P6300Endothelial cell activation by pro-inflammatory cytokines exerts novel paracrine effects on co-cultured cardiomyocytes

Background

Anti-inflammatory therapies have failed to meet expectations in recent clinical trials for heart failure, despite the number of studies demonstrating pro-fibrotic, arrhythmogenic and hypertrophic effects of inflammation. To enlighten this, we sought to examine the contribution of non-myocytes in the cardiac inflammatory response. Endothelial cells (EC) can regulate cardiomyocyte (CM) function with multiple soluble factors. While many studies have shown the effects of pro-inflammatory cytokines on EC or CM separately, it is still unclear how the activation of EC can affect CM function.

Purpose

We studied the effect of pro-inflammatory pre-conditioning of EC on CM in indirect co-culture systems and in an ex vivo model of cardiac tissue. We hypothesised that pro-inflammatory activation of EC would alter the contractility of co-cultured CM.

Methods

Human cardiac microvascular EC were first pre-conditioned for 24h with Cytomix (1 ng/ml TNF-α, 1 ng/ml IL-1β, 25 ng/ml IL-6 Rα/IL-6 chimera) and co-cultured in a transwell system (pore size: 0.4μm) with adult rat ventricular CM. Co-culture supernatants were screened using a Cytokine Profiler Array. In vitro analysis of calcium handling in CM utilised the optical mapping technique and Fluo-4. Contractility of cardiac tissue was measured ex vivo using myocardial slices of 300 μm, prepared from left ventricles of adult rat and cultured for 24h with field stimulation and a fixed stretch producing a sarcomeric length of 2.2 μm.

Results

Treatment of EC by Cytomix prior to co-cultures induced a release of CC and CXC chemokines, G-/GM-CSF, ST2 and the adhesion molecule ICAM-1. Using published RNAseq datasets we noticed that adult CM do not constitutively express the receptors for the chemokines identified with the Profiler Array. However, duration of calcium transients in CM was significantly reduced from 454 to 322 ms in co-cultures with EC pre-conditioned by Cytomix, compared to untreated EC. Amplitude and time to peak were unchanged. In contrast, myocardial slices treated with Cytomix demonstrated a significant increase in contractility compared to control (from 3.3 to 5.3 mN/mm2) but no significant change in the duration of contraction (from 467 to 434 ms) or the rate of relaxation.

Conclusions

Pre-conditioned EC exert paracrine effects on the calcium handling of isolated CM, suggesting pro-inflammatory activation of proximal EC can affect CM function. In myocardial slices, pro-inflammatory stimulation provoked an inotropic response. The divergence of effect with findings in isolated cells may reflect differences in experimental design and multicellularity. Future work will aim to characterise the soluble mediators involved, and selectively target EC in slices to contextualise the effects described in co-cultures. Ultimately, this may inform the development of novel anti-inflammatory strategies for clinical use.

Acknowledgement/Funding

British Heart Foundation

[Mycotic aneurysm of the iliac artery disclosed by an abdominal mass]

BACKGROUND

Mycotic aneurysms are classic complications of infective endocarditis. Their diagnosis can be difficult when they are located in deep vessels.

CASE REPORT

A 8 year-old boy was admitted for psoitis, tenderness of the left iliac fossa and a palpable mass. He was treated with antibiotics for 2 months for infective endocarditis, but vomiting and fever began after 3 weeks of therapy. Blood cultures showed Staphylococcus epidermidis. Ultrasonography of the mass showed findings compatible with an abscess but sampling of its contents showed blood. Immediate Doppler echography showed that the mass was an aneurysm of the left iliac artery. This diagnosis was confirmed by CT scan and aortography. The aneurysm was excised and a satisfactory repair was made using a Gore-tex graft.

CONCLUSION

Although this mass had no clinical vascular characteristics, its origin should have been recognized because of the history of infective endocarditis and a better analysis of the ultrasonographic findings.

[Tumoral calcinosis. Apropos of a further case in a child]

Tumor-like calcinosis is an infrequent condition whose etiology is poorly understood. Calcifications develop in the subcutaneous tissue neighboring the large joints. All age groups can be affected, although the disease is more common before the age of twenty years. A new case of tumor-like calcinosis in an eight-year-old girl is reported here. A huge mass in the right hip region and a smaller mass around the right elbow were found. Biologic studies revealed increased serum phosphorus levels with normal serum calcium levels. Roentgenograms confirmed the diagnosis of tumor-like calcinosis by showing calcified masses independent from the bones of the neighboring joint. Management consisted in complete removal of both masses. Outcome was favorable. In this patient's family, the disease appears to be inherited according to a dominant pattern, although recessive autosomal transmission is believed to be more common.

[Pneumoblastoma]

Pneumoblastoma is a rare malignant pulmonary tumor. A new case is reported in a 2 years 5 month-old girl. Because the lack of locoregional extension an isolated surgical excision was performed. However, 6 months later, a local relapse occurred, with inframediastinal extension and cerebral metastases. On the occasion of this case, the authors review the problems set by the histogenesis of this tumor, its therapeutic indications, poorly codified due to its rarity and, overall, its often unfavourable outcome.