### Article  
**Baseline Concentrations of Various Immune Biomarkers Determine Their Increase after Consumption of a Postbiotic Based on Cow's Milk Fermented with _Lactobacillus paracasei_ CBA L74 in Both Newborns and Young Children**  
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Footnote 12: https:lipoteichoic acids, enzymes, bacteriocins, proteins, while microbial metabolites include lactic acid, peptides/proteins, organic acids, and short chain fatty acids (SCFAs) [5]. The beneficial impact of postbiotics is based on the observation that the positive effects elicited by the gut microbiome (GM) are mainly mediated by the production of metabolites [5]. Postbiotics exert similar beneficial health effects to probiotics, but the absence of viable microorganisms abolishes the risks associated with their intake. Consumption of probiotics might result in the occurrence of health issues to the consumer, such as translocation of microbes over the gut epithelium, the cross-over of antibiotic resistance genes, and sepsis [6]. These are caused by the introduction of viable bacteria into the gastro-intestinal tract. These issues might be circumvented using postbiotics, not only for the adult consumer but also for the (very) young, especially when the immune system starts to develop. Increasing preclinical and clinical evidence supports the efficacy of the postbiotic product derived from cow's milk fermentation with the probiotic _Lactobacillus paracasi_ CBA L74 (FM-CBA L74) in preventing pediatric infectious diseases and affecting the maturation of the host defense mechanism [7; 8; 9; 10; 11; 12]. These effects are paralleled with a beneficial regulation of innate and adaptive immune response and gut microbiota composition and function. These observations led us to analyze the impact of consumption of FM-CBA L74 on the baseline dependency of the change in various immune factors in more depth, especially when the immune status is developing. Within the present study three studies have been identified to address the impact of the intake of the postbiotic (FM-CBA L74) on various immune markers in newborns and young children. These markers include \(\alpha\)- and \(\beta\)-defensin, cathelicidin, and secretory immunoglobulin-A (s-IgGA). Of these factors, defensins and cathelicidin (LL-37) are small cationic innate immunity peptides that exhibit a pivotal role in killing pathogens, by membrane disruption, but also display other functionalities, such as activation of various cell types, chemotactic activity, and cytotoxicity [13; 14]. The \(\alpha\)- and \(\beta\)-defensins are produced by neutrophils, macrophages, epithelial and Paneth cells. Secretory Immunoglobulin A (s-IgGA) plays an important role in the first line of adaptive defense in the gastrointestinal tract by blocking the adherence of pathogenic bacteria to epithelial cell receptors and by inhibition of the activity of bacterial toxins [15]. Moreover, its impact on the establishment of gut microbiota and the development of immunity shortly after birth is underlined as well [16]. It is evident that s-IgGA has a major impact on the adaptive component of immunity, already at the start of life [17]. The distinction between the innate and adaptive component is not as strict as suggested [18; 19], but it is evident that the above-mentioned factors are of extreme importance in the defense against unwanted entry of pathogenic microorganisms. This is particularly true at birth when immunity is naive while at the same time intestinal permeability represents a serious threat [20]. Both in vitro and in vivo data showed that intake of FM-CBA L74 affected the immune response substantially, such as downregulating the inflammatory reaction by decreasing levels of IL-12p70 and increasing those of IL-10 [9]. This results in protection against colitis development in mice.