Transcriptome changes in overweight neutered female dogs undergoing a weight loss program with or without Spirulina (Arthrospira platensis) supplementation

BACKGROUND: Obesity is a well-known concern in pets that often poses challenges in terms of successful maintenance of weight loss after different types of interventions. Nutraceuticals could represent a promising strategy to handle this disease. Among them, Arthrospira platensis (Spirulina) is reported to have beneficial effects in obese dogs, rodents, and humans, possibly due to the richness in several bioactive compounds. In this perspective, omics techniques could be useful tools to unravel both the mechanisms behind obesity, possible unsuccessful clinical outcomes, and the beneficial effects of nutraceuticals. Nevertheless, limited studies evaluating the effects of weight loss programs on obese canine patients, with or without nutraceutical supplementation, using high-throughput transcriptomic analysis, are currently available. In this study, in the context of a twelve-week randomized, double-blinded, controlled dietary trial, twelve healthy overweight neutered female dogs were equally divided into two groups receiving a weight loss diet with (SPI) or without (PLA) the supplementation of Spirulina. In both groups, Retrievers were the most represented breeds. Transcriptomic effects were assessed using RNA-sequencing (RNA-seq) on whole blood samples collected at three different time points, T0 (day 1), T1 (day 42), and T2 (day 84). RESULTS: According to RNA-seq results, several genes involved in iron transport, homeostasis, and heme biosynthesis were found to be regulated. Moreover, a transcriptional modulation of genes involved in lipid β-oxidation, ferroptosis, and thermogenesis was observed. Most changes were time-dependent, with relatively modest unique effects of Spirulina (only 63 unique differentially expressed genes, DEGs), showing some encouraging outcomes linked to anti-inflammatory and pro-apoptotic pathways. CONCLUSIONS: This study could be considered a starting point to explore the mechanisms behind weight loss and Spirulina supplementation in overweight/obese neutered female dogs. Iron homeostasis is a sort of red thread in our evidence, underlining the importance of the fine-tuning of this micronutrient in obesity. Despite the possible masking effect of the diet, meaningful insights about Spirulina supplementation were disclosed, suggesting its possible beneficial effects. Nevertheless, wider investigations are needed, increasing the number of subjects, comparing other tissues and taking into consideration specific cell populations.