Abstract

POEMS syndrome is defined by the presence of peripheral neuropathy (P), monoclonal plasma cell disorder (M), organomegaly (O), endocrinopathy (E), and skin changes (S). Virtually all patients will have sclerotic bone lesions, although the mechanisms of their development have not been clarified to-date. Increased plasma level of VEGF is another characteristic of the disease. However, there is very little information for the role of other angiogenic molecules in POEMS pathogenesis. The aim of this study was to evaluate bone metabolism and angiogenic cytokines in POEMS and compare the results with multiple myeloma (MM) and osteosclerotic patients of other etiology. Seven patients with POEMS at diagnosis (6M/1F; median age: 49 years) were evaluated. A series of bone remodeling indices were measured: i) bone resorption markers [C- and N- telopeptide of type-I collagen (CTX and NTX), TRACP-5b], ii) bone formation markers [bone-alkaline phosphatase, osteocalcin (OC), and C-terminal propeptide of type-I collagen (CICP)], and iii) osteoclast regulators [soluble RANKL, osteoprotegerin (OPG), MIP-1α, and TNF-α]. Furthermore, the following angiogenic cytokines were measured in the plasma of POEMS patients: VEGF, VEGF-A, angiogenin, angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), and bFGF. All above molecules were also measured in 25 newly diagnosed, untreated MM patients (14M/11F, median age: 64 years) and 20 healthy controls. Bone markers were also evaluated in 24 patients with HbS/beta-thalassemia (10M/14F, median age: 43 years) who presented with osteosclerosis, i.e. osteosclerotic bone lesions in plain radiography and a median T-score of lumbar spine Bone Mineral Density of +3.6 (range: +2 to +7.9). All POEMS patients had P, O, E, S, edema and thombocytosis; 6 had E and 2 Castleman’s disease. Six patients had sclerotic bone lesions, while 4 had also a lytic component in their bone lesions. POEMS patients had increased levels of sRANKL (p=0.003), OPG (p=0.008), TNF-α (p=0.001), NTX (p<0.001), CTX (p=0.001) and CICP (p=0.001) compared with controls. Interestingly, NTX levels were even higher in POEMS than in MM patients (p<0.01). NTX and CTX were elevated in POEMS compared with osteosclerotic HbS/β-thal patients (p<0.01), who had reduced bone resorption compared with controls. POEMS patients had increased levels of OC and CICP compared with MM (p=0.02 and p=0.003, respectively), and increased levels of OC compared with osteosclerotic HbS/β-thal patients (p<0.01). In terms of angiogenic cytokines, POEMS patients had increased levels of all studied cytokines compared with controls (p<0.01). All POEMS patients had at least 1.8-fold higher value of VEGF-A (the major angiogenic component of VEGF) compared with the higher value observed in controls. Furthermore, VEGF (p=0.03), VEGF-A (p<0.001), angiogenin (p<0.001), and bFGF (p=0.01) were higher in POEMS than in MM. The ratio of Ang-1/Ang-2 was very low in POEMS compared with both controls and MM. These results suggest that POEMS patients have increased bone turnover in contrast to MM patients who have reduced bone formation and osteosclerotic HbS/β-thal patients who have diminished bone resorption. Furthermore the imbalance of Ang-1/Ang-2 pathway and the increased levels of angiogenic cytokines, even compared with MM, may indicate possible targets for the development of novel agents against POEMS.

Author notes

Disclosure: No relevant conflicts of interest to declare.