Lumican deficiency promotes pulmonary arterial remodeling

Lumican promotes calcific aortic valve disease through H3 histone lactylation

BACKGROUND AND AIMS

Valve interstitial cells (VICs) undergo a transition to intermediate state cells before ultimately transforming into the osteogenic cell population, which is a pivotal cellular process in calcific aortic valve disease (CAVD). Herein, this study successfully delineated the stages of VIC osteogenic transformation and elucidated a novel key regulatory role of lumican (LUM) in this process.

METHODS

Single-cell RNA-sequencing (scRNA-seq) from nine human aortic valves was used to characterize the pathological switch process and identify key regulatory factors. The in vitro, ex vivo, in vivo, and double knockout mice were constructed to further unravel the calcification-promoting effect of LUM. Moreover, the multi-omic approaches were employed to analyse the molecular mechanism of LUM in CAVD.

RESULTS

ScRNA-seq successfully delineated the process of VIC pathological transformation and highlighted the significance of LUM as a novel molecule in this process. The pro-calcification role of LUM is confirmed on the in vitro, ex vivo, in vivo level, and ApoE-/-//LUM-/- double knockout mice. The LUM induces osteogenesis in VICs via activation of inflammatory pathways and augmentation of cellular glycolysis, resulting in the accumulation of lactate. Subsequent investigation has unveiled a novel LUM driving histone modification, lactylation, which plays a role in facilitating valve calcification. More importantly, this study has identified two specific sites of histone lactylation, namely, H3K14la and H3K9la, which have been found to facilitate the process of calcification. The confirmation of these modification sites' association with the expression of calcific genes Runx2 and BMP2 has been achieved through ChIP-PCR analysis.

CONCLUSIONS

The study presents novel findings, being the first to establish the involvement of lumican in mediating H3 histone lactylation, thus facilitating the development of aortic valve calcification. Consequently, lumican would be a promising therapeutic target for intervention in the treatment of CAVD.

Lumican, a Multifunctional Cell Instructive Biomarker Proteoglycan Has Novel Roles as a Marker of the Hypercoagulative State of Long Covid Disease

This study has reviewed the many roles of lumican as a biomarker of tissue pathology in health and disease. Lumican is a structure regulatory proteoglycan of collagen-rich tissues, with cell instructive properties through interactions with a number of cell surface receptors in tissue repair, thereby regulating cell proliferation, differentiation, inflammation and the innate and humoral immune systems to combat infection. The exponential increase in publications in the last decade dealing with lumican testify to its role as a pleiotropic biomarker regulatory protein. Recent findings show lumican has novel roles as a biomarker of the hypercoagulative state that occurs in SARS CoV-2 infections; thus, it may also prove useful in the delineation of the complex tissue changes that characterize COVID-19 disease. Lumican may be useful as a prognostic and diagnostic biomarker of long COVID disease and its sequelae.

Pathogenic mechanisms and therapeutic implications of extracellular matrix remodelling in cerebral vasospasm

Cerebral vasospasm significantly contributes to poor prognosis and mortality in patients with aneurysmal subarachnoid hemorrhage. Current research indicates that the pathological and physiological mechanisms of cerebral vasospasm may be attributed to the exposure of blood vessels to toxic substances, such as oxyhaemoglobin and inflammation factors. These factors disrupt cerebral vascular homeostasis. Vascular homeostasis is maintained by the extracellular matrix (ECM) and related cell surface receptors, such as integrins, characterised by collagen deposition, collagen crosslinking, and elastin degradation within the vascular ECM. It involves interactions between the ECM and smooth muscle cells as well as endothelial cells. Its biological activities are particularly crucial in the context of cerebral vasospasm. Therefore, regulating ECM homeostasis may represent a novel therapeutic target for cerebral vasospasm. This review explores the potential pathogenic mechanisms of cerebral vasospasm and the impacts of ECM protein metabolism on the vascular wall during ECM remodelling. Additionally, we underscore the significance of an ECM protein imbalance, which can lead to increased ECM stiffness and activation of the YAP pathway, resulting in vascular remodelling. Lastly, we discuss future research directions.

Obesity impacts hypoxia adaptation of the lung

Obesity is mostly associated with adverse health consequences, but may also elicit favorable effects under chronic conditions. This "obesity paradox" is under debate for pulmonary diseases. As confounding factors complicate conclusions from human studies, this study used a controlled animal model combining diet-induced obesity and chronic hypoxia as a model for pulmonary hypertension and chronic obstructive pulmonary disease. Male C57BL/6 mice were fed control or high-fat diet for 30 wk, and half of the animals were exposed to chronic hypoxia (13% O2) for 3 wk. Hypoxia induced right ventricular hypertrophy, thickening of pulmonary arterial and capillary walls, higher lung volumes, and increased hemoglobin concentrations irrespective of the body weight. In contrast, lung proteomes differed substantially between lean- and obese-hypoxic mice. Many of the observed changes were linked to vascular and extracellular matrix (ECM) proteins. In lean-hypoxic animals, circulating platelets were reduced and abundances of various clotting-related proteins were altered, indicating a hypercoagulable phenotype. Moreover, the septal ECM composition was changed, and airspaces were significantly distended pointing to lung hyperinflation. These differences were mostly absent in the obese-hypoxic group. However, the obesity-hypoxia combination induced the lowest blood CO2 concentrations, indicating hyperventilation for sufficient oxygen supply. Moreover, endothelial surface areas were increased in obese-hypoxic mice. Thus, obesity exerts differential effects on lung adaptation to hypoxia, which paradoxically include not only adverse but also rather protective changes. These differences have a molecular basis in the lung proteome and may influence the pathogenesis of lung diseases. This should be taken into account for future individualized prevention and therapy.NEW & NOTEWORTHY An "obesity paradox" is discussed for pulmonary diseases. By linking lung proteome analyses to pulmonary structure and function, we demonstrate that diet-induced obesity affects lung adaptation to chronic hypoxia in various ways. The observed changes include not only adverse but also protective effects and are associated with altered abundances of vascular and extracellular matrix proteins. These results highlight the existence of relevant differences in individuals with obesity that may influence the pathogenesis of lung diseases.

Cathepsin S Inhibition Suppresses Experimental Systemic Lupus Erythematosus-Associated Pulmonary Arterial Remodeling

Patients with systemic lupus erythematosus (SLE) associated with pulmonary arterial hypnertension (PAH) receive targeted therapy for PAH to decrease pulmonary arterial systolic pressure and significantly prolong their survival. Cysteine cathepsin proteases play critical roles in the progression of cardiovascular disease. Inhibition of cathepsin S (Cat S) has been shown to improve SLE and lupus nephritis. However, the effect of Cat S inhibitors on SLE-associated PAH (SLE-PAH) remains unclear, and there is no animal model for translational research on SLE-PAH. We hypothesized that the inhibition of Cat S may affect PAH development and arterial remodeling associated with SLE. A female animal model of SLE-PAH, female MRL/lpr (Lupus), was used to evaluate the role of pulmonary arterial remodeling in SLE. The key finding of the research work is the establishment of an animal model of SLE associated with PAH in female MRL/lpr mice that is able to evaluate pulmonary arterial remodeling starting from the age of 11 weeks to 15 weeks. Cat S protein level was identified as a marker of experimental SLE. Pulmonary hypertension in female MRL/lpr (Lupus) mice was treated by administering the selective Cat S inhibitor Millipore-219393, which stimulated peroxisome proliferator-activated receptor-gamma (PPARγ) in the lungs to inhibit Cat S expression and pulmonary arterial remodeling. Studies provide an animal model of female MRL/lpr (Lupus) associated with PAH and a deeper understanding of the pathogenesis of SLE-PAH. The results may define the role of cathepsin S in preventing progressive and fatal SLE-PAH and provide approaches for therapeutic interventions in SLE-PAH.