Rafika Ben Chaouacha Chekir

Invited by Serge Picaud, Pr. Rafika BEN CHAOUACHA-CHEKIR, Institut Supérieur de Biotechnologie Sidi Thabet / Université de la Manouba_BiotechPole Sidi Thabet, will give a talk on Wednesday 7th of June, 4.00 PM, in the conference room of the UCL, 13 Rue Moreau.

This talk will be dealing with "The Tunisian Psammomys obesus, the superior model for diabetic retinopathy similar to humans : Cellular, Molecular, and Functional Characterizations."

Many rodent models of diabetic retinopathy (DR) with varying degrees of similarity to human disease have been used in research of diabetes mellitus and its complications. The diurnal rodent model Psammomys obesus (P.ob) was introduced in the 1960s by Schmidt Nielsen as a new model for studying diabetes. In its natural environment, P.ob consumes a low-calorie native plant halophyte, but in captivity, many individuals kept with a standard laboratory diet develop overweight with diabetes. Our previous studies showed that the retina of P.ob is rich in cones 41% of the total number of photoreceptors. The S cones represent an important proportion among the two types of cones present M and S. Also, our results suggest that the retinal function of P.ob, especially the cone-mediated function, share several features with that of human subjects. Based on these results, P. ob seems to be an interesting model to study the pathologies related to the cones which characterize the central vision in humans. Type 2 diabetes, induced after treatment of 7 months with a high-calorie diet, affects neuronal, glial, vascular tissues as well as the composition of the vitreous of the retina. Our ERG findings in P.ob that had been affected with diabetes for 7 months, revealed a significant decrease of all ERG components in both scotopic and photopic conditions. To investigate the progression of DR in P.ob, we monitored clinically the DR from 0 day to 7 months using electroretinography (ERG) and imaging techniques. After the onset of DR, all ERG components decreased progressively. We recently focused on the early manifestation observed in the retina structure and function in the diet-induced T2D of P.ob and how these changes progressed over the 7-month period, especially 0 day: control, 3 months (early stage diabetes with no proliferative DR) and 6-7 months (advanced stage diabetes with proliferative DR). The retinal function in P.ob, as assessed with the ERG, was shown to share similarities with that of human, it would represent a unique model to test the preventive and curative effects of biomolecules, nutraceuticals, or biosimilar drugs depending on the evolution and classification of DR, which is a reversible pathology if the therapeutic management is done at an early stage for each cell type. The latter claim is strengthened by the fact that in our model, we observed that neuronal dysfunction as assessed with the ERG preceded by more than 5 months the vascular changes as assessed with ophthalmoscopy, findings that are in agreement with those previously published on human diabetic patients.

Selected bio
Prof. Rafika Ben Chaouacha-Chekir, is a Professor in Biology, Animal and Human Ecophysiology and Pathophysiology at ISBST (University of Manouba). She has received her PhD Doctorate in Endocrinology from Jussieu Paris VI in 1983 and her State Doctorate Es Biological Sciences from the National Museum of Natural History, Jussieu Paris VI in 1989. From 1984 to 1994 she was the Head of the Research unit, 01/RU/09-01 General and Comparative Ecophysiology at Monastir Faculty of Dental Medecine. From 1995 to 2010 she was the head of the Sciences Biology department at the Faculty of Sciences Monastir and the head of the research unit 01//RU/09-01 General and Comparative Ecophysiology at Monastir Faculty of Dental Medecine. She founded Sidi Thabet Higher Institute of Biotechnology ISBST in 2004 and she was its 1st director from 2004 to 2010. Since 2017; She is the Director of LR17ES03 Research Laboratory Physipathology, Food and Biomolecules at ISBST. She has received the 1st award ‘concours innov 2021 API’ in the category of collaborative innovation with her Project: Ani-Biobanque au service des industries pharmaceutiques, agroalimentaires et des industries annexes. She has received many research grants (i.e. bilateral projects: tuniso- moroccan project, tuniso-italian project, tuniso-spanish project…) and national grant (i.e. lead of PAQ Collabora project 2020-2022: Ani-Biobank: Tunisian rodents used for testing biomolecules of economic interest) and has published more than 25 research papers in Psammomys obesus diabetic retinopathy model since 2011.