Inflammation is associated with a reduced number of pro-angiogenic Tie-2 monocytes and endothelial progenitor cells in patients with critical limb ischemia

BACKGROUND

Inflammation is the driving force in atherosclerosis. One central strategy in the treatment for PAD is the promotion of angiogenesis. Here, pro-angiogenic Tie-2-expressing monocytes (TEM) and endothelial progenitor cells (EPC) play a crucial role. Critical limb ischemia (CLI) is characterized by a severe, chronic inflammatory response; thus, progression of the disease might be related to the deleterious effects of inflammation on pro-angiogenic cells.

METHODS

Forty-five patients with intermittent claudication (IC) [three groups: Rutherford (R)-1, -2, or -3; each n = 15], 20 patients with CLI [n = 20; Rutherford 4 (15 %), 5 (40 %), and 6 (45 %)], and 20 healthy controls were included in the study. Analysis of TEM and EPC was performed from whole blood by flow cytometry. Treatment for IC patients was conservative, and CLI patients underwent surgical revascularization. Follow-up was performed after mean of 7.1 months.

RESULTS

In comparison with healthy controls, we found increased proportions of TEM and EPC in dependence of the severity of PAD, with the highest level in patients with severe claudication (R3) (p < 0.01). In contrast, for patients with CLI, we found a significantly reduced expression of both TEM and EPC in comparison with healthy controls (p < 0.05) or IC patients (R-1, R-2, and R-3) (all p < 0.001). At follow-up, TEM and EPC in CLI patients increased significantly (both p < 0.001). Serum levels of fibrinogen and CRP were significantly increased in CLI patients (all p < 0.001), but decreased at follow-up (all p < 0.05). TEM and EPC proportions correlated inversely with levels of fibrinogen [(TEM: r = −0.266; p < 0.01) (EPC: r = −0.297; p < 0.001)], CRP (TEM: r = −0.283; p < 0.01) (EPC: r = −0.260; p < 0.01).

CONCLUSIONS

We found a strong association of diverse inflammatory markers with a reduced proportion of pro-angiogenic TEM or EPC in patients with CLI, giving rise to the speculation that a severe chronic inflammation might lead to deleterious effects on TEM and EPC, possibly interfering with angiogenesis, thus promoting an aggravation of the disease.

Leukocyte-platelet aggregates-a phenotypic characterization of different stages of peripheral arterial disease

The formation of monocyte-platelet aggregates and neutrophil-platelet aggregates (MPA and NPA, respectively) is influenced by inflammation, but also might contribute to an exacerbation of inflammatory responses in atherosclerotic plaque. The purpose of this study was to analyze MPA and NPA proportions in regard to different stages of peripheral arterial disease (PAD). Forty-five patients with intermittent claudication (IC) (3 groups: Rutherford (R)-1, R-2, and R-3; each n = 15), 20 patients with critical limb ischemia (CLI) (Rutherford 5 (40%) and 6 (60%)), and 20 healthy controls were studied. Analyses of monocyte (Mon) subpopulations (CD14++CD16- (classical) Mon1, CD14++CD16+ (intermediate) Mon2, CD14+CD16++ (non-classical) Mon3), MPA, and NPA was performed from whole blood by flow cytometry. Controls showed an increased proportion of the Mon1 subpopulation (p < 0.001), whereas CLI patients showed a significant increase of the Mon2 subpopulation compared to controls, R-1, or R-2 patients (p < 0.0001). For the Mon3 subpopulation, CLI and R-3 patients showed an increased proportion (p < 0.05). MPA formation with the proinflammatory Mon2 and Mon3 subpopulations was increased in CLI patients (both p < 0.01). Similarly, NPA was significantly increased in CLI patients (p < 0.05). Serological markers of inflammation and procoagulation (fibrinogen [r = 0.459, p < 0.001], soluble triggering receptor expressed on myeloid cells (sTREM-1) [r = 0.237, p < 0.05] and P-Selectin [r = 0.225, p < 0.05]) correlated directly with MPA formation on the Mon2 subpopulation. We found an association of inflammatory and procoagulatory markers with increased formation of MPA on the Mon2 subpopulation. Since R-3 patients also had significantly increased MPA, one can speculate that the inflammatory burden might promote an aggravation of the disease.

Influence of exercise training on proangiogenic TIE-2 monocytes and circulating angiogenic cells in patients with peripheral arterial disease

BACKGROUND

Inflammation is the driving force in atherosclerosis. One central strategy in the treatment of peripheral arterial disease (PAD) is the promotion of angiogenesis. Here, proangiogenic Tie-2 expressing monocytes (TEM) and circulating angiogenic cells (CAC) play a crucial role. Exercise training (ET) is recommended in PAD patients at Fontaine stage II to promote angiogenesis.

METHODS

40 patients with intermittend claudication (IC) [2 groups: supervised ET (SET) vs. non-supervised ET (nSET), each n = 20] and 20 healthy controls were included in the study. Analysis of TEM and CAC was performed from whole blood by flow-cytometry. TEM were identified via CD45, CD86, CD14, CD16 and analysed for the expression of Tie-2. CAC were identified via their expression of CD45 (CD45dim), CD34 and VEGF-R2 (CD309/KDR). Follow up was performed after mean of 7.65 ± 1.62 months.

RESULTS

In comparison to healthy controls, we found increased proportions of CAC (p < 0.0001) and similar TEM numbers in both ET groups. At follow-up (FU) TEM poroportions increased (p < 0.001) and CAC proportions decreased (p < 0.01), but both more significantly in SET (p < 0.001) than nSET (p = 0.01). Only in SET fibrinogen levels decreased and VEGF-A increased (both p < 0.05). Finally, we found in both ET groups a significant increase in absolute walking distance but with a higher individual increase in SET (p < 0.01). TEM and CAC proportions correlated inversely with the absolute walking distance (CAC: r = -0.296, p = 0.02; TEM: r = -0.270, p = 0.04) as well as with ABI (CAC: r = -0.394, p < 0.01; TEM: r = -0.382, p < 0.01).

CONCLUSIONS

ET influences the distribution of CAC and TEM proportions. nSET, although still effective in regard to an improved walking distance, is less effective in the influence of proangiogenic cells and inflammatory burden than SET. Our results indicate SET to be a more preferential exercise form, supporting the necessity to establish more SET programs.

Low IL-10/TNFα ratio in patients with coronary artery disease and reduced left ventricular ejection fraction with a poor prognosis after 10 years

Monocytes and dendritic cells (DC) produce tumour necrosis factor (TNF)α during inflammatory processes, but secrete interleukin (IL)-10 simultaneously in order to balance the pro-inflammation. In the present study, we investigated the expression of TNFα and IL-10 by monocytes and DC in patients with a poor cardiovascular prognosis after 10 years. Peripheral blood monocytes were isolated from 30 patients with coronary artery disease (CAD) with stable angina pectoris (SAP), or with an acute coronary syndrome (ACS). Monocytes were differentiated over 7 days to DC. Intracellular accumulation of TNFα and IL-10 in monocytes and DC was analysed by flow cytometry and correlated with the heart function, total and cardiovascular (CV) mortality, as well as with cardiovascular event rate over 10 years. We observed a decreased left ventricular function (LV-EF) for both SAP and ACS patients (p<0.01), as well as a reduced IL-10/TNFα ratio for monocytes (p=0.01) and DC (p<0.01) for both patient groups in comparison to age-matched control group. Only the IL-10/TNFα ratio for monocytes correlated with LV-EF (r=0.4302; p<0.01). Patients with a low LV-EF as well as patients with a low IL-10/TNFα ratio showed an increased cardiovascular mortality over 10 years (both p<0.05). The IL-10/TNFα ratio is decreased in patients with low ejection fraction and poor prognosis. The reduced heart function correlates with an increased proinflammatory state (low monocytic IL-10/TNFα ratio) in patients with CAD. This observed imbalance of IL-10 and TNFα in monocytes might explain pathophysiological processes in atherosclerosis and heart failure.

Differentiation of Monocyte Derived Dendritic Cells in End Stage Renal Disease is Skewed Towards Accelerated Maturation

BACKGROUND

Dendritic cells (DC) play an important role in the induction of immune responses. Patients with end stage renal disease (ESRD) suffer from chronic inflammation, leading to a secondary, uremic immunodeficiency associated with alterations in monocyte subpopulations with increased proinflammatory capacities.

OBJECTIVES

The aim of this study was to examine, under isolated conditions, whether alterations in monocyte subpopulations may affect in vitro maturation of dendritic cells (DC) in patients with ESRD, thus allowing us to draw conclusions for the situation in vivo.

MATERIAL AND METHODS

Monocytes from 30 patients undergoing hemodialysis (HD) and 15 healthy volunteers were enriched from peripheral blood leukocytes, differentiated into immature DC (iDC) in medium containing IL-4 and GM-CSF, and were induced with LPS to differentiate into mature DC (mDC). Monocyte subpopulations and DC maturation stages were phenotypically characterized using flow-cytometry.

RESULTS

Although phenotypically indistinguishable, the number of both iDC and mDC that were generated from uremic monocytes was significantly higher compared to those from healthy controls (p=0.02 and p=0.03, respectively). This was associated with an increased number of CD14+ CD16+ monocytes (p=0.02) and by a higher maturation efficiency of mDC in patients (p=0.04).

CONCLUSIONS

A high percentage of CD14+ CD16+ monocytes in patients with ESRD is associated with an increased propensity to differentiate into DC. This indicates that chronic inflammation may substantiate the biased consistence of monocyte subpopulations leading to profound alteration in DC generation and maturation in ESRD.

CXCL9, but not CXCL10, promotes CXCR3-dependent immune-mediated kidney disease

Chemokines are instrumental in macrophage- and T cell-dependent diseases. The chemokine CCL2 promotes kidney disease in two models of immune-mediated nephritis (MRL-Fas(lpr) mice and the nephrotoxic serum nephritis model), but evidence suggests that multiple chemokines are involved. For identification of additional therapeutic targets for immune-mediated nephritis, chemokine ligands and receptors in CCL2-/- and wild-type (WT) MRL-Fas(lpr) kidneys were profiled. The focus was on intrarenal chemokine ligand/receptor pairs that were highly upregulated downstream of CCL2; the chemokine CXCL10 and its cognate receptor, CXCR3, stood out as potential therapeutic targets. However, renal disease was not suppressed in CXCL10-/- MRL-Fas(lpr) mice, and CXCL10-/- C57BL/6 mice were not protected from nephrotoxic serum nephritis compared with WT mice. Because CXCR3 engages with the ligand CXCL9, CXCR3-/- , CXCL9-/- , and CXCL10-/- B6 mice were compared with WT mice with nephrotoxic serum nephritis. Kidney disease, measured by loss of renal function and histopathology, was suppressed in both CXCR3-/- and CXCL9-/- mice but not in CXCL10-/- mice. With nephrotoxic serum nephritis, CXCR3-/- and CXCL9-/- mice had fewer intrarenal activated T cells and activated macrophages. Both IgG glomerular deposits and antigen-specific IgG in serum were reduced in these mice, suggesting that although CXCR3 and CXCL9 initiate nephritis through cell-mediated events, renal inflammation may be sustained by their regulation of IgG. It is concluded that specific blockade of CXCL9

Inducible co-stimulator null MRL-Faslpr mice: uncoupling of autoantibodies and T cell responses in lupus

MRL/MpJ-Tnfrsf6lpr (MRL-Faslpr) mice develop a spontaneous T cell-dependent autoimmune disease that shares features with human lupus, including fatal nephritis, systemic pathology, and autoantibodies (autoAb). The inducible co-stimulator (ICOS) is upregulated on activated T cells and modulates T cell-mediated responses. To investigate whether ICOS has an essential role in regulating autoimmune lupus nephritis and the systemic illness in MRL-Faslpr mice, ICOS null (-/-) MRL Faslpr and ICOS intact (+/+) MRL-Faslpr strains (wild-type [WT]) were generated and compared. It was determined that in ICOS-/- MRL-Faslpr as compared with the WT strain, (1) there is a significant reduction in circulating IgG and double-stranded DNA autoantibody isotype titers, and (2) there is an amplification of the frequency of intrarenal T cells generating IFN-gamma and TNF-alpha in ICOS-/- versus WT mice. Of note, eliminating ICOS in the MRL-Faslpr strain does not alter renal pathology or function. Despite the reduction in circulating IgG and autoantibody isotypes (G1, G2a, and G2b), the amount of these IgG isotypes depositing in kidneys is similar. Furthermore, the systemic illness (skin, salivary and lacrimal glands, lungs, lymphadenopathy, and splenomegaly) is equivalent in ICOS-/- MRL-Faslpr and WT mice. These findings highlight the danger of relying on individual parameters, such as quantitative serum Ig levels and T cell functions, as prognostic indicators of lupus.