Abstract

Background
The CXC motif chemokine ligand 8 (CXCL8)-CXC motif chemokine receptor 1/2 (CXCR1/2) axis has been implicated in type 1 diabetes mellitus (T1DM). Its actions on non-immune cells may also contribute to T1DM-associated complications, including painful diabetic peripheral neuropathy (DPN) and diabetic retinopathy (DR).
Methods
We assessed the efficacy of early (4–8 weeks) or late (8–12 weeks) daily ladarixin (LDX) for the treatment of streptozotocin (STZ)-induced T1DM and the related complications of DPN or DR in male rats.
Results
Early LDX mitigated STZ-induced dysmetabolism (i.e., blood glucose, insulin), inflammation in dorsal root ganglion/ sciatic nerve (interleukin-1β and tumor necrosis factor-α expression) and mechanical allodynia and thermal hyperalgesia, indicative of DPN. Moreover, vitreous citrullinated histone H3 (CitH3) and plasma GRO/CINC1 (CXCL8) increase were attenuated. Late LDX failed to reverse STZ-induced changes in metabolic parameters (i.e., blood glucose, insulin, C-peptide, pancreatic β-cell number and function). Strikingly, even in the absence of an effect on glycemic control, late LDX mitigated STZ-induced mechanical allodynia and thermal hyperalgesia and vitreous (CXCL8, CitH3) and retinal (CXCL8, CXCR1/2, myeloperoxidase, CitH3) inflammatory/pro-angiogenic (vascular endothelial growth factor, CD34) signs of DR.
Conclusion
These data confirm the efficacy of LDX in STZ-induced T1DM and provide evidence of a protective effect also against DPN and onset of DR which is independent of its effect on β-cell functionality preservation and glycemic control.

• Keywords: Diabetes mellitus, type 1; Diabetic neuropathies; Diabetic retinopathy; Interleukin-8; Receptors, interleukin-8A; Receptors, interleukin-8B