To validate levels of SLPI and MMP9 in saliva as biomarkers for (local) inflammatory responses in humans, further studies to investigate salivary levels of SLPI and MMP-9 in relation to chronic inflammation (overtraining, burn-out, IBD, obesity, age and infections commonly seen after strenuous exercise, i. Here, MMP9 is linked to obesity due to melanocortin 4 receptor deficiency.