No abstract

The persistence of proinflammatory macrophages, which are recruited to the granulation tissue, impairs the healing of diabetic wounds. Herein, we examined the role of vascular endothelial growth factor receptor type 1 (VEGFR1) signaling in streptozotocin (STZ)-induced diabetic wound healing. Angiogenesis, lymphangiogenesis, and the healing of full-thickness skin wounds were impaired in STZ-treated wild-type (WT) mice compared with vehicle-treated WT mice, with attenuated recruitment of VEGFR1-positive macrophages expressing vascular endothelial growth factor (VEGF)-A, VEGF-C, and VEGF-D to the wound granulation tissue. These phenomena were even more prevalent in STZ-treated VEGFR1 tyrosine kinase knockout mice (VEGFR1 TK(-/-) mice). STZ-treated WT mice, but not STZ-treated VEGFR1 TK(-/-) mice, showed accelerated wound healing when treated with placenta growth factor. Compared with that of STZ-treated WT mice, the wound granulation tissue of STZ-treated VEGFR1 TK(-/-) mice contained more VEGFR1-positive cells expressing IL-1β [a classic (M1) activated macrophage marker] and fewer VEGFR1-positive cells expressing the mannose receptor [CD206; an alternatively activated (M2) macrophage marker]. Treatment of STZ-treated VEGFR1 TK(-/-) mice with an IL-1β-neutralizing antibody restored impaired wound healing and angiogenesis/lymphangiogenesis and induced macrophages in the wound granulation tissue to switch to an M2 phenotype. Taken together, these results suggest that VEGFR1 signaling plays a role in regulating the balance between macrophage phenotypes in STZ-induced diabetic wounds, prevents impaired diabetic wound healing, and promotes angiogenesis/lymphangiogenesis.

These results indicated that TP signalling facilitates ischaemia-induced angiogenesis via P-selectin-mediated platelet adhesion to PSGL-1 on the ECs at ischaemic sites and the supply of pro-angiogenic factors by the adherent platelets.

Angiotensin II is involved in tumor growth; however, the precise mechanism is not known. Platelets also contribute to tumor growth, and angiotensin II type 1 receptor (AT1) is expressed on the platelet surface. We hypothesized that interaction of platelets with tumor cells through AT1 receptor signaling promotes tumor metastasis. B16F1 melanoma cells were intravenously injected into Agtr1a knockout mice (AT1a(-/-)) and wild-type littermates (WT); the AT1a(-/-) mice exhibited a reduction in lung colonies. Angiotensin II induced expression of P-selectin on platelets in WT but not in AT1a(-/-) mice. A selective P-selectin neutralizing antibody decreased lung colony numbers in WT but not in AT1a(-/-) mice. Levels of vascular endothelial growth factor (VEGF) and stromal cell-derived factor 1 (SDF-1) receptor in platelets at metastatic locus were lower in AT1a(-/-) mice. Treatment of neutralizing antibodies against VEGF and CXCR4 decreased lung colony numbers in WT but not in AT1a(-/-) mice. In AT1a(-/-) mice, and both mobilization of progenitor cells expressing CXCR4(+)VEGFR1(+) cells from bone marrow and their recruitment to lung tissues were suppressed. These results suggest that AT1A signaling plays a critical role in tumor metastasis through P-selectin-mediated interactions of platelets with tumor and endothelial cells and through the AT1A signaling-dependent production of VEGF and SDF-1, which may be involved in mobilization of CXCR4(+)VEGFR1(+) cells.

Aims: Sarcopenia is a serious problem because of its poor prognosis. Growth differentiation factor 15 (GDF15) is associated with mitochondrial dysfunction, inflammation, insulin resistance and oxidative stress, which may play crucial roles for the development of sarcopenia. We aimed to examine whether serum GDF15 level is associated with muscle mass, strength and lower extremity function in older patients with cardiometabolic disease. Methods: Serum GDF15 levels were measured in 257 patients with cardiometabolic diseases (including 133 patients with diabetes) who had visited the frailty clinic, using a latex turbidimetric immunoassay. Appendicular skeletal muscle index, handgrip strength, timed-upand-go test and gait speed were evaluated. Power, speed, balance and total scores based on the sit-to-stand test were calculated to assess lower extremity function. Results: The highest tertile of serum GDF15 was independently associated with low handgrip strength, low gait speed, long timed-up-and-go time and scores of lower extremity function but not an appendicular skeletal muscle index in multiple logistic regression analyses after adjustment for covariates. Patients in the highest tertile of GDF15 were at the risk of having three to nine times lower grip strength, three times lower gait speed, five to six times lower mobility and five to 11 times reduction in lower extremity function as compared with those in the lowest GDF15 tertile dependent on the models. Conclusions: Elevated serum GDF15 level was independently associated with low muscle strength and lower extremity function in older patients with cardiometabolic disease. Serum GDF15 could be one of the biomarkers for muscle weakness and low physical performance.