Differential effects of Epigallocatechin‐3‐gallate containing supplements on correcting skeletal defects in a Down syndrome mouse model

Abstract

Scope Down syndrome (DS), caused by trisomy of human chromosome 21 (Hsa21), is characterized by a spectrum of phenotypes including skeletal abnormalities. The Ts65Dn DS mouse model exhibits similar skeletal phenotypes as humans with DS. DYRK1A, a kinase encoded on Hsa21, has been linked to deficiencies in bone homeostasis in DS mice and individuals with DS. Treatment with Epigallocatechin-3-gallate (EGCG), a known inhibitor of Dyrk1a, improves some skeletal abnormalities associated with DS in mice. EGCG supplements are widely available but the effectiveness of different EGCG-containing supplements have not been well studied. Methods and results Six commercially available supplements containing EGCG were analyzed, and two of these supplements were compared with pure EGCG for their impact on skeletal deficits in a DS mouse model. The results demonstrate differential effects of commercial supplements on correcting skeletal abnormalities in Ts65Dn mice. Different EGCG-containing supplements display differences in degradation, polyphenol content and effects on trisomic bone. Conclusions This work suggests that the dose of EGCG and composition of EGCG-containing supplements may be important in correcting skeletal deficits associated with DS. Careful analyses of these parameters may lead to a better understanding of how to improve skeletal and other deficits that impair individuals with DS.

Epigallocatechin-3-gallate (EGCG) consumption in the Ts65Dn model of Down syndrome fails to improve behavioral deficits and is detrimental to skeletal phenotypes

“…These results suggest that in bone, there may be an “inverted U” function of optimal Dyrk1a activity, such that an optimal range of activity is necessary to achieve maximum skeletal strength, and falling below the threshold (as with high doses of EGCG) or exceeding an upper boundary (as with excess activity in trisomy) may be detrimental to bone strength. Additionally, when we treated Ts65Dn mice with two EGCG-containing supplements that delivered lower daily dosages (3–4 mg/kg/day EGCG), we found that the structure of the bone improved but the strength decreased [44]. These data suggested that other catechins or a combination of catechins could have a detrimental effect on skeletal strength.…”

“…EGCG (>95% purity, as determined by LC/MS analyses [44]) was prepared by making a stock solution of 15 mg/mL EGCG in phosphate buffered saline (PBS). Treatments were delivered via the drinking water in a concentration of 0.4 mg/mL EGCG, prepared by diluting the stock solution in tap water, and pH balanced (5–5.5) by slowing adding phosphoric acid (approximately 100μL/100mL tap water).…”

“…EGCG is a small molecular inhibitor of DYRK1A activity and is thought to function by binding to the ATP binding domain of the protein thereby inhibiting its kinase activity [42, 43]. EGCG, either alone or in supplements containing EGCG, has been tested as a potential therapy in mouse models of DS [23, 26, 44–48] and in humans with DS [45, 49, 50]. In one recent study [45] trisomic mice were given an EGCG-containing supplement (Life Extension ® Mega Green Tea Extract, Lightly Caffeinated) in drinking water that was reported to deliver 2–3 mg of EGCG per day per mouse (i.e., a daily dosage of ~80–120 mg/kg [for a 25 g mouse] that would yield a final effective dosage of ~40–60 mg/kg per day after accounting for the known degradation of EGCG [23, 44]).…”

“…The current study administered a dosage of pure EGCG intended to approximate the EGCG dosage that we determined was delivered in the De la Torre et al . [45] study (~50 mg/kg/day), which includes our correction for the ~50% degradation of EGCG that is known to occur when EGCG is dissolved in the drinking water [23, 44]. Thus, Ts65Dn mice were administered either EGCG [0.4mg/mL, stabilized in acidified water], which yielded a target average daily intake of ~50 mg/kg/day after correction for known degradation, or acidified water alone.…”

Targeting trisomic treatments: optimizing Dyrk1a inhibition to improve Down syndrome deficits

“…The other catechins found in EGCG‐containing supplements, such as epigallocatechin (EGC), epicatechin gallate (ECG) epigallate (EG), and epicatechin (EC) could be acting synergistically with EGCG, or could be exerting effects independently of EGCG (Abeysekera et al. ). For example, EGCG‐containing supplements exhibit differential effects on various skeletal measures, with some supplements improving trabecular structure, yet others being detrimental to bone strength (Abeysekera et al.…”