Relationship Between Presence Of Osteolytic Lesions, Cytogenetic Features and Bone Marrow Levels Of Cytokines and Chemokines In Multiple Myeloma Patients: Role Of Chemokine (C-C motif) Ligand 20

Osteolytic lesions are the main feature of multiple myeloma (MM) patients. In the last years the pathophysiological role of several cytokines and chemokines such as RANKL, osteoprotegerin (OPG), DKK-1, Interleukin- (IL)-3, IL-7, Activin A, chemokine (C-C motif) ligand (CCL)-3 and CCL20 has been highlighted in MM bone disease although the relationships between their bone marrow (BM) levels, cytogenetic features and the skeletal involvement are not yet defined.

A total cohort of 365 consecutive patients with monoclonal gammopathy has been evaluated in this study including 250 patients with symptomatic MM, 62 patients with smoldering MM (SMM) and 53 patients with MGUS. A group of 29 healthy subjects was also included. X-ray survey, magnetic resonance imaging (MRI) and positron emission tomography (PET)/computerized tomography (CT) scan were performed in MM patients The presence of the main cytogenetic abnormalities (hyperdiploid karyotype, del13, t(4;14), t(11;14), 17p-, amp1) has been investigated in purified CD138+ MM cells by FISH analysis and the BM plasma levels of soluble (s) and total RANKL, OPG, IL-3, IL-7, DKK-1, Activin A, CCL3 and CCL20 were measured by ELISA assay. Quantitative variables were compared by non-parametric Kruskal-Wallis and Mann-Whitney tests as appropriate and categorical variables were analyzed by Chi-square test.

MM patients showed higher BM median levels of Activin A, sRANKL, DKK-1, CCL20 and IL-7 as compared to N (p<0.05) and those of Activin A, DKK-1 and CCL20 as compared to MGUS and to SMM (p<0.01). BM plasma levels of Activin A, sRANKL and sRANKL/OPG ratio were significant higher in high-risk cytogenetic MM patients as compared to standard risk ones (p<0.05) as well as Activin A, CCL3 and CCL20 BM levels correlated with ISS staging being higher in stage III as compared to stage I and II (p<0.005).

Regarding the bone status we found that 60%, 86% and 66% of MM patients were positive at X-ray survey, MRI and PET/CT scan respectively. Any significant relationship was not observed between X-rays or PET/CT scan positivity and the presence of cytogenetic abnormalities (p=NS) whereas MM patients with high-risk cytogenetic showed higher positivity to the MRI scan than standard risk (100% vs. 77%, p=0.03). Significant higher BM levels of DKK-1 and CCL20 (p<0.005) were found in all MM patients with almost one osteolytic lesion as compared to those negative at the X-ray survey whereas Activin A (p=0.05), DKK-1 (p=0.009) CCL3 (p=0.05), and CCL20 (p<0.001) were significantly higher into the BM of patients with high bone disease (more than three lesions) as compared to those with low bone disease. MM patients with a positive MRI scan have higher BM levels of RANKL, DKK-1, CCL3 and CCL20 as compared to those negative (p<0.05). On the other hand, MM patients positive at the PET/CT scan with more of three lesions have significant higher BM levels of RANKL and CCL3 as compared to those negative or with less of three lesions (p<0.05). Finally by a logistic multivariate analysis we found that among the cytokines and chemokines analyzed and the clinical and cytogenetic features CCL20 levels were the only significant predictor of the presence of skeletal involvement (OD ratio: 1.03; p=0.014).

In conclusion our study defines the relationship between skeletal involvement, cytogenetic feature and the profiles of BM cytokines and chemokines showing that CCL20 is a critical marker related to the presence of osteolytic bone disease in MM patients.