Expression of Toll-Like Receptor 2 by Dendritic Cells Is Essential for the DnaJ-ΔA146Ply-Mediated Th1 Immune Response against Streptococcus pneumoniae

Abstract

The fusion protein DnaJ-ΔA146Ply could induce cross-protective immunity against pneumococcal infection via mucosal and subcutaneous immunization in mice in the absence of additional adjuvants. DnaJ and Ply are both Toll-like receptor 4 (TLR4) but not TLR2 ligands. However, we found that TLR2 mice immunized subcutaneously with DnaJ-ΔA146Ply showed significantly lower survival rates and higher bacterial loads in nasal washes than did wild-type (WT) mice after being challenged with pneumococcal strain D39 or 19F. The gamma interferon (IFN-γ) level in splenocytes decreased in TLR2 mice, indicating that Th1 immunity elicited by DnaJ-ΔA146Ply was impaired in these mice. We explored the mechanism of protective immunity conferred by DnaJ-ΔA146Ply and the role of TLR2 in this process. DnaJ-ΔA146Ply effectively promoted dendritic cell (DC) maturation via TLR4 but not the TLR2 signaling pathway. In a DnaJ-ΔA146Ply-treated DC and naive CD4 T cell coculture system, the deficiency of TLR2 in DCs resulted in a significant decline of IFN-γ production and Th1 subset differentiation. The same effect was observed in adoptive-transfer experiments. In addition, TLR2 DCs showed remarkably lower levels of the Th1-polarizing cytokine IL-12p70 than did WT DCs, suggesting that TLR2 was indispensable for DnaJ-ΔA146Ply-induced IL-12 production and Th1 proliferation. Thus, our findings illustrate that dendritic cell expression of TLR2 is essential for optimal Th1 immune response against pneumococci in mice immunized subcutaneously with DnaJ-ΔA146Ply.

In-silico Analysis of Pneumococcal Heat-Shock Protein (DnaJ) to Predict Novel Multi-Epitope Vaccine Candidates

“…ClusPro and DimPlot results of DnaJ and HLA-DRB1*01:01 (the most common binding allele in the Iran population) docking complex showed the lowest energy binding of -809.63 Kcal/mol and 63 cluster members indicating good binding affinity and coupling of this protein with human MHCII via 11 hydrogen bonds. It was reported that DnaJ contributes to the activation of bone marrow-derived dendritic cells (BMDCs) and phagocytosis of macrophage, leading to the development of innate, humoral and cellular immunities through Toll-like receptors 4 and 2 (TLR-4 and TLR-2) [20,21,48]. For a more detailed understanding of the amino acid residues of DnaJ involved in the interacting interface with TLRs molecules, molecular docking was performed.…”

“…It was reported that DnaJ contributes to the activation of bone marrow-derived dendritic cells (BMDCs) and phagocytosis of macrophage, leading to the development of innate, humoral and cellular immunities through Toll-like receptors 4 and 2 (TLR4 and TLR2) [20,21,48]. For a more detailed understanding of the amino acid residues of DnaJ involved in the interacting interface with TLRs and MHC molecules, molecular docking was performed.…”

“…The main feature of this protein is the presence of a highly conserved J-domain, containing 70 amino acids in its Nterminus with four helical structures [17]. Several studies have shown that immunization with DnaJ can stimulate cellular and mucosal immune responses in mice [18][19][20][21] and elevate protection against nasopharyngeal colonization in nasal or lung and invasive infections, caused by various pneumococcal serotypes [13]. Pneumococci are an extracellular pathogen and humoral immunity plays a major role in the clearing of pneumococci from invasive infections, especially bacteremia or meningitis.…”

Immunoinformatics-guided approach for designing a pan-proteome multi-epitope subunit vaccine against African swine fever virus

“…Since the crystal structure of the obtained TLR4 did not initially include any docked molecule, three (3) known TLR4-agonists: enzyme lumazine synthase from Brucella spp. 128 , resuscitation-promoting factor (Rpf) E from Mycobacterium tuberculosis 129 , and fusion protein DnaJ- A146Ply from Streptococcus pneumoniae 130 were docked to the TLR4 crystal structure to serve as control. The G values and molecular interactions of the TLR4-agonists complexes were compared to the ASFV vaccine construct.…”

Bacterial Protein Toll-Like-Receptor Agonists: A Novel Perspective on Vaccine Adjuvants

“…However, DnaJ-ΔA146Ply, which is a genetic fusion of DnaJ and a ply mutant (ΔA146Ply), induces protection of mice in a TLR2-dependent manner. Furthermore, TLR2 deficiency reduces the ability of DnaJ-ΔA146Ply to induce Th1 type immune response (60). Another protein from S. pneumoniae , endopeptidase O (PepO) exhibits TLR2 and TLR4 agonist properties.…”