Papain‐Based Vaccination Modulates Schistosoma mansoni Infection‐Induced Cytokine Signals

Abstract

We have previously shown that immunization of outbred rodents with cysteine peptidases-based vaccine elicited type 2-biased immune responses associated with consistent and reproducible protection against challenge Schistosoma mansoni. We herein start to elucidate the molecular basis of C57BL/6 mouse resistance to S. mansoni following treatment with the cysteine peptidase, papain. We evaluated the early cytokine signals delivered by epidermal, dermal, and draining lymph node cells of na€ ıve, and S. mansoni -infected mice treated 1 day earlier with 0 or 50 lg papain, or immunized twice with papain only (10 lg/ mouse), papain-free recombinant S. mansoni glyceraldehyde 3-phosphate dehydrogenase and 2-Cys peroxiredoxin peptide (10 and 15 lg/mouse, respectively = antigen Mix), or papain-adjuvanted antigen Mix. Schistosoma mansoni infection induced epidermal and lymph node cells to release type 1, type 2 and type 17 cytokines, known to counteract each other. Expectedly, humoral immune responses were negligible until patency. Papain pretreatment or papain-based vaccination diminished or shut off S. mansoni infection early induction of type 1, type 17 and type 2 cytokines except for thymic stromal lymphopoietin and programmed the immune system towards a polarized type 2 immune milieu, associated with highly significant (P < 0.005 -<0.0001) resistance to S. mansoni infection.

Protective immune responses against Schistosoma mansoni infection by immunization with functionally active gut-derived cysteine peptidases alone and in combination with glyceraldehyde 3-phosphate dehydrogenase

“…mansoni were obtained from SBSP/TBRI, and used immediately after shedding from Biomphalaria alexandrina snails. CD1 mice were infected via whole body exposure as previously described [11, 13]. Hamsters were anesthetized, the abdomen shaved and wetted with sterile deionized water, and then exposed to cercariae via the ring method as previously described [12].…”

“…mansoni infection, at the time when larvae are still resident in the epidermis, following the protocol described by Jensen et al [23] with minor modifications. The whole procedure was recently detailed [13]. Lymph node cells (LNC) from inguinal and popliteal lymph nodes (LN) were recovered (3 mice per group) four days after S .…”

“…Spleen cells (SC) were prepared from spleens removed from three mice per group at seven and 14 days after S . mansoni infection [11, 13, 14]. …”

“…EC, LNC and SC were cultured at a concentration of 1 x 10 6 cells/200 μl culture medium/well in duplicate wells of 96 round-bottomed well plates (Corning Costar, Bedford, MA), stimulated with 0 or 20 μg/ml membrane filter (0.45 μm)-sterilized immunogen, and maintained at 37°C in a humidified atmosphere containing 3.0% CO 2 . After 72 h of incubation, cultured cells were frozen and thawed for release of intracellular cytokines, the lysate centrifuged (15,000 x g ) and supernatants stored at -76°C until assayed for cytokine concentrations by capture enzyme-linked immunosorbent assay (ELISA) [11, 13, 14]. …”

“…mansoni cercariae [11]. We also discovered that a similar level of protection could be achieved by delivering antigens with the cysteine peptidase, papain, which also induces type 2 immune responses [11–13]. To avoid employing a plant-derived peptidase, we then showed that the gut-derived papain-like cysteine peptidases of Schistosoma mansoni , cathepsin B1 (SmCB1), and Fasciola hepatica , cathepsin L1 (FhCL1), could induce predominant type 2 immune responses and highly significant ( P < 0.005) reduction of between 66% and 75% in challenge S .…”