The Relationship of Cholesterol Responses to Mitochondrial Dysfunction and Lung Inflammation in Chronic Obstructive Pulmonary Disease

Rosuvastatin restores liver tissue-resident NK cell activation in aged mice by improving mitochondrial function

BACKGROUND AND AIM

Aging has an impact on Natural Killer (NK) cells surveillance against tumors and infections. Our study aims to assess the aging effects on metabolic and mitochondrial markers influencing NK cell activity.

METHODS

C57BL/6 J mice aged 12, 24, 48, and 72 weeks were used. Liver injury serum and histological markers, pro-inflammatory cytokines [IL-1β, IL-2, IL-6] and chemoattractant markers [CCL2, CXCL8] were assessed. Moreover, cholesterol metabolic markers [HMG-CoA synthetase, HMG-CoA reductase, mevalonate kinase], mitochondrial biogenesis [PGC1α] and functional gene markers [TFAM, HSPA9, Seahorse, apoptosis] in liver trNK cells, were assessed by RT-PCR. Senescence [p16, p21], exhaustion [PD-1, TIGIT, LAG3], activation [CD107a, NKp46], and chemokine receptor [CCR2, CXCR1] markers were assessed in trNK cells using flow cytometry. Liver trNK cells of aged mice were treated with Rosuvastatin [10μM] for 12 h.

RESULTS

Data showed a linear increase in liver injury markers, pro-inflammatory and chemotaxis along aging. These results were associated with reductions in liver trNK cell counts and activations with a noticeable decrease in their chemoattractant receptor expressions. TrNK cells of aged mice exhibited elevated markers of senescence and exhaustion with a gradual increase in cholesterol accumulation. Mitochondrial biogenesis and functional gene markers showed a decrease in their expressions in aged mice while ameliorated following rosuvastatin treatment. Results were correlated with a decrease in cholesterol metabolism and restoring their NK cell activity.

CONCLUSION

Our study demonstrates age-related cholesterol accumulation in trNK cells correlated with senescence and functional impairment. Rosuvastatin is suggested to boost, rejuvenate and recover NK cell functionality.

Protective effects of statins on pulmonary function in patients with persistent hyperlipidemia: a retrospective cohort study

BACKGROUND

Pulmonary function tests offer crucial parameters for evaluating lung health and predicting clinical outcomes. Hyperlipidemia, a prevalent metabolic disorder, has been linked to declining pulmonary function. Statins are an essential therapy for lowering lipid levels in hyperlipidemia.

OBJECTIVES

This study aims to investigate the therapeutic potential of statins in mitigating the decline in pulmonary function.

DESIGN

This is a retrospective cohort study.

METHODS

Out of 8286 patients who underwent spirometry testing from January 2018 to December 2020, 492 patients were included in the final analysis. The relationship between statin usage, dosage, along with other biometric indices and spirometry parameters were evaluated. Multivariate logistic regression analyses were employed to assess the association between statin use and the decline in pulmonary function.

RESULTS

In patients with persistent hyperlipidemia, the use of statins was associated with a higher predicted percentage of forced expiratory volume in 1 second (FEV1) compared to non-users (84.0% vs 78.0%, p = 0.015). Logistic regression models further revealed that statin use independently prevented FEV1 decline, irrespective of dosage (adjusted OR 0.036, 95% CI: 0.002-0.618 in lower statins dose group and adjusted OR 0.170, 95% CI: 0.019-1.552 in higher statins dose group).

CONCLUSION

The findings suggested that statin usage, regardless of dosage, independently mitigated the decline in pulmonary function among patients with persistent hyperlipidemia. Early initiation of statin therapy may hold promise for individuals experiencing hyperlipidemia and declining pulmonary function.

Activation of LXR signaling ameliorates apoptosis of alveolar epithelial cells in Bronchopulmonary dysplasia

BACKGROUND AND PURPOSES

Liver X receptors (LXRs) are specialized nuclear receptors essential for maintaining cholesterol homeostasis, modulating LXR activity could have therapeutic potential in lung diseases. Bronchopulmonary dysplasia (BPD) is a chronic lung disease characterized by impaired alveolar development, in which apoptosis of alveolar epithelial cells is a key contributing factor. The current research focuses on exploring the potential mechanism by which the LXR pathway regulating alveolar epithelial type II cell apoptosis in response to hyperoxia exposure.

METHODS

BPD infants and non-BPD preterm infants were enrolled to measure serum total cholesterol (TC) levels. To further investigate the role of cholesterol metabolism in BPD, a neonatal rat model of BPD was established, and in vitro studies were conducted using mouse lung epithelial cells (MLE12). These experiments aimed to explore the impact of hyperoxia on cholesterol metabolism and assess the effects of LXR agonist intervention.

RESULTS

Elevated serum TC levels in BPD infants were observed, accompanied by lung cholesterol overload in BPD rats. Hyperoxia exposure also led to intracellular cholesterol accumulation in MLE12 cells, which may be attributed to the downregulated LXR signaling pathway. Activation of the LXR pathway prevented apoptosis and mitochondrial dysfunction in MLE12 cell. In BPD rats, intervention with the LXR agonist restored alveolar architecture and reduced alveolar epithelial type II cell apoptosis, which was associated with decreased oxidative stress and lung cholesterol accumulation.

CONCLUSIONS

Disrupted cholesterol metabolism and impaired homeostasis in premature infants may contribute to the development of BPD. Targeting LXR signaling may provide potential therapeutic targets in BPD.

CLINICAL TRIAL NUMBER

Not applicable.

Loss of lysosomal acid lipase results in mitochondrial dysfunction and fiber switch in skeletal muscles of mice

OBJECTIVE

Lysosomal acid lipase (LAL) is the only enzyme known to hydrolyze cholesteryl esters (CE) and triacylglycerols in lysosomes at an acidic pH. Despite the importance of lysosomal hydrolysis in skeletal muscle (SM), research in this area is limited. We hypothesized that LAL may play an important role in SM development, function, and metabolism as a result of lipid and/or carbohydrate metabolism disruptions.

RESULTS

Mice with systemic LAL deficiency (Lal-/-) had markedly lower SM mass, cross-sectional area, and Feret diameter despite unchanged proteolysis or protein synthesis markers in all SM examined. In addition, Lal-/- SM showed increased total cholesterol and CE concentrations, especially during fasting and maturation. Regardless of increased glucose uptake, expression of the slow oxidative fiber marker MYH7 was markedly increased in Lal-/-SM, indicating a fiber switch from glycolytic, fast-twitch fibers to oxidative, slow-twitch fibers. Proteomic analysis of the oxidative and glycolytic parts of the SM confirmed the transition between fast- and slow-twitch fibers, consistent with the decreased Lal-/- muscle size due to the "fiber paradox". Decreased oxidative capacity and ATP concentration were associated with reduced mitochondrial function of Lal-/- SM, particularly affecting oxidative phosphorylation, despite unchanged structure and number of mitochondria. Impairment in muscle function was reflected by increased exhaustion in the treadmill peak effort test in vivo.

CONCLUSION

We conclude that whole-body loss of LAL is associated with a profound remodeling of the muscular phenotype, manifested by fiber type switch and a decline in muscle mass, most likely due to dysfunctional mitochondria and impaired energy metabolism, at least in mice.