Fibrosis independent atrial fibrillation in older patients is driven by substrate leukocyte infiltration: diagnostic and prognostic implications to patients undergoing cardiac surgery

Background

The objectives of the study were to characterize and quantify cellular inflammation and structural remodeling of human atria and correlate findings with molecular markers of inflammation and patient surrogate outcome.

Methods

Voluntary participants undergoing heart surgery were enrolled in the study and blood samples were collected prior to surgery, and right atrium samples were harvested intraoperatively. Blood samples were analyzed by flow cytometry and complete blood counts. Atrial samples were divided for fixed fibrosis analysis, homogenized for cytokine analysis and digested for single cell suspension flow cytometry.

Results

A total of 18 patients were enrolled and samples assessed. Isolated cells from the atria revealed a CD45+ population of ~ 20%, confirming a large number of leukocytes. Further characterization revealed this population as 57% lymphocytes and 26% monocyte/macrophages (MoΦ), with the majority of the latter cells being classical (CD14++/CD16−). Interstitial fibrosis was present in 87% of samples and correlated significantly with patient age. Older patients (> 65) had significantly more atrial fibrosis and cellular inflammation. AFib patients had no distinguishing feature of atrial fibrosis and had significantly greater CD45+ MoΦ, increased expression of MMP9 and presented with a significant correlation in length of stay to CCL-2/MCP-1 and NLR (neutrophil-to-lymphocyte ratio).

Conclusion

Atrial fibrosis is correlated with age and not determinate to AFib. However, severity of atrial leukocyte infiltration and markers of matrix degradation are determinant to AFib. This also correlated with CCL2 (or MCP-1) and NLR-indicative of marked inflammation. These data show the potential importance of diagnostic and prognostic assessments that could inform clinical decision making in regard to the intensity of AFib patient management.

Responses of female reproductive hormones and histopathology in the reproductive organs and associated lymph nodes of Boer does challenged with Corynebacterium pseudotuberculosis and its immunogenic corynomycolic acid extract

BACKGROUND

Corynebacterium pseudotuberculosis biotype ovis is a bacterium that causes caseous lymphadenitis (CLA), a chronic disease of sheep and goats characterized by the formation of suppurative abscesses in superficial and visceral lymph nodes and internal organs of small ruminants. This study was designed to evaluate the reproductive hormonal changes (estrogen and progesterone) and histopathology in the reproductive organs and associated lymph nodes of does challenged with C. pseudotuberculosis biotype ovis and its immunogen; corynomycolic acid. A total of 12 healthy non-pregnant female goats were grouped into three: A, B and C consisting of four does each. Group A was intradermally inoculated with 2 mL of sterile phosphate buffered saline (PBS) pH 7 (negative control group); group B was intradermally inoculated with 2 mL of corynomycolic acid extract (CMAs), while group C was intradermally inoculated with 2 mL of 10⁹ colony-forming unit (cfu) of live C. pseudotuberculosis. Blood samples were also collected at predetermined intervals for estrogen and progesterone hormonal assays. The does were euthanized 90 days post challenge and tissue samples of the uterus, ovaries, fallopian tubes, cervix and associated lymph nodes were collected and fixed in 10% neutral buffered formalin for histopathological processing. The result showed various degrees of histopathological changes (hemorrhage, congestion, degeneration, necrosis, edema, leucocytic infiltrations) in the reproductive organs and associated lymph nodes of both inoculation groups. Increases in estrogen hormone concentration were observed in both inoculation groups in comparison to the control group. However, progesterone concentration was only increased in group C. This study highlighted that corynomycolic acid extract from C. pseudotuberculosis biotype ovis resulted in significant histopathology in the reproductive organs and associated lymph nodes of does and increase estrogen concentration.