RESUMEN

Musculoskeletal disorders (MSDs) are the most frequent cause of disability in Europe. Reduced mobility and quality of life of the patients are often associated with pain due to chronic inflammation. The inflammatory process, accompanied by a destruction of the cartilage and bone tissue, is discussed as a result of (A) the infiltration of immune cells into the joints, (B) an altered homeostasis of the joint cavity (synovium) with a critical role of bone remodeling cells, and (C) release of inflammatory factors including adipokines in the arthritic joint. In addition to the classical medication, low-dose radiation therapy using photons or radon spa treatments has shown to reduce pain and improve the mobility of the patients. However, the cellular and molecular mechanisms of anti-inflammatory effects of radon are yet poorly understood. We analyzed blood and serum samples from 32 patients, suffering from MSDs, who had been treated in the radon spa in Bad Steben (Germany). Before and after therapy, we measured the levels of markers related to bone metabolism (collagen fragments type-1, cartilage oligomeric matrix protein, receptor activator of NFκB ligand, and osteoprotegerin) in the serum of patients. In addition, adipokines related to inflammation (visfatin, leptin, resistin, and adiponectin) were analyzed. Some of these factors are known to correlate with disease activity. Since T cells play an important role in the progression of the disease, we further analyzed in blood samples the frequency of pro- and anti-inflammatory T cell subpopulations (CD4+IL17+ T cells and CD4+FoxP3+ regulatory T cells). Overall, we found a decrease of collagen fragments (CTX-I), indicating decreased bone resorption, presumably by osteoclasts, in the serum of MSD patients. We also observed reduced levels of visfatin and a consistent trend toward an increase of regulatory T cells in the peripheral blood, both indicating attenuation of inflammation. However, key proteins of bone metabolism were unchanged on a systemic level, suggesting that these factors act locally after radon spa therapy of patients with MSDs.

RESUMEN

As a means to analyze anti-inflammatory effects by radiation and/or by cholinergic mechanisms, we found that cultured primary human osteoblasts express most cholinergic components. After X-ray irradiation, their level of acetylcholinesterase (AChE) was strongly elevated. As a 3D model, we cultured mesenchymal stem cells isolated from E11 mouse embryos as micromass nodules, and differentiated them into chondro- and osteoblasts. They were stimulated by 5 or 10 ng/ml of the inflammatory cytokine TNF-α to mimic an inflammatory condition in vitro, before exposure to 2 Gy X-rays. Effects on chondro- and osteoblasts of TNF-α, of X-rays, or both were analysed by Alcian Blue, or Alizarin Red staining, respectively. Acetylcholinesterase (AChE) activity was visualized histochemically. The results showed that treatment with TNF-α affected cartilage and bone formation in vitro, while X-rays reversed the effects of TNF-α. After irradiation, both AChE and alkaline phosphatase (ALP) activities, a marker for bone mineralization, were raised, suggesting that X-rays stimulated cholinergic mechanisms during calcification. Notably, the TNFα-effects on cultures were also counterbalanced after AChE activity was blocked by BW284c51. These findings suggest a complex crosstalk between radiation, cholinergic and inflammatory mechanisms, which could have wide significances, e.g. for understanding rheumatoid arthritis.

Asunto(s)

Acetilcolinesterasa/metabolismo , Inhibidores de la Colinesterasa/farmacología , Inflamación/patología , Factor de Necrosis Tumoral alfa/farmacología , Animales , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/efectos de la radiación , Células Cultivadas , Colina/metabolismo , Condrocitos/citología , Condrocitos/efectos de los fármacos , Condrocitos/efectos de la radiación , Humanos , Ratones , Osteoblastos/citología , Osteoblastos/efectos de los fármacos , Osteoblastos/enzimología , Osteoblastos/efectos de la radiación , Rayos X

RESUMEN

Ionizing radiation generates DNA double-strand breaks (DSB) which, unless faithfully repaired, can generate chromosomal rearrangements in hematopoietic stem and/or progenitor cells (HSPC), potentially priming the cells towards a leukemic phenotype. Using an enhanced green fluorescent protein (EGFP)-based reporter system, we recently identified differences in the removal of enzyme-mediated DSB in human HSPC versus mature peripheral blood lymphocytes (PBL), particularly regarding homologous DSB repair (HR). Assessment of chromosomal breaks via premature chromosome condensation or γH2AX foci indicated similar efficiency and kinetics of radiation-induced DSB formation and rejoining in PBL and HSPC. Prolonged persistence of chromosomal breaks was observed for higher LET charged particles which are known to induce more complex DNA damage compared to X-rays. Consistent with HR deficiency in HSPC observed in our previous study, we noticed here pronounced focal accumulation of 53BP1 after X-ray and carbon ion exposure (intermediate LET) in HSPC versus PBL. For higher LET, 53BP1 foci kinetics was similarly delayed in PBL and HSPC suggesting similar failure to repair complex DNA damage. Data obtained with plasmid reporter systems revealed a dose- and LET-dependent HR increase after X-ray, carbon ion and higher LET exposure, particularly in HR-proficient immortalized and primary lymphocytes, confirming preferential use of conservative HR in PBL for intermediate LET damage repair. HR measured adjacent to the leukemia-associated MLL breakpoint cluster sequence in reporter lines revealed dose dependency of potentially leukemogenic rearrangements underscoring the risk of leukemia-induction by radiation treatment.