Can Lacticaseibacillus rhamnosus CRL1505 postbiotic improve emergency myelopoiesis in immunocompromised mice?

We evaluated whether viable and non-viable Lacticaseibacillus rhamnosus CRL1505 (Lr05V or Lr05NV, respectively) was able to improve emergency myelopoiesis induced by Streptococcus pneumoniae (Sp) infection. Adult Swiss-mice were orally treated with Lr05V or Lr05NV during five consecutive days. The Lr05V and Lr05NV groups and untreated control group received an intraperitoneal dose of cyclophosphamide (Cy-150 mg/kg). Then, the mice were nasally challenged with Sp (107 UFC/mice) on day 3 post-Cy injection. After the pneumococcal challenge, the innate and myelopoietic responses were evaluated. The control group showed a high susceptibility to pneumococcal infection, an impaired innate immune response and a decrease of hematopoietic stem cells (HSCs: Lin-Sca-1+c-Kit+), and myeloid multipotent precursors (MMPs: Gr-1+Ly6G+Ly6C-) in bone marrow (BM). However, lactobacilli treatments were able to significantly increase blood neutrophils and peroxidase-positive cells, while improving cytokine production and phagocytic activity of alveolar macrophages. This, in turn, led to an early Sp lung clearance compared to the control group. Furthermore, Lr05V was more effective than Lr05NV to increase growth factors in BM, which allowed an early HSCs and MMPs recovery with respect to the control group. Both Lr05V and Lr05NV were able to improve BM emergency myelopiesis and protection against respiratory pathogens in mice undergoing chemotherapy.

Modulation of the inflammation-coagulation interaction during pneumococcal pneumonia by immunobiotic Lactobacillus rhamnosus CRL1505: role of Toll-like receptor 2.

The present study evaluated the effect of nasally given Lactobacillus rhamnosus CRL1505 on the immunocoagulative response during pneumococcal infection in immunocompetent mice. In addition, we aimed to gain insight into the mechanism involved in the immunomodulatory effect of the L. rhamnosus CRL1505 strain by evaluating the role of TLR2. Results showed that nasally given L. rhamnosus CRL1505 effectively regulates inflammation and hemostatic alterations during the pneumococcal infection. Immunobiotic treatment significantly reduced permeability of the bronchoalveolar-capillary barrier, and general cytotoxicity, decreasing lung tissue damage. The CRL1505 strain improved the production of TNF-α, IFN-γ, and IL-10 after pneumococcal challenge. In addition, increased TM and TF expressions were found in lungs of L. rhamnosus CRL1505-treated mice. Moreover, we demonstrated, for the first time, that the TLR2 signaling pathway has a role in the induction of IFN-γ and IL-10 and in the reduction of TF. The results also allow us to speculate that a PRR, other than TLR2, may mediate the immunobiotic activity of L. rhamnosus CRL1505 and could explain changes in TNF-α and TM.