## 4 Discussion
plantarum_ CNTA 628 significantly increased the TNF- \(\alpha\) secretion after LPS treatment in RAQ 264.7 cells, which would indicate the activation of the immune system through a specific pathway. No effect was observed in IL-8 production, contrary to other works where the ability of _L. plantarum_ to decrease IL-8 production in intestinal cells has been reported for particular strains [61; 62], suggesting that cytokine modulation varies by strain. Overall, the in vitro assessment demonstrated that _L. plantarum_ CNTA 628 shows great probiotic potential with strain-specific effects, suggesting that the composition of each strain directly affects immunomodulation in human cells. This phenomenon reinforces the potential of designing _L. plantarum_ strains for different patient profiles. In the same line, previous studies have reported that the health-promoting activities of a probiotic bacteria are strain-specific. Therefore, we conducted a functional evaluation of the potential metabolic effects of supplementation with _L. plantarum_ CNTA 628. _C. elegans_ has become a widely used in vivo model in a variety of research areas, including obesity, thanks to its anatomical simplicity, its short life cycle, its capability to self-reproduce and its approximate 65% genetic ontology with humans [63]. The similar metabolic pathways and their regulation have allowed researchers to characterize and describe complex processes such as the regulation of lipid storage, aging, or oxidative stress responses [63]. Regarding lipid metabolism, in both humans and _C. elegans_ fatty acids (FAs) are the essential building blocks that constitute storage lipids (TAGs), membrane lipids (phospholipids and sphingolipids), and signaling lipids (fatty acyl amides, eicosanoids, and others). The FAs can be synthesized from de novo or derived from dietary fatty acids obtained from the _E. coli_ bacteria on which they feed. Together with the synthesis of FAs, the catabolic processes under which _C. elegans_ use stored lipids for energy production and the signaling properties of the involved molecules are well described. Also, the metabolism of FAs is linked to the uptake, processing and utilization of glucose and carbohydrate pathways [64; 65; 66]. Furthermore, glucose-supplemented media offer a dependable method to mimic diabetic or energy imbalance conditions, enabling the evaluation of parameters such as excessive fat accumulation, oxidative damage, cellular aging, and longevity in _C. elegans_[67]. In this context, the addition of drugs or bioactive compounds that disrupt their biologic processes can be studied and described as a starting point to assess their potential on humans [39; 68]. Finally, this nematode model has been widely used in probiotic studies as a robust in vivo platform for rapidly identifying microorganisms with possible anti-inflammatory, anti-obesity, and beneficial health properties [22; 69]. As previously described, we demonstrated that treatment with different doses of _L. plantarum_ CNTA 628 induced a total lipid reduction effect in _C. elegans_ under normal (NGM media) and high-glucose (10 mM)-loaded (NGMg media) conditions (Figure 7), suggesting a fat-reducing activity of this probiotic strain. Different works have described the modulation of fat storage by different probiotic strains. In a study by [PERSON] et al. [70], a total of 38 bacterial strains were tested for probiotic properties in _C. elegans_. The effect of some bifidobacterium_ and _lactobacillus_ strains on fat reduction was evaluated by the same Nile red staining and measurement of the emitted fluorescence. An alternative to this technique was used by [PERSON] et al. [71] in a study with _Lactobacillus pentosus_ MJ[M60383], in which the inhibition of lipid accumulation in _C. elegans_ was assessed by staining triglycerides with Oil red O (ORO). It is noteworthy that different works have studied fat accumulation in _C. elegans_ and how it can be modified by probiotic strains including _L. plantarum_[16] or _Pediococcus acidilactici_[36; 72].