Innate immune cytokine responses of <i>L</i>. <i>major</i> infected WT and CatB^-/- mice.

<p>WT and CatB^-/- were subcutaneously inoculated with 3x10⁶ stationary phase promastigotes of <i>L</i>. <i>major</i> in the footpads and experimental read-outs were measured weekly as indicated. Levels of TNF <b>(A)</b> and IL-1β <b>(B)</b> were measured in footpads of <i>L</i>. <i>major</i> -infected WT (filled bars) and CatB^-/- (empty bars) mice by specific ELISA. Level of expression of TNF <b>(C)</b> and IL-6 <b>(D)</b> transcripts in footpads or TNF <b>(E)</b> and IL-6 <b>(F)</b> transcripts in lymph nodes of <i>L</i>. <i>major</i> -infected WT (filled bars) and CatB^-/- (empty bars) mice were measured by RT-PCR. All PCR data values are normalized to the expression of the HPRT gene. Data depicted represent the mean and SEM of at least 3 independent experiments with n ≥ 4 mice/group/time point. * p<0.05; ** p<0.01; *** p<0.001; **** p<0.0001</p

Adaptive immune cell dynamics in responses to <i>L</i>. <i>major</i> infection of WT and CatB^-/- mice.

<p>WT and CatB^-/- were subcutaneously inoculated with 3x10⁶ stationary phase promastigotes of <i>L</i>. <i>major</i> in the footpads and experimental read-outs were measured weekly as indicated. <b>(A)</b> Gating strategy used for analysis. Cell numbers in draining lymphnodes of <i>L</i>. <i>major</i> -infected WT (filled bars) and CatB^-/- (empty bars) mice <b>(B)</b>. Percentages of CD19+ B cells <b>(C)</b>, CD3+ T cells <b>(D)</b>, CD4+ T cells <b>(E)</b> and CD8+ T cells <b>(F)</b> gated on the lymphocyte gate and foxp3+CD25+ Tregs <b>(G)</b> gated on the CD4+ gate from lymph nodes of <i>L</i>. <i>major</i> -infected WT (filled bars) and CatB^-/- (empty bars) mice. Data depicted represent the mean and SEM of at least 3 independent experiments with n ≥ 4 mice/group/time point. * p<0.05; ** p<0.01; *** p<0.001; **** p<0.0001</p

CatB^-/- T cells secrete more IFNγ but less IL-2 and have impaired proliferation as compared to WT T cells.

<p><i>In vitro</i> CD3 T cells purified from spleens of naïve WT and CatB^-/- mice were labelled with CFSE or not and stimulated overnight with PMA or with anti-CD3. Supernatants were harvested for cytokine detection at 24, 48 and 72h and CFSE dilution was assessed by FACS at 72h. Concentration of IFNγ <b>(A)</b> and IL-2 <b>(B)</b> in supernatants of PMA stimulated CD3 T cells from WT (filled bars) and CatB^-/- (empty bars) mice. <b>(C)</b> Percentage of CD4 cells that have undergone 1, 2 or 3 divisions based on CFSE labelling at 72h after stimulation with plate-bound anti-CD3 of purified T cells from WT (filled bars) and CatB^-/- (empty bars) mice. <i>In vivo</i> purified CD3 T cells were transferred into recipient RAG2^-/-γc^-/- mice and BrdU assay was performed on day 21 after transfer. <b>(D)</b> Percentage of BrdU+ CD4 and CD8 cells identified among CD45+ cells in spleens of RAG2^-/-γc^-/- mice reconstituted with purified CD3 T cells from WT (filled bars) and CatB^-/- (empty bars) mice at day 21 after transfer. Figures depict representative data pooled from 3 independent repeats with n ≥ 5 mice/group * p<0.05; ** p<0.01; *** p<0.001; **** p<0.0001</p

CatB^-/- mice resolve L. major subcutaneous infection faster than WT.

<p>WT, TLR9^-/-, AEP^-/-, CatL^-/-, CatS^-/- and CatB^-/- were subcutaneously inoculated with 3x10⁶ stationary phase promastigotes of <i>L</i>. <i>major</i> in the footpads and experimental read-outs were measured weekly as indicated. (<b>A)</b> Mean footpad thickness (±SEM) of infected mice (WT–filled circle; TLR9^-/-- empty circle). (<b>B)</b> Mean footpad thickness (±SEM) of infected mice (WT–filled circle; AEP^-/-- empty circle). (<b>C)</b> Mean footpad thickness (±SEM) of infected mice (WT–filled circle; CatL^-/-- empty circle). (<b>D)</b> Mean footpad thickness (±SEM) of infected mice (WT–filled circle; CatS^-/-- empty circle) (<b>E)</b> Mean footpad thickness (±SEM) of infected mice (WT–filled circle; CatB^-/-- empty circle). <b>(F)</b> Logarithm base 10 of limit dilution for parasite burden from footpads of infected mice (WT—filled bars; CatB^-/-- empty bars), middle line represents mean value per group. Figures depict representative data pooled from at least 3 independent repeats with n ≥ 8 mice/group/time point. * p<0.05; ** p<0.01; *** p<0.001; **** p<0.0001</p

CatB^-/- and WT BMDCs respond similarly to TLR-agonists or <i>L</i>. <i>major</i>.

<p>BMDCs from WT and CatB^-/- mice were stimulated with LPS (100ng/ml) and CpG (250ng/ml) or with live or killed <i>L</i>. <i>major</i> promastigotes (1:5 MOI) for 24h to determine secreted cytokines by ELISA (<b>A</b> and <b>B</b>) or for 6h to assess mRNA by RT-PCR (<b>C</b> and <b>D</b>). <b>(A)</b> Concentration of IL-6 and TNF in supernatants of BMDCs from WT (filled bars) and CatB^-/- (empty bars) mice stimulated with LPS or CpG or <b>(B)</b> with live or killed <i>L</i>. <i>major</i>. <b>(C)</b> Level of expression of IL-12p40, IL-12p35, IL-6, IFNβ, IL-10 and TNF transcripts from BMDCs of WT (filled bars) and CatB^-/- (empty bars) mice stimulate with LPS or CpG or <b>(D)</b> with live or killed <i>L</i>. <i>major</i>. The mRNA expression levels were normalized to the expression of the HPRT gene and calculated as the n-fold difference with the level of expression in unstimulated cells. Data depicted represent the mean and SEM of three independent experiments. No statistical differences were found.</p

Similar antigen presentation capacity of BMDCs from WT and CatB^-/- mice.

<p>WT and CatB^-/- were infected subcutaneously with 3x10⁶ stationary phase promastigotes of <i>L</i>. <i>major</i> in the footpads. On days 21 and 28, lymph nodes were harvested and whole cells or purified CD4 cells from these were co-cultured overnight with WT or CatB^-/- BMDCs that were non-stimulated as control or activated by PMA, killed or live <i>L</i>. <i>major</i>. Supernatants were harvested for cytokine determination by specific ELISA and unadherent cells were harvested for intracellular cytokine staining by FACS. <b>(A-B)</b> IFNγ levels secreted by lymph node (dLNs) cells and (<b>C-D)</b> percentage of IFNγ+ cells gated on CD4+ cells in these dLNs from <i>L</i>. <i>major</i>-infected WT <b>(A, C)</b> or CatB^-/- <b>(B, D)</b> mice after co-culture with WT (filled bars) or CatB^-/- (empty bars) BMDCs. <b>(E-F)</b> IFNγ levels secreted by CD4+ cells and <b>(G-H)</b> percentage of IFNγ+ cells gated on CD4+ cells from purified CD4+ cells of <i>L</i>. <i>major</i>-infected WT <b>(E, G)</b> or CatB^-/- <b>(F, H)</b> mice that were co-cultured with WT (filled bars) or CatB^-/- (empty bars) BMDCs. Data depicted represent the mean and SEM of at least 3 independent experiments with n ≥ 4 donor mice/group.</p

Cathepsin B-Deficient Mice Resolve Leishmania major Inflammation Faster in a T Cell-Dependent Manner.

International audienceA critical role for intracellular TLR9 has been described in recognition and host resistance to Leishmania parasites. As TLR9 requires endolysosomal proteolytic cleavage to achieve signaling functionality, we investigated the contribution of different proteases like asparagine endopeptidase (AEP) or cysteine protease cathepsins B (CatB), L (CatL) and S (CatS) to host resistance during Leishmania major (L. major) infection in C57BL/6 (WT) mice and whether they would impact on TLR9 signaling. Unlike TLR9-/-, which are more susceptible to infection, AEP-/-, CatL-/- and CatS-/- mice are as resistant to L. major infection as WT mice, suggesting that these proteases are not individually involved in TLR9 processing. Interestingly, we observed that CatB-/- mice resolve L. major lesions significantly faster than WT mice, however we did not find evidence for an involvement of CatB on either TLR9-dependent or independent cytokine responses of dendritic cells and macrophages or in the innate immune response to L. major infection. We also found no difference in antigen presenting capacity. We observed a more precocious development of T helper 1 responses accompanied by a faster decline of inflammation, resulting in resolution of footpad inflammation, reduced IFNγ levels and decreased parasite burden. Adoptive transfer experiments into alymphoid RAG2-/-γc-/- mice allowed us to identify CD3+ T cells as responsible for the immune advantage of CatB-/- mice towards L. major. In vitro data confirmed the T cell intrinsic differences between CatB-/- mice and WT. Our study brings forth a yet unappreciated role for CatB in regulating T cell responses during L. major infection