An analysis of IL-8, IL-6, TNF-α cytokines in breast milk and the relationship between milk nutrients and clinical diagnosis

The aim of this study was to assess cytokine levels (interleukin - IL-6, interleukin - IL-8, interferon gamma - IFN-γ, tumor necrosis factor - TNF-α) in breast milk and to determine the relationship between cytokine levels and factors such as the composition of breast milk microbiota, clinical diagnosis, nutrient content of breast milk (fat, crude protein, total solids, energy, carbohydrates), maternal age, number of children, infant gender, diet, and consumption of sweets. The abundance of cytokines was analyzed in relation to clinical diseases, and cytokine concentrations were below 145 ng/mL in 48% of the samples and above 146 ng/mL in 52% of the samples. Clinical diseases were bound by a strong correlation with milk nutrients such as fat, total solids, energy, and carbohydrates, rather than the presence of bacterial pathogens such as Klebsiella oxytoca. In turn, bacterial pathogens were correlated with selected nutrients, but not with the identified cytokines. However, cytokines were highly correlated with the studied breast milk nutrients. In addition, the signal intensity measured in the matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) assay was correlated with cytokine abundance in the enzyme-linked immunosorbent assay (ELISA). These findings suggest that the presence and concentrations of cytokines can be influenced by the evaluated parameters, the maternal diet (directly), and external factors (indirectly) such as maternal age and metabolic profile.