Early stage of metabolic dysfunction associated steatotic liver disease disrupts circadian rhythm and induces neuroinflammation in rats

Abstract
Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) is a chronic liver disease affecting 25% of the European population, with rising global incidence. Liver damage includes ballooning, steatosis, inflammation and fibrosis. Associated brain disorders include sleep, cognitive issues, anxiety, and depression. While neurological complications in advanced MASLD are well documented, early cerebral manifestations remain largely unexplored. This study aimed at developing an MASLD rat model to assess the onset of early brain damage, focusing on impairments of the circadian cycle rhythm and associated neuroinflammation. Sprague Dawley rats were divided into two groups: one received a high-fat, high-cholesterol (HFHC) diet for 90 days, while the other received a standard diet. Histological analysis showed significant hepatic steatosis, ballooning, and inflammation in the HFHC group (p < 0.01). These lesions correlated with elevated hepatic triglycerides (p < 0.01), increased Alanine Aminotransferase, Aspartate Aminotransferase, total cholesterol, and low-density lipoprotein, alongside decreased plasma high-density lipoprotein. Behavioural analysis using activity wheels revealed that the HFHC rats steadily maintained their activity level during the rest periods when compared with controls (p < 0.05). This behavioural alteration occurred alongside neuroinflammation, demonstrated by changes in the expression of 36 and 17 inflammatory mediators in the cerebellum and frontal cortex respectively. These changes were associated with an increase in the expression of glial cell markers (Aif1 and Gfap genes) and an increase in the number of microglial cells, affecting the frontal cortex and cerebellum differently. This rat model of early MASLD shows circadian rhythm disturbances, which could reflect sleep disorders in humans. These early brain disturbances specific to MASLD, which occur before the symptoms of liver disease become clinically apparent, could therefore be used as an early diagnosis marker for MASLD patients.

Voir la publication

Nous sommes heureux d'annoncer notre participation au 49_^ème Colloque de l’AFSTAL, “Des animaux et des machines” qui se tiendra du 19 au 21 novembre 2025 à Nantes. Venez nous rencontrer sur notre stand 81.

Sex-dependent effects of intestinal epithelial TLR4 deletion induced before activity-based anorexia

Rationale A role for the microbiota-gut-brain axis in the pathophysiology of anorexia nervosa (AN) has emerged in the last decade. An alteration of intestinal Toll-like receptor type 4 (TLR4) has been reported in the activity-based anorexia (ABA) model with an increase in its expression at the cell surface of colonic epithelial cells. In addition, inducible TLR4 invalidation in intestinal epithelial cells (IECs) was associated with behavioral and energy balance changes in ABA mice. The aim of this study was to assess the intestinal response, e.g. inflammation, gut barrier function and gut microbiota composition, to TLR4 invalidation in IEC in ABA mice.

Methods Male and female Villin-CreERT2-TLR4 LoxP C57Bl/6 mice were injected with tamoxifen to induce a specific invalidation of TLR4 in IECs (TLR4IEC-/- mice). Then, wild-type (wt) and TLR4IEC-/- mice were subjected or not to the ABA protocol which combines an access to a running wheel and a progressively limited access to food. After 12 days, colon samples were collected and the expression of 44 mRNAs encoding proteins involved in inflammatory response, gut barrier function and homeostatic regulation was measured by qPCR. Results were compared by a two-way ANOVA (ABA x TLR4IEC-/-). Gut microbiota composition was analysed by 16S rRNA Illumina sequencing.

Results In both male and female ABA TLR4IEC-/- mice, the kinetics of body weight loss was slowed down. In addition, male and female ABA TLR4IEC-/- mice showed an increase and a decrease in food intake, respectively. In males, TLR4 invalidation in IEC was associated with a reduction of Tlr2, Ticam1, Myd88, Tnfα, IκBα, Irf3, Cxcr3 and Tgfβ mRNA expression and fecal calprotectin levels under control conditions but not in response to the ABA model. In females, Myd88, Il6, Cxcl1 and Ccl2 mRNA levels were increased by TLR4IEC invalidation in control mice but not in ABA, except for Ccl2. TLR4 invalidation also affected the expression of genes involved in gut barrier function in control and ABA mice in a sex-dependent manner. Male mice exhibited more marked alterations. For instance, male CT TLR4IEC-/- showed a decrease of numerous targets (Ocln, Marveld2, F11r, Tjp1, Cldn7, Cldn12, Cldn15). ABA TLR4IEC-/- mice did not exhibit this decrease but other changes were observed such as an increase in Cldn3 and Cldn7 mRNA levels. Finally, TLR4IEC invalidation in control mice, but not in ABA, altered the gut microbiota in a sex dependent manner with an increase in the abundance of Parasutterella and Desulfovibrio genera in females and males, respectively. Interestingly, the ABA model per se induced an increase in the abundance of the Lactobacillus genus in both sexes, which was not observed in ABA TLR4IEC-/-.

Conclusions Our study shows for the first time the impact of inducible TLR4 invalidation in IEC on the intestinal response. We highlighted numerous colonic alterations regarding epithelial permeability, mucosal inflammation and gut microbiota composition, in control and ABA conditions: all were partially reversed in ABA TLR4IEC-/-. TLR4 invalidation in IEC also induced changes in energy homeostasis in response to the ABA model both in female and male mice. Further studies are warranted to deeply evaluate the underlying mechanisms.

Nous avons participé en tant que sponsor au 22ème Symposium ComTech qui a eu lieu le jeudi 23 janvier 2025, à ASIEM à Paris 7ème autour du thème « La douleur : Tous concernés ! ». 

Voir le livre des résumés !

Therapeutic potential of siRNA PMP22-SQ nanoparticles for Charcot-Marie-Tooth 1A neuropathy in rodents and non-human primates

Small interfering RNA (siRNA) has shown promising results for the treatment of Charcot-Marie-Tooth disease 1A (CMT1A) caused by overexpression of peripheral myelin protein (PMP22), leading to myelin dysfunction and axonal damage. Recently, we developed siRNA PMP22-squalene (SQ) nanoparticles (NPs) for intravenous use. Three consecutive injections of siRNA PMP22-SQ NPs at a cumulative dose of 1.5 mg/kg restored motor function in C61 transgenic mouse models. Pharmacokinetic studies showed a long half-life of antisense siRNA PMP22 in the sciatic nerve, and spinal cord, indicating targeted release potential. We further assessed the efficiency and safety of siRNA PMP22-SQ NPs in two healthy male non-human primates (Macaca fascicularis) after administering four escalating doses (0.1, 0.5, 2.5 and 4.5 mg/kg at one week interval). Interestingly, the siRNA PMP22-SQ NPs reduced PMP22 mRNA expression by approximately 70 % and probably induced an early-stage hereditary neuropathy with pressure palsies (HNPP)-like condition in two normal NHP. No preliminary toxicity was observed in organs or blood parameters of the two NHPs. Interestingly, the nerve conduction velocity decreased after the third injection of siRNA PMP22-SQ NPS. These results demonstrate the therapeutic potential of siRNA PMP22-SQ NPs, supporting advancement to further pre-clinical testing.

• TAM-ST : 1.25 x 7 mm
• TAM-MT : 1.40 x 8 mm

Voir Puce Température TAM-T

Nous avons le plaisir de vous informer de notre participation en tant que sponsor à la ComTech le jeudi 23 janvier 2025, à ASIEM à Paris 7e qui aura pour thème "La douleur : Tous concernés !".
Voir le programme ici.

Permet d'identifier les animaux et de mesurer la température instantanée en un seul geste. 

Voir Puce Température TAM-MT

Pour simplifier la mesure de poids et de température d'un animal, grâce à l'interaction directe avec votre feuille Excel, le logiciel TAMSync effectue une recherche permettant l'enregistrement du poids et/ou de la température de votre animal dans la cellule correspondante.

Gain de temps, rapidité, fiabilité pour vos mesures de poids et de temperature !