IL‐17‐producing CD4+ T cells (Th17) have been classified as a new T helper cell subset. Using an IL‐17 fate mapping mouse strain, which genetically fixes the memory of IL‐17 expression, we ...demonstrate that IL‐17A/F‐expressing T helper cells generated either in vitro or in vivo are not a stable T‐cell subset. Upon adoptive transfer of IL‐17F‐reporter‐positive Th17 cells to RAG‐deficient or WT animals, encephalitogenic Th17 cells partially lose IL‐17 expression and upregulate IFN‐γ. Additionally, we show that Th1 cells can convert in vivo to IL‐17A/IFN‐γ‐coexpressing cells in the mesenteric lymph nodes (mLN). Our data classify IL‐17A and IL‐17F as cytokines produced transiently in response to the local microenvironment, thus showing that IL‐17 expression does not define an end‐stage T helper cell subset.
Multiple sclerosis (MS) is often accompanied by optic nerve inflammation. And some patients experience permanent vision loss. We examined if the grade of optic nerve infiltration and demyelination ...affects the severity of clinical signs in an experimental autoimmune encephalomyelitis (EAE) model. The loss of retinal ganglion cells (RGC) and alterations in glia activity were also investigated.
C57BL/6 mice were immunized with peptide MOG35-55 in complete Freund's adjuvant (CFA) and controls received PBS in CFA. Then 23 days post immunization eyes were prepared for flatmounts and stained with Nissl to evaluated neuronal density. Clinical EAE symptoms as well as cell infiltration and demyelination in the optic nerve were examined. Retinal sections were stained with hematoxylin and eosin and silver stain. Immunohistochemistry was used to label RGCs (Brn-3a), apoptotic cells (caspase 3), macroglia (glial fibrillary acidic protein (GFAP)), microglia (Iba1), macrophages (F 4/80) and interleukin-6 (IL-6) secretion.
EAE symptoms started at day 8 and peaked at day 15. Cell infiltrations (P = 0.0047) and demyelination (P = 0.0018) of EAE nerves correlated with the clinical score (r > 0.8). EAE led to a significant loss of RGCs (P< 0.0001). Significantly more caspase 3+ cells were noted in these animals (P = 0.0222). They showed an increased expression of GFAP (P< 0.0002) and a higher number of microglial cells (P< 0.0001). Also more macrophages and IL-6 secretion were observed in EAE mice.
MOG immunization leads to optic neuritis and RGC loss. EAE severity is related to the severity of optic nerve inflammation and demyelination. EAE not only affects activation of apoptotic signals, but also causes a glial response in the retina.
T cell responses play an important role in protection against beta-coronavirus infections, including SARS-CoV-2, where they associate with decreased COVID-19 disease severity and duration. To enhance ...T cell immunity across epitopes infrequently altered in SARS-CoV-2 variants, we designed BNT162b4, an mRNA vaccine component that is intended to be combined with BNT162b2, the spike-protein-encoding vaccine. BNT162b4 encodes variant-conserved, immunogenic segments of the SARS-CoV-2 nucleocapsid, membrane, and ORF1ab proteins, targeting diverse HLA alleles. BNT162b4 elicits polyfunctional CD4+ and CD8+ T cell responses to diverse epitopes in animal models, alone or when co-administered with BNT162b2 while preserving spike-specific immunity. Importantly, we demonstrate that BNT162b4 protects hamsters from severe disease and reduces viral titers following challenge with viral variants. These data suggest that a combination of BNT162b2 and BNT162b4 could reduce COVID-19 disease severity and duration caused by circulating or future variants. BNT162b4 is currently being clinically evaluated in combination with the BA.4/BA.5 Omicron-updated bivalent BNT162b2 (NCT05541861).
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•BNT162b4 encodes conserved, immunogenic segments of the SARS-CoV-2 N, M, and ORF1ab antigens•Mass spectrometry detects BNT162b4 encoded peptides bound to diverse HLA-I alleles•BNT162b4 elicits non-spike T cell responses in mice while maintaining spike immunity•BNT162b4 protects animals from severe disease and enhances viral clearance by BNT162b2
Adding non-spike targeting components to mRNA vaccination elicits promising T cell responses against SARS-CoV-2 variant strains in rodent models of COVID-19.
Arrival of encephalitogenic T cells at inflammatory foci represents a critical step in development of experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis. EBI2 ...and its ligand, 7α,25-OHC, direct immune cell localization in secondary lymphoid organs. CH25H and CYP7B1 hydroxylate cholesterol to 7α,25-OHC. During EAE, we found increased expression of CH25H by microglia and CYP7B1 by CNS-infiltrating immune cells elevating the ligand concentration in the CNS. Two critical pro-inflammatory cytokines, interleukin-23 (IL-23) and interleukin-1 beta (IL-1β), maintained expression of EBI2 in differentiating Th17 cells. In line with this, EBI2 enhanced early migration of encephalitogenic T cells into the CNS in a transfer EAE model. Nonetheless, EBI2 was dispensable in active EAE. Human Th17 cells do also express EBI2, and EBI2 expressing cells are abundant within multiple sclerosis (MS) white matter lesions. These findings implicate EBI2 as a mediator of CNS autoimmunity and describe mechanistically its contribution to the migration of autoreactive T cells into inflamed organs.
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•EBI2 in T cells is highly regulated and stabilized in Th17 cells by IL-1β and IL-23•CH25H, CYP7B1, and 7α,25-OHC are elevated in the CNS in EAE•EBI2 expression by Th17 cells promotes passive EAE•Infiltrating cells in MS lesions express EBI2
Wanke et al. show that EBI2 is expressed by Th17 cells in inflammation and that EBI2 promotes early CNS infiltration in passive EAE. Furthermore, they show that CH25H, CYP7B1, and 7α,25-OHC are upregulated in the CNS in EAE and that EBI2 expressing cells are highly present in MS lesions.
Keratinocytes (KCs) form the outer epithelial barrier of the body, protecting against invading pathogens. Mice lacking the IL-17RA or both IL-17A and IL-17F develop spontaneous Staphylococcusaureus ...skin infections. We found a marked expansion of T17 cells, comprised of RORγt-expressing γδ T cells and T helper 17 cells in the skin-draining lymph nodes of these mice. Contradictory to previous suggestions, this expansion was not a result of a direct negative feedback loop because we found no expansion of T17 cells in mice lacking IL-17 signaling specifically in T cells. Instead, we found that the T17 expansion depended on the microbiota and was observed only when KCs were deficient for IL-17RA signaling. Indeed, mice that lack IL-17RA only in KCs showed an increased susceptibility to experimental epicutaneous infection with S. aureus together with an accumulation of IL-17A−producing γδ T cells. We conclude that deficiency of IL-17RA on KCs leads to microbiota dysbiosis in the skin, which triggers the expansion of IL-17A−producing T cells. Our data show that KCs are the primary target cells of IL-17A and IL-17F, coordinating the defense against microbial invaders in the skin.
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A safe and effective vaccine against COVID-19 is urgently needed in quantities that are sufficient to immunize large populations. Here we report the preclinical development of two vaccine candidates ...(BNT162b1 and BNT162b2) that contain nucleoside-modified messenger RNA that encodes immunogens derived from the spike glycoprotein (S) of SARS-CoV-2, formulated in lipid nanoparticles. BNT162b1 encodes a soluble, secreted trimerized receptor-binding domain (known as the RBD-foldon). BNT162b2 encodes the full-length transmembrane S glycoprotein, locked in its prefusion conformation by the substitution of two residues with proline (S(K986P/V987P); hereafter, S(P2) (also known as P2 S)). The flexibly tethered RBDs of the RBD-foldon bind to human ACE2 with high avidity. Approximately 20% of the S(P2) trimers are in the two-RBD 'down', one-RBD 'up' state. In mice, one intramuscular dose of either candidate vaccine elicits a dose-dependent antibody response with high virus-entry inhibition titres and strong T-helper-1 CD4
and IFNγ
CD8
T cell responses. Prime-boost vaccination of rhesus macaques (Macaca mulatta) with the BNT162b candidates elicits SARS-CoV-2-neutralizing geometric mean titres that are 8.2-18.2× that of a panel of SARS-CoV-2-convalescent human sera. The vaccine candidates protect macaques against challenge with SARS-CoV-2; in particular, BNT162b2 protects the lower respiratory tract against the presence of viral RNA and shows no evidence of disease enhancement. Both candidates are being evaluated in phase I trials in Germany and the USA
, and BNT162b2 is being evaluated in an ongoing global phase II/III trial (NCT04380701 and NCT04368728).
We and others recently showed that IL-17-producing Th17 cells are highly unstable in their phenotype and swiftly upregulate T-bet and Th1-associated cytokines in the inflamed CNS of mice with EAE 1. ...This inherent plasticity was recently associated with IL-23, IFN-γ or IL-12 signalling on effector T cells 2,3.
To understand the role of IFN-γ and IL-27 signaling for plasticity of Th17 cells in vivo.
We use mice lacking the IFN-γ receptor 2 chain specifically in T cells (CD4cre×IFNγR2FL/FL) as well as blocking antibodies for IFN-γ and IL-27-p28 and knockout mice for IL-27-EBI3. Further we use IL-17 reporter mice to sort Th17 cells prior adoptive transfer. We use experimental autoimmune encephalomyelitis (EAE) as in vivo CNS inflammation model in which Th17 cells play an important role and in which plasticity of Th17 cells is predominant found in the CNS.
Using CD4cre×IFNγR2FL/FL mice we found that IFN-g signaling on T cells has a suppressive role in transfer EAE but it is negligible for Th17 plasticity in vivo. We therefore screened several cytokines in vitro and found that IL-27 signaling has a strong impact on Th17 plasticity. In vitroTh17 cells shifted strongly to Th1 when restimulated with IL-12 and IL-27 even in absence of IFN-γ signaling. To investigate the in vivo effects of IL-28 and IFN-γ on Th17 plasticity, experiments are currently performed in CD4cre×IFNγR2FL/FL mice in combination with an IL-27-p28 neutralizing monoclonal antibody or the complete IL-27-EBI3 knockout model.
Although IFN-γ signaling on T cells has a suppressive role in transfer EAE it does not by itself influence Th17 plasticity in the CNS. We suggest that it may act in a redundant fashion with other cytokines such as IL-27 to induce the Th1 shift of Th17 cells under inflammatory conditions.
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