Cystic fibrosis transmembrane regulator correction attenuates heart failure-induced lung inflammation

Exploring the diversity of CFTR gene mutations in cystic fibrosis individuals of South Asia

OBJECTIVE

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the CFTR gene. This study aimed to identify the spectrum of CFTR variants reported in individuals with CF from South Asia (ISA).

DATA SOURCES AND STUDY SELECTION

We conducted a PubMed search for CFTR variants reported in ISA. Full text of original articles and case reports was read to compile data on reported variants. To gather additional data, we independently cross-referenced each variant with the CFTR Mutation Database and ClinVar.

RESULTS

Our investigation identified a total of 92 CFTR variants reported across 30 articles. The most frequently tested, and reported variant was ΔF508 with a global frequency of 69.74%. Notably, we found 14 pathogenic CFTR mutations shared among ISA, originating from more than one South Asian country: ΔF508, 1525-1 G > A, G542X, S549N, R117H, S549R, R709X, V456A, Y569D, L1077P, 1161delC, 1898 + 1 G > T, G551D, and 2184insA.

CONCLUSION

In summary, the higher prevalence of consanguinity and the limited availability of CF diagnostic resources in South Asia considerably contribute to the prevalence of genetic disorders like CF. The spectrum of CFTR mutations exhibits noticeable variations within South Asian and other populations. The inclusion of current study-enlisted CFTR gene variants is highly recommended for CF disease genetic testing in South Asia which may aid in achieving a precise diagnosis, enhancing disease management, and discovering drugs for currently untreatable genetic variants. It is also imperative to conduct a comprehensive study in this region, especially in previously unexplored countries such as Nepal, Bhutan, Maldives, and Bangladesh.

Mechanism of breast cancer immune microenvironment in prognosis of heart failure

The treatment of breast cancer can potentially impose a burden on the heart, leading to an increased risk of heart failure. Studies have shown that more than half of breast cancer patients die from non-tumor-related causes, with cardiovascular disease (CVD) being the leading cause of death. However, the underlying mechanism linking breast cancer prognosis and heart failure remains unclear. To investigate this, we conducted an analysis where we compared the differentially expressed genes (DEGs) in early and advanced breast cancer with genes associated with heart failure. This analysis revealed 18 genes that overlapped between the two conditions, with 15 of them being related to immune function. This suggests that immune pathways may play a role in the prognosis of breast cancer patients with heart failure. Using gene expression data from 1260 breast cancer patients, we further examined the impact of these 15 genes on survival time. Additionally, through enrichment analysis, we explored the functions and pathways associated with these genes in relation to breast cancer and heart failure. By constructing a transformer model, we discovered that the expression patterns of these 15 genes can accurately predict the occurrence of heart failure. The model achieved an AUC of 0.86 and an AUPR of 0.91. Moreover, through analysis of single-cell sequencing data from breast cancer patients undergoing PD-1 treatment and experiencing heart failure, we identified a significant number of cell-type-specific genes that were shared between both diseases. This suggests that changes in gene expression in immune cells following breast cancer treatment may be associated with the development of heart failure.

Ivacaftor therapy post myocardial infarction augments systemic inflammation and evokes contrasting effects with respect to tissue inflammation in brain and lung

Acquired cystic fibrosis transmembrane regulator (CFTR) dysfunctions have been associated with several conditions, including myocardial infarction (MI). Here, CFTR is downregulated in brain, heart, and lung tissue and associates with inflammation and degenerative processes. Therapeutically increasing CFTR expression attenuates these effects. Whether potentiating CFTR function yields similar beneficial effects post-MI is unknown. The CFTR potentiator ivacaftor is currently in clinical trials for treatment of acquired CFTR dysfunction associated with chronic obstructive pulmonary disease and chronic bronchitis. Thus, we tested ivacaftor as therapeutic strategy for MI-associated target tissue inflammation that is characterized by CFTR alterations. MI was induced in male C57Bl/6 mice by ligation of the left anterior descending coronary artery. Mice were treated with ivacaftor starting ten weeks post-MI for two consecutive weeks. Systemic ivacaftor treatment ameliorates hippocampal neuron dendritic atrophy and spine loss and attenuates hippocampus-dependent memory deficits occurring post-MI. Similarly, ivacaftor therapy mitigates MI-associated neuroinflammation (i.e., reduces higher proportions of activated microglia). Systemically, ivacaftor leads to higher frequencies of circulating Ly6C⁺ and Ly6C^hi cells compared to vehicle-treated MI mice. Likewise, an ivacaftor-mediated augmentation of MI-associated pro-inflammatory macrophage phenotype characterized by higher CD80-positivity is observed in the MI lung. In vitro, ivacaftor does not alter LPS-induced CD80 and tumor necrosis factor alpha mRNA increases in BV2 microglial cells, while augmenting mRNA levels of these markers in mouse macrophages and differentiated human THP-1-derived macrophages. Our results suggest that ivacaftor promotes contrasting effects depending on target tissue post-MI, which may be largely dependent on its effects on different myeloid cell types.

Can Bioactive Food Substances Contribute to Cystic Fibrosis-Related Cardiovascular Disease Prevention?

Advances in cystic fibrosis (CF) care have significantly improved the quality of life and life expectancy of patients. Nutritional therapy based on a high-calorie, high-fat diet, antibiotics, as well as new therapies focused on CFTR modulators change the natural course of the disease. They do so by improving pulmonary function and growing BMI. However, the increased weight of such patients can lead to unwanted long-term cardiovascular effects. People with CF (pwCF) experience several cardiovascular risk factors. Such factors include a high-fat diet and increased dietary intake, altered lipid metabolism, a decrease in the level of fat-soluble antioxidants, heightened systemic inflammation, therapeutic interventions, and diabetes mellitus. PwCF must pay special attention to food and eating habits in order to maintain a nutritional status that is as close as possible to the proper physiological one. They also have to benefit from appropriate nutritional counseling, which is essential in the evolution and prognosis of the disease. Growing evidence collected in the last years shows that many bioactive food components, such as phytochemicals, polyunsaturated fatty acids, and antioxidants have favorable effects in the management of CF. An important positive effect is cardiovascular prevention. The possibility of preventing/reducing cardiovascular risk in CF patients enhances both quality of life and life expectancy in the long run.

Restoring myocardial infarction-induced long-term memory impairment by targeting the cystic fibrosis transmembrane regulator

BACKGROUND

Cognitive impairment is a serious comorbidity in heart failure patients, but effective therapies are lacking. We investigated the mechanisms that alter hippocampal neurons following myocardial infarction (MI).

METHODS

MI was induced in male C57Bl/6 mice by left anterior descending coronary artery ligation. We utilised standard procedures to measure cystic fibrosis transmembrane regulator (CFTR) protein levels, inflammatory mediator expression, neuronal structure, and hippocampal memory. Using in vitro and in vivo approaches, we assessed the role of neuroinflammation in hippocampal neuron degradation and the therapeutic potential of CFTR correction as an intervention.

FINDINGS

Hippocampal dendrite length and spine density are reduced after MI, effects that associate with decreased neuronal CFTR expression and concomitant microglia activation and inflammatory cytokine expression. Conditioned medium from lipopolysaccharide-stimulated microglia (LCM) reduces neuronal cell CFTR protein expression and the mRNA expression of the synaptic regulator post-synaptic density protein 95 (PSD-95) in vitro. Blocking CFTR activity also down-regulates PSD-95 in neurons, indicating a relationship between CFTR expression and neuronal health. Pharmacologically correcting CFTR expression in vitro rescues the LCM-mediated down-regulation of PSD-95. In vivo, pharmacologically increasing hippocampal neuron CFTR expression improves MI-associated alterations in neuronal arborisation, spine density, and memory function, with a wide therapeutic time window.

INTERPRETATION

Our results indicate that CFTR therapeutics improve inflammation-induced alterations in hippocampal neuronal structure and attenuate memory dysfunction following MI.

FUNDING

Knut and Alice Wallenberg Foundation [F 2015/2112]; Swedish Research Council [VR; 2017-01243]; the German Research Foundation [DFG; ME 4667/2-1]; Hjärnfonden [FO2021-0112]; The Crafoord Foundation; Åke Wibergs Stiftelse [M19-0380], NMMP 2021 [V2021-2102]; the Albert Påhlsson Research Foundation; STINT [MG19-8469], Lund University; Canadian Institutes of Health Research [PJT-153269] and a Heart and Stroke Foundation of Ontario Mid-Career Investigator Award.