Autoimmune activation as a determinant of atrial fibrillation among Turks: A prospective evaluation

Effects of potassium channel knockdown on peripheral blood T lymphocytes and NFAT signaling pathway in Xinjiang Kazak patients with hypertension

BACKGROUD AND AIM

T lymphocytes are involved in the occurrence and development of essential hypertension, and potassium channels are thought to be critical for lymphocyte activation. This study is to examine the roles of the voltage-gated potassium channels (Kv1.3) and calcium-activated potassium channels (KCa3.1) in peripheral blood T lymphocytes in Kazakh hypertensive patients of Xinjiang, China, mainly focusing on the effects of these channels on nuclear factor of activated T cells (NFAT) and inflammatory cytokines of T lymphocytes.

METHOD

Kv1.3 and KCa3.1 gene silencing were performed in cultured T lymphocytes from Kazakh patients with severe hypertension. T cell proliferation after gene silencing was measured using CCK-8. The mRNA and protein expression levels were measured using RT-qPCR and Western blot analysis, respectively. Nuclear translocation of NFAT was observed using laser confocal fluorescence microscopy. Inflammatory cytokine levels were detected with ELISA.

RESULTS

Compared with control group, gene silencing of Kv1.3 and KCa3.1 respectively inhibited the proliferation of T cells. Moreover, compared with the control group, the mRNA expression levels of NFAT, IL-6 and IFN-γ were significantly decreased after gene silencing. Furthermore, the NFAT protein expression level was significantly down-regulated. In addition, the levels of IFN-γ and IL-6 in the cell culture supernatant were significantly decreased.

CONCLUSION

Both Kv1.3 and KCa3.1 potassium channels activated T lymphocytes and enhanced the cytokine secretion possibly through CaN/NFAT signaling pathway, which may in turn induce micro-inflammatory responses and trigger the occurrence and progression of hypertension.

Association between serum apolipoprotein B and atrial fibrillation: a case-control study

The relationship between apolipoprotein B (APOB) and atrial fibrillation (AF) is less well-known. We aimed to investigate the association between APOB and AF by gender. We conducted a case-control study including 1913 consecutive hospitalized patients to analyze the association between APOB and AF. 950 AF patients and 963 age-, sex-matched non-AF patients with sinus rhythm were evaluated. T-test, Mann-Whitney test, ANOVA, and Chi-square analysis were performed to analyze baseline data and intergroup comparisons. Pearson's correlation tests or Spearman correlation tests were performed to determine the interrelationships. Multiple regression analysis was performed to adjust for covariables. The receiver operator characteristic (ROC) curve was constructed to examine the performance of APOB. AF patients had lower APOB (P < 0.001) and an independent negative association between APOB and AF in both genders adjusting for confounding factors (OR 0.121, 95% CI 0.067-0.220, P < 0.001), regardless of statin use. APOB was positively correlated with total cholesterol (TC) (r = 0.529, p < 0.001), low-density lipoprotein cholesterol (LDL-C) (r = 0.545, p < 0.001), apolipoprotein A1 (APOA1) (r = 0.083, p < 0.001), and albumin (ALB) (r = 0.134, p < 0.001). ROC curve analysis showed that APOB level = 0.895 g/L was the most optimal cut-off value, the area under the ROC curve was 0.722. This study shows a protective association of APOB with AF in men and women. It implies APOB may be a potential biomarker for AF with a promising cut-off point of 0.895 g/L and may involve initiating and maintaining AF along with several metabolic factors.

Case-Control Study to Investigate the Association Between Serum Apolipoprotein B/A1 Ratio and Atrial Fibrillation by Sex in 920 Patients from China

BACKGROUND The serum apolipoprotein B/A1 ratio (APOB/APOA1) has been shown to predict cardiovascular events, whereas the effect of the APOB/APOA1 ratio on atrial fibrillation (AF) is less known. We investigated the association between the APOB/APOA1 ratio and AF by sex in 920 patients from China. MATERIAL AND METHODS We reviewed clinical data on 1840 hospitalized patients, including 920 patients with AF (male/female: 460/460, age: 68.62±10.36 years) and 920 age- and sex-matched patients without AF with sinus rhythm in China between January 2019 and September 2021. Pearson correlation analysis was performed to investigate the correlation between APOB/APOA1 ratio and AF-related metabolic factors. Logistic regression analysis was used to determine the odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS Low serum APOB/APOA1 ratios in male and female patients were significantly associated with AF after adjusting for confounding factors (OR 0.159, 95% CI 0.058-0.432, P<0.05). Serum APOB/APOA1 ratio was positively correlated with triglyceride (TG) (r=0.146, P<0.05) and total cholesterol (TC) (r=0.227, P<0.05) and was negatively correlated with albumin (ALB) (r=-0.128, P<0.05) and prealbumin (PAB) (r=-0.107, P<0.05). There was no significant difference of APOB/APOA1 ratio in different subtypes, complications, and statin use in patients with AF (P>0.05). CONCLUSIONS A low serum APOB/APOA1 ratio in male and female patients from China was significantly related to AF. This finding implies that a low serum APOB/APOA1 ratio may be associated with the causes of AF. Further studies are needed to determine causalities.

Anaphylaxis-induced atrial fibrillation and anesthesia: Pathophysiologic and therapeutic considerations

Atrial fibrillation is the most common cardiac arrhythmia in western society affecting more than 35 million individuals worldwide annually. It is a common postoperative complication and may also occur spontaneously during general and local anesthesia administration. Aging, diabetes mellitus, hypertension, and cardiovascular diseases including cardiomyopathies, congenital cardiac anomalies, heart failure, myocardial ischemia, pericarditis, previous cardiac surgery, vascular disease, and valvular heart disease are some correlated factors. Beyond age, increased incidence of atrial fibrillation has been correlated to autoimmune system activation as it is the underlying mechanism of persistent atrial fibrillation development. Current research supports an association between the complement system activation and lymphocyte-pro-inflammatory cytokines release with the cardiac conduction system and atrial fibrosis. The loss of CD28 antigen from CD4+ CD28+ T lymphocytes seems to play a major role in atrial fibrillation development and prognosis. Except atrial fibrillation, a variety of additional electrocardiographic changes, resembling those with digitalis intoxication may accompany anaphylaxis and particularly Kounis syndrome. Histamine is one well-known mediator in allergic and inflammatory conditions as physiologically regulates several cardiovascular and endothelial functions with arrhythmogenic potential. The increased oxidative stress, measured by the redox potentials of glutathione, has been correlated with atrial fibrillation incidence and prevalence. The use of antazoline, a first-generation antihistamine agent used for rapid conversion of recent-onset atrial fibrillation in patients with preserved left ventricular function and for rapid atrial fibrillation termination during accessory pathway ablation denotes that anaphylaxis-induced histamine production could be the cause of atrial fibrillation at least in some instances. The anaphylaxis diagnosis in anesthesia can be challenging owing to the absence of cutaneous manifestetions such as flushing, urticaria, or angioedema. Anticoagulation for stroke prevention, rate and rhythm control medications, invasive methods such as radiofrequency ablation or cryoablation of pulmonary veins as well surgical ablation constitute the treatment basis of atrial fibrillation. Understanding the underlying mechanisms of atrial fibrillation by cardiologists, anesthesiologists and surgeons, as well as potential treatments, to optimize care is of paramount importance.

Label-free proteomic analysis of serum exosomes from paroxysmal atrial fibrillation patients

Background

Atrial fibrillation (AF) is the most common cardiac heterogeneous rhythm disorder. It represents a major cause of mortality and morbidity, mainly related to embolic events and heart failure. Mechanisms of AF are complex and remain incompletely understood. Recent evidence suggests exosomes are membrane-coated objects released by many cell-types. Their presence in body fluids and the variable surface composition and content render them attractive as a mechanism for potential biomarkers. However, the content of serum exosomes of AF patients has not been fully delineated.

Methods

In this work, the serum exosomes from AF patients and healthy donors were used to compare changes in the exosome protein content. Exosomes were isolated from serum of AF patients and healthy donors and their purity was confirmed by Western blotting assays and transmission electron microscopy (TEM). Label-free LC–MS/MS quantitative proteomic analysis was applied to analyze protein content of serum exosomes.

Results

A total of 440 exosomal protein groups were identified, differentially expressed proteins were filtrated with fold change ≥ 2.0 (AF/controls protein abundance ratio ≥ 2 or ≤ 0.5) and p value less than 0.05 (p < 0.05), significantly changed in abundance group contains 39 elevated proteins and 18 reduced proteins, while consistent presence/absence expression profile group contains 40 elevated proteins and 75 reduced proteins. Bioinformatic analysis of differential exosomal proteins confirmed the significant enrichment of components involved in the anticoagulation, complement system and protein folding. Parallel-Reaction Monitoring Relative Quantitative Analysis (PRM) further suggested that AF related to complement system and protein folding.

Conclusions

These results revealed the composition and potential function of AF serum exosomes, thus providing a new perspective on the complement system and protein folding to AF.