The toll of the gridiron: damage-associated molecular patterns and hypertension in American football

Extracellular vesicle mitochondrial DNA levels are associated with race and mitochondrial DNA haplogroup

Circulating cell-free mitochondrial DNA (ccf-mtDNA) acts as a damage-associated molecular pattern molecule and may be cargo within extracellular vesicles (EVs). ccf-mtDNA and select mitochondrial DNA (mtDNA) haplogroups are associated with cardiovascular disease. We hypothesized that ccf-mtDNA and plasma EV mtDNA would be associated with hypertension, sex, self-identified race, and mtDNA haplogroup ancestry. Participants were normotensive (n = 107) and hypertensive (n = 108) African American and White adults from the Healthy Aging in Neighborhoods of Diversity across the Life Span study. ccf-mtDNA levels were higher in African American participants compared with White participants in both plasma and EVs, but ccf-mtDNA levels were not related to hypertension. EV mtDNA levels were highest in African American participants with African mtDNA haplogroup. Circulating inflammatory protein levels were altered with mtDNA haplogroup, race, and EV mtDNA. Our findings highlight that race is a social construct and that ancestry is crucial when examining health and biomarker differences between groups.

Effects of acute endurance exercise and exhaustive exercise on innate immune signals induced by mtDNA

Objective: Numerous studies have shown that mitochondrial DNA (mtDNA) can trigger innate immune signaling, and exercise can induce mitochondrial stress. Therefore, this study is aimed at investigating the influence of different types of acute exercise on the innate immune signaling triggered by mtDNA.

Methods: Male C57BL/6 mice ( n = 18) were randomly and equally divided into three groups. They were control group, acute moderate-intensity endurance exercise group (AMIE), and 3-day exhaustive exercise group (EE) respectively. Mice were sacrificed immediately after exercise. The spleen, liver, and blood were taken for analysis.

Results: The amount of mtDNA in the liver cytoplasm and plasma was significantly decreased after AMIE ( p < .05). However, the amount of mtDNA in plasma was increased after EE (p < .05). The mRNA expression of TFAM, and most TLR9 and cGAS/STING signaling pathway-related genes in the liver and spleen was markedly elevated, whereas the expression of those genes in leukocytes was reduced after AMIE. Furthermore, AMIE significantly decreased the protein expression of NLRP3 inflammasome in the liver ( p < .05) and STING in spleen ( p < .01). Also, AMIE and EE caused a drop in circulating IFN-β levels ( p < .05).

Conclusion: A single bout of moderate-intensity exercise reduces mtDNA-induced innate immune signaling and suppresses inflammatory responses by decreasing hepatic cytoplasmic and circulating mtDNA. However, repeated bouts of exhaustive exercise stimulate innate immune signaling by increasing levels of circulating mtDNA.

Mitochondrial DNA and Exercise: Implications for Health and Injuries in Sports

Recently, several studies have highlighted the tight connection between mitochondria and physical activity. Mitochondrial functions are important in high-demanding metabolic activities, such as endurance sports. Moreover, regular training positively affects metabolic health by increasing mitochondrial oxidative capacity and regulating glucose metabolism. Exercise could have multiple effects, also on the mitochondrial DNA (mtDNA) and vice versa; some studies have investigated how mtDNA polymorphisms can affect the performance of general athletes and mtDNA haplogroups seem to be related to the performance of elite endurance athletes. Along with several stimuli, including pathogens, stress, trauma, and reactive oxygen species, acute and intense exercise also seem to be responsible for mtDNA release into the cytoplasm and extracellular space, leading to the activation of the innate immune response. In addition, several sports are characterized by a higher frequency of injuries, including cranial trauma, associated with neurological consequences. However, with regular exercise, circulating cell-free mtDNA levels are kept low, perhaps promoting cf-mtDNA removal, acting as a protective factor against inflammation.

Season-Long Heart-Rate Variability Tracking Reveals Autonomic Imbalance in American College Football Players

PURPOSE

To track cardiac-autonomic functioning, indexed by heart-rate variability, in American college football players throughout a competitive period.

METHODS

Resting heart rate (RHR) and the natural logarithm root mean square of successive differences (LnRMSSD) were obtained throughout preseason and ∼3 times weekly leading up to the national championship among 8 linemen and 12 nonlinemen. Seated 1-minute recordings were performed via mobile device and standardized for time of day and proximity to training.

RESULTS

Relative to preseason, linemen exhibited suppressed LnRMSSD during camp-style preparation for the playoffs (P = .041, effect size [ES] = -1.01), the week of the national semifinal (P < .001, ES = -1.27), and the week of the national championship (P = .005, ES = -1.16). As a combined group, increases in RHR (P < .001) were observed at the same time points (nonlinemen ES = 0.48-0.59, linemen ES = 1.03-1.10). For all linemen, RHR trended upward (positive slopes, R2 = .02-.77) while LnRMSSD trended downward (negative slopes, R2 = .02-.62) throughout the season. Preseason to postseason changes in RHR (r = .50, P = .025) and LnRMSSD (r = -.68, P < .001) were associated with body mass.

CONCLUSIONS

Heart-rate variability tracking revealed progressive autonomic imbalance in the lineman position group, with individual players showing suppressed values by midseason. Attenuated parasympathetic activation is a hallmark of impaired recovery and may contribute to cardiovascular maladaptations reported to occur in linemen following a competitive season. Thus, a descending pattern may serve as an easily identifiable red flag requiring attention from performance and medical staff.

Phosphatidylglycerol and surfactant: A potential treatment for COVID-19?

A hypothesis concerning the potential utility of surfactant supplementation for the treatment of critically ill patients with COVID-19 is proposed, along with a brief summary of the data in the literature supporting this idea. It is thought that surfactant, which is already approved by the Food and Drug Administration for intratracheal administration to treat neonatal respiratory distress syndrome in pre-term infants, could benefit COVID-19-infected individuals by: (1) restoring surfactant damaged by lung infection and/or decreased due to the virus-induced death of the type II pneumocytes that produce it and (2) reducing surface tension to decrease the work of breathing and limit pulmonary edema. In addition, a constituent of surfactant, phosphatidylglycerol, could mitigate COVID-19-induced lung pathology by: (3) decreasing excessive innate immune system stimulation via its inhibition of toll-like receptor-2 and -4 activation by microbial components and cellular proteins released by damaged cells, thereby limiting inflammation and the resultant pulmonary edema, and (4) possibly blocking spread of the viral infection to non-infected cells in the lung. Therefore, it is suggested that surfactant preparations containing phosphatidylglycerol be tested for their ability to improve lung function in critically ill patients with COVID-19.

Atrogin1-induced loss of aquaporin 4 in myocytes leads to skeletal muscle atrophy

The water channel aquaporin 4 (AQP4) regulates the flux of water across the cell membrane, maintaining cellular homeostasis. Since AQP4 is enriched in the sarcolemma of skeletal muscle, a functional defect in AQP4 may cause skeletal muscle dysfunction. To investigate a novel mechanism underlying skeletal muscle atrophy, we examined AQP4 expression and its regulation in muscle using the rotator cuff tear (RCT) model. Human and mouse AQP4 expression was significantly decreased in atrophied muscle resulting from RCT. The size and the number of myotubes were reduced following AQP4 knockdown. Atrogin 1-mediated ubiquitination of AQP4 was verified with an ubiquitination assay after immunoprecipitation of AQP4 with an anti-AQP4 antibody. In this study, we identified high mobility group box 1 (HMGB1) as a potent upstream regulator of atrogin 1 expression. Atrogin 1 expression was increased by recombinant mouse HMGB1 protein, and the HMGB1-induced atrogin 1 expression was mediated via NF-κB signaling. Our study suggests that loss of AQP4 appears to be involved in myocyte shrinkage after RCT, and its degradation is mediated by atrogin 1-dependent ubiquitination. HMGB1, in its function as a signaling molecule upstream of the ubiquitin ligase atrogin 1, was found to be a novel regulator of muscle atrophy.

Blood Biomarker Profiling and Monitoring for High-Performance Physiology and Nutrition: Current Perspectives, Limitations and Recommendations

Blood test data were traditionally confined to the clinic for diagnostic purposes, but are now becoming more routinely used in many professional and elite high-performance settings as a physiological profiling and monitoring tool. A wealth of information based on robust research evidence can be gleaned from blood tests, including: the identification of iron, vitamin or energy deficiency; the identification of oxidative stress and inflammation; and the status of red blood cell populations. Serial blood test data can be used to monitor athletes and make inferences about the efficacy of training interventions, nutritional strategies or indeed the capacity to tolerate training load. Via a profiling and monitoring approach, blood biomarker measurement combined with contextual data has the potential to help athletes avoid injury and illness via adjustments to diet, training load and recovery strategies. Since wide inter-individual variability exists in many biomarkers, clinical population-based reference data can be of limited value in athletes, and statistical methods for longitudinal data are required to identify meaningful changes within an athlete. Data quality is often compromised by poor pre-analytic controls in sport settings. The biotechnology industry is rapidly evolving, providing new technologies and methods, some of which may be well suited to athlete applications in the future. This review provides current perspectives, limitations and recommendations for sports science and sports medicine practitioners using blood profiling and monitoring for nutrition and performance purposes.

Double-stranded RNA and Toll-like receptor activation: a novel mechanism for blood pressure regulation

Toll-like receptors (TLRs), such as TLR4 and 9, recognize pathogen-associated molecular pattern (PAMPs) and danger-associated molecular patterns (DAMPs) and are associated with increased blood pressure (BP). TLR3, residing in the endosomal compartment, is activated by viral double-stranded RNA (dsRNA) leading to activation of TIR receptor domain-containing adaptor inducing IFN-β (TRIF) dependent pathway. Besides foreign pathogens, the immune system responds to endogenous markers of cellular damage such as mitochondrial dsRNA (mtdsRNA). New evidence has shown a link between dsRNA and increased BP. Moreover, TLR3 activation during pregnancy was demonstrated to develop preeclampsia-like symptoms in both rats and mice. Hence, we hypothesize that the dsRNA derived from viral nucleic acids or cellular damage (mtdsRNA) will increase the inflammatory state through activation of TLR3, contributing to vascular dysfunction and increased BP. Therefore, inhibition of TLR3 could be a therapeutic target for the treatment of hypertension with potential improvement in vascular reactivity and consequently, a decrease in BP.

Influence of Smoking on the Expression of Genes and Proteins Related to Fat Infiltration, Inflammation, and Fibrosis in the Rotator Cuff Muscles of Patients With Chronic Rotator Cuff Tears: A Pilot Study

PURPOSE

To evaluate the altered gene and protein expression patterns in the rotator cuff muscles of smokers and non-smokers with rotator cuff tears and to identify the smoking-associated key genetic factor(s) involved in rotator cuff muscle physiology.

METHODS

Twenty-four samples of rotator cuff muscle from 12 current heavy smokers (mean age 61.8 ± 5.1 years) and age- and sex-matched 12 non-smokers (mean age 61.8 ± 6.9 years) with medium-sized tears were acquired during arthroscopic surgery. As a statistical method, the propensity score matching technique was used to select control group by 1:1 matching for age and sex. Inclusion criteria were patients who underwent arthroscopic repair for medium-sized full-thickness rotator cuff tears and those that were current smokers with a smoking history >20 packs/year. Patients lacking medium-sized tears, those with recent steroid injection history, isolated subscapularis tear, preoperative stiff shoulder, acute traumatic tear, or previous surgery on the same shoulder, or those that declined to participate were excluded. Alterations in the expression of genes and proteins associated with myogenesis, inflammation, adipogenesis, and muscle fibrosis were compared between smokers and non-smokers with reverse-transcription quantitative polymerase chain reaction, western blotting, and immunohistochemistry.

RESULTS

Histologic analysis revealed increased inflammation and remarkable fat accumulation and fibrogenesis in the rotator cuff muscle from smokers compared with that from non-smokers. The mRNA expression levels of inflammatory high mobility group box 1 (HMGB1; P = .043), adipogenic CCAAT/enhancer-binding protein alpha (P = .046) and peroxisome proliferator-activated receptor gamma (PPARγ; P = .048), myogenic differentiation 1 (P = .032), fibrogenic alpha-smooth muscle actin (α-SMA; P = .033), and metalloproteinase 9 (P = .036) were significantly greater in samples from smokers than from non-smokers. A correlation was observed between gene and protein expression of HMGB1 (P = .034), PPARγ (P = .021), and α-SMA (P = .021).

CONCLUSIONS

Smokers with rotator cuff tears showed high inflammation, large fat infiltration, and fibrosis in rotator cuff muscle that is associated with the increased expression of HMGB1, PPARγ, and α-SMA, respectively.

LEVEL OF EVIDENCE

Case control study (Prognostic level III).

Biomarkers for vascular ageing in aorta tissues and blood samples

OBJECTIVES

Functional and quantitative alterations and senescence of circulating and expanded endothelial progenitor cells (EPC), as well as systemic and tissue modifications of angiogenetic and inflammatory molecules, were evaluated for predicting age-related vessel wall remodeling, correlating them to intima media thickness (IMT) in the common carotid artery (CCA), a biomarker of early cardiovascular disease and aortic root dilation.

POPULATIONS AND METHODS

A homogenous Caucasian population was included in the study, constituted by 160 healthy subjects (80 old subjects, mean age 72 ± 6.4, range 66-83 years; and 80 younger blood donors, mean age 26.2 ± 3.4, range 21-33 years), and 60 old subjects (mean age 73 ± 1.4 (range 66-83) years) with aortic root dilatation and hypertension, and 60 old people (70 ± 2.8 (age range 66-83)) with sporadic ascending aorta aneurysm (AAA). In addition, 20 control individuals (10 men and 10 women, mean age: 65 ± 8), were also included in the study for evaluating the gene expression's levels, in aorta tissues. Appropriate techniques, practises, protocols, gating strategies and statistical analyses were performed in our evaluations.

RESULTS

Interestingly, old people had a significantly reduced functionality and a high grade of senescence (high SA-β-Gal activity and high levels of TP53, p21 and p16 genes) of EPC expanded than younger subjects. The values of related parameters progressively augmented from the old subjects, in good healthy shape, to subjects with hypertension and aorta dilation, and AAA. Moreover, they significantly impacted the endothelium than the alterations in EPC number. No changes, but rather increased systemic levels of VEGF and SDF-1 were also assessed in old people vs. younger donors. Old people also showed significantly increased systemic levels of inflammatory cytokines, and a reciprocal significant reduction of systemic s-Notch 1 than younger subjects. These parameters, also including the number EPC alterations, resulted to be significantly sustained in old people bearers of an inflammatory combined genotype. Consistent with these data, a reduced expression of Notch-1 gene, accompanied by a sustained expression of inflammatory genes (i.e. TLR4, IL-1β, IL-6 and IL-17) were detected in aortic tissues from old control people and AAA cases. Finally, we detected the biological effects induced by all the detected alterations on vessel wall age-related remodeling, by evaluating the IMT in the population studied and correlating it to these alterations. The analysis demonstrated that the unique independent risk predictors for vascular ageing are age, the EPC reduced migratory activity and senescence, high grade of expression of genes inducing EPC senescence and chronic tissue and systemic inflammation.

CONCLUSIONS

Thus, we propose these parameters, of easy determination in biological samples (i.e. blood and tissue samples) from alive human population, as optimal biomarkers for vascular ageing.

Neutrophil extracellular traps and fibrocytes in ST-segment elevation myocardial infarction

Leukocyte-mediated inflammation is central in atherothrombosis and ST-segment elevation myocardial infarction (STEMI). Neutrophil extracellular traps (NETs) have been shown to enhance atherothrombosis and stimulate fibroblast function. We analyzed the effects of NETs on cardiac remodeling after STEMI. We measured double-stranded (ds)DNA and citrullinated histone H3 (citH3) as NET surrogate markers in human culprit site and femoral blood collected during primary percutaneous coronary intervention (n = 50). Fibrocytes were characterized in whole blood by flow cytometry, and in culprit site thrombi and myocardium by immunofluorescence. To investigate mechanisms of fibrocyte activation, isolated NETs were used to induce fibrocyte responses in vitro. Enzymatic infarct size was assessed using creatine-phosphokinase isoform MB area under the curve. Left ventricular function was measured by transthoracic echocardiography. NET surrogate markers were increased at the culprit site compared to the femoral site and were positively correlated with infarct size and left ventricular dysfunction at follow-up. In vitro, NETs promoted fibrocyte differentiation from monocytes and induced fibrocyte activation. Highly activated fibrocytes accumulated at the culprit site and in the infarct transition zone. Our data suggest that NETs might be important mediators of fibrotic remodeling after STEMI, possibly by stimulating fibrocytes.

Mechanisms of isolevuglandin-protein adduct formation in inflammation and hypertension

Inflammation has been implicated in the pathogenesis of hypertension and recent evidence suggests that isolevuglandin (IsoLG)-protein adducts play a role. Several hypertensive stimuli contribute to formation of IsoLG-protein adducts including excess dietary salt and catecholamines. The precise intracellular mechanisms by which these hypertensive stimuli lead to IsoLG-protein adduct formation are still not well understood; however, there is now evidence implicating NADPH-oxidase derived reactive oxygen species (ROS) in this process. ROS oxidize arachidonic acid leading to formation of IsoLGs, which non-covalently adduct to lysine residues and alter protein structure and function. Recent studies suggest that these altered proteins act as neo-antigens leading to an autoimmune state that results in hypertension. The goal of this mini-review is to highlight some of the hypertensive stimuli and the mechanisms contributing to IsoLG-protein adduct formation leading to inflammation and hypertension.

Outpatient physical therapy cardiovascular assessment: Physical therapist perspective and experience

Background: Physical therapists are recognized healthcare providers who play an important role in cardiovascular disease prevention. Heart rate (HR) and blood pressure (BP) are important parameters in cardiovascular risk assessment; however, physical therapists do not usually integrate them into clinical practice. Therefore, this study aimed to examine the current practice and opinion of outpatient physical therapists toward HR and BP measurements in clinics. Methods: A 12-item survey questionnaire was distributed to outpatient physical therapists. Five senior staff from different specialties, including orthopedic, neurology, pediatric, cardiopulmonary, and sport specialties, participated in a focus group interview to gather their opinions. Results: In total, 285 (56%: male) physical therapists participated. Only 68 (24%) measured HR and BP; of these, 27 (41%) used manual sphygmomanometers. Nearly one-fifth reported that cardiovascular adverse events, such as syncope and chest pain, occurred during therapeutic exercise of their patients and were the highest among the sport and orthopedic physical therapists. Most physical therapists felt that measuring cardiovascular indices is not their job and does not add value to their treatment plan. Conclusion: Majority of the physical therapists were not measuring HR and BP during clinical assessment, although some reported cardiovascular adverse events occurring in their patients.

Out of the frying pan and into the fire: damage-associated molecular patterns and cardiovascular toxicity following cancer therapy

Cardio-oncology is a new and rapidly expanding field that merges cancer and cardiovascular disease. Cardiovascular disease is an omnipresent side effect of cancer therapy; in fact, it is the second leading cause of death in cancer survivors after recurrent cancer. It has been well documented that many cancer chemotherapeutic agents cause cardiovascular toxicity. Nonetheless, the underlying cause of cancer therapy-induced cardiovascular toxicity is largely unknown. In this review, we discuss the potential role of damage-associated molecular patterns (DAMPs) as an underlying contributor to cancer therapy-induced cardiovascular toxicity. With an increasing number of cancer patients, as well as extended life expectancy, understanding the mechanisms underlying cancer therapy-induced cardiovascular disease is of the utmost importance to ensure that cancer is the only disease burden that cancer survivors have to endure.

Blood Pressure and LV Remodeling Among American-Style Football Players

OBJECTIVES

This study sought to determine the relationships among American-style football (ASF) participation, acquired left ventricular (LV) hypertrophy, and LV systolic function as assessed using contemporary echocardiographic parameters.

BACKGROUND

Participation in ASF has been associated with development of hypertension and LV hypertrophy. To what degree these processes impact LV function is unknown.

METHODS

This was a prospective, longitudinal cohort study evaluating National Collegiate Athletic Association Division I football athletes stratified by field position (linemen: n = 30; vs. nonlinemen, n = 57) before and after a single competitive season, using transthoracic echocardiography. LV systolic function was measured using complementary parameters of global longitudinal strain (GLS) (using 2-dimensional speckle-tracking) and ejection fraction (EF) (2-dimensional biplane).

RESULTS

ASF participation was associated with field position-specific increases in systolic blood pressure (SBP) (a Δ SBP of 10 ± 8 mm Hg in linemen vs. a Δ SBP of 3 ± 7 mm Hg in nonlinemen; p < 0.001) and an overall increase in incident LV hypertrophy (pre-season = 8% vs. post-season = 25%, p < 0.05). Linemen who developed LV hypertrophy had concentric geometry (9 of 11 [82%]) with decreased GLS (Δ = -1.1%; p < 0.001), whereas nonlinemen demonstrated eccentric LV hypertrophy (8 of 10 [80%]) with increased GLS (Δ = +1.4%; p < 0.001). In contrast, LV ejection fraction in the total cohort, stratified by field position, was not significantly affected by ASF participation. Among the total cohort, lineman field position, post-season weight, SBP, average LV wall thickness, and relative wall thickness were all independent predictors of post-season GLS.

CONCLUSIONS

ASF participation at a lineman field position may lead to a form of sport-related myocardial remodeling that is pathologic rather than adaptive. Future study will be required to determine if targeted efforts to control blood pressure, minimize weight gain, and to include an element of aerobic conditioning in this subset of athletes may attenuate this process and translate into tangible downstream health benefits.

Toll-like receptor 4 mediates vascular remodeling in hyperhomocysteinemia

Although hyperhomocysteinemia (HHcy) is known to promote downstream pro-inflammatory cytokine elevation, the precise mechanism is still unknown. One of the possible receptors that could have significant attention in the field of hypertension is toll-like receptor 4 (TLR-4). TLR-4 is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. Its mutation can attenuate the effects of HHcy-mediated vascular inflammation and mitochondria- dependent cell death that suppresses hypertension. In this review, we observed that HHcy induces vascular remodeling through immunological adaptation, promoting inflammatory cytokine up-regulation (IL-1β, IL-6, TNF-α) and initiation of mitochondrial dysfunction leading to cell death and chronic vascular inflammation. The literature suggests that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death inducing peripheral vascular remodeling. In the previous studies, we have characterized the role of TLR-4 mutation in attenuating vascular remodeling in hyperhomocysteinemia. This review includes, but is not limited to, the physiological synergistic aspects of the downstream elevation of cytokines found within the vascular inflammatory cascade. These events subsequently induce mitochondrial dysfunction defined by excessive mitochondrial fission and mitochondrial apoptosis contributing to vascular remodeling followed by hypertension.

Dendritic cells and isolevuglandins in immunity, inflammation, and hypertension

Hypertension is the major risk factor for morbidity and mortality from myocardial infarction, stroke, heart failure, and chronic kidney disease. Despite its importance, the pathogenesis of essential hypertension is poorly understood. During the past several years, it has become evident that T cells contribute to hypertension. Activated T cells accumulate in the perivascular space and the kidney and release cytokines that promote vascular dysfunction and end-organ damage. Although dendritic cells play a pivotal role in initiating adaptive immune responses, T cells have taken center stage in studies implicating the immune system in the genesis of hypertension. The mechanisms by which T cells are activated and the antigens involved are poorly understood. We recently showed that hypertension is associated with increased dendritic cell production of the T_H17 polarizing cytokines, IL-6, IL-1β, and IL-23. This occurs in part by increased superoxide production via NADPH oxidase and protein modification by highly reactive isolevuglandins (IsoLGs). IsoLGs are produced via the isoprostane pathway of free radical-mediated lipid peroxidation and, when adducted to proteins, have the potential to act as neoantigens. In this review, we discuss recent advances in our understanding of the role of antigen-presenting dendritic cells in the pathophysiology of hypertension and highlight potential neoantigens that may contribute to this disease.

Toll-like receptor 4 mutation suppresses hyperhomocysteinemia-induced hypertension

Hyperhomocysteinemia (HHcy) has been observed to promote hypertension, but the mechanisms are unclear. Toll-like receptor 4 (TLR-4) is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. TLR-4 activation has been known to promote inflammation that has been associated with the pathogenesis of hypertension. In this study we hypothesize that HHcy induces hypertension by TLR-4 activation, which promotes inflammatory cytokine (IL-1β, IL-6, and TNF-α) upregulation and initiation of mitochondria-dependent apoptosis, leading to cell death and chronic vascular inflammation. To test this hypothesis, we used C57BL/6J (WT) mice, cystathionine β-synthase (CBS)-deficient (CBS^+/-) mice with genetic mild HHcy, C3H/HeJ (C3H) mice with TLR-4 mutation, and mice with combined genetic HHcy and TLR-4 mutation (CBS^+/-/C3H). Ultrasonography of the superior mesenteric artery (SMA) detected an increase in wall-to-lumen ratio, resistive index (RI), and pulsatility index (PI). Tail cuff blood pressure (BP) measurement revealed elevated BP in CBS^+/- mice. RI, PI, and wall-to-lumen ratio of the SMA in CBS^+/-/C3H mice were similar to the control group, and BP was significantly alleviated. TLR-4, IL-1β, IL-6, and TNF-α expression were upregulated in the SMA of CBS^+/- mice and reduced in the SMA of CBS^+/-/C3H mice. Molecules involved in the mitochondria-mediated cell death pathway (BAX, caspase-9, and caspase-3) were upregulated in CBS^+/- mice and attenuated in CBS^+/-/C3H mice. We conclude that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death, inducing hypertension. TLR-4 mutation attenuates vascular inflammation and cell death, which suppress hypertension.

Modulation of endothelial function by Toll like receptors

Endothelial cells (EC) are able to actively control vascular permeability, coagulation, blood pressure and angiogenesis. Most recently, a role for endothelial cells in the immune response has been described. Therefore, the endothelium has a dual role controlling homeostasis but also being the first line for host defence and tissue damage repair thanks to its ability to mount an inflammatory response. Endothelial cells have been shown to express pattern-recognition receptors (PRR) including Toll-like receptors (TLR) that are activated in response to stimuli within the bloodstream including pathogens and damage signals. TLRs are strategic mediators of the immune response in endothelial cells but they also regulate the angiogenic process critical for tissue repair. Nevertheless, endothelial activation and angiogenesis can contribute to some pathologies. Thus, inappropriate endothelial activation, also known as endothelial dysfunction, through TLRs contributes to tissue damage during autoimmune and inflammatory diseases such as atherosclerosis, hypertension, ischemia and diabetes associated cardiovascular diseases. Also TLR induced angiogenesis is required for the growth of some tumors, atherosclerosis and rheumatoid arthritis, among others. In this review we discuss the importance of various TLRs in modulating the activation of endothelial cells and their importance in immunity to infection and vascular disease as well as their potential as therapeutic targets.