Immunomodulating Effects of Heat-Killed Lactobacillus rhamnosus and Lactobacillus reuteri on Peripheral Blood Mononuclear Cells from Healthy Dogs

Canine atopic dermatitis (AD) is a T-cell-driven inflammatory skin disease, characterized by an imbalance between the Th1 and Th2 immune responses. Probiotics (live bacteria) and postbiotics (inactivated, killed bacteria) have garnered attention for the management of AD in humans and dogs. Both probiotics and postbiotics possess immunomodulating properties that could be beneficial for allergic patients. This study aims to evaluate the immunomodulating effects of Tyndallized (heat-killed) postbiotics of <i>Lactobacillus rhamnosus</i> and <i>Lactobacillus reuteri,</i> which are active components of the Linkskin products (Nextmune, Palazzo Pignano, Cremona, Italy). Peripheral blood mononuclear cells (PBMCs) were isolated from healthy dogs and incubated separately with each postbiotic. The cytokine levels in the supernatants were measured before and after 12, 24, 48, and 72 h of incubation. Both Tyndallized lactobacilli significantly increased the levels of IL-12 and IFN-γ (Th1 cytokines) and IL-10 (associated with T regulatory cells), while the levels of the Th2 cytokine IL-4 remained stable. Overall, these two <i>Lactobacillus</i> postbiotics stimulated canine PBMCs to produce a cytokine profile typically associated with an anti-allergic response. Further studies are needed to evaluate the benefit of these postbiotics as an adjuvant for the reactive treatment or for the prevention of relapses of allergic flares in atopic dogs.