Leukotriene B4 receptor 2 gene polymorphism (rs1950504, Asp196Gly) leads to enhanced cell motility under low-dose ligand stimulation

Two distinct forms of human BLT2: long-form and short-form BLT2

BLT2 is a low-affinity leukotriene B4 receptor that plays an essential role in the pathogenesis of various inflammatory diseases, including asthma and cancer. BLT2 is minimally expressed in a normal internal environment but is overexpressed in a stress-induced inflammatory environment. Recent research indicated that human BLT2 has two distinct forms. Although their functions are likely to be different, very few studies investigated these differences. Therefore, this paper will discuss about the two distinct forms of human BLT2; the short-form of BLT2 and the long-form of BLT2.

Three Months of Strength Training Changes the Gene Expression of Inflammation-Related Genes in PBMC of Older Women: A Randomized Controlled Trial

Here, we investigate changes in inflammation-related gene-expression in peripheral mononuclear blood cells (PBMC) by strength training. A total of 14 women aged ≥65 years were randomized into 3 months of either 3×/week intensive strength training (IST: 3×10 rep at 80% 1RM), strength endurance training (SET: 2×30 reps at 40% 1RM) or control (CON: 3×30 sec stretching). Differentially expressed genes (fold change ≤0.67 or ≥1.5) were identified by targeted RNA-sequencing of 407 inflammation-related genes. A total of 98 genes (n = 61 pro-inflammatory) were significantly affected. IST and SET altered 14 genes in a similar direction and 19 genes in the opposite direction. Compared to CON, IST changed the expression of 6 genes in the same direction, and 17 genes in the SET. Likewise, 18 and 13 genes were oppositely expressed for, respectively, IST and SET compared to CON. Changes in gene expression affected 33 canonical pathways related to chronic inflammation. None of the altered pathways overlapped between IST and SET. Liver X Receptor/Retinoid X Receptor Activation (LXR/RXR) and Triggering Receptor Expressed On Myeloid Cells 1 (TREM1) pathways were enriched oppositely in both training groups. We conclude that three months IST and SET can induce changes in CLIP-related gene expression in PBMC, but by affecting different genes and related pathways.

Contributory Role of BLT2 in the Production of Proinflammatory Cytokines in Cecal Ligation and Puncture-Induced Sepsis

BLT2 is a low-affinity receptor for leukotriene B4, a potent lipid mediator of inflammation generated from arachidonic acid via the 5-lipoxygenase pathway. The aim of this study was to investigate whether BLT2 plays any role in sepsis, a systemic inflammatory response syndrome caused by infection. A murine model of cecal ligation and puncture (CLP)-induced sepsis was used to evaluate the role of BLT2 in septic inflammation. In the present study, we observed that the levels of ligands for BLT2 (LTB4 [leukotriene B4] and 12(S)-HETE [12(S)-hydroxyeicosatetraenoic acid]) were significantly increased in the peritoneal lavage fluid and serum from mice with CLP-induced sepsis. We also observed that the levels of BLT2 as well as 5-LO and 12-LO, which are synthesizing enzymes for LTB4 and 12(S)-HETE, were significantly increased in lung and liver tissues in the CLP mouse model. Blockade of BLT2 markedly suppressed the production of sepsis-associated cytokines (IL-6 [interleukin-6], TNF-α [tumor necrosis factor alpha], and IL-1β [interleukin-1β] as well as IL-17 [interleukin-17]) and alleviated lung inflammation in the CLP group. Taken together, our results suggest that BLT2 cascade contributes to lung inflammation in CLP-induced sepsis by mediating the production of inflammatory cytokines. These findings suggest that BLT2 may be a potential therapeutic target for sepsis patients.

Leukotriene B4 receptors contribute to house dust mite-induced eosinophilic airway inflammation via TH2 cytokine production

Leukotriene B₄ (LTB₄) is a lipid mediator of inflammation that is generated from arachidonic acid via the 5-lipoxygenase pathway. Previous studies have reported that the receptors of LTB₄, BLT1, and BLT2 play mediatory roles in the allergic airway inflammation induced by ovalbumin (OVA). However, considering that house dust mites (HDMs) are the most prevalent allergen and well-known risk factor for asthmatic allergies, we are interested in elucidating the contributory roles of BLT1/2 in HDM-induced allergic airway inflammation. Our aim in this study was to investigate whether BLT1/2 play any roles in HDM-induced allergic airway inflammation. In this study, we observed that the levels of ligands for BLT1/2 [LTB₄ and 12(S)-HETE (12(S)-hydroxyeicosatetraenoic acid)] were significantly increased in bronchoalveolar lavage fluid (BALF) after HDM challenge. Block-ade of BLT1 or BLT2 as well as of 5-lipoxygenase (5-LO) or 12-lipoxygenase (12-LO) markedly suppressed the production of T_H2 cytokines (IL-4, IL-5, and IL-13) and alleviated lung inflammation and mucus secretion in an HDM-induced eosinophilic airway-inflammation mouse model. Together, these results indicate that the 5-/12-LO-BLT1/2 cascade plays a role in HDM-induced airway inflammation by mediating the production of T_H2 cytokines. Our findings suggest that BLT1/2 may be a potential therapeutic target for patients with HDM-induced allergic asthma.

Leukotriene B4 receptors play critical roles in house dust mites-induced neutrophilic airway inflammation and IL-17 production

Increased levels of neutrophils in bronchoalveolar lavage fluid (BALF) were associated with asthma severity. As leukotriene B4 (LTB₄) is a principal chemoattractant molecule for neutrophils, its receptors, BLT1 and BLT2, may contribute to neutrophil-dominant airway inflammation. In the present study, we established a mouse model of steroid-resistant, neutrophil-dominant airway inflammation by house dust mite (HDM)/lipopolysaccharide (LPS) sensitization and HDM challenge, and we investigated whether BLT1/BLT2 signaling was associated with the development of neutrophilic airway inflammation. Blockade of BLT1 or BLT2 significantly suppressed airway inflammation and IL-17 production in this mouse model. The 5-LO and 12-LO enzymes, which catalyze the synthesis of BLT1/BLT2 ligands, were also critically associated with neutrophil-dominant airway inflammation and the synthesis of IL-17. Collectively, our results suggest that the 5-/12-LO-BLT1/BLT2-linked cascade significantly contributes to neutrophil-dominant severe airway inflammation via IL-17 synthesis in HDM-induced neutrophilic asthma.

Study of a supplement and a genetic test for lymphedema management

Malformations in the lymphatic vasculature, injury, surgery, trauma or toxic damage may lead to swelling of the limbs caused by inefficient lymphatic uptake and flow (lymphedema). Lymphedema can be congenital or acquired. Primary lymphedema is rare and caused by mutations in single genes, secondary lymphedema is more common and caused by a trauma in association with a genetic predisposition. We decided to develop a genetic test that would determine the genetic predisposition to the onset of lymphedema and to predict the course of the disease by analyzing polymorphisms involved in leukotriene B4 (LTB4) synthetic pathway, and variants involved in the onset of secondary lymphedema. There are not many compounds available for the treatment of the negative effects of lymph accumulation, we therefore designed a food supplement based on the hydroxytyrosol, that has anti-oxidant, anti-bacterial and anti-inflammatory activities.

Single-Nucleotide Polymorphisms (SNP) Mining and Their Effect on the Tridimensional Protein Structure Prediction in a Set of Immunity-Related Expressed Sequence Tags (EST) in Atlantic Salmon (Salmo salar)

Single-nucleotide polymorphisms (SNPs) are single genetic code variations considered one of the most common forms of nucleotide modifications. Such SNPs can be located in genes associated to immune response and, therefore, they may have direct implications over the phenotype of susceptibility to infections affecting the productive sector. In this study, a set of immune-related genes (cc motif chemokine 19 precursor [ccl19], integrin β2 (itβ2, also named cd18), glutathione transferase omega-1 [gsto-1], heat shock 70 KDa protein [hsp70], major histocompatibility complex class I [mhc-I]) were analyzed to identify SNPs by data mining. These genes were chosen based on their previously reported expression on infectious pancreatic necrosis virus (IPNV)-infected Atlantic salmon phenotype. The available EST sequences for these genes were obtained from the Unigene database. Twenty-eight SNPs were found in the genes evaluated and identified most of them as transition base changes. The effect of the SNPs located on the 5’-untranslated region (UTR) or 3’-UTR upon transcription factor binding sites and alternative splicing regulatory motifs was assessed and ranked with a low-medium predicted FASTSNP score risk. Synonymous SNPs were found on itβ2 (c.2275G > A), gsto-1 (c.558G > A), and hsp70 (c.1950C > T) with low FASTSNP predicted score risk. The difference in the relative synonymous codon usage (RSCU) value between the variant codons and the wild-type codon (ΔRSCU) showed one negative (hsp70 c.1950C > T) and two positive ΔRSCU values (itβ2 c.2275G > A; gsto-1 c.558G > A), suggesting that these synonymous SNPs (sSNPs) may be associated to differences in the local rate of elongation. Nonsynonymous SNPs (nsSNPs) in the gsto-1 translatable gene region were ranked, using SIFT and POLYPHEN web-tools, with the second highest (c.205A > G; c484T > C) and the highest (c.499T > C; c.769A > C) predicted score risk possible. Using homology modeling to predict the effect of these nonsynonymous SNPs, the most relevant nucleotide changes for gsto-1 were observed for the nsSNPs c.205A > G, c484T > C, and c.769A > C. Molecular dynamics was assessed to analyze if these GSTO-1 variants have significant differences in their conformational dynamics, suggesting these SNPs could have allosteric effects modulating its catalysis. Altogether, these results suggest that candidate SNPs identified may play a crucial potential role in the immune response of Atlantic salmon.

Mediatory roles of leukotriene B4 receptors in LPS-induced endotoxic shock

Sepsis, a systemic inflammatory response syndrome caused by infection, is the most common disease in patients treated in intensive care units. Endotoxic shock, the most critical form of sepsis, is caused by gram-negative bacterial infection. However, the detailed mechanism of endotoxic shock remains unclear. In the present study, we observed that the production of leukotriene B₄ (LTB₄) and 12(S)-hydroxyeicosatetraenoic acid (HETE), inflammatory lipid mediators acting on LTB₄ receptors (BLT1 and BLT2), was significantly upregulated in peritoneal lavage fluid (PF) and serum from an LPS-induced endotoxic shock mouse model. Furthermore, BLT1/2-dependent signaling pathways mediated the expression of IL-17, IL-6, and IL-1β, key cytokines for the development of endotoxic shock, via NF-κB activation in the LPS-induced endotoxic shock mouse model. Additionally, inhibition of BLT1/2 significantly attenuated inflammation and tissue damage associated with endotoxic shock and enhanced the survival rate of mice with this inflammatory complication. Together, these results suggest that LTB₄ receptors play critical mediatory roles in the development of endotoxic shock. Our findings point to LTB₄ receptors as potential therapeutic targets for the treatment of endotoxic shock.

TRAIL attenuates sulforaphane-mediated Nrf2 and sustains ROS generation, leading to apoptosis of TRAIL-resistant human bladder cancer cells

Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) can preferentially initiate apoptosis in malignant cells with minimal toxicity to normal cells. Unfortunately, many human cancer cells are refractory to TRAIL-induced apoptosis through many unknown mechanisms. Here, we report that TRAIL resistance can be reversed in human bladder cancer cell lines by treatment with sulforaphane (SFN), a well-known chemopreventive isothiocyanate in various cruciferous vegetables. Combined treatment with SFN and TRAIL (SFN/TRAIL) significantly induced apoptosis concomitant with activation of caspases, loss of mitochondrial membrane potential (MMP), Bid truncation, and induction of death receptor 5. Transient knockdown of Bid prevented collapse of MMP induced by SFN/TRAIL, consequently reducing apoptotic effects. Furthermore, SFN increased both the generation of reactive oxygen species (ROS) and the activation of nuclear factor erythroid 2-related factor 2 (Nrf2), which is an anti-oxidant enzyme. Interestingly, TRAIL effectively suppressed SFN-mediated nuclear translocation of Nrf2, and the period of ROS generation was more extended compared to that of treatment with SFN alone. In addition, silencing of Nrf2 increased apoptosis in cells treated with SFN/TRAIL; however, blockade of ROS generation inhibited apoptotic activity. These data suggest that SFN-induced ROS generation promotes TRAIL sensitivity and SFN can be used for the management of TRAIL-resistant cancer.