Th17‐related cytokines contribute to recall‐like expansion/effector function of HMBPP‐specific Vγ2Vδ2 T cells after Mycobacterium tuberculosis infection or vaccination

Abstract

Whether cytokines can influence the adaptive immune response by antigen-specific γδ T cells during infections or vaccinations remains unknown. We previously demonstrated that, during BCG/Mycobacterium tuberculosis (Mtb) infections, Th17-related cytokines markedly upregulated when phosphoantigen-specific VγVδ2 T cells expanded. In this study, we examined the involvement of Th17-related cytokines in the recall-like responses of Vγ2Vδ2 T cells following Mtb infection or vaccination against TB. Treatment with IL-17A/IL-17F or IL-22 expanded phosphoantigen 4-hydroxy-3-methyl-but-enyl pyrophosphate (HMBPP)-stimulated Vγ2Vδ2 T cells from BCG-vaccinated macaques but not from naïve animals, and IL-23 induced greater expansion than the other Th17-related cytokines. Consistently, Mtb infection of macaques also enhanced the ability of IL-17/IL-22 or IL-23 to expand HMBPP-stimulated Vγ2Vδ2 T cells. When evaluating IL-23 signaling as a prototype, we found that HMBPP/IL-23-expanded Vγ2Vδ2 T cells from macaques infected with Mtb or vaccinated with BCG or Listeria ΔactA prfA*-ESAT6/Ag85B produced IL-17, IL-22, IL-2, and IFN-γ. Interestingly, HMBPP/IL-23-induced production of IFN-γ in turn facilitated IL-23-induced expansion of HMBPP-activated Vγ2Vδ2 T cells. Furthermore, HMBPP/IL-23-induced proliferation of Vγ2Vδ2 T cells appeared to require APC contact and involve the conventional and novel protein kinase C signaling pathways. These findings suggest that Th17-related cytokines can contribute to recall-like expansion and effector function of Ag-specific γδ T cells after infection or vaccination.

Assessment of recombinant plasmid expressing fusion antigen Ag85B-Rv3425 in management of acute tuberculosis infection in mice

“…The single-cell suspension (4 ml) was obtained by gently grounding spleen through a 75 µm cell strainer and underlayed by 4 ml pre-warmed Lymphocyte-M (Cedar Lane Lab, Burlington, VT, USA). Density-gradient centrifugation was performed at 1,250 x g for 25 min to isolate splenocytes (16,17). Cells were counted and diluted to a final concentration of 5x10 6 cells/ml in RPMI-1640 medium (Invitrogen; Thermo Fisher Scientific, Inc., Waltham, MA, USA) supplemented with 10 U/ml penicillin, 10 µg/ml streptomycin and 10% fetal bovine serum (Invitrogen; Thermo Fisher Scientific, Inc.).…”

Protective immune responses of major Vγ2Vδ2 T-cell subset in M. tuberculosis infection

“…This in vivo correlate prompts a hypothesis or possibility that Th17-related cytokines involve expansion or recall-like responses of Vγ2Vδ2T cells after infections. Now new NHP studies showed that IL-17A/IL-17F, IL-22 or IL-23 could expand phosphoantigen HMBPP-stimulated Vγ2Vδ2 T cells from BCG-vaccinated macaques but hardly from naïve animals [23 •• ] (Figure 2). IL-23 induced greater expansion than other Th17-related cytokines [23 •• ].…”

“…Now new NHP studies showed that IL-17A/IL-17F, IL-22 or IL-23 could expand phosphoantigen HMBPP-stimulated Vγ2Vδ2 T cells from BCG-vaccinated macaques but hardly from naïve animals [23 •• ] (Figure 2). IL-23 induced greater expansion than other Th17-related cytokines [23 •• ]. Consistently, Mtb infection of macaques also enhanced the ability to IL-17/IL-22 or IL-23 to expand HMBPP-stimulated Vγ2Vδ2 T cells (Figure 2).…”

“…Interestingly, comparative studies showed that while IL-2 could remarkably expand HMBPP-activated Vγ2Vδ2 T cells in both naïve and Mtb/BCG-infected macaques, IL-23 favored recall-like of the activated γδ T cells after infection or vaccination [23 •• ] (Figure 2). The reason for such a difference is currently not known.…”

“…In fact, Vγ2Vδ2 T cells expanded by HMBPP/IL-2 administration were shown to produce anti-TB cytokines IFN-γ, TNF-α, and perforin [24,25]. Similarly, IL-23 expansion of HMBPP-activated Vγ2Vδ2T cells from macaques infected with Mtb, BCG or Listeria could differentiate effector function of these γδ T cells for producing IL-17, IL-22, and IFN-γ [23 •• ] (Figure 2). Furthermore, HMBPP/IL-23-induced proliferation of Vγ2Vδ2T cells appeared to require APC contact and involve the conventional and novel protein kinase C (PKC) signaling pathways [23 •• ].…”