Smad and p38 MAP kinase-mediated signaling of proteoglycan synthesis in vascular smooth muscle

Atherosclerosis is the underlying pathological process of most cardiovascular disease. A critical component of the "response to retention" hypothesis of atherogenesis is proteoglycan/low density lipoprotein (LDL) binding. Transforming growth factor β (TGF-β) is present in atherosclerotic lesions, regulates vascular smooth muscle cell (VSMC) proteoglycan synthesis via an unknown signaling pathway, and increases proteoglycan/LDL binding. This pathway was investigated using the activin receptor-like kinase 5 (ALK5) inhibitor SB431542 and inhibitors of p38 MAP kinase as a possible downstream or alternative mediator. TGF-β stimulated and SB431542 inhibited the phosphorylation of Smad2/3. In human VSMC, TGF-β increased [ 35S]sulfate incorporation into proteoglycans associated with a 19% increase in glycosaminoglycan (GAG) chain size by size exclusion chromatography. SB431542 caused a concentration-dependent decrease in TGF-β-mediated [ 35S]sulfate incorporation with 92% inhibition at 3 μM. Two different p38 MAP kinase inhibitors, SB203580 and SB202190, but not the inactive analogue SB202474, concentration dependently blocked TGF-β-mediated [ 35S]sulfate incorporation. TGF-β increased [ 3H]glucosamine incorporation into glycosaminoglycans by 180% and [ 35S]Met/Cys incorporation into proteoglycan core proteins by 35% with both effects completely inhibited by SB431542. Blocking both Smad2/3 and p38 MAP kinase pathways prevented the effect of TGF-β to increase proteoglycan to LDL binding. TGF-β mediates its effects on proteoglycan synthesis in VSMCs via the ALK5/Smad2/3 phosphorylation pathway as well as via the p38 MAP kinase signaling cascade. Further studies of downstream pathways controlling proteoglycan synthesis may identify potential therapeutic targets for the prevention of atherosclerosis and cardiovascular disease

Thrombin-mediated proteoglycan synthesis utilizes both protein-tyrosine kinase and serine/threonine kinase receptor transactivation in vascular smooth muscle cells

Background: GPCR transactivation of PTKRs and TGF-αRs mediates proteoglycan synthesis in human VSMC. Results: Transactivation of TGF-αRs is integrin-dependent, and inhibition of both transactivation pathways blocks proteoglycan synthesis. Conclusion: GPCR utilize transactivation pathways and not classical signaling in proteoglycan synthesis. Significance: GPCR transactivation of receptor kinase pathways may be broader and more significant than previously recognized

Population-level risks of alcohol consumption by amount, geography, age, sex, and year: a systematic analysis for the Global Burden of Disease Study 2020

BACKGROUND: The health risks associated with moderate alcohol consumption continue to be debated. Small amounts of alcohol might lower the risk of some health outcomes but increase the risk of others, suggesting that the overall risk depends, in part, on background disease rates, which vary by region, age, sex, and year. METHODS: For this analysis, we constructed burden-weighted dose-response relative risk curves across 22 health outcomes to estimate the theoretical minimum risk exposure level (TMREL) and non-drinker equivalence (NDE), the consumption level at which the health risk is equivalent to that of a non-drinker, using disease rates from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2020 for 21 regions, including 204 countries and territories, by 5-year age group, sex, and year for individuals aged 15-95 years and older from 1990 to 2020. Based on the NDE, we quantified the population consuming harmful amounts of alcohol. FINDINGS: The burden-weighted relative risk curves for alcohol use varied by region and age. Among individuals aged 15-39 years in 2020, the TMREL varied between 0 (95% uncertainty interval 0-0) and 0·603 (0·400-1·00) standard drinks per day, and the NDE varied between 0·002 (0-0) and 1·75 (0·698-4·30) standard drinks per day. Among individuals aged 40 years and older, the burden-weighted relative risk curve was J-shaped for all regions, with a 2020 TMREL that ranged from 0·114 (0-0·403) to 1·87 (0·500-3·30) standard drinks per day and an NDE that ranged between 0·193 (0-0·900) and 6·94 (3·40-8·30) standard drinks per day. Among individuals consuming harmful amounts of alcohol in 2020, 59·1% (54·3-65·4) were aged 15-39 years and 76·9% (73·0-81·3) were male. INTERPRETATION: There is strong evidence to support recommendations on alcohol consumption varying by age and location. Stronger interventions, particularly those tailored towards younger individuals, are needed to reduce the substantial global health loss attributable to alcohol. FUNDING: Bill & Melinda Gates Foundation

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Endothelin-1 stimulation of proteoglycan synthesis in vascular smooth muscle is mediated by endothelin receptor transactivation of the transforming growth factor-β type I receptor

We utilized human vascular smooth muscle cells to address the question if a G-protein-coupled receptor, the endothelin (ET) receptor, could transactivate a serine/threonine kinase receptor, specifically the transforming growth factor (TGF)-β receptor, TβRI. Functionality of the interaction was addressed by studying endothelin-1-stimulated proteoglycan synthesis. Signaling molecules were assessed by Western blotting and proteoglycan synthesis by [ S]sulfate and S-met/cys incorporation and molecular size by SDS-PAGE. Endothelin-1 treatment led to a time- and concentration- dependent increase in cytosolic phosphoSmad2C, which was inhibited by the mixed endothelin receptor antagonist bosentan and the TβRI antagonist SB431542. Endothelin-1 treatment led to a time-dependent increase in nuclear phosphoSmad2C. Endothelin-1-stimulated proteoglycan synthesis was partially inhibited (40%) by SB431542 and completely blocked by bosentan. The effect of endothelin-1 to stimulate an increase in glycosaminoglycan size on biglycan was also blocked in a concentration-dependent manner by SB431542. These data extend the current paradigm of G-protein coupled receptor signaling to include the transactivation of the serine kinase receptor for TGF-β (TβRI). This response should be considered in the context of response to endothelin-1, and the options for therapeutically targeting endothelin-1 are accordingly broadened to include downstream signaling otherwise associated with TGF-β receptor activation

Characterisation of Ki11502 as a potent inhibitor of PDGF β receptor-mediated proteoglycan synthesis in vascular smooth muscle cells

Platelet-derived growth factor (PDGF) receptor signalling is implicated in cardiovascular diseases such as atherosclerosis and restenosis. PDGF expression levels are elevated in atherosclerotic lesions and play a key role in migration and proliferation of vascular smooth muscle cells in the neointima. PDGF stimulates glycosaminoglycan elongation on vascular proteoglycans biglycan and decorin, a process implicated in the aetiology of atherosclerosis. We investigated the ability of the specific kinase inhibitor Ki11502 to inhibit PDGF β receptor phosphorylation and proteoglycan synthesis in human vascular smooth muscle cells. Ki11502 inhibited PDGF-mediated tyrosine phosphorylation of the PDGF β receptor autophosphorylation site and at least six other receptor-associated proteins. Ki11502 also caused a concentration-dependent inhibition of PDGF-stimulated [H]-thymidine incorporation. Total proteoglycan synthesis was assessed as incorporation of [S]-sulfate. PDGF-induced a two-fold increase in [S]-sulfate incorporation into proteoglycans secreted over 24 h and was inhibited in a concentration-dependent manner by Ki11502. PDGF treatment resulted in a statistically significant (P < 0.01) increase in total proteoglycan core protein secretion. Treatment of cells with Ki11502 (300 nM) had no effect on basal core protein secretion and completely abolished the PDGF-stimulated component. Analysis of isolated cleaved glycosaminoglycan chains by size-exclusion chromatography demonstrated that PDGF stimulated the synthesis and secretion of proteoglycans with elongated glycosaminoglycan chains and this effect was inhibited by Ki11502. Inhibition was also seen in the length of xyloside-glycosaminoglycan chains. The results demonstrate that Ki11502 is a potent and selective inhibitor of PDGF β receptor phosphorylation, proliferation and proteoglycan synthesis in human vascular smooth muscle cells

A competing risk analysis of predictors of time to lost to follow-up among adults with TB/HIV coinfection in Bahir Dar

Abstract Lost to follow-up (LTFU), defined as interrupting anti-TB treatment for ≥ 8 consecutive weeks or missing anti-retroviral therapy (ART) appointments for > 90 days, is a barrier to TB/HIV coinfection management. Poor treatment adherence, a driver of multidrug resistance in TB/HIV, poses critical challenges to case management. Overestimating effect sizes when considering mutually exclusive events, like LTFU from ART and anti-TB treatment, can occur if sources of error are not properly accounted for in competing events. However, studies estimating the effect sizes of predictors of time to LTFU using competing risk analysis are scarce. Hence, this study aimed to investigate the predictors of time to LTFU among adults with TB/HIV coinfection. We conducted a multicenter facility-based retrospective follow-up study. We randomly selected 471 TB/HIV coinfected adults. Data were extracted using standardised checklists. The LTFUs from ART and anti-TB treatment were events of interest and competing events, respectively, and others were censored. The data were entered into Epi data and then exported to Stata and Rstudio. Statistical differences were tested by Gray’s test, and the cumulative incidence of each event was estimated by a cumulative incidence function. Bivariable and multivariable competing risk regression models were fitted, and variables with p values < 0.05 were considered significant predictors. Incidence rates of LTFU for ART and TB treatment were 3.90 and 19.17 per 1000 person-months of observation (PMOs), respectively. The predictors of ART LTFU included rural residence (adjusted subdistribution hazard ratio (SDHR): 3.39), WHO stage IV (SDHR: 2.88), haemoglobin < 11 g/dl (SDHR: 3.56), and opportunistic infections (OIs) (SDHR: 3.65). For TB treatment LTFU, significant predictors were rural residence (SDHR: 0.11), divorced (SDHR: 2.81), widowed (SDHR: 5.92), BMI < 18.5 (SDHR: 0.41), ambulatory functional status (SDHR: 2.59), adverse drug effects (SDHR: 2.87), and poor ART adherence (SDHR: 5.72). Considering errors in competing events, ART LTFU was higher among rural dwellers, individuals with advanced disease, nutritional deficits, or adverse drug effects requiring prioritised, multifaceted interventions. Targeted strategies such as intensified monitoring, adherence counselling, nutritional support, proactive management of drug-related side effects, marital instability, OIs and poor ART adherence should be integrated into the existing ART/TB program to mitigate LTFU