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Osteoarthritis may be caused by changes in communication between chondrocyte cells

23 Apr 2013

According to a research Project by Spanish scientists presented in the OARSI 2013 CongressThese finding will play a key role to better understand the physiopathology of joint diseases affecting the proper functioning of cartilage and joints.The findings of seven nationwide studies presented at the OARSI Congress might serve as the basis for new osteoarthritis treatment research. It is estimated that 10% of the Spanish population suffer from osteoarthritis.

Until now, it was believed that the cells responsible for the formation and maintenance of joint cartilage, the chondrocytes, were isolated-however, it has been proved that chondrocytes are bound by a network of cell connections. In fact, “the chondrocytes of osteoarthritis patients present changes in the expression and location of the proteins that form these communication channels. Therefore, changes in the function of these channels might lead to the development of osteoarthritis.” These are the conclusions of a Spanish paper presented in the Congress of the Osteoarthritis Research Society International (OARSI) held from 18th to 21st April, 2013, at Philadelphia, USA.

To be more precise, the group led by Drs. María Dolores Mayán and Francisco Blanco, from the A Coruña Institute of Biomedical Research (INIBIC) have proved that tissue chondrocytes are physically bound by means of a cell connection network which confers them the ability to directly exchange information-second messengers, small ARN molecules, nutrients such as glucose, as well as the ability to give a coordinated, uniform answer to stimuli or damage to the cells.

These results will help us to understand how joint cartilage works, and without doubt it will contribute towards the development of new therapeutic targets for the treatment of joint conditions,” explained Dr. Mayán, who attended the OARSI congress thanks to one of the OARSI scholarships of the Spanish Society of Rheumatology (SER) and Bioibérica Farma.

More precisely, chondrocytes are physically connected through tiny extensions of cytoplasm that allow contact between cells. Communication takes place through conexine channels (known as Gap bounds or Gap Junctions). These channels are responsible for electric synapses in brain cells or for the transmission of electric pulses between heart cells. The results shown by the research group demonstrated that, in the case of joint cartilage, the existence of a cell network and that of conexin channels, allow for metabolic coupling and information exchange.

That paper, entitled ‘Comunicación intercelular entre condrocitos inmersos en cartílago articular a través de largas extensiones citoplasmáticas y canales de conexinas: intercambio de segundos mensajeros y acoplamiento metabólico’, comes to the conclusion that conexines and their channels could be playing a key role in cell communication and metabolic co-ordination with the aim of preserving physiology and homeostasis of the cartilage, thus preserving the structure of the cartilage and keeping the joints in good shape.

These conclusions, along with the results of some papers previously published by American Journal of Pathology, suggest that changes in the role of connexins and their channels might be the cause of conditions such as osteoarthritis.

Seven OARSI Scholarships
During the OARSI Congress, the SER and Bioiberica Farma granted seven scholarships to projects dealing with a number of issues related to that rheumatic condition.

Osteoarthritis is a degenerative disease that over the last few years has gained importance due to its major prevalence and its socio-health and economical impact, due to the disability it causes to patients. It is estimated that this condition affects approximately 10% of the Spanish population, according to the EPISER study of the Spanish Society of Rheumatology.

The projects that have received a scholarship are the following:

Epigenetic regulation during fetal femur development: DNA methylation matters
Dra. Mª Carmen de Andrés González. Hospital Clínico Universitario de Santiago de Compostela (A Coruña)

Hydrogen sulfide donors aleviate iL-1β induced inflammation-like effects in human articular osteoarthritic chondrocytes
Dra. Elena Fernández Burguera. INIBIC-Hospital Universitario A Coruña.

Downregulation of wnt signaling pathway and mir335 through mir335 in mscs from osteoarthritis patients
Dr. Benjamín Fernández Gutiérrez. Hospital Clínico Universitario San Carlos (Madrid)

TGF-β1 increases oxidative stress in human osteoarthritis articular chondrocytes through mechanisms involving Nox4
Dra. Laura Lugo García. Fundación Jiménez Díaz (Madrid)

Articular chondrocytes are physically connected through a cellular network that is responsible of the metabolic coupling between chondrocytes located in different layers of the tissue
Dra. María Dolores Mayán Santos. INIBIC-Hospital Universitario A Coruña.

The mtDNA haplogroups influence the progression of osteoarthritis (OA). Data from the osteoarthritis initiative (OAI)
Dr. Ignacio Rego Pérez. INIBIC-Hospital Universitario A Coruña.

Oligomycin, an inhibitor of complex v of mitochondrial respiratory chain, induces an inflammatory response in rat knee joint
Dr. Carlos Vaamonde García. INIBIC-Hospital Universitario A Coruña (A Coruña)