High Plasma Pentraxin 3 Levels in Diabetic Polyneuropathy Patients with Nociceptive Pain

Diabetic polyneuropathy is the most common neurologic complication of diabetes mellitus. Underlying mechanisms of diabetic polyneuropathy are related to various metabolic and inflammatory pathways. Pentraxin 3 (PTX3) is an acute phase protein that is produced locally at the inflammatory sites by several cell types. Thioredoxin binding protein 2 (TBP2) is a thioredoxin regulator involved in intracellular energy pathways and cell growth. We measured the plasma levels of PTX3 and TBP2 in type 2 diabetic patients (n = 27) with pain complaints and compared their levels with those of healthy age- and sex-matched subjects (n = 24). Moreover, the diabetic patients were divided into two groups using the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) pain scale: patients with nociceptive pain that is caused by tissue damage and patients with neuropathic pain that is caused by nerve damage. Patients with LANSS scores of < 12 were considered to have nocicceptive pain (n = 15), while patients with LANSS scores of ≥ 12 were considered to have neuropathic pain (n = 12). We found that PTX3 levels were significantly higher in diabetic patients compared to controls (p = 0.03), but there was no significant difference in the TBP2 levels. Importantly, patients with nociceptive pain had significantly higher PTX3 levels compared to patients with neuropathic pain (p < 0.05). Thus, plasma PTX3 levels can be helpful for discrimination of nociceptive pain from neuropathic pain in diabetic patients. We propose that PTX3 may contribute to the onset of nociceptive pain.