Murepavadin promotes the killing efficacies of aminoglycoside antibiotics against Pseudomonas aeruginosa by enhancing membrane potential.

Murepavadin is a peptidomimetic that specifically targets the lipopolysaccharide transport protein LptD of Pseudomonas aeruginosa. Here, we found that murepavadin enhances the bactericidal efficacies of tobramycin and amikacin. We further demonstrated that murepavadin enhances bacterial respiration activity and subsequent membrane potential, which promotes intracellular uptake of aminoglycoside antibiotics. In addition, the murepavadin-amikacin combination displayed a synergistic bactericidal effect in a murine pneumonia model.

Fluid shear stress-mediated Piezo1 alleviates osteocyte apoptosis by activating the PI3K/Akt pathway.

Glucocorticoid-induced osteoporosis serves as a primary cause for secondary osteoporosis and fragility fractures, representing the most prevalent adverse reaction associated with prolonged glucocorticoid use. In this study, to elucidate the impact and underlying mechanisms of fluid shear stress (FSS)-mediated Piezo1 on dexamethasone (Dex)-induced apoptosis, we respectively applied Dex treatment for 6 h, FSS at 9 dyne/cm2 for 30 min, Yoda1 treatment for 2 h, and Piezo1 siRNA transfection to intervene in MLO-Y4 osteocytes. Western blot analysis was used to assess the expression of Cleaved Caspase-3, Bax, Bcl-2, and proteins associated with the PI3K/Akt pathway. Additionally, qRT-PCR was utilized to quantify the mRNA expression levels of these molecules. Hoechst 33258 staining and flow cytometry were utilized to evaluate the apoptosis levels. The results indicate that FSS at 9 dyne/cm2 for 30 min significantly upregulates Piezo1 in osteocytes. Following Dex-induced apoptosis, the phosphorylation levels of PI3K and Akt are markedly suppressed. FSS-mediated Piezo1 exerts a protective effect against Dex-induced apoptosis by activating the PI3K/Akt pathway. Additionally, downregulating the expression of Piezo1 in osteocytes using siRNA exacerbates Dex-induced apoptosis. To further demonstrate the role of the PI3K/Akt signaling pathway, after intervention with the PI3K pathway inhibitor, the activation of the PI3K/Akt pathway by FSS-mediated Piezo1 in osteocytes was significantly inhibited, reversing the anti-apoptotic effect. This study indicates that under FSS, Piezo1 in MLO-Y4 osteocytes is significantly upregulated, providing protection against Dex-induced apoptosis through the activation of the PI3K/Akt pathway.

Endoplasmic reticulum protein of 57 kDa sulfhydration promotes intestinal calcium absorption to attenuate primary osteoporosis.

Endogenous hydrogen sulfide (H2S) plays an important role in bone metabolism. However, the exact role of H2S in intestinal calcium and phosphorus absorption and its potential in preventing and treating primary osteoporosis remains unknown. Therefore, this study aimed to investigate the potential of H2S in promoting intestinal calcium and phosphorus absorption and alleviating primary osteoporosis. We measured the apparent absorptivity of calcium, femoral bone density, expression and sulfhydration of the duodenal endoplasmic reticulum protein of 57 kDa (ERp57), duodenal cystathionine γ-lyase (CSE) expression, and serum H2S content in adult and old CSE-knockout and wild-type mice. We also assessed intracellular reactive oxygen species (ROS) and Ca2+ content in CSE-overexpressing or knockout intestinal epithelial cell (IEC)-6 cells. In senile mice, CSE knockout decreased endogenous H2S, ERp57 sulfhydration, and intestinal calcium absorption and worsened osteoporosis, which were partially reversed by GYY4137, an H2S donor. CSE overexpression in IEC-6 cells increased ERp57 sulfhydration, protein kinase A and C activity, and intracellular Ca2+, whereas CSE knockout exerted the opposite effects. Furthermore, hydrogen peroxide (H2O2) stimulation had similar effects as in CSE knockout, which were reversed by pretreatment with sodium hydrosulfide before H2O2 stimulation and restored by DL-dithiothreitol. These findings suggest that H2S attenuates primary osteoporosis by preventing ROS-induced ERp57 damage in intestinal epithelial cells by enhancing ERp57 activity and promoting intestinal calcium absorption, thereby aiding in developing therapeutic interventions to prevent osteoporosis.

Tissue engineering strategies hold promise for the repair of articular cartilage injury.

Articular cartilage damage and wear can result in cartilage degeneration, ultimately culminating in osteoarthritis. Current surgical interventions offer limited capacity for cartilage tissue regeneration and offer only temporary alleviation of symptoms. Tissue engineering strategies are increasingly recognized as promising modalities for cartilage restoration. Currently, various biological scaffolds utilizing tissue engineering materials are extensively employed in both fundamental and clinical investigations of cartilage repair. In order to optimize the cartilage repair ability of tissue engineering scaffolds, researchers not only optimize the structure and properties of scaffolds from the perspective of materials science and manufacturing technology to enhance their histocompatibility, but also adopt strategies such as loading cells, cytokines, and drugs to promote cartilage formation. This review provides an overview of contemporary tissue engineering strategies employed in cartilage repair, as well as a synthesis of existing preclinical and clinical research. Furthermore, the obstacles faced in the translation of tissue engineering strategies to clinical practice are discussed, offering valuable guidance for researchers seeking to address these challenges.

Artificial Intelligence Aids Detection of Rotator Cuff Pathology: A Systematic Review.

PURPOSE: To determine the model performance of artificial intelligence (AI) in detecting rotator cuff pathology using different imaging modalities and to compare capability with physicians in clinical scenarios. METHODS: The review followed the PRISMA guidelines and was registered on PROSPERO. The criteria were as follows: 1) studies on the application of AI in detecting rotator cuff pathology using medical images, and 2) studies on smart devices for assisting in diagnosis were excluded. The following data were extracted and recorded: statistical characteristics, input features, AI algorithms used, sample sizes of training and testing sets, and model performance. The data extracted from the included studies were narratively reviewed. RESULTS: A total of 14 articles, comprising 23,119 patients, met the inclusion and exclusion criteria. The pooled mean age of the patients was 56.7 years, and the female rate was 56.1%. The area under the curve (AUC) of the algorithmic model to detect rotator cuff pathology from ultrasound images, MRI images, and radiographic series ranged from 0.789 to 0.950, 0.844 to 0.943, and 0.820 to 0.830, respectively. Notably, 1 of the studies reported that AI models based on ultrasound images demonstrated a diagnostic performance similar to that of radiologists. Another comparative study demonstrated that AI models using MRI images exhibited greater accuracy and specificity compared to orthopedic surgeons in the diagnosis of rotator cuff pathology, albeit not in sensitivity. CONCLUSIONS: The detection of rotator cuff pathology has been significantly aided by the exceptional performance of AI models. In particular, these models are equally adept as musculoskeletal radiologists in using ultrasound to diagnose rotator cuff pathology. Furthermore, AI models exhibit statistically superior levels of accuracy and specificity when using MRI to diagnose rotator cuff pathology, albeit with no marked difference in sensitivity, in comparison to orthopaedic surgeons. LEVEL OF EVIDENCE: Level III, systematic review of Level III studies.

Decreased sagittal slope of the medial tibial spine and deep concavity of the lateral tibial spine are risk factors for noncontact anterior cruciate ligament injury.

PURPOSE: This study aimed to assess the relationship between the geometric features of tibial eminence and susceptibility to noncontact anterior cruciate ligament (ACL) injuries. METHODS: Patients with unilateral noncontact knee injuries between 2015 and 2021 were consecutively enroled in this study. Based on knee magnetic resonance imaging (MRI) and arthroscopic visualisation, patients were categorised into the case group (ACL rupture) and control group (ACL intact). Using MRI, the geometric features of tibial eminence were characterised by measuring the sagittal slopes, depth of concavity and coronal slopes of the inclined surfaces of the tibial spines. Univariate and multivariate logistic regressions were conducted to explore independent associations between quantified geometric indices of tibial eminence and the risk of noncontact ACL injuries. RESULTS: This study included 187 cases and 199 controls. A decreased sagittal slope of the medial tibial spine (MTSSS) (combined group: odds ratio [OR]: 0.87 [0.82, 0.92], p < 0.001; females: OR: 0.88 [0.80, 0.98], p = 0.020; males: OR: 0.87 [0.81, 0.93], p < 0.001) and an increased depth of concavity in the lateral tibial spine (LTSD) (combined group: OR: 1.51 [1.24, 1.85], p < 0.001; females: OR: 1.65 [1.12, 2.43], p = 0.012; males: OR: 1.44 [1.11, 1.89], p = 0.007) were independent risk factors for noncontact ACL injuries. Moreover, a steeper coronal slope of the inclined surface of the medial tibial spine was a significant predictor of noncontact ACL injuries for males (MTSCS: OR: 1.04 [1.01, 1.08], p = 0.015) but not for females. CONCLUSION: Geometric features of tibial eminence, particularly a decreased MTSSS and an increased LTSD, were identified as independent risk factors for noncontact ACL injuries. These findings will help clinicians identify individuals at high risk of ACL injury and facilitate the development of targeted prevention strategies. LEVEL OF EVIDENCE: Level III.

Hepatocellular cystathionine γ lyase/hydrogen sulfide attenuates nonalcoholic fatty liver disease by activating farnesoid X receptor.

BACKGROUND AND AIMS: Hydrogen sulfide (H2 S) plays a protective role in NAFLD. However, whether cystathionine γ lyase (CSE), a dominant H2 S generating enzyme in hepatocytes, has a role in the pathogenesis of NAFLD is currently unclear. APPROACH AND RESULTS: We showed that CSE protein expression is dramatically downregulated, especially in fibrotic areas, in livers from patients with NAFLD. In high-fat diet (HFD)-induced NAFLD mice or an oleic acid-induced hepatocyte model, the CSE/H2 S pathway is also downregulated. To illustrate a regulatory role for CSE in NAFLD, we generated a hepatocyte-specific CSE knockout mouse (CSELKO ). Feeding an HFD to CSELKO mice, they showed more hepatic lipid deposition with increased activity of the fatty acid de novo synthesis pathway, increased hepatic insulin resistance, and higher hepatic gluconeogenic ability compared to CSELoxp control mice. By contrast, H2 S donor treatment attenuated these phenotypes. Furthermore, the protection conferred by H2 S was blocked by farnesoid X receptor (FXR) knockdown. Consistently, serum deoxycholic acid and lithocholic acid (FXR antagonists) were increased, and tauro-ß-muricholic acid (FXR activation elevated) was reduced in CSELKO . CSE/H2 S promoted a post-translation modification (sulfhydration) of FXR at Cys138/141 sites, thereby enhancing its activity to modulate expression of target genes related to lipid and glucose metabolism, inflammation, and fibrosis. Sulfhydration proteomics in patients' livers supported the CSE/H2 S modulation noted in the CSELKO mice. CONCLUSIONS: FXR sulfhydration is a post-translational modification affected by hepatic endogenous CSE/H2 S that may promote FXR activity and attenuate NAFLD. Hepatic CSE deficiency promotes development of nonalcoholic steatohepatitis. The interaction between H2 S and FXR may be amenable to therapeutic drug treatment in NAFLD.

Bone mineral density is associated with composite dietary antioxidant index among US adults: results from NHANES.

This cross-sectional study investigated the relationship between composite dietary antioxidant index (CDAI) and individual dietary antioxidant intakes, including vitamins A, C, and E, zinc, selenium, and carotenoids, and bone mineral density (BMD) in the US population aged 20 years older. We found a positive correlation between CDAI and femoral BMD. Moreover, higher intakes of vitamin C, vitamin E, selenium, zinc, and carotenoids were associated with higher femoral BMD. INTRODUCTION: While individual dietary antioxidants have shown beneficial effects on bone metabolism, the diverse and potentially interacting nature of dietary components may limit the accuracy of evaluating their impact on bone health. Thus, this study aims to investigate the association between CDAI and BMD. Additionally, we explore the relationship between the intake of individual components of the CDAI and BMD. METHODS: The CDAI is a novel index evaluating total dietary antioxidant intake, considering vitamins A, C, and E, zinc, selenium, and carotenoids. A cross-sectional analysis was conducted using data from participants aged ≥ 20 in the National Health and Nutrition Examination Survey (2005-2010, 2013-2014, and 2017-2018). We utilized multivariate linear regression models to examine the relationship between CDAI, individual dietary antioxidants, including vitamins A, C, and E, zinc, selenium, carotenoids, and femoral BMD. RESULTS: The final analysis included 10,584 participants with a mean age of 50.73 ± 16.65 years. After multivariate adjustment, the second to fourth quartiles of CDAI (- 2.00-0.04, 0.04-2.54, and 2.54-70.78) exhibited higher femoral BMD compared to the first quartile of CADI (- 7.34 to - 2.00). Multiple regression analysis revealed that higher intakes of vitamin C, vitamin E, selenium, zinc, and carotenoids were associated with higher femoral BMD. CONCLUSIONS: CDAI serves as a comprehensive tool for evaluating the overall antioxidant capacity of antioxidants in diets. Additionally, our study shows a positive correlation between CDAI and BMD, which indicates that the combined intake of dietary antioxidants may help reduce the risk of osteoporosis in adults.

Metabolic associated fatty liver disease and bone mineral density: a cross-sectional study of the National Health and Nutrition Examination Survey 2017-2018.

This research is a cross-sectional study based on the participants aged 50 years and older from National Health and Nutrition Examination Survey (NHANES) database. The metabolic associated fatty liver disease (MAFLD) population has higher BMD and a lower risk of osteoporosis than those without MAFLD. INTRODUCTION: MAFLD is a new definition presented by panel of experts based on non-alcoholic fatty liver disease in 2020. However, the link between MAFLD and bone mineral density (BMD) is uncertain. Thus, the present study aimed to investigate the relationship between MAFLD and BMD. METHODS: This cross-sectional study included subjects aged ≥ 50 years from the National Health and Nutrition Examination Survey 2017-2018. Multivariate linear regression models were performed to investigate the association between MAFLD and BMD. Moreover, the relationship between MAFLD and osteoporosis was assessed using multiple logistic regression models. RESULTS: Finally, 817 participants (non-MAFLD, n = 436; MAFLD, n = 381) were included in the final analysis. The results demonstrated that participants with MAFLD showed higher femoral BMDs than those without MAFLD, especially among males aged ≥ 50 years and females aged ≥ 65 years. Moreover, the results showed that obese men (BMI ≥ 30 kg/m2) with MAFLD had higher femoral BMDs than the control group according to subgroup analyses stratified by BMI, but this trend was not present in women. In addition, multiple logistic regression models showed that participants with MAFLD had no increased risks of osteoporosis. CONCLUSION: The present study found that the MAFLD population has higher BMD and a lower risk of osteoporosis than those without MAFLD. Because the present study was a cross-sectional study, we could not identify the cause-effect relation between MAFLD and BMD. Therefore, additional research needs to be performed to explore the influences of MAFLD on bone metabolism in the future.

The tibial tunnel drilling angles of 60° provided a lower ultimate load to failure on a single bundle posterior cruciate ligament graft using interference screw fixation compared to 30°/45°.

PURPOSE: To biomechanically compare the initial fixation strength of grafts among three tibial tunnel angles (30°/45°/60°) in transtibial posterior cruciate ligament (PCL) reconstruction. METHODS: A series of transtibial PCL reconstruction models were established with porcine tibias and bovine tendons. Specimens were randomly assigned to three groups according to the angles between the tibial tunnel and the perpendicular line of the tibial shaft: Group A (30°, n = 12), Group B (45°, n = 12), and Group C (60°, n = 12). The area of the tunnel entrance, the segmental bone mineral density (sBMD) of the graft fixation site of the tibia and the maximum insertion torque of the interference screw were measured. Finally, load to failure tests were carried out on the graft-screw-tibia constructs at the same rate. RESULTS: Ultimate load to failure in Group C (335.2 ± 107.5 N) was significantly lower than that in Group A (584.1 ± 127.9 N, P < 0.01) and Group B (521.9 ± 95.9 N, P < 0.01). There were no significant differences between biomechanical properties of Groups A and B (n.s.). The posterior part fractures of the tibial tunnel exit occurred in eight specimens of Group C. In addition, the ultimate load was proven to be related to insertion torque (rho = 0.7, P < 0.01), sBMD (rho = 0.7, P < 0.01), and the area of the tunnel entrance (rho =- 0.4, P = 0.01). CONCLUSION: The ultimate load to failure was significantly lower in tibial PCL interference screw fixation for tunnels drilled at 60° compared to 30°/45°. In addition, the ultimate load was significantly correlated with insertion torque, sBMD and the area of the tunnel entrance. Given that the load to failure of distal fixation may not be sufficient for early postoperative rehabilitation, a 60° tunnel should not be recommended to drill in tibia during PCL reconstruction.

VSMC-Specific Deletion of FAM3A Attenuated Ang II-Promoted Hypertension and Cardiovascular Hypertrophy.

RATIONALE: Dysregulated purinergic signaling transduction plays important roles in the pathogenesis of cardiovascular diseases. However, the role and mechanism of vascular smooth muscle cell (VSMC)-released ATP in the regulation of blood pressure, and the pathogenesis of hypertension remain unknown. FAM3A (family with sequence similarity 3 member A) is a new mitochondrial protein that enhances ATP production and release. High expression of FAM3A in VSMC suggests it may play a role in regulating vascular constriction and blood pressure. OBJECTIVE: To determine the role and mechanism of FAM3A-ATP signaling pathway in VSMCs in the regulation of blood pressure and the pathogenesis of hypertension. METHODS AND RESULTS: In the media layer of hypertensive rat and mouse arteries, and the internal mammary artery of hypertensive patients, FAM3A expression was increased. VSMC-specific deletion of FAM3A reduced vessel contractility and blood pressure levels in mice. Moreover, deletion of FAM3A in VSMC attenuated Ang II (angiotensin II)-induced vascular constriction and remodeling, hypertension, and cardiac hypertrophy in mice. In cultured VSMCs, Ang II activated HSF1 (heat shock factor 1) to stimulate FAM3A expression, activating ATP-P2 receptor pathway to promote the change of VSMCs from contractile phenotype to proliferative phenotype. In the VSMC layer of spontaneously hypertensive rat arteries, Ang II-induced hypertensive mouse arteries and the internal mammary artery of hypertensive patients, HSF1 expression was increased. Treatment with HSF1 inhibitor reduced artery contractility and ameliorated hypertension of spontaneously hypertensive rats. CONCLUSIONS: FAM3A is an important regulator of vascular constriction and blood pressure. Overactivation of HSF1-FAM3A-ATP signaling cascade in VSMCs plays important roles in Ang II-induced hypertension and cardiovascular diseases. Inhibitors of HSF1 could be potentially used to treat hypertension.

Fluid shear stress-induced down-regulation of microRNA-140-5p promotes osteoblast proliferation by targeting VEGFA via the ERK5 pathway.

PURPOSE: Fluid shear stress (FSS) plays a critical role in osteoblast proliferation. However, the role of miRNA in osteoblast proliferation induced by FSS and the possible molecular mechanisms remain to be defined. The aim of the present study was to investigate whether miR-140-5p regulates osteoblast proliferation under FSS and its molecular mechanism. MATERIALS AND METHODS: miR-140-5p expression was measured by qRT-PCR. Western blot was used to measure the expressions of P-ERK1/2, ERK1/2, P-ERK5 and ERK5. The levels of VEGFA, PCNA, CDK4 and Cyclin D1 were identified through qRT-PCR and western blot, respectively. Cell proliferation was detected by CCK-8 assay and EdU labeling assay. Dual-luciferase reporter assay was used to validate the target of miR-140-5p. RESULTS: miR-140-5p was significantly down-regulated when MC3T3-E1 cells were exposed to FSS. We then confirmed that up-regulation of miR-140-5p inhibited and down-regulation of miR-140-5p promoted osteoblast proliferation. In addition, FSS promotes osteoblast proliferation via down-regulating miR-140-5p. Luciferase reporter assay demonstrated that VEGFA is a direct target of miR-140-5p. Furthermore, transfection of mimic-140-5p inhibited the up-regulation of VEGFA protein level induced by FSS, suggesting that FSS regulates VEGFA protein expression via miR-140-5p. Further investigations demonstrated that VEGFA could promote osteoblast proliferation. Lastly, we demonstrated that miR-140-5p regulates osteoblast proliferation and ERK5 activation through VEGFA. CONCLUSIONS: Our study demonstrates that FSS-induced the down-regulation of miR-140-5p promotes osteoblast proliferation through activing VEGFA/ERK5 signaling pathway. These findings may provide a novel mechanism of FSS-induced osteoblast proliferation and offer a new avenue to further investigate osteogenesis induced by mechanical loading.

The association between body fat distribution and bone mineral density: evidence from the US population.

OBJECTIVE: To investigate the association between different body fat distribution and different sites of BMD in male and female populations. METHODS: Use the National Health and Nutrition Examination Survey (NHANES) datasets to select participants. The weighted linear regression model investigated the difference in body fat and Bone Mineral Density (BMD) in different gender. Multivariate adjusted smoothing curve-fitting and multiple linear regression models were used to explore whether an association existed between body fat distribution and BMD. Last, a subgroup analysis was performed according to age and gender group. RESULTS: Overall, 2881 participants were included in this study. Compared to males, female participants had lower BMD (P < 0.05) and higher Gynoid fat mass (P < 0.00001), while there was no difference between Android fat mass (P = 0.91). Android fat mass was positively associated with Total femur BMD (Males, ß = 0.044, 95% CI = 0.037, 0.051, P < 0.00001; Females, ß = 0.044, 95% CI = 0.039, 0.049, P < 0.00001), Femoral neck BMD (Males, ß = 0.034, 95% CI = 0.027, 0.041, P < 0.00001; Females, ß = 0.032, 95% CI = 0.027, 0.037, P < 0.00001), and Total spine BMD (Males, ß = 0.036, 95% CI = 0.029, 0.044, P < 0.00001; Females, ß = 0.025, 95% CI = 0.019, 0.031, P < 0.00001). The Gynoid fat mass, subgroup analysis of age and ethnicity reached similar results. CONCLUSION: Body fat in different regions was positively associated with BMD in different sites, and this association persisted in subgroup analyses across age and race in different gender.

Nocturnal sleep duration and bone mineral density: a cross-sectional study of the National Health and Nutrition Examination Survey (NHANES) 2007-2014.

BACKGROUND: This study aimed to investigate the association between sleep duration and bone mineral density (BMD) and determine whether vitamin D (VD) status influenced the association between sleep duration and BMD. METHODS: National Health and Nutrition Examination Survey 2007-2014 participants aged ≥ 40 years were included in this study. BMD testing was conducted with dual-energy X-ray absorptiometry examinations. Moreover, all individuals were divided into four groups according to self-reported nocturnal sleep duration (7-8 h; 6 h; < 6 h; and > 8 h). In addition, the differences in BMD between the normal sleep duration group and other groups were calculated using multiple linear regression models. RESULTS: Overall, the median age of the overall study population was 55.00 years old, with 46.97% of men distributed. Participants sleeping > 8 h/night had lower BMDs than those sleeping 7-8 h/night. Moreover, the association between unhealthy sleep duration (especially > 8 h/night) and low BMD was more pronounced in older individuals, men, postmenopausal women, and subjects with inadequate VD intakes (< 15.00 µg/day) or deficient/insufficient serum 25-hydroxyvitamin D (< 75.00 nmol/L). CONCLUSIONS: In conclusion, unhealthy sleep duration, especially long sleep duration, was associated with decreased BMD, particularly among individuals aged > 60 years, men, or postmenopausal women. Moreover, VD status might influence the association between sleep duration and BMD, especially in the context of inadequate VD intake or deficient/insufficient serum 25-hydroxyvitamin D levels. However, given the limitations of the present study, further investigation is warranted to confirm this association and to explore potential mechanisms.

An increased posterior tibial slope is associated with a higher risk of graft failure following ACL reconstruction: a systematic review.

PURPOSE: The posterior tibial slope (PTS) is considered a risk factor for anterior cruciate ligament (ACL) injury. However, the influence of PTS on graft failure following ACL reconstruction remains relatively unknown. Therefore, this systematic review was conducted to investigate whether PTS could be a potential risk factor for graft failure after ACL reconstruction. METHODS: PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure Database, and Wanfang Database were comprehensively searched from inception to March 31, 2021. Observational studies reporting the associations of medial tibial plateau slope (MTPS) or lateral tibial plateau slope (LTPS) with graft failure after ACL reconstruction were evaluated. RESULTS: Twenty studies involving 12 case-control studies, 4 retrospective studies and 4 cross-sectional studies including 5326 patients met the final inclusion criteria. The high heterogeneity and the characteristics of nonrandomized controlled trials limited data synthesis. Fifteen of the 20 included studies detected a significant association between increased PTS and ACL graft failure, while 5 studies concluded that increased PTS was not associated with ACL graft failure. Ten studies suggested that MTPS is associated with ACL graft failure, and six studies suggested that LTPS is associated with ACL graft failure. The mean MTPS values for nonfailure group ranged from 3.5° ± 2.5° to 14.4° ± 2.8°. For the graft failure group, MTPS ranged from 4.71° ± 2.41° to 17.2° ± 2.2°. The mean LTPS values for nonfailure group ranged from 2.9° ± 2.1° to 11.9° ± 3.0°. For the graft failure group, LTPS ranged from 5.5° ± 3.0° to 13.3° ± 3.0°. The reported PTS values that caused ACL graft failure was greater than 7.4° to 17°. CONCLUSION: Based on the current clinical evidence, increased PTS is associated with a higher risk of ACL graft failure after ACL reconstruction. Despite various methods of measuring PTS have high reliability, there is still vast disagreement in the actual value of PTS. LEVEL OF EVIDENCE: IV.

Hydrogen sulphide reduces hyperhomocysteinaemia-induced endothelial ER stress by sulfhydrating protein disulphide isomerase to attenuate atherosclerosis.

Hyperhomocysteinaemia (HHcy)-impaired endothelial dysfunction including endoplasmic reticulum (ER) stress plays a crucial role in atherogenesis. Hydrogen sulphide (H2 S), a metabolic production of Hcy and gasotransmitter, exhibits preventing cardiovascular damages induced by HHcy by reducing ER stress, but the underlying mechanism is unclear. Here, we made an atherosclerosis with HHcy mice model by ApoE knockout mice and feeding Pagien diet and drinking L-methionine water. H2 S donors NaHS and GYY4137 treatment lowered plaque area and ER stress in this model. Protein disulphide isomerase (PDI), a modulation protein folding key enzyme, was up-regulated in plaque and reduced by H2 S treatment. In cultured human aortic endothelial cells, Hcy dose and time dependently elevated PDI expression, but inhibited its activity, and which were rescued by H2 S. H2 S and its endogenous generation key enzyme-cystathionine γ lyase induced a new post-translational modification-sulfhydration of PDI. Sulfhydrated PDI enhanced its activity, and two cysteine-terminal CXXC domain of PDI was identified by site mutation. HHcy lowered PDI sulfhydration association ER stress, and H2 S rescued it but this effect was blocked by cysteine site mutation. Conclusively, we demonstrated that H2 S sulfhydrated PDI and enhanced its activity, reducing HHcy-induced endothelial ER stress to attenuate atherosclerosis development.

Fluid shear stress regulates osteoblast proliferation and apoptosis via the lncRNA TUG1/miR-34a/FGFR1 axis.

LncRNAs and microRNAs play critical roles in osteoblast differentiation and bone formation. However, their exact roles in osteoblasts under fluid shear stress (FSS) and the possible mechanisms remain unclear. The aim of this study was to explore whether and how miR-34a regulates osteoblast proliferation and apoptosis under FSS. In this study, FSS down-regulated miR-34a levels of MC3T3-E1 cells. MiR-34a up-regulation attenuated FSS-induced promotion of proliferation and suppression of apoptosis. Luciferase reporter assay revealed that miR-34a directly targeted FGFR1. Moreover, miR-34a regulated osteoblast proliferation and apoptosis via FGFR1. Further, we validated that lncRNA TUG1 acted as a competing endogenous RNA (ceRNA) to interact with miR-34a and up-regulate FGFR1 protein expression. Furthermore, lncRNA TUG1 could promote proliferation and inhibit apoptosis. Taken together, our study revealed the key role of the lncRNA TUG1/miR-34a/FGFR1 axis in FSS-regulated osteoblast proliferation and apoptosis and may provide potential therapeutic targets for osteoporosis.

CD4+ T-Cell Endogenous Cystathionine γ Lyase-Hydrogen Sulfide Attenuates Hypertension by Sulfhydrating Liver Kinase B1 to Promote T Regulatory Cell Differentiation and Proliferation.

BACKGROUND: Hydrogen sulfide (H2S) has antihypertension and anti-inflammatory effects, and its endogenous-generation key enzyme cystathionine γ lyase (CSE) is expressed in CD4+ T cells. However, the role of CD4+ T-cell endogenous CSE/H2S in the development of hypertension is unclear. METHODS: Peripheral blood lymphocytes were isolated from hypertensive patients or spontaneously hypertensive rats, then H2S production and expression of its generation enzymes, cystathionine ß synthase and CSE, were measured to determine the major H2S generation system changes in hypertension. Mice with CSE-specific knockout in T cells (conditional knockout, by CD4cre mice hybridization) and CD4 null mice were generated for investigating the pathophysiological relevance of the CSE/H2S system. RESULTS: In lymphocytes, H2S from CSE, but not cystathionine ß synthase, responded to blood pressure changes, supported by lymphocyte CSE protein changes and a negative correlation between H2S production with systolic blood pressure and diastolic blood pressure, but positive correlation with the serum level of interleukin 10 (an anti-inflammatory cytokine). Deletion of CSE in T cells elevated BP (5-8 mm Hg) under the physiological condition and exacerbated angiotensin II-induced hypertension. In keeping with hypertension, mesenteric artery dilation impaired association with arterial inflammation, an effect attributed to reduced immunoinhibitory T regulatory cell (Treg) numbers in the blood and kidney, thus causing excess CD4+ and CD8+ T cell infiltration in perivascular adipose tissues and kidney. CSE knockout CD4+ T cell transfer into CD4 null mice, also showed the similar phenotypes' confirming the role of endogenous CSE/H2S action. Adoptive transfer of Tregs (to conditional knockout mice) reversed hypertension, vascular relaxation impairment, and immunocyte infiltration, which confirmed that conditional knockout-induced hypertension was attributable, in part, to the reduced Treg numbers. Mechanistically, endogenous CSE/H2S promoted Treg differentiation and proliferation by activating AMP-activated protein kinase. In part, it depended on activation of its upstream kinase, liver kinase B1, by sulfhydration to facilitate its substrate binding and phosphorylation. CONCLUSION: The constitutive sulfhydration of liver kinase B1 by CSE-derived H2S activates its target kinase, AMP-activated protein kinase, and promotes Treg differentiation and proliferation, which attenuates the vascular and renal immune-inflammation, thereby preventing hypertension.

The mechanosensory and mechanotransductive processes mediated by ion channels and the impact on bone metabolism: A systematic review.

Mechanical environments were associated with alterations in bone metabolism. Ion channels present on bone cells are indispensable for bone metabolism and can be directly or indirectly activated by mechanical stimulation. This review aimed to discuss the literature reporting the mechanical regulatory effects of ion channels on bone cells and bone tissue. An electronic search was conducted in PubMed, Embase and Web of Science. Studies about mechanically induced alteration of bone cells and bone tissue by ion channels were included. Ion channels including TRP family channels, Ca2+ release-activated Ca2+ channels (CRACs), Piezo1/2 channels, purinergic receptors, NMDA receptors, voltage-sensitive calcium channels (VSCCs), TREK2 potassium channels, calcium- and voltage-dependent big conductance potassium (BKCa) channels, small conductance, calcium-activated potassium (SKCa) channels and epithelial sodium channels (ENaCs) present on bone cells and bone tissue participate in the mechanical regulation of bone development in addition to contributing to direct or indirect mechanotransduction such as altered membrane potential and ionic flux. Physiological (beneficial) mechanical stimulation could induce the anabolism of bone cells and bone tissue through ion channels, but abnormal (harmful) mechanical stimulation could also induce the catabolism of bone cells and bone tissue through ion channels. Functional expression of ion channels is vital for the mechanotransduction of bone cells. Mechanical activation (opening) of ion channels triggers ion influx and induces the activation of intracellular modulators that can influence bone metabolism. Therefore, mechanosensitive ion channels provide new insights into therapeutic targets for the treatment of bone-related diseases such as osteopenia and aseptic implant loosening.

ERK5 negatively regulates Kruppel-like factor 4 and promotes osteogenic lineage cell proliferation in response to MEK5 overexpression or fluid shear stress.

Aim of the study: Fluid shear stress (FSS) plays a critical role in osteoblast proliferation via extracellular signal-regulated kinase 5 (ERK5). Kruppel-like factor 4 (KLF4) knockout robustly enhances bone formation due to increased osteoblast differentiation and mineralization. However, the effect of KLF4 on osteoblast proliferation is unresolved. Therefore, the aim of our study was to investigate the effect of KLF4 on osteogenic lineage cell proliferation and the relationship between KLF4 and ERK5. Materials and methods: MC3T3-E1 cells were treated with FSS and/or KLF4 siRNA, cell viability was accessed by Edu labeling and CCK-8 assay, and proliferative gene expression were assessed by PCR array. Bone marrow stromal cells (BMSCs) were infected with adenovirus expressing KLF4 and/or constitutively active MEK5, cell viability was evaluated using crystal violet staining, colony formation assay, and cell WST1 assay. The levels of KLF4 and ERK5 phosphorylation were identified through qRT-PCR and western blot, respectively. Results: KLF4 expression was significantly down-regulated by FSS exposure, however, this was reversed by ERK5 siRNA. KLF4 overexpression inhibited colony formation efficiency and cell viability in BMSCs. Adenoviruses expressing constitutively active MEK5 increased ERK5 phosphorylation, which inhibited KLF4 expression, and promoted BMSC proliferation. FSS-induced osteoblast proliferation also involved elevation of Cyclin B2 and Cdc14b as well as repressed expression of P27. Conclusions: KLF4 negatively regulates osteogenic lineage cell proliferation, and ERK5 negatively regulates KLF4 expression and promotes osteogenic lineage cell proliferation.