Dataset Information

TLR4 accessory molecule RP105 (CD180) regulates monocyte-driven arteriogenesis in a murine hind limb ischemia model.

ABSTRACT:

Aims

We investigated the role of the TLR4-accessory molecule RP105 (CD180) in post-ischemic neovascularization, i.e. arteriogenesis and angiogenesis. TLR4-mediated activation of pro-inflammatory Ly6Chi monocytes is crucial for effective neovascularization. Immunohistochemical analyses revealed that RP105+ monocytes are present in the perivascular space of remodeling collateral arterioles. As RP105 inhibits TLR4 signaling, we hypothesized that RP105 deficiency would lead to an unrestrained TLR4-mediated inflammatory response and hence to enhanced blood flow recovery after ischemia.

Methods and results

RP105-/- and wild type (WT) mice were subjected to hind limb ischemia and blood flow recovery was followed by Laser Doppler Perfusion Imaging. Surprisingly, we found that blood flow recovery was severely impaired in RP105-/- mice. Immunohistochemistry showed that arteriogenesis was reduced in these mice compared to the WT. However, both in vivo and ex vivo analyses showed that circulatory pro-arteriogenic Ly6Chi monocytes were more readily activated in RP105-/- mice. FACS analyses showed that Ly6Chi monocytes became activated and migrated to the affected muscle tissues in WT mice following induction of hind limb ischemia. Although Ly6Chi monocytes were readily activated in RP105-/- mice, migration into the ischemic tissues was hampered and instead, Ly6Chi monocytes accumulated in their storage compartments, bone marrow and spleen, in RP105-/- mice.

Conclusions

RP105 deficiency results in an unrestrained inflammatory response and monocyte over-activation, most likely due to the lack of TLR4 regulation. Inappropriate, premature systemic activation of pro-inflammatory Ly6Chi monocytes results in reduced infiltration of Ly6Chi monocytes in ischemic tissues and in impaired blood flow recovery.

SUBMITTER: Bastiaansen AJ

PROVIDER: S-EPMC4063870 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Publications

TLR4 accessory molecule RP105 (CD180) regulates monocyte-driven arteriogenesis in a murine hind limb ischemia model.

Bastiaansen Antonius J N M AJ Karper Jacco C JC Wezel Anouk A de Boer Hetty C HC Welten Sabine M J SM de Jong Rob C M RC Peters Erna A B EA de Vries Margreet R MR van Oeveren-Rietdijk Annemarie M AM van Zonneveld Anton Jan AJ Hamming Jaap F JF Nossent A Yaël AY Quax Paul H A PH

PloS one 20140619 6

<h4>Aims</h4>We investigated the role of the TLR4-accessory molecule RP105 (CD180) in post-ischemic neovascularization, i.e. arteriogenesis and angiogenesis. TLR4-mediated activation of pro-inflammatory Ly6Chi monocytes is crucial for effective neovascularization. Immunohistochemical analyses revealed that RP105+ monocytes are present in the perivascular space of remodeling collateral arterioles. As RP105 inhibits TLR4 signaling, we hypothesized that RP105 deficiency would lead to an unrestraine ...[more]

PMID: 24945347

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Project description:Older patients are thought to tolerate acute ischemia more poorly than younger patients. Since aging may depress both angiogenesis and arteriogenesis, we determined the effects of age on both angiogenesis and arteriogenesis in a model of severe acute limb ischemia.Young adult (3-months-old) and aged (18-months-old) C57BL/6 mice underwent right common iliac artery and vein ligation and transection. Data were collected on days 0, 7, and 14. Perfusion was measured with a laser Doppler scan and compared to the contralateral limb. Functional deficits were evaluated with the Tarlov scale. Capillary density and endothelial progenitor cell (EPC) number were determined by direct counting lectin-positive/alpha-actin-negative cells and VEGFR2/CXCR4 dually-positive cells, respectively; angiography was performed to directly assess arteriogenesis.Young adult and aged mice had a similar degree of decreased perfusion after iliac ligation (young, n = 15: 20.4 +/- 1.9%, vs aged, n = 20: 19.6 +/- 1.3%; P = .72, analysis of variance [ANOVA]); however, young mice recovered faster and to a greater degree than aged mice (day 7, 35 +/- 6% vs 17 +/- 4%, P = .046; day 14, 60 +/- 5% vs 27 +/- 7%, P = .0014). Aged mice had worse functional recovery by day 14 compared to young mice (2.3 +/- 0.3 vs 4.3 +/- 0.4; P = .0021). Aged mice had increased capillary density (day 7, 12.9 +/- 4.4 vs 2.8 +/- 0.3 capillaries/hpf; P = .02) and increased number of EPC incorporated into the ischemic muscle (day 7, 8.1 +/- 0.9 vs 2.5 +/- 1.9 cells; P = .007) compared to young mice, but diminished numbers of collateral vessels to the ischemic limb (1 vs 9; P = .01), as seen on angiography.After severe hind limb ischemia, aged animals become ischemic to a similar degree as young animals, but aged animals have significantly impaired arteriogenesis and functional recovery compared to younger animals. These results suggest that strategies to stimulate arteriogenesis may complement those that increase angiogenesis, and may result in improved relief of ischemia.

Project description:Background Circadian rhythm disorders, often seen in modern lifestyles, are a major social health concern. The aim of this study was to examine whether circadian rhythm disorders would influence angiogenesis and blood perfusion recovery in a mouse model of hind limb ischemia. Methods and Results A jet-lag model was established in C57BL/6J mice using a light-controlled isolation box. Control mice were kept at a light/dark 12:12 (12-hour light and 12-hour dark) condition. Concentrations of plasma vascular endothelial growth factor and circulating endothelial progenitor cells in control mice formed a circadian rhythm, which was diminished in the jet-lag model (P<0.05). The jet-lag condition deteriorated tissue capillary formation (P<0.001) and tissue blood perfusion recovery (P<0.01) in hind limb ischemia, which was associated with downregulation of vascular endothelial growth factor expression in local ischemic tissue and in the plasma. Although the expression of clock genes (ie, Clock, Bmal1, and Cry) in local tissues was upregulated after ischemic injury, the expression levels of cryptochrome (Cry) 1 and Cry2 were inhibited by the jet-lag condition. Next, Cry1 and Cry2 double-knockout mice were examined for blood perfusion recoveries and a reparative angiogenesis. Cry1 and Cry2 double-knockout mice revealed suppressed capillary density (P<0.001) and suppressed tissue blood perfusion recovery (P<0.05) in the hind limb ischemia model. Moreover, knockdown of CRY1/2 in human umbilical vein endothelial cells was accompanied by increased expression of WEE1 and decreased expression of HOXC5. This was associated with decreased proliferative capacity, migration ability, and tube formation ability of human umbilical vein endothelial cells, respectively, leading to impairment of angiogenesis. Conclusions Our data suggest that circadian rhythm disorder deteriorates reparative ischemia-induced angiogenesis and that maintenance of circadian rhythm plays an important role in angiogenesis.

Project description:OBJECTIVE:Peripheral arterial disease can cause not only ischemia but also skeletal muscle damage. It has been known that macrophages (MPs) play an important role in coordinating muscle repair; however, phenotype transition of monocyte-MP in ischemic muscle has not been well defined. Hence, the purpose of this study was to examine the temporal recruitment of MPs and to explore their therapeutic effect on ischemic muscle regeneration. METHODS:Unilateral femoral artery excision was performed on C57BL/6 mice. Myeloid cells were isolated from the ischemic muscles, characterized using flow cytometry. Bone marrow-derived MPs were injected (2 × 106 cells) into the ischemic gastrocnemius muscle 24 hours after injury. Blood flow recovery was measured using laser speckle imaging. Functional outcome was evaluated by assessing the contractile force of ischemic muscles. Histologic analysis included quantification of myofiber size, collagen deposition, number of inflammatory and MyoD-expressing cells, and capillary density. RESULTS:Neutrophils and inflammatory monocytes-MPs were present at day 1 after injury. The mature MPs then remained elevated as the dominant population from day 5 to day 21 with the observation of regenerating fibers. Functional measurements revealed that the force production was significantly enhanced after treatment with proinflammatory M1 MPs (94.9% vs 77.9%; P < .05), and this was consistent with increased myofiber size, capillary- fiber ratio, and perfusion (78.6% vs 39.9%; P < .05). Moreover, the percentage of MyoD-expressing nuclei was significantly higher at day 4, indicating that M1 MPs may hasten muscle repair. Whereas early delivery of anti-inflammatory M2 MPs improved myofiber size, this was accompanied by persistent fibrosis suggesting ongoing tissue remodeling, and lower force production was observed. CONCLUSIONS:We demonstrated the dynamics of myeloid cells in skeletal muscle after ischemic insult, and the administration of exogenous M1 MPs in a temporally coordinated manner successfully improved angiogenesis and skeletal muscle regeneration. Our results suggested that cell therapy using MPs may be a promising adjunctive therapeutic approach for peripheral arterial disease.

Dataset Information

TLR4 accessory molecule RP105 (CD180) regulates monocyte-driven arteriogenesis in a murine hind limb ischemia model.

Aims

Methods and results

Conclusions

Publications

TLR4 accessory molecule RP105 (CD180) regulates monocyte-driven arteriogenesis in a murine hind limb ischemia model.

Similar Datasets

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