Background: The extracellular matrix is associated with diabetic complications; however, chondroitin sulfate (CS) role remains unclear. Herein, genetically engineered mice lacking the rate-limiting CS-synthesizing enzyme, CS N-acetylgalactosaminyltransferase-1 (T1), were used to clarify CS effects on diabetic neuropathy. Diabetes was induced by streptozotocin injection in 6-week-old male T1 knockout (T1KO) and wild-type (WT) mice.
Results: Previously reported preliminary data at the former ADA meeting revealed that thermal nociception and the number of plantar peripheral nerve fibers were disrupted in diabetic WT mice, whereas in diabetic T1KO were preserved. Moreover, conduction velocity in the sciatic nerve was significantly declined in diabetic WT than in T1KO mice. [A1] Immunohistochemical data revealed loss of calcitonin gene-related peptide-positive neurons in the dorsal root ganglia (DRG) in diabetic WT mice, whereas those neurons were protected in diabetic T1KO mice. Moreover, DRG gene expression analysis showed that caspase-3 and -9 were reduced in T1KO compared with WT mice. To investigate the mechanisms underlying these events, the role of pericytes, which are important CS-expressing components of the blood-nerve barrier (BNB), was explored. Assessment of the retinal vessels, which represent a good model to evaluate pericyte functions and easier to access than peripheral nerves, revealed a higher proportion of pericyte-deficient retina blood vessels in diabetic WT than in T1KO mice upon administration of a platelet-derived growth factor receptor (PDGFR) β antibody. Therefore, pericytes in T1KO mice were more resistant against PDGFRβ antibody than those of WT mice. Thus, it is possible that the BNB in T1KO mice may be more resistant against external stress, including diabetes.
Conclusions: Reduced CS production may induce beneficial effects to prevent diabetic neuropathy by improving pericyte function.
H. Ishiguro: None. T. Ushiki: None. A. Honda: None. T. Mikami: None. H. Kitagawa: None. K. Sango: None. M. Masuko: None. M. Igarashi: None. H. Sone: Research Support; Self; Astellas Pharma Inc., Eisai Co., Ltd., Kyowa Kirin Co., Ltd., Novo Nordisk, Ono Pharmaceutical Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Pharmaceutical Co.