Role of CD4+ T-cells for regulating splenic myelopoiesis and monocyte differentiation after experimental myocardial infarction

Myocardial infarction (MI) induces the generation of proinflammatory Ly6Chigh monocytes in the spleen and the recruitment of these cells to the myocardium. CD4+ Foxp3+ CD25+ T-cells (Tregs) promote the healing process after myocardial infarction by engendering a pro-healing differentiation state in myocardial monocyte-derived macrophages. We aimed to study the effects of CD4+ T-cells on splenic myelopoiesis and monocyte differentiation. We instigated MI in mice and found that MI-induced splenic myelopoiesis is abrogated in CD4+ T-cell deficient animals. Conventional CD4+ T-cells promoted myelopoiesis in vitro by cell-cell-contact and paracrine mechanisms, including interferon-gamma (IFN-γ) signalling. Depletion of regulatory T-cells enhanced myelopoiesis in vivo, as evidenced by increases in progenitor cell numbers and proliferative activity in the spleen 5 days after MI. The frequency of CD4+ T-cells-producing factors that promote myelopoiesis increased within the spleen of Treg-depleted mice. Moreover, depletion of Tregs caused a proinflammatory bias in splenic Ly6Chigh monocytes, which showed predominantly upregulated expression of IFN-γ responsive genes after MI. Our results indicate that conventional CD4+ T-cells promote and Tregs attenuate splenic myelopoiesis and proinflammatory differentiation of monocytes.

Human-like Response of Pig T Cells to Superagonistic Anti-CD28 Monoclonal Antibodies

Because of its size, anatomical similarities, and now also accessibility to genetic manipulations, pigs are used as animal models for human diseases and immune system development. However, expression and function of CD28, the most important costimulatory receptor expressed by T cells, so far is poorly understood in this species. Using a newly generated mAb (mAb 3D11) with specificity for pig CD28, we detected CD28 on CD8⁺ and CD4⁺ αβ T cells. Among γδ T cells, CD28 expression was restricted to a small CD2⁺ subpopulation of phenotypically naive cells. Functionally, CD28 ligation with mAb 3D11-costimulated porcine T cells, enhanced proliferation and cytokine secretion in vitro. We used a second, likewise newly generated but superagonistic, anti-CD28 mAb (CD28-SA; mAb 4D12) to test the function of CD28 on porcine T cells in a pilot study in vivo. Injection of the CD28-SA into pigs in vivo showed a very similar dose-response relationship as in humans (i.e., 100 µg/kg body weight [BW]) of CD28-SA induced a cytokine release syndrome that was avoided at a dose of 10 µg/kg BW and below. The data further suggest that low-dose (10 µg/kg BW) CD28-SA infusion was sufficient to increase the proportion of Foxp3⁺ regulatory T cells among CD4⁺ T cells in vivo. The pig is thus a suitable animal model for testing novel immunotherapeutics. Moreover, data from our pilot study in pigs further suggest that low-dose CD28-SA infusion might allow for selective expansion of CD4⁺ regulatory T cells in humans.

Localization of the femoral artery bifurcation: hips don't lie – in at least 97% of cases

Background

The most common vascular access for structural cardiac interventions such as transcatheter aortic valve implantation (TAVI) is the common femoral artery (CFA). Depending on the procedure CFA puncture has to be performed not only unilaterally, but also bilaterally. Since incorrect localization of femoral access can lead to severe vascular complications, specific knowledge about the exact position of the CFA bifuraction is helpful. Such information might be systematically obtained from pre-TAVI CT scans.

Methods

We performed a retroperspective analysis of consecutive contrast-enhanced pre-TAVI CT angiography data sets (n=1000) to determine the CFA bifurcation localization relative to the femoral head and the correlation to contralateral CFA bifurcation location.

Results

The site of the CFA bifurcation was in 67.2% below the femoral head (−−), in 24.3% within the lower third of the femoral head (−), in 7.4% in the mid (0) and in 1.2% within the upper third (+) of the femoral head. Bifurcations above (++) the femoral head were not detected. CFA bifurcations below the femoral head showed the highest prevalence within men and women in all age groups (50–59, 60–69, 70–79, 80–89, 90–99 years). Bilateral agreement of CFA bifurcations was observed in only 69.3% and was independent of one-sided hip replacement (agreement 72.7%) or two-sided hip replacement (agreement 78.7%). A congruent contralateral left CFA bifurcation below the femoral head could be predicted in 80.6%, whereas CFA bifurcations within the lower and upper margins of the femoral head were congruent in only 65.7% (of these, 49.2% for the lower third, 29.7% for the mid and 36.4% for the upper third).

Conclusion

In conclusion, punctures within the upper third of the femoral head will provide an ideal puncture site in at least 97% of cases, independent of age, sex, or previous hip replacement.

Funding Acknowledgement

Type of funding sources: None.

Resolution of leaflet thrombosis under anticoagulant therapy in patients after transcatheter aortic valve implantation: influence of prosthesis type and size

Introduction

Leaflet thrombosis can frequently be identified by computed tomography angiography (CTA) in patients after transcatheter aortic valve implantation (TAVI). Oral anticoagulation is assumed to lead to resolution of thrombosis. We analyzed the resolution of leaflet thrombosis after TAVI by anticoagulant therapy in serial CTA and assessed the influence of prosthesis type.

Methods

Consecutive TAVI patients who underwent CTA follow-up were screened and individuals with leaflet thrombosis on CTA (defined by the presence of hypo-attenuated leaflet thickening, HALT) in whom oral anticoagulation was initiated and who underwent follow-up CTA were included. The type of anticoagulation was according to physicians' discretion. We assessed the resolution of HALT and compared patients with and without resolution of HALT regarding prosthesis type, prosthesis diameter and type of anticoagulation.

Results

Out of 395 patients screened for participation, 36 patients (mean age 80±7, 67% men) with leaflet thrombosis underwent follow-up CTA at a medial interval of 3 months (IQR: 3; 5.75 months) after anticoagulation was initiated. 36 patients received either vitamin-K antagonists (n=28, 78%) or Factor-Xa Inhibitors (n=8, 22%). A total of 22 (61%) balloon-expandable and 14 (39%) self-expandable transcatheter aortic valves were implanted. Nominal prosthesis diameter was 23, 25, 26, 27 and 29 mm in 7 (19%), 1 (3%), 10 (28%), 7 (19%) and 11 (31%) patients, respectively. 30 patients (83%) with anticoagulation showed resolution of HALT, whereas persistent HALT was detected in 6 patients (17%), of whom 1 patient with balloon-expandable and 5 patients with self-expandable valve. No difference was seen in duration of anticoagulation between patients with and without resolution of HALT (p=0.984). In univariate analysis, prosthesis type (balloon-expandable vs. self-expandable valves) showed a significant association of self-expandable valves with lack of resolution of leaflet thrombosis (p=0.017). In multivariable logistic regression analysis, this association persisted (p=0.043) and was independent of the type of anticoagulation (p=0.660) and prosthesis diameter (p=0.942).

Conclusion

Persisting leaflet thrombosis despite anticoagulation is not infrequent and seems to be associated with prosthesis-type rather than small valve diameter or type of anticoagulation. Further research is necessary to identify structural aortic valve determinants for this finding.

Funding Acknowledgement

Type of funding source: None

The association of pericoronary adipose tissue attenuation with major adverse cardiac events (MACE) and atherosclerosis-relevant inflammatory mediators

Background

Increased attenuation of pericoronary adipose tissue (PCAT) around the right coronary artery (RCA) is a new imaging biomarker to detect coronary inflammation derived from routine coronary CT angiography (CTA).

Purpose

We aimed to investigate a potential association between RCA PCAT attenuation and i) serum levels of atherosclerosis-relevant cytokines, ii) different grades of coronary calcification iii) future coronary revascularization within the same coronary artery and iV) MACE (defined by revascularization, myocardial infarction (MI) and/or cardiac death).

Methods

In 293 stable individuals (59.0±9.8 years, 69% males) with intermediate likelihood for coronary artery disease (CAD) blood was drawn and subsequently analyzed for different atherosclerosis-relevant cytokines interleukin (IL)-2, IL- 4, IL-6, IL-7, IL-8, IL-10, IL-13, Il-15, IL-17, TNF-a, IP-10, CRP, MCP-1, MIP-1a, Eotaxin and GM-CSF, followed by coronary calcium scoring (CCS) in non-contrast CT followed by CTA. PCAT CT attenuation (HU) was measured around the RCA (10 to 50 mm from RCA ostium) and the proximal 40 mm of the left anterior descending artery (LAD) and the circumflex artery (LCX) using semi-automated software. Increased RCA PCAT attenuation was defined as PCAT attenuation above the highest quartile (>−73.5 HU). A long-term follow-up over 9.6 years was performed.

Results

PCAT attenuation was similar in different grades of coronary calcification (CAC=0,-80.3 HU; CAC 1–99, −79.2 HU; CAC 100–400, −79.5 HU; CAC >400, −81.0 HU; p>0.05). Adipocytokine MCP-1 (r=0.23, p<0.01) and pro-inflammatory mediator IL-7 (r=0.12, p=0.04) correlated positively with RCA PCAT attenuation, whereas anti-inflammatory mediators Il-4, -10 and -13 correlated inversely (each r<−0.12, each p<0.05). In patients with increased RCA PCAT attenuation the serum levels of MCP-1 were increased (2.37 vs. 2.20, p<0.01), whereas anti-inflammatory mediators IL-4 and -13 were reduced (each p<0.05). 40 patients experienced MACE during follow-up. In multivariable Cox regression analysis, when adjusted by age, gender, baseline medications, obstructive coronary stenosis and CCS, the highest quartiles of PCAT attenuation are an independent predictor of MACE (HR 7.9, p=0.035). In patients with percutaneous coronary intervention (PCI) of the RCA during follow-up, RCA PCAT attenuation was increased at baseline CTA (−73.1 vs −80.2 HU, p=0.008). In patients with PCI of the LAD or LCX during follow-up, PCAT attenuation of LAD and LCX were not increased at baseline CTA (p>0.05).

Conclusions

The information captured by PCAT attenuation is independent of coronary calcification and showed a trend towards a weak association with serum levels of atherosclerosis-relevant inflammatory biomarkers. Increased RCA PCAT attenuation is an independent predictor of MACE and could guide future prevention strategies in stable patients.

Funding Acknowledgement

Type of funding source: None

Influence of lesion location on the accuracy of CT derived FFR: head-to-head comparison with invasive FFR

Background

The accuracy of CT-derived FFR (FFRCT) has been repeatedly reported. However, the influence of lesion location on accuracy is unknown. Therefore, we evaluated the diagnostic accuracy of FFRCT to detect lesion-specific ischemia and determined the influence of lesion location (proximal vs. distal vessel segments) compared to invasively measured FFR in patients with suspected CAD.

Methods

A total of 136 vessels in which “Dual-Source”-CT coronary angiography had been performed due to suspected CAD and who were further referred for invasive coronary angiography with invasive FFR measurement within three months of the index CT examination were retrospectively identified and screened for inclusion in this analysis. Patients with either left main coronary artery stenoses, bifurcation or ostial stenoses were excluded. Invasive FFR was measured using a pressure wire (CERTUS®, St. Jude Medical, Minnesota, USA or Verrata®, Volcano, San Diego, USA). FFRCT was calculated using an on-site prototype (cFFR Version 3.0, Siemens Healthineers, Forchheim, Germany). All vessels were analyzed by an experienced observer blinded to the results of invasive FFR. Stenoses with invasively measured FFR ≤0.80 were classified as hemodynamically significant. We evaluated the diagnostic accuracy of FFRCT in proximal vs. non-proximal vessel segments. Proximal lesions included stenoses located in segment one, six, eleven and twelve. All other stenoses were categorized as distal lesions.

Results

Out of 136 coronary stenoses, 47 (35%) were located in proximal segments and 89 (65%) lesions were located in distal segments. Compared to invasive FFR, the sensitivity of FFRCT to correctly identify/exclude hemodynamically significant stenoses in proximal vessel segments was 93% (95% CI: 68–99.8%) and the specificity was 100% (95% CI: 89–100%), compared to a sensitivity of 72% (95% CI: 46.5–90%) and a specificity of 87% (95% CI: 77–94%) for FFRCT in distal lesions. The positive predictive value was 100% and the negative predictive value was 97% (95% CI: 82.8–99.5%) compared to a positive predictive value of 59% (95% CI: 42–93.9%) and a negative predictive value of 93% (95% CI: 85.4–96.3%) for proximal vs. distal vessel segment, respectively. This corresponds to an accuracy of 98% vs. 84%, respectively (p=0.02). ROC-Curve analysis showed a slightly higher – albeit non-significant – area under the curve for FFRCT to detect hemodynamic relevance in proximal lesions compared to distal lesions (AUC 0.95, p<0.001 vs. AUC: 0.86, p<0.001, respectively, p=0.2).

Conclusion

FFRCT obtained using an on-site prototype shows overall a high diagnostic accuracy for detecting lesions causing ischemia as compared to invasive FFR with a trend towards better diagnostic performance in proximal vessel segments.

Funding Acknowledgement

Type of funding source: None

Tumor necrosis factor-α links heat and inflammation with Fabry pain

Fabry disease (FD) is an X-linked lysosomal storage disorder associated with pain triggered by heat or febrile infections. We modelled this condition by measuring the cytokine expression of peripheral blood mononuclear cells (PBMC) from FD patients in vitro upon stimulation with heat and lipopolysaccharide (LPS). We enrolled 67 FD patients and 37 healthy controls. We isolated PBMC, assessed their gene expression of selected pro- and anti-inflammatory cytokines, incubated them with heat, LPS, globotriaosylceramide (Gb3), and tumor necrosis factor-α (TNF), and measured TNF secretion in the supernatant and intracellular Gb3 accumulation, respectively. We found increased TNF, interleukin (IL-)1β, and toll-like receptor 4 (TLR4) gene expression in FD men (p < .05 to p < .01). TNF and IL-10 were higher, and IL-4 was lower in the subgroup of FD men with pain compared to controls (p < .05 to p < .01). Hereby, TNF was only increased in FD men with pain and classical mutations (p < .05) compared to those without pain. PBMC from FD patients secreted more TNF upon stimulation with LPS (p < .01) than control PBMC. Incubation with Gb3 and an additional α-galactosidase A inhibitor did not further increase TNF secretion, but incubation with TNF greatly increased the Gb3 load in FD PBMC compared to controls (p < .01). Also, LPS incubation and heat challenge (40 °C) increased Gb3 accumulation in PBMC of patients compared to baseline (p < .05 each), while no alterations were observed in control PBMC. Our data show that TNF holds a crucial role in the pathophysiology of FD associated pain, which may open a novel perspective for analgesic treatment in FD pain.