Three Copies of Four Interferon Receptor Genes Underlie a Mild Type I Interferonopathy in Down Syndrome

Down syndrome (DS) is characterized by the occurrence of three copies of human chromosome 21 (HSA21). HSA21 contains a cluster of four interferon receptor (IFN-R) genes: IFNAR1, IFNAR2, IFNGR2, and IL10RB. DS patients often develop mucocutaneous infections and autoimmune diseases, mimicking patients with heterozygous gain-of-function (GOF) STAT1 mutations, which enhance cellular responses to three types of interferon (IFN). A gene dosage effect at these four loci may contribute to the infectious and autoimmune manifestations observed in individuals with DS. We report high levels of IFN-αR1, IFN-αR2, and IFN-γR2 expression on the surface of monocytes and EBV-transformed-B (EBV-B) cells from studying 45 DS patients. Total and phosphorylated STAT1 (STAT1 and pSTAT1) levels were constitutively high in unstimulated and IFN-α- and IFN-γ-stimulated monocytes from DS patients but lower than those in patients with GOF STAT1 mutations. Following stimulation with IFN-α or -γ, but not with IL-6 or IL-21, pSTAT1 and IFN-γ activation factor (GAF) DNA-binding activities were significantly higher in the EBV-B cells of DS patients than in controls. These responses resemble the dysregulated responses observed in patients with STAT1 GOF mutations. Concentrations of plasma type I IFNs were high in 12% of the DS patients tested (1.8% in the healthy controls). Levels of type I IFNs, IFN-Rs, and STAT1 were similar in DS patients with and without recurrent skin infections. We performed a genome-wide transcriptomic analysis based on principal component analysis and interferon modules on circulating monocytes. We found that DS monocytes had levels of both IFN-α- and IFN-γ-inducible ISGs intermediate to those of monocytes from healthy controls and from patients with GOF STAT1 mutations. Unlike patients with GOF STAT1 mutations, patients with DS had normal circulating Th17 counts and a high proportion of terminally differentiated CD8⁺ T cells with low levels of STAT1 expression. We conclude a mild interferonopathy in Down syndrome leads to an incomplete penetrance at both cellular and clinical level, which is not correlate with recurrent skin bacterial or fungal infections. The constitutive upregulation of type I and type II IFN-R, at least in monocytes of DS patients, may contribute to the autoimmune diseases observed in these individuals.

Differential Responses of Blood Essential Amino Acid Levels Following Ingestion of High-Quality Plant-Based Protein Blends Compared to Whey Protein-A Double-Blind Randomized, Cross-Over, Clinical Trial

This study assessed the bio-equivalence of high-quality, plant-based protein blends versus Whey Protein Isolate (WPI) in healthy, resistance-trained men. The primary endpoint was incremental area under the curve (iAUC) of blood essential Amino Acids (eAAs) 4 hours after consumption of each product. Maximum concentration (Cmax) and time to maximum concentration (Tmax) of blood leucine were secondary outcomes. Subjects (n = 18) consumed three plant-based protein blends and WPI (control). An analysis of Variance model was used to assess for bio-equivalence of total sum of blood eAA concentrations. The total blood eAA iAUC ratios of the three blends were [90% CI]: #1: 0.66 [0.58-0.76]; #2: 0.71 [0.62-0.82]; #3: 0.60 [0.52-0.69], not completely within the pre-defined equivalence range [0.80-1.25], indicative of 30-40% lower iAUC versus WPI. Leucine Cmax of the three blends was not equivalent to WPI, #1: 0.70 [0.67-0.73]; #2: 0.72 [0.68-0.75]; #3: 0.65 [0.62-0.68], indicative of a 28-35% lower response. Leucine Tmax for two blends were similar to WPI (#1: 0.94 [0.73-1.18]; #2: 1.56 [1.28-1.92]; #3: 1.19 [0.95-1.48]). The plant-based protein blends were not bio-equivalent. However, blood leucine kinetic data across the blends approximately doubled from fasting concentrations, whereas blood Tmax data across two blends were similar to WPI. This suggests evidence of rapid hyperleucinemia, which correlates with a protein's anabolic potential.

Blood Essential Amino Acid Levels After Ingestion of High Quality Plant-Based Protein Blends Compared to Whey Protein: A Double Blind, Randomized, Cross-Over, Clinical Trial (P08-057-19)

Objectives

This study assessed the blood essential amino acid (eAA) response after consumption of high quality (PDCAAS = 1.0) plant-based protein blends versus whey protein (WPI, control) in healthy, resistance-trained adult men. Secondary Objectives assessed the blood leucine response (Cmax and Tmax).

Methods

The study was an acute, randomized, double-blind cross-over study. Participants consumed one of four study products: Blend 1 (34 grams of pea and pumpkin protein); Blend 2 (33 grams of pea, pumpkin, sunflower and coconut protein); Blend 3 (hydrolyzed version of Blend 1). Leucine was matched at 2.6 grams across test beverages equal to WPI (24 grams protein). Total eAA content was 12 grams across beverages. Fasting blood was collected and samples at 15 min, 30 min, 1 h, 2 h, 3 h and 4 h post consumption. Blood eAA were measured by UPLC. Repeated measures ANOVA assessed for equivalence of the total sum of blood eAA concentration. Primary endpoint was iAUC over 4 hours after consumption of the study blends. Cmax and Tmax of blood leucine response were secondary outcomes.

Results

Eighteen men (25.4 ± 4.64 y) with a BMI of 24.4 ±3.35 kg.m−2 completed the study. The eAA iAUC over 4 hours of plant-based protein blends were not equivalent to WPI, the three ratios [90% CI]: Blend #1: 0.66 [0.58–0.76]; Blend #2: 0.71 [0.62–0.82], Blend #3: 0.60 [0.52–0.69] fell below the pre-defined equivalence threshold [0.80–1.25], indicative of a 30 to 40% decrease compared to WPI. Leucine Cmax over 4-hours of plant-based protein blends were not equivalent to WPI Blend #1: 0.70 [0.67–0.73]; Blend #2: 0.72 [0.68–0.75], Blend #3: 0.65 [0.62–0.68], indicative of a 28 to 35% decrease compared to WPI. Leucine Tmax for Blend #1 and Blend #3 were close to WPI (Blend #1: 0.94 [0.73–1.18]; Blend #2: 1.56 [1.28–1.92]; Blend #3: 1.19 [0.95–1.48]).

Conclusions

This study represents the first human investigation in which blood eAA responses to high-quality, plant protein blends were compared to WPI. Although the eAA iAUC were not equivalent between plant protein blends and whey control, the leucine kinetic data across our plant protein blends showed an ∼2-fold increase from fasting. Further, similar Tmax data across two plant protein blends suggest a rapid hyperleucinemia. Future studies should assess the impact of high-quality plant proteins on muscle protein synthesis.

Funding Sources

Sequel Naturals, Danone Research.