV) and a control group consisting of healthy patients who underwent an implant replacement. In both groups, we performed the protein extraction and semiquantitative analysis for the determination of protein concentration on myofibroblasts and macrophages. Western Blot analysis of protein levels shows a significant increase in the expression of CysLTR in patients with capsular contracture. Our final results show that the increase in the levels of mRNA coding for CysLTR actually translates into an effective increase in protein levels of these mRNA transcripts. These findings could at least partially provide a biomolecular basis that justifies the use of specific antileukotriene drugs in the treatment of this disease.

Advances in mechanisms of asthma, allergy, and immunology in 2008

This review summarizes selected articles appearing in 2008 in the Journal. Articles chosen include those improving our understanding of mechanisms of allergic diseases by focusing on human basophil, mast cell, and eosinophil biology; IgE and its high-affinity receptor on various cells; novel properties of omalizumab; airways remodeling; and genetics. Articles from other journals have been included to supplement the topics presented.

Differential Expression of Cysteinyl Leukotriene Receptor 1 and 15-Lipoxygenase-1 in Non-Hodgkin Lymphomas

BackgroundArachidonic acid metabolites have been suggested to play an important role in carcinogenesis. We have recently reported that the cysteinyl leukotriene receptor 1 (CysLT1) and 15-lipoxygenase-1 (15-LO-1) are expressed by the malignant Hodgkin Reed-Sternberg cells of Hodgkin lymphoma and certain Hodgkin lymphoma cell lines, and that these cells convert arachidonic acid to the novel proinflammatory eoxins. Materials and MethodsThe expression of the CysLT1 receptor and 15-LO-1 was investigated in a broad range of non-Hodgkin lymphomas (NHLs) by immunohistochemistry. The functionality of the CysLT1 receptor in primary mediastinal B-cell lymphoma (PMBCL) cell lines was studied by calcium mobilization assays. ResultsPrimary mediastinal B-cell lymphoma was the only NHL entity showing tumor cells positive for the CysLT1 receptor (9 of 10 tumors), and the PMBCL cell line Med-B1 expressed functional CysLT1 receptors, responding with a robust calcium signal upon cysteinyl leukotriene challenge. Furthermore, the tumor cells in 1 of 4 T-cell—derived anaplastic large-cell lymphomas, in contrast to all other studied NHLs, strongly expressed 15-LO-1. ConclusionAmong the NHL entities included in this study, the CysLT1 receptor was exclusively expressed by the tumor cells of PMBCL. Thus, this further corroborates the pathologic overlap between PMBCL and classical Hodgkin lymphoma.

Cysteinyl Leukotriene Receptors Are Expressed by Tonsillar T Cells of Children With Obstructive Sleep Apnea

Increased expression of cysteinyl leukotriene receptors (cysteinyl leukotriene receptor-1 [LT1-R]; cysteinyl leukotriene receptor-2 [LT2-R]) has been detected in adenotonsillar tissue from children with sleep-disordered breathing (SDB) compared to control subjects. LT1-R has been localized in myeloperoxidase-positive cells. This phenomenon possibly contributes to lymphoid tissue enlargement and may be related to systemic inflammation. To characterize cells expressing LT1-R and LT2-R in tonsillar tissue and assess serum C-reactive protein (CRP) levels in children with and without SDB. Immunohistochemistry with LT1-R and LT2-R antibodies was used to examine tonsils from children who had tonsillectomy (with or without adenoidectomy) for SDB and from control subjects operated for recurrent tonsillitis/otitis. All participants underwent preoperative polysomnography and measurement of morning serum CRP. Fifteen children with SDB (mean age +/- SD, 6.4 +/- 2.1 years; apnea-hypopnea index, 9.6 +/- 5.6 episodes per hour) and 11 control subjects (age, 7.5 +/- 2.8 years; apnea-hypopnea index, 7 +/- 0.3/h) were examined. Immunoreactivity for LT1-R and LT2-R was detected in tonsillar extrafollicular areas of all subjects with SDB but not of control subjects. Cells expressing leukotriene receptors were CD3+ lymphocytes. Children with SDB and control subjects were similar regarding CRP levels: 0.11 +/- 0.15 mg/dL vs 0.09 +/- 0.15 mg/dL, respectively (p > 0.05). Tonsils of children with SDB but not of control subjects have enhanced expression of cysteinyl leukotriene receptors in T lymphocytes without an associated increase in serum CRP concentration. Up-regulation of LT1-R and LT2-R could potentially promote tonsillar enlargement in children with obstructive sleep apnea.

Expression of Cysteinyl Leukotriene Receptors by CD34+ Umbilical Cord Blood (CB) - Progenitor Cells: Relevance to Atopic Development

RATIONALE: The cysteinyl leukotrienes (cysLTs) are potent, bioactive lipids that contribute to allergic and inflammatory diseases. Pharmacological studies have identified two classes of cysLT receptors (cysLTR1 and cysLTR2), which are expressed on a variety of cell types, including human peripheral blood CD34+ cells. However, no information is yet available regarding cysLTR expression on human umbilical CB progenitor cells. We examined the expression of cysLTR1 and cysLTR2 on human CB CD34+ progenitor cells, in order to be able to assess their potential relevance to the development of atopy.

Pathogenesis of nonsteroidal antiinflammatory drug-induced asthma

To summarize recent findings related to the pathogenic mechanisms of aspirin-induced asthma with emphasis on molecular genetic mechanisms. The overproduction of cysteinyl leukotrienes with the increased expression of cysteinyl leukotriene receptor 1 (CYSLTR1) is a consistent finding in aspirin-induced asthma patients. Recent data have suggested a dysregulation of cyclooxygenase-2 and prostaglandin E2, increased levels of 15-hydroxyeicosatetranoic acid, and decreased lipoxin generation as characteristics of the condition. The HLA allele DPB10301 was documented as a strong genetic marker for susceptibility in an Asian population. Leukotriene C4 synthase has been established as a key genetic determinant of aspirin-induced asthma, but recent studies have demonstrated that several single nucleotide polymorphisms in the promoters of prostaglandin E2 receptor subtype 2, CYSLTR1 and CYSLTR2 and T-box expressed in T cells (TBX21) could increase risk for the condition. Although cyclooxygenase-2 and thromboxane A2 receptor polymorphisms were not associated with aspirin-induced asthma phenotype, they may exert functional effects. The identification of genetic markers for aspirin-induced asthma susceptibility along with in-vitro functional studies would help to elucidate the pathogenesis of the condition. Further studies of the interactions among genes and between genes and the environment will be essential.

Increased expression of cysteinyl leukotriene receptor-1 in the brain mediates neuronal damage and astrogliosis after focal cerebral ischemia in rats

Cysteinyl leukotrienes are potent pro-inflammatory mediators. Cysteinyl leukotriene receptor 1 is one of the two cysteinyl leukotriene receptors cloned. We recently reported that cysteinyl leukotriene receptor 1 antagonists protected against cerebral ischemic injury, and an inducible expression of cysteinyl leukotriene receptor 1 was found in neuron- and glial-appearing cells after traumatic injury in human brain. To determine the role of cysteinyl leukotriene receptor 1 in ischemic brain injury, we investigated the temporal and spatial profile of cysteinyl leukotriene receptor 1 expression in rat brain from 3 h to 14 days after 30 min of middle cerebral artery occlusion, and observed the effect of pranlukast, a cysteinyl leukotriene receptor 1 antagonist, on the ischemic injury. We found that cysteinyl leukotriene receptor 1 mRNA expression was up-regulated in the ischemic core both 3–12 h and 7–14 days, and in the boundary zone 7–14 days after reperfusion. In the ischemic core, cysteinyl leukotriene receptor 1 was primarily localized in neurons 24 h, and in macrophage/microglia 14 days after reperfusion; while in the boundary zone it was localized in proliferated astrocytes 14 days after reperfusion. Pranlukast attenuated neurological deficits, reduced infarct volume and ameliorated neuron loss in the ischemic core 24 h after reperfusion; it reduced infarct volume, ameliorated neuron loss and inhibited astrocyte proliferation in the boundary zone 14 days after reperfusion. Thus, we conclude that cysteinyl leukotriene receptor 1 mediates acute neuronal damage and subacute/chronic astrogliosis after focal cerebral ischemia.

Differential Expression of Cysteinyl Leukotriene Receptors 1 and 2 in Tonsils of Children With Obstructive Sleep Apnea Syndrome or Recurrent Infection

Recurrent tonsillitis and sleep apnea are the major indications for tonsillectomy in children. We hypothesized that the recurrent vibration in the upper airway of snoring children would promote inflammatory changes in the tonsillar tissue and would lead to the up-regulation of cysteinyl leukotriene (LT) receptors (Rs). To assess the expression patterns of the human LT-Rs in children undergoing tonsillectomy, and compare those patterns in children having recurrent throat infections (RIs) and children with obstructive sleep apnea syndrome (SA). Tonsillar tissue from 17 children with SA and 13 with RIs was subjected to quantitative polymerase chain reaction using specific primers for LT1-R and LT2-R, and to immunohistochemistry and Western blotting for protein expression of LT1-R and LT2-R. Messenger RNA encoding for the expression of LT1-R and LT2-R was detected in the tonsils of all children. Immunoblots revealed significantly higher expressions of LT1-R and LT2-R in the tonsils of children with SA. The topographic pattern of both receptors differed among the tonsils of children with SA and RI. LT1-R and LT2-R are expressed in pediatric tonsillar tissue, are more abundant in SA patients, and demonstrate a specific topographic pattern of expression. These findings suggest that an inflammatory process involving LT expression and regulation occurs in children with SA.