Oral but Not Parenteral Interleukin (IL)-12 Redirects T Helper 2 (Th2)-type Responses to an Oral Vaccine Without Altering Mucosal IgA Responses

Abstract

Our past studies have shown that the mucosal adjuvant cholera toxin (CT) induces T helper type 2 (Th2) responses with systemic IgG1, IgE and mucosal secretory IgA (S-IgA) antibodies (Abs). In this study, recombinant murine IL-12 (rmIL-12) was given either parenterally or orally to mice orally immunized with tetanus toxoid (TT) and CT to determine whether this cytokine could redirect the CT-induced Th2-type responses and what effect this shift would have on S-IgA Ab responses. Intraperitoneal administration of rmIL-12 shifted TT-specific responses toward Th1-type and resulted in CD4+ T cells producing IFN-γ and IL-2 with markedly reduced levels of Th2-type cytokines. This cytokine profile was accompanied by increased delayed-type hypersensitivity (DTH) and shifts in serum IgG1 to IgG2a and IgG3 anti-TT Ab responses. Further, serum IgE and S-IgA Ab responses were markedly reduced by parenteral IL-12. When IL-12 complexed to liposomes was given orally both shifts to IgG2a and IgG3 and low IgE Abs again occurred concomitant with enhanced serum IFN-γ and DTH responses. Interestingly, oral rmIL-12 did not result in significant levels of serum IL-12 nor altered S-IgA Ab responses and resulted in higher levels of some Th2-type cytokines both in vitro and in vivo when compared with parenteral IL-12. Our results show that the shifts in systemic immune responses with intact S-IgA Abs which occur after oral delivery of IL-12-liposomes are due to cytokine effects in the Peyer's patches and suggest new strategies for the targeted manipulation of Th1- and Th2-type responses to mucosal vaccines.

Effective Mucosal Immunity to Anthrax: Neutralizing Antibodies and Th Cell Responses Following Nasal Immunization with Protective Antigen

“…Elevated levels of IL-4 and Th2-type responses and only minimal IFN-␥ secretion were detected in culture supernatants of rPA-stimulated CD4 ϩ T cells isolated from mucosal or systemic lymphoid tissues. These findings are consistent with the pattern of PA-specific IgG subclass responses and the now well-described Th2 bias of immune responses induced by CT as mucosal adjuvant (26,30,52,53,(55)(56)(57). Our study is the first to dissect the pattern of PAspecific Th cell responses after immunization with rPA.…”

“…Indeed, the pattern of IgG subclass response is known to mirror Th cell-derived cytokine responses (51), and different IgG subclasses (i.e., the complement-fixing IgG2a and IgG3 Abs vs the noncomplement-fixing IgG1 and IgG2b) are involved in distinct mechanisms of host protection. It has been shown that CT as mucosal adjuvant generally promotes CD4 ϩ Th2-associated IgG subclasses with IgG1 and IgG2b and no or minimal IgG2a Ab responses (23,52,53). The induction of PA-specific IgG1 and IgG2b Ab responses by nasal PA plus CT suggests that rPA only acted as a protein Ag and did not influence the adjuvanticity of CT.…”

Low dose oral administration of cytokines for treatment of allergic asthma

“…In particular, oral but not parenteral interleukin (IL)-12 redirects Th2-type responses to an oral vaccine without altering mucosal IgA responses [8] and suppresses anaphylactic reactions in a murine model of peanut hypersensivity [9].…”

“…Another route, oral delivery, might offer a means of engaging the cytokine network, to foster beneficial effects in animals and humans [8,11]. In addition oral administration of cytokines seems to give better results with respect to other routes [12].…”

Oral QS-21 Requires Early IL-4 Help for Induction of Mucosal and Systemic Immunity

“…Concentrations of IgM, IgG, or IgA Abs were determined by addition of a 1/3000 dilution of HRP-conjugated goat anti-mouse ␥-, -, or ␣-heavy chain-specific antisera (Southern Biotechnology Associates, Birmingham, AL). To determine IgG subclass titers, we used biotin-conjugated rat monoclonal anti-mouse ␥1 (Gl 7.3; 2 g/ml), ␥2a (R19-15; 1 g/ml), ␥2b (R12-3; 0.5 g/ml) or ␥3 (R40-82; 1 g/ml) heavy chain-specific Abs (PharMingen, San Diego, CA), followed by HRP-conjugated streptavidin (Life Technologies, Gaithersburg, MD) (24,30). The color was developed at room temperature for 15 min with ABTS substrate (Sigma), and the absorbance was measured at 415 nm.…”