Association of the ESR1 (rs9340799), OLR1 (rs3736234), LIPC (rs2070895), VDR (rs2228570), and CETP (rs708272) Polymorphisms With Risk of Coronary Artery Disease in Iranian Patients.

BACKGROUND: Coronary artery disease (CAD) is a devastating illness and a leading cause of death worldwide, primarily caused by atherosclerosis resulting from a genetic-environmental interaction. This study aimed to investigate the relationship between the ESR1 (rs9340799), OLR1 (rs3736234), LIPC (rs2070895), VDR (rs2228570), and CETP (rs708272) polymorphisms, lipid profile parameters, and CAD risk in a southeast Iranian population. METHODS: A total of 400 subjects (200 CAD patients with hyperlipidemia and 200 healthy controls) were enrolled in this case-control study. Five selected polymorphisms were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. RESULTS: For all single nucleotide polymorphisms (SNPs), the population under study was in the Hardy-Weinberg equilibrium. The T-risk allele frequency of rs2228570 was associated with an increased risk of CAD. The TT and CT genotypes of rs2228570 had also been associated with the risk of CAD. Additionally, the TT genotype was associated with higher serum low-density lipoprotein cholesterol (LDL-c) and high-density lipoprotein cholesterol (HDL-c) levels. The GG genotype of the rs3736234 was associated with higher body mass index (BMI) and triglyceride (TG) levels, and the AA genotype of the rs708272 was associated with higher HDL-c levels. Based on these findings, we propose that the VDR (rs2228570) polymorphism was associated with serum HDL-c and LDL-c levels and may serve as potential risk factors for CAD within the Iranian population. Moreover, rs3736234 and rs708272 influence the concentrations of TG and HDL-c, respectively. CONCLUSION: These findings provided insights into the complex interplay between genetic variations, cardiovascular risk, and lipid metabolism.

Atherosclerosis and Toll-Like Receptor4 (TLR4), Lectin-Like Oxidized Low-Density Lipoprotein-1 (LOX-1), and Proprotein Convertase Subtilisin/Kexin Type9 (PCSK9).

Atherosclerosis is a leading cause of death in the world. A significant body of evidence suggests that inflammation and various players are implicated and have pivotal roles in the formation of atherosclerotic plaques. Toll-like receptor 4 (TLR4) is linked with different stages of atherosclerosis. This receptor is highly expressed in the endothelial cells (ECs) and atherosclerotic plaques. TLR4 activation can lead to the production of inflammatory cytokines and related responses. Lectin-like oxidized low-density lipoprotein-1 (LOX-1), an integral membrane glycoprotein with widespread expression on the ECs, is involved in atherosclerosis and has some common pathways with TLR4 in atherosclerotic lesions. In addition, proprotein convertase subtilisin/kexin type9 (PCSK9), which is a regulatory enzyme with different roles in cholesterol uptake, is implicated in atherosclerosis. At present, TLR4, PCSK9, and LOX-1 are increasingly acknowledged as key players in the pathogenesis of atherosclerotic cardiovascular diseases. Herein, we presented the current evidence on the structure, functions, and roles of TLR4, PCSK9, and LOX-1 in atherosclerosis.

LOX-1 regulation of H-type vascular endothelial cell regeneration in hyperglycemia.

AIMS: Diabetic osteoporosis (DOP) is the most common secondary form of osteoporosis. Diabetes mellitus affects bone metabolism; however, the underlying pathophysiological mechanisms remain unclear. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression is upregulated in conditions characterized by vascular injury, such as atherosclerosis, hypertension, and diabetes. Additionally, Notch, HIF-1α, and VEGF are involved in angiogenesis and bone formation. Therefore, we aimed to investigate the expression of Notch, HIF-1α, and VEGF in the LOX-1 silencing state. METHODS: Rat bone H-type vascular endothelial cells (THVECs) were isolated and cultured in vitro. Cell identification was performed using immunofluorescent co-expression of CD31 and Emcn. Lentiviral silencing vector (LV-LOX-1) targeting LOX-1 was constructed using genetic recombination technology and transfected into the cells. The experimental groups included the following: NC group, HG group, LV-LOX-1 group, LV-CON group, HG + LV-LOX-1 group, HG + LV-CON group, HG + LV-LOX-1 + FLI-06 group, HG + LV-CON + FLI-06 group, HG + LV-LOX-1 + LW6 group, and HG + LV-CON + LW6 group. The levels of LOX-1, Notch, Hif-1α, and VEGF were detected using PCR and WB techniques to investigate whether the expression of LOX-1 under high glucose conditions has a regulatory effect on downstream molecules at the gene and protein levels, as well as the specific molecular mechanisms involved. RESULTS: High glucose (HG) conditions led to a significant increase in LOX-1 expression, leading to inhibition of angiogenesis, whereas silencing LOX-1 can reverse this phenomenon. Further analysis reveals that changes in LOX-1 will promote changes in Notch/HIF-1α and VEGF. Moreover, Notch mediates the activation of HIF-1α and VEGF. CONCLUSIONS: The activation of LOX-1 and the inhibition of Notch/HIF-1α/VEGF in THVECs are the main causes of DOP. These findings contribute to our understanding of the pathogenesis of DOP and offer a novel approach for preventing and treating osteoporosis.

Lipoxygenases regulate digestive enzyme inhibitor activities in developing seeds of field-grown soybean against the southern green stink bug (Nezara viridula).

Soybean (Glycine max ) is the world's most widely grown seed legume. One of the most important pests that decrease seed quality and reduce yield of soybean crops is the southern green stink bug (Nezara viridula ). Insect damage triggers accumulation of defensive compounds such as protease inhibitors (PIs), isoflavonoids and reactive oxygen species, which are regulated by the lipoxygenase (LOX)-regulated jasmonic acid (JA) to stop insect feeding. This study identified and characterised the role of LOX isoforms in the modulation of chemical defences in seeds of field-grown soybean that decreased digestive enzyme activities of N. viridula after insect attack. Stink bugs attack increased LOX 1 and LOX 2 expression, and activities of LOX 1 and LOX 3 isoenzymes in developing soybean seeds. In addition, stink bug damage and methyl jasmonate application induced expression and activity of both cysteine PIs and trypsin PIs in developing soybean seeds, suggesting that herbivory induced JA in soybean seeds. High PI activity levels in attacked seeds decreased cysteine proteases and α-amylases activities in the gut of stink bugs that fed on field-grown soybean. We demonstrated that LOX isoforms of seeds are concomitantly induced with JA-regulated PIs by stink bugs attack, and these PIs inhibit the activity of insect digestive enzymes. To our knowledge, this is the first study to investigate the participation of LOX in modulating JA-regulated defences against stink bugs in seeds of field-grown soybean, and our results suggest that soybean PIs may inhibit α-amylase activity in the gut of N. viridula .

Transcriptional reprogramming during human osteoclast differentiation identifies regulators of osteoclast activity.

Enhanced osteoclastogenesis and osteoclast activity contribute to the development of osteoporosis, which is characterized by increased bone resorption and inadequate bone formation. As novel antiosteoporotic therapeutics are needed, understanding the genetic regulation of human osteoclastogenesis could help identify potential treatment targets. This study aimed to provide an overview of transcriptional reprogramming during human osteoclast differentiation. Osteoclasts were differentiated from CD14+ monocytes from eight female donors. RNA sequencing during differentiation revealed 8 980 differentially expressed genes grouped into eight temporal patterns conserved across donors. These patterns revealed distinct molecular functions associated with postmenopausal osteoporosis susceptibility genes based on RNA from iliac crest biopsies and bone mineral density SNPs. Network analyses revealed mutual dependencies between temporal expression patterns and provided insight into subtype-specific transcriptional networks. The donor-specific expression patterns revealed genes at the monocyte stage, such as filamin B (FLNB) and oxidized low-density lipoprotein receptor 1 (OLR1, encoding LOX-1), that are predictive of the resorptive activity of mature osteoclasts. The expression of differentially expressed G-protein coupled receptors was strong during osteoclast differentiation, and these receptors are associated with bone mineral density SNPs, suggesting that they play a pivotal role in osteoclast differentiation and activity. The regulatory effects of three differentially expressed G-protein coupled receptors were exemplified by in vitro pharmacological modulation of complement 5 A receptor 1 (C5AR1), somatostatin receptor 2 (SSTR2), and free fatty acid receptor 4 (FFAR4/GPR120). Activating C5AR1 enhanced osteoclast formation, while activating SSTR2 decreased the resorptive activity of mature osteoclasts, and activating FFAR4 decreased both the number and resorptive activity of mature osteoclasts. In conclusion, we report the occurrence of transcriptional reprogramming during human osteoclast differentiation and identified SSTR2 and FFAR4 as antiresorptive G-protein coupled receptors and FLNB and LOX-1 as potential molecular markers of osteoclast activity. These data can help future investigations identify molecular regulators of osteoclast differentiation and activity and provide the basis for novel antiosteoporotic targets.

Role of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Inflammation and Pathogen-Associated Interactions.

BACKGROUND: Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is known as a major receptor for oxidized low-density lipoproteins (oxLDL) and plays a significant role in the genesis of atherosclerosis. Recent research has shown its involvement in cancer, ischemic stroke, and diabetes. LOX-1 is a C-type lectin receptor and is involved in the activation of immune cells and inflammatory processes. It may further interact with pathogens, suggesting a role in infections or the host's response. SUMMARY: This review compiles the current knowledge of potential implications of LOX-1 in inflammatory processes and in host-pathogen interactions with a particular emphasis on its regulatory role in immune responses. Also discussed are genomic and structural variations found in LOX-1 homologs across different species as well as potential involvements of LOX-1 in inflammatory processes from the angle of different cell types and organ-specific interactions. KEY MESSAGES: The results presented reveal both similar and different structures in human and murine LOX-1 and provide clues as to the possible origins of different modes of interaction. These descriptions raise concerns about the suitability, particularly of mouse models, that are often used in the analysis of its functionality in humans. Further research should also aim to better understand the mostly unknown binding and interaction mechanisms between LOX-1 and different pathogens. This pursuit will not only enhance our understanding of LOX-1 involvement in inflammatory processes but also identify potential targets for immunomodulatory approaches.

LOX-1 acts as an N6-methyladenosine-regulated receptor for Helicobacter pylori by binding to the bacterial catalase.

The role of N6-methyladenosine (m6A) modification of host mRNA during bacterial infection is unclear. Here, we show that Helicobacter pylori infection upregulates host m6A methylases and increases m6A levels in gastric epithelial cells. Reducing m6A methylase activity via hemizygotic deletion of methylase-encoding gene Mettl3 in mice, or via small interfering RNAs targeting m6A methylases, enhances H. pylori colonization. We identify LOX-1 mRNA as a key m6A-regulated target during H. pylori infection. m6A modification destabilizes LOX-1 mRNA and reduces LOX-1 protein levels. LOX-1 acts as a membrane receptor for H. pylori catalase and contributes to bacterial adhesion. Pharmacological inhibition of LOX-1, or genetic ablation of Lox-1, reduces H. pylori colonization. Moreover, deletion of the bacterial catalase gene decreases adhesion of H. pylori to human gastric sections. Our results indicate that m6A modification of host LOX-1 mRNA contributes to protection against H. pylori infection by downregulating LOX-1 and thus reducing H. pylori adhesion.

High-fat diet causes endothelial dysfunction in the mouse ophthalmic artery.

Obesity is a significant health concern that leads to impaired vascular function and subsequent abnormalities in various organs. The impact of obesity on ocular blood vessels, however, remains largely unclear. In this study, we examined the hypothesis that obesity induced by high-fat diet produces vascular endothelial dysfunction in the ophthalmic artery. Mice were subjected to a high-fat diet for 20 weeks, while age-matched controls were maintained on a standard diet. Reactivity of isolated ophthalmic artery segments was assessed in vitro. Reactive oxygen species (ROS) were quantified in cryosections by dihydroethidium (DHE) staining. Redox gene expression was determined in ophthalmic artery explants by real-time PCR. Furthermore, the expression of nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2), the receptor for advanced glycation end products (RAGE), and of the lectin-like oxidized low-density-lipoprotein receptor-1 (LOX-1) was determined in cryosections using immunofluorescence microscopy. Ophthalmic artery segments from mice on a high-fat diet exhibited impaired vasodilation responses to the endothelium-dependent vasodilator acetylcholine, while endothelium-independent responses to nitroprusside remained preserved. DHE staining intensity in the vascular wall was notably stronger in mice on a high-fat diet. Messenger RNA expression for NOX2 was elevated in the ophthalmic artery of mice subjected to high fat diet. Likewise, immunostainings revealed increased expression of NOX2 and of RAGE, but not of LOX-1. These findings suggest that a high-fat diet triggers endothelial dysfunction by inducing oxidative stress in the ophthalmic artery via involvement of RAGE and NOX2.

Associations of CKIP-1 and LOX-1 polymorphisms with the risk of type 2 diabetes mellitus with hypertension among Chinese adults.

AIMS: Type 2 diabetes mellitus (T2DM) and hypertension are common high-incidence diseases, closely related, and have common pathogenic basis such as oxidative stress. Casein kinase 2 interacting protein-1 (CKIP-1) and low-density lipoprotein receptor (LOX-1) are considered to be important factors affect the level of oxidative stress in the body. The main purpose of this study was to explore the relationship between CKIP-1 (rs6693817 A > T, rs2306235 C > G) and LOX-1 (rs1050283 G > A, rs11053646 C > G) polymorphisms and the risk of hypertension and diabetes, and try to find new candidate genes for diabetes and diabetes with hypertension etiology in Chinese population. METHODS: 574 T2DM patients and 597 controls frequently matched by age and sex were selected for genotyping of CKIP-1 (rs6693817 A > T, rs2306235 C > G) and LOX-1 gene (rs1050283 G > A, rs11053646 C > G). Logistic regression was used to analyze the correlation between different genotypes and the risk of T2DM and T2DM with hypertension, and the results were expressed as odds ratio (OR) and 95% confidence interval (95% CI). RESULTS: We found that the risk of T2DM in the AA + AT genotype of rs6693817 was higher than that in the TT genotype in Chinese population (OR = 1.318, 95%CI: 1.011-1.717, P = 0.041), and the difference was still significant after adjustment (OR = 1.370, 95%CI: 1.043-1.799, Padjusted = 0.024), the difference of heterozygotes (AT vs TT: OR = 1.374, 95%CI: 1.026-1.840, Padjusted = 0.033) was statistically significant. But after Bonferroni correction, the significance of the above sites disappeared. And rs6693817 was associated with the risk of T2DM combined with hypertension before and after adjustment in dominant model (OR = 1.424, 95% CI: 1.038-1.954, P = 0.028; OR = 1.460, 95% CI: 1.057-2.015, Padjusted = 0.021, respectively) and in heterozygote model (OR = 1.499, 95% CI: 1.069-2.102, P = 0.019; OR = 1.562, 95% CI: 1.106-2.207, Padjusted = 0.011, respectively). However, only the statistical significance of the heterozygous model remained after Bonferroni correction. rs2306235, rs1050283 and rs11053646 were not significantly correlated with T2DM and T2DM combined with hypertension risk (P > 0.05). CONCLUSIONS: The results suggest that CKIP-1 rs6693817 is related to the susceptibility of Chinese people to T2DM with hypertension, providing a new genetic target for the treatment of diabetes with hypertension with in the future.

Transient receptor potential channel TRPM4 favors oxidized low-density lipoprotein-induced coronary endothelial cell dysfunction via a mechanism involving ferroptosis.

Accelerating the repair of damaged endothelium can effectively inhibit the progression of atherosclerosis (AS). Transient receptor potential channel TRPM4 is a non-selective cation channel activated by internal Ca2+, which is expressed in endothelial cells. This study aimed to reveal the potential role of TRPM4 in AS along with the mechanism. Human coronary artery endothelial cells (HCAECs) induced by ox-LDL was regarded as an in vitro model. The impacts of TRPM4 knockdown on cellular inflammation response, oxidative stress, normal endothelial function and lipid peroxidation were evaluated. Given that ferroptosis promotes AS progression, the effects of TRPM4 on intracellular iron ions and ferroptosis-related proteins was determined. Afterwards, HCAECs were treated with ferroptosis inducer erastin, and the influence of ferroptosis in the cellular model was revealed. TRPM4 was elevated in response to ox-LDL treatment in HCAECs. TRPM4 knockdown reduced the inflammation response, oxidative stress and lipid peroxidation caused by ox-LDL, and maintained the normal function of HCAECs. Erastin treatment destroyed the impacts of TRPM4 knockdown that are beneficial for cells to resist ox-LDL, showing the enhancement of the above adverse factors. Together, this study found that TRPM4 knockdown reduced ox-LDL-induced inflammation, oxidative stress, and dysfunction in HCAECs, possibly via a mechanism involving Fe2+ and ferroptosis-related proteins.

Knockdown of LOX-1 ameliorates bone quality and generation of type H blood vessels in diabetic mice.

Our previous studies have shown that lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) is expressed in liver sinusoidal endothelial cells, and oxidized low-density lipoprotein induces liver sinusoidal dysfunction and defenestration through the LOX-1/ROS/NF-kB pathway, revealing that LOX-1 can mediate liver sinusoidal barrier function, involved in the regulation of non-alcoholic fatty liver disease. Here, we investigated whether, in the context of bone metabolic diseases, LOX-1 could affect bone quality and type H blood vessels in diabetic mice. We used db/db mice as model and found that LOX-1 knockdown can ameliorate bone quality and type H blood vessel generation in db/db mice. This further verifies our hypothesis that LOX-1 is involved in the regulation of bone quality and type H blood vessel homeostasis, thus inhibiting osteoporosis progression in db/db mice.

LOX-1 Receptor: A Diagnostic Tool and Therapeutic Target in Atherogenesis.

Low-density lipoprotein (LDL) and oxidized LDL (oxLDL) are major contributors to atherogenesis, as endogenous antigens, via several receptors such as LOX 1. A PubMed search was conducted in order to identify relevant articles regarding LOX-1's role in the atherosclerosis, diagnosis, prognostic use and molecules that could be used for therapy. The references of the manuscripts obtained were also reviewed, in order to find additional relevant bibliography. LOX-1 is a lectin-like pattern recognition receptor, mostly expressed in endothelial cells (ECs) which can bind a variety of molecules, including oxLDL and C-reactive protein (CRP). LOX-1 plays a key role in oxLDL's role as a causative agent of atherosclerosis through several pathologic mechanisms, such as oxLDL deposition in the subintima, foam cell formation and endothelial dysfunction. Additionally, LOX-1 acts a scavenger receptor for oxLDL in macrophages and can be responsible for oxLDL uptake, when stimulated. Serum LOX-1 (sLOX-1) has emerged as a new, potential biomarker for diagnosis of acute coronary syndromes, and it seems promising for use along with other common biomarkers in everyday clinical practice. In a therapeutic perspective, natural as well as synthetic molecules exert anti-LOX-1 properties and attain the receptor's pathophysiological effects, thus extensive research is ongoing to further evaluate molecules with therapeutic potential. However, most of these molecules need further trials in order to properly assess their safety and efficacy for clinical use. The aim of this review is to investigate LOX-1 role in atherogenesis and explore its potential as diagnostic tool and therapeutic target.

Elevated soluble LOX-1 predicts risk of first-time myocardial infarction.

BACKGROUND: There is an unmet clinical need for novel therapies addressing the residual risk in patients receiving guideline preventive therapy for coronary heart disease. Experimental studies have identified a pro-atherogenic role of the oxidized LDL receptor LOX-1. We investigated the association between circulating soluble LOX-1 (sLOX-1) and the risk for development of myocardial infarction. METHODS: The study subjects (n = 4658) were part of the Malmö Diet and Cancer study. The baseline investigation was carried out 1991-1994 and the incidence of cardiovascular events monitored through national registers during a of 19.5 ± 4.9 years follow-up. sLOX-1 and other biomarkers were analyzed by proximity extension assay and ELISA in baseline plasma. RESULTS: Subjects in the highest tertile of sLOX-1 had an increased risk of myocardial infarction (hazard ratio (95% CI) 1.76 (1.40-2.21) as compared with those in the lowest tertile. The presence of cardiovascular risk factors was related to elevated sLOX-1, but the association between sLOX-1 and risk of myocardial infarction remained significant when adjusting for risk factors. CONCLUSIONS: In this prospective population study we found an association between elevated sLOX-1, the presence of carotid disease and the risk for first-time myocardial infarction. Taken together with previous experimental findings of a pro-atherogenic role of LOX-1, this observation supports LOX-1 inhibition as a possible target for prevention of myocardial infarction.

Activation of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) represents a possible target for treatment of the residual inflammatory risk in cardiovascular patients on guideline therapy.Having high levels of soluble LOX-1, a marker of cellular LOX-1 activation, is associated with an increased risk for development of myocardial infarction and heart failure.sLOX-1 levels correlated with major cardiovascular risk factors and biomarkers reflecting LDL oxidation.

Wall Teichoic Acid Mediates Staphylococcus aureus Binding to Endothelial Cells via the Scavenger Receptor LOX-1.

The success of Staphylococcus aureus as a major cause for endovascular infections depends on effective interactions with blood-vessel walls. We have previously shown that S. aureus uses its wall teichoic acid (WTA), a surface glycopolymer, to attach to endothelial cells. However, the endothelial WTA receptor remained unknown. We show here that the endothelial oxidized low-density lipoprotein receptor 1 (LOX-1) interacts with S. aureus WTA and permits effective binding of S. aureus to human endothelial cells. Purified LOX-1 bound to isolated S. aureus WTA. Ectopic LOX-1 expression led to increased binding of S. aureus wild type but not of a WTA-deficient mutant to a cell line, and LOX-1 blockage prevented S. aureus binding to endothelial cells. Moreover, WTA and LOX-1 expression levels correlated with the efficacy of the S. aureus-endothelial interaction. Thus, LOX-1 is an endothelial ligand for S. aureus, whose blockage may help to prevent or treat severe endovascular infections.

Correlation of sLOX-1 and CSF1 with the pathological progression of hypoxic-ischemic encephalopathy in neonatal rats.

To provide clinical evidence for the management of hypoxic-ischemic encephalopathy (HIE) by analyzing the role of soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) and colony-stimulating factor-1 (CSF1) in the disease. We purchased 15 Sprague-Dawley (SD) rat pups and randomized them into five groups (n=3), of which one group was untreated as the control group and the other four were modeled by HIE. After modeling, a group was treated as a model group without any treatment, another group was injected with sLOX-1-silencing lentiviral vector (sLOX-1-si group), and the third and fourth were injected with CSF1-silencing lentiviral vector (CSF1-si group) and an equal amount of normal saline (blank group), respectively. After the corresponding intervention, the rat tissue in each group was obtained to observe the pathological injury by HE and TUNEL staining. In addition, sLOX-1, CSF1, 5-hydroxytryptamine (5-HT), dopamine (DA), and norepinephrine (NE) levels in brain tissue of each group were determined. The model group showed more severe pathological damage of the hippocampus and higher neuronal apoptosis than the control group. Besides, higher sLOX-1 and CSF1 levels and lower 5-HT, DA and NE contents were identified in the model group versus the control group (P<0.05). Compared with the blank group, sLOX-1-si and CSF1-si groups showed significantly alleviated hippocampal damage, inhibited neuronal apoptosis, reduced 5-HT, DA, NE, Bax, and cl-caspase-3, and increased Bcl-2 (P<0.05). Silencing sLOX-1 and CSF1 expression ameliorated the pathological injury of HIE and inhibited neuronal apoptosis.

"Affimer" synthetic protein scaffolds block oxidized LDL binding to the LOX-1 scavenger receptor and inhibit ERK1/2 activation.

In multicellular organisms, a variety of lipid-protein particles control the systemic flow of triacylglycerides, cholesterol, and fatty acids between cells in different tissues. The chemical modification by oxidation of these particles can trigger pathological responses, mediated by a group of membrane proteins termed scavenger receptors. The lectin-like oxidized low-density lipoprotein (LOX-1) scavenger receptor binds to oxidized low-density lipoprotein (oxLDL) and mediates both signaling and trafficking outcomes. Here, we identified five synthetic proteins termed Affimers from a phage display library, each capable of binding recombinant LOX-1 extracellular (oxLDL-binding) domain with high specificity. These Affimers, based on a phytocystatin scaffold with loop regions of variable sequence, were able to bind to the plasma membrane of HEK293T cells exclusively when human LOX-1 was expressed. Binding and uptake of fluorescently labeled oxLDL by the LOX-1-expressing cell model was inhibited with subnanomolar potency by all 5 Affimers. ERK1/2 activation, stimulated by oxLDL binding to LOX-1, was also significantly inhibited (p < 0.01) by preincubation with LOX-1-specific Affimers, but these Affimers had no direct agonistic effect. Molecular modeling indicated that the LOX-1-specific Affimers bound predominantly via their variable loop regions to the surface of the LOX-1 lectin-like domain that contains a distinctive arrangement of arginine residues previously implicated in oxLDL binding, involving interactions with both subunits of the native, stable scavenger receptor homodimer. These data provide a new class of synthetic tools to probe and potentially modulate the oxLDL/LOX-1 interaction that plays an important role in vascular disease.

Klotho inhibits renal ox-LDL deposition via IGF-1R/RAC1/OLR1 signaling to ameliorate podocyte injury in diabetic kidney disease.

OBJECTIVE: Diabetic kidney disease (DKD) is characterized by the abnormal deposition of oxidized low-density lipoprotein (ox-LDL), which contributes to podocyte damage. Klotho, an aging suppressor that plays a critical role in protecting podocytes in DKD, is mainly expressed in kidney tubular epithelium and secreted in the blood. However, it has not been established whether Klotho can alleviate podocyte injury by inhibiting renal ox-LDL deposition, and the potential molecular mechanisms require further investigation. METHODS: We conducted a comprehensive analysis of serum and kidney biopsy samples obtained from patients diagnosed with DKD. Additionally, to explore the underlying mechanism of Klotho in the deposition of ox-LDL in the kidneys, we employed a mouse model of DKD with the Klotho genotype induced by streptozotocin (STZ). Furthermore, we conducted meticulous in vitro experiments on podocytes to gain further insights into the specific role of Klotho in the deposition of ox-LDL within the kidney. RESULTS: Our groundbreaking study unveiled the remarkable ability of the soluble form of Klotho to effectively inhibit high glucose-induced ox-LDL deposition in podocytes affected by DKD. Subsequent investigations elucidated that Klotho achieved this inhibition by reducing the expression of the insulin/insulin-like growth factor 1 receptor (IGF-1R), consequently leading to a decrease in the expression of Ras-related C3 botulinum toxin substrate 1 (RAC1) and an enhancement of mitochondrial function. Ultimately, this series of events culminated in a significant reduction in the expression of the oxidized low-density lipoprotein receptor (OLR1), thereby resulting in a notable decrease in renal ox-LDL deposition in DKD. CONCLUSION: Our findings suggested that Klotho had the potential to mitigate podocyte injury and reduced high glucose-induced ox-LDL deposition in glomerulus by modulating the IGF-1R/RAC1/OLR1 signaling. These results provided valuable insights that could inform the development of novel strategies for diagnosing and treating DKD.

Epigenetic regulation of 15-lipoxygenase-1 expression in human chondrocytes by promoter methylation.

OBJECTIVE AND DESIGN: 15-Lipoxygenase-1 (15-LOX-1) catalyzes the biosynthesis of many anti-inflammatory and immunomodulatory lipid mediators and was reported to have protective properties in several inflammatory conditions, including osteoarthritis (OA). This study was designed to evaluate the expression of 15-LOX-1 in cartilage from normal donors and patients with OA, and to determine whether it is regulated by DNA methylation. METHODS: Cartilage samples were obtained at autopsy from normal knee joints and from OA-affected joints at the time of total knee joint replacement surgery. The expression of 15-LOX-1 was evaluated using real-time polymerase chain reaction (PCR). The role of DNA methylation in 15-LOX-1 expression was assessed using the DNA methyltransferase inhibitor 5-Aza-2'-desoxycytidine (5-Aza-dC). The effect of CpG methylation on 15-LOX-1 promoter activity was evaluated using a CpG-free luciferase vector. The DNA methylation status of the 15-LOX-1 promoter was determined by pyrosequencing. RESULTS: Expression of 15-LOX-1 was upregulated in OA compared to normal cartilage. Treatment with 5-Aza-dC increased 15-LOX-1 mRNA levels in chondrocytes, and in vitro methylation decreased 15-LOX-1 promoter activity. There was no difference in the methylation status of the 15-LOX-1 gene promoter between normal and OA cartilage. CONCLUSION: The expression level of 15-LOX-1 was elevated in OA cartilage, which may be part of a repair process. The upregulation of 15-LOX-1 in OA cartilage was not associated with the methylation status of its promoter, suggesting that other mechanisms are involved in its upregulation.

15-lipoxygenase and cyclooxygenase expression profile and their related modulators in COVID-19 infection.

BACKGROUND: The role of the lipoxygenase (LOX) and cyclooxygenase (COX) enzymes in maintaining cellular homeostasis and regulating immune responses promoted us in this study to analyze the pattern of changes in 15-lipoxygenase and cyclooxygenase isoforms and their related cytokines in SARS-CoV-2 infection. METHODS: 15-LOX-1, 15-LOX-2, COX-1 and COX-2 gene expression levels were determined using qRT-PCR in nasopharynx specimens from patients with severe [N = 40] and non-severe [N = 40] confirmed SARS-CoV-2 infections and healthy controls. Circulating levels of lL-6, lL-10, PGE2, and IFN-γ were measured in patients and healthy controls using ELISA assay. The associations between the measured variables and the patient's clinic-pathological characteristics were assessed for all groups. RESULTS: The expression level of 15-LOX-1 was elevated significantly in male patients with severe infection; although female patients showed a different expression profile. 15-LOX-2 expression level was considerably increased in male patients with severe infection; while changes in its expression remained inconclusive in female patients. The relationship between 15-LOX expression and the male gender was prominent. Both COX isoforms expression showed elevation in male and female patients that were correlated with disease severity. The simultaneous increase in lL-6, PGE2 and IFN-γ levels also decrease in lL-10 in patients with severe infection indicating the possible regulatory network related to the COX and 15-LOX enzymes in the output of the SARS-CoV-2 infection. CONCLUSION: The results of this study determined the pattern of possible changes in key enzymes of prostaglandin and eicosanoids synthesis pathway and their mediators, which can be helpful in mapping the SARS-CoV-2 pathogenicity and pharmaceutical approaches.

Investigating the catalytic efficiency of C22-Fatty acids with LOX human isozymes and the platelet response of the C22-oxylipin products.

Polyunsaturated fatty acids (PUFAs) have been extensively studied for their health benefits because they can be oxidized by lipoxygenases to form bioactive oxylipins. In this study, we investigated the impact of double bond placement on the kinetic properties and product profiles of human platelet 12-lipoxygenase (h12-LOX), human reticulocyte 15-lipoxygenase-1 (h15-LOX-1), and human endothelial 15-lipoxygenase-2 (h15-LOX-2) by using 22-carbon (C22) fatty acid substrates with differing double bond content. With respect to kcat/KM values, the loss of Δ4 and Δ19 led to an 18-fold loss of kinetic activity for h12-LOX, no change in kinetic capability for h15-LOX-1, but a 24-fold loss for h15-LOX-2 for both C22-FAs. With respect to the product profiles, h12-LOX produced mainly 14-oxylipins. For h15-LOX-1, the 14-oxylipin production increased with the loss of either Δ4 and Δ19, however, the 17-oxylipin became the major species upon loss of both Δ4 and Δ19. h15-LOX-2 produced mostly the 17-oxylipin products throughout the fatty acid series. This study also investigated the effects of various 17-oxylipins on platelet activation. The results revealed that both 17(S)-hydroxy-4Z,7Z,10Z,13Z,15E,19Z-DHA (17-HDHA) and 17-hydroxy-4Z,7Z,10Z,13Z,15E-DPAn6 (17-HDPAn6) demonstrated anti-aggregation properties with thrombin or collagen stimulation. 17-hydroxy-7Z,10Z,13Z,15E,19Z-DPAn3 (17-HDPAn3) exhibited agonistic properties, and 17-hydroxy-7Z,10Z,13Z,15E-DTA (17-HDTA) showed biphasic effects, inhibiting collagen-induced aggregation at lower concentrationsbut promoting aggregation at higher concentrations. Both 17-hydroxy-13Z,15E,19Z-DTrA (17-HDTrA), and 17-hydroxy-13Z,15E-DDiA (17-HDDiA) induced platelet aggregation. In summary, the number and placement of the double bonds affect platelet activation, with the general trend being that more double bonds generally inhibit aggregation, while less double bonds promote aggregation. These findings provide insights into the potential role of specific fatty acids and their metabolizing LOX isozymes with respect to cardiovascular health.