Triiodothyronine enhances various forms of kidney-specific Klotho protein and suppresses the Wnt/β-catenin pathway: Insights from in-vitro, in-vivo and in-silico investigations

Age-related diseases are intricately linked to the molecular processes underlying aging, with the decline of the antiaging protein Klotho being a key factor. Investigating these processes is crucial for developing therapeutic strategies. The age-associated reduction in Klotho expression, coupled with a decline in the endocrine hormone triiodothyronine (T3), prompted a detailed exploration of their potential interplay. Our research, conducted through both in-vitro and in-vivo studies on BALB/c mice, unveiled a significant capacity of T3 to upregulate various forms of Klotho via ATF-3/p-c-Jun transcription factor. This effect was particularly noteworthy in aged individuals, where Klotho expression had waned compared to their younger counterparts. Importantly, T3 demonstrated a promising therapeutic impact in rejuvenating Klotho expression in this context. Further investigations elucidated the molecular mechanisms underlying T3's impact on aging-related pathways. In-vitro and in-vivo experiments established T3's ability to downregulate the Wnt/β-Catenin pathway by enhancing Klotho expression. In-silico analyses provided insights into Klotho's intricate role, showing its capacity to inhibit Wnt ligands such as Wnt3 and Wnt8a, consequently disrupting their interaction with the Wnt receptor. Additionally, T3 was found to downregulate kidney-specific GSK-3β expression through the augmentation of Klotho expression. The study also highlighted T3's role in maintaining calcium and phosphate homeostasis via Klotho. This comprehensive investigation not only sheds light on the intricate mechanisms governing aging processes but also presents promising avenues for therapeutic interventions targeting the Wnt/β-Catenin pathway implicated in various age-associated diseases.

Association of Energy and Macronutrients Intake with S-Klotho Plasma Levels in Middle-Aged Sedentary Adults: A Cross-Sectional Study

BACKGROUND

The ageing process can be influenced by energy intake and different macronutrients within the diet. The soluble form of the α-Klotho gene (called S-Klotho) is widely considered as a powerful anti-ageing biomarker.

OBJECTIVE

To analyze the association of energy, dietary energy density and macronutrient intake with S-Klotho plasma levels in middle-aged sedentary adults.

METHODS

A total of 72 (52.8% women) middle-aged sedentary adults (53.7 ± 5.2 years old) participated in the study. Energy and macronutrients intake (i.e. fat, carbohydrate and protein) were assessed using three non-consecutive 24-h recalls. S-Klotho plasma levels were measured in the Ethylenediaminetetraacetic acid (EDTA) plasma using a solid-phase sandwich enzyme-linked immunosorbent assay.

RESULTS

No association was observed between energy, dietary energy density or macronutrient intake and S-Klotho plasma levels in men (all P≥ 0.1). We found an inverse association between energy, protein and carbohydrate intake with S-Klotho plasma levels in women (all P≤0.043), which disappeared after controlling for age, lean mass index and sedentary time. An inverse association was observed between dietary energy density and S-Klotho plasma levels in women after controlling for covariates (all P≤0.05).

CONCLUSION

In summary, the present study showed an inverse association of dietary energy density with S-Klotho plasma levels in middle-aged women. In addition, our data suggest that the associations between energy and macronutrient intake could be highly dependent on lean mass and sedentary time.

Combined administration of docosahexaenoic acid and thyroid hormone synergistically enhances rat liver levels of resolvins RvD1 and RvD2

Supplementation with omega-3 fatty acids or thyroid hormone (T₃) exhibit negative effects on inflammatory reactions in experimental animals. The aim of this work was to assess the hypothesis that docosahexaenoic acid (DHA) plus T₃ co-administration enhances liver resolvin (Rv) levels as inflammation resolution mediators. Combined DHA (daily doses of 300 mg/kg for 3 consecutive days)-T₃ (0.05 mg/kg at the fourth day) administration significantly increased the content of hepatic RvD1 and RvD2, without changes in that of RvE1 and RvE2, an effect that exhibits synergy when compared to the separate DHA and T₃ treatments. Under these conditions, liver DHA levels increased by DHA administration were diminished when combined with T₃ (p < 0.05), suggesting enhancement in resolvin D biosynthesis in extrahepatic tissues. It is concluded that co-administration of DHA and T₃ rises the capacity of the liver for inflammation resolution by augmenting RvD1(2) availability, which represents an important protocol in hepatoprotection in the clinical setting.

Reduction of high-fat diet-induced liver proinflammatory state by eicosapentaenoic acid plus hydroxytyrosol supplementation: involvement of resolvins RvE1/2 and RvD1/2

High-fat diet (HFD)-fed mice show obesity with development of liver steatosis and a proinflammatory state without establishing an inflammatory reaction. The aim of this work was to assess the hypothesis that eicosapentaenoic acid (EPA) plus hydroxytyrosol (HT) supplementation prevents the inflammatory reaction through enhancement in the hepatic resolvin content in HFD-fed mice. Male C57BL/6J mice were fed an HFD or a control diet and supplemented with EPA (50 mg/kg/day) and HT (5 mg/kg/day) or their respective vehicles for 12 weeks. Measurements include liver levels of EPA, DHA and palmitate (gas chromatography), liver resolvins and triglyceride (TG) and serum aspartate transaminase (AST) (specific kits) and hepatic and serum inflammatory markers (quantitative polymerase chain reaction and enzyme-linked immunosorbent assay). Compared to CD, HFD induced body weight gain, liver steatosis and TG accumulation, with up-regulation of proinflammatory markers in the absence of histological inflammation or serum AST changes; these results were accompanied by higher hepatic levels of resolvins RvE1, RvE2, RvD1 and RvD2, with decreases in EPA and DHA contents. EPA+HT supplementation in HFD feeding synergistically reduced the steatosis score over individual treatments and increased the hepatic levels of EPA, DHA and resolvins, with attenuation of proinflammatory markers. Lack of progression of HFD-induced proinflammatory state into overt inflammation is associated with resolvin up-regulation, which is further increased by EPA+HT supplementation eliciting steatosis attenuation. These findings point to the importance of combined protocols in hepatoprotection due to the involvement of cross-talk mechanisms, which increase effectiveness and diminish dosages, avoiding undesirable effects.