IL-17-producing helper T (Th17) cells are critical for host defense against extracellular pathogens but also drive numerous autoimmune diseases. Th17 cells that differ in their inflammatory potential ...have been described including IL-10-producing Th17 cells that are weak inducers of inflammation and highly inflammatory, IL-23-driven, GM-CSF/IFNγ-producing Th17 cells. However, their distinct developmental requirements, functions and trafficking mechanisms in vivo remain poorly understood. Here we identify a temporally regulated IL-23-dependent switch from CCR6 to CCR2 usage by developing Th17 cells that is critical for pathogenic Th17 cell-driven inflammation in experimental autoimmune encephalomyelitis (EAE). This switch defines a unique in vivo cell surface signature (CCR6(-)CCR2(+)) of GM-CSF/IFNγ-producing Th17 cells in EAE and experimental persistent extracellular bacterial infection, and in humans. Using this signature, we identify an IL-23/IL-1/IFNγ/TNFα/T-bet/Eomesodermin-driven circuit driving GM-CSF/IFNγ-producing Th17 cell formation in vivo. Thus, our data identify a unique cell surface signature, trafficking mechanism and T-cell intrinsic regulators of GM-CSF/IFNγ-producing Th17 cells.
Basophils support the survival of plasma cells in mice Rodriguez Gomez, Manuel; Talke, Yvonne; Goebel, Nicole ...
The Journal of immunology (1950),
2010-Dec-15, 2010-12-15, 20101215, Letnik:
185, Številka:
12
Journal Article
Recenzirano
Odprti dostop
We have previously shown that basophils support humoral memory immune responses by increasing B cell proliferation and Ig production as well as inducing a Th2 and B helper phenotype in T cells. Based ...on the high frequency of basophils in spleen and bone marrow, in this study we investigated whether basophils also support plasma cell survival and Ig production. In the absence of basophils, plasma cells of naive or immunized mice rapidly undergo apoptosis in vitro and produce only low amounts of Igs. In contrast, in the presence of basophils and even more in the presence of activated basophils, the survival of plasma cells is markedly increased and continuous production of Igs enabled. This effect is partially dependent on IL-4 and IL-6 released from basophils. Similar results were obtained when total bone marrow cells or bone marrow cells depleted of basophils were cultured in the presence or absence of substances activating basophils. When basophils were depleted in vivo 6 mo after immunization with an Ag, specific Ig production in subsequent bone marrow cultures was significantly reduced. In addition, depletion of basophils for 18 d in naive mice significantly reduced the number of plasma cells in the spleen. These data indicate that basophils are important for survival of plasma cells in vitro and in vivo.
Fibrocytes are collagen-type-I-producing cells that arise at low frequency from hematopoietic cells. We have analyzed in mice which leukocyte subsets are required for generation of fibrocytes and ...show that murine fibrocytes develop from the subpopulation of CD11b⁺ CD115⁺ Gr1⁺ monocytes under the control of CD4⁺ T cells. In the absence of CD4⁺ T cells, differentiation of fibrocytes was markedly reduced in vitro and in vivo. In the presence of CD4⁺ T cells, the characteristics of T-cell activation critically determined development of fibrocytes. Polyclonal activation of CD4⁺ T cells induced the release of soluble factors that completely prevented the outgrowth of fibrocytes and could be identified as IL-2, TNF, IFN-γ, and IL-4. Application of IL-2 and TNF significantly reduced the appearance of fibrocytes and the severity of fibrosis in the model of unilateral ureteral obstruction. In contrast, activation of CD4⁺ T cells in the presence of calcineurin inhibitors, but not mTOR inhibitors, markedly enhanced the outgrowth of fibrocytes and renal deposition of collagen I. Taken together, we show that differentiation of fibrocytes is critically dependent on CD4⁺ T cells and that the context of T-cell activation determines whether development of fibrocytes is supported or blocked. Our data may have implications for prevention of organ fibrosis in autoimmune diseases and transplantation.
Although neutralizing monoclonal antibodies (mAbs) against epitopes within the alphavirus E2 protein can protect against infection, the functional significance of non-neutralizing mAbs is poorly ...understood. Here, we evaluate the activity of 13 non-neutralizing mAbs against Mayaro virus (MAYV), an emerging arthritogenic alphavirus. These mAbs bind to the MAYV virion and surface of infected cells but fail to neutralize infection in cell culture. Mapping studies identify six mAb binding groups that localize to discrete epitopes within or adjacent to the A domain of the E2 glycoprotein. Remarkably, passive transfer of non-neutralizing mAbs protects against MAYV infection and disease in mice, and their efficacy requires Fc effector functions. Monocytes mediate the protection of non-neutralizing mAbs in vivo, as Fcγ-receptor-expressing myeloid cells facilitate the binding, uptake, and clearance of MAYV without antibody-dependent enhancement of infection. Humoral protection against alphaviruses likely reflects contributions from non-neutralizing antibodies through Fc-dependent mechanisms that accelerate viral clearance.
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•Anti-MAYV antibodies protect against infection without neutralizing the virus•Protection by non-neutralizing anti-MAYV antibodies requires Fc effector function•Anti-MAYV antibody Fc effector functions require monocytes to mediate protection•Non-neutralizing anti-MAYV antibodies promote abortive infection in myeloid cells
Earnest et al. characterize the protective antibody response against Mayaro virus, an emerging arthritogenic alphavirus. They find that antibody-mediated protection in mice does not require virus neutralization but can rely on Fc effector functions associated with myeloid cells.
Tumor development and progression is shaped by the tumor microenvironment (TME), a heterogeneous assembly of infiltrating and resident host cells, their secreted mediators and intercellular matrix. ...In this context, tumors are infiltrated by various immune cells with either pro-tumoral or anti-tumoral functions. Recently, we published our non-invasive immunization platform DIVA suitable as a therapeutic vaccination method, further optimized by repeated application (DIVA
2
). In our present work, we revealed the therapeutic effect of DIVA
2
in an MC38 tumor model and specifically focused on the mechanisms induced in the TME after immunization. DIVA
2
resulted in transient tumor control followed by an immune evasion phase within three weeks after the initial tumor inoculation. High-dimensional flow cytometry analysis and single-cell mRNA-sequencing of tumor-infiltrating leukocytes revealed cytotoxic CD8
+
T cells as key players in the immune control phase. In the immune evasion phase, inflammatory CCR2
+
PDL-1
+
monocytes with immunosuppressive properties were recruited into the tumor leading to suppression of DIVA
2
-induced tumor-reactive T cells. Depletion of CCR2
+
cells with specific antibodies resulted in prolonged survival revealing CCR2
+
monocytes as important for tumor immune escape in the TME. In summary, the present work provides a platform for generating a strong antigen-specific primary and memory T cell immune response using the optimized transcutaneous immunization method DIVA
2
. This enables protection against tumors by therapeutic immune control of solid tumors and highlights the immunosuppressive influence of tumor infiltrating CCR2
+
monocytes that need to be inactivated in addition for successful cancer immunotherapy.
Current understanding about the roles of microglia versus macrophages in viral encephalitis is limited. We previously showed that the signaling of a single prostaglandin, PGD
2
, through its DP1 ...receptor on myeloid cells is critical for optimal immune responses in infected mice.
ABSTRACT
Microglia and macrophages initiate and orchestrate the innate immune response to central nervous system (CNS) virus infections. Microglia initiate neurotropic coronavirus clearance from the CNS, but the role of infiltrating macrophages is not well understood. Here, using mice lacking cell-specific expression of DP1, the receptor for prostaglandin D
2
(PGD
2
), we delineate the relative roles of PGD
2
signaling in microglia and macrophages in murine coronavirus-infected mice. We show that the absence of PGD
2
/DP1 signaling on microglia recapitulated the suboptimal immune response observed in global DP1
−/−
mice. Unexpectedly, the absence of the DP1 receptor on macrophages had an opposite effect, resulting in enhanced activation and more rapid virus clearance. However, microglia are still required for disease resolution, even when macrophages are highly activated, in part because they are required for macrophage recruitment to sites of infection. Together, these results identify key differences in the effects of PGD
2
/DP1 signaling on microglia and macrophages and illustrate the complex relationship between the two types of myeloid cells.
IMPORTANCE
Current understanding about the roles of microglia versus macrophages in viral encephalitis is limited. We previously showed that the signaling of a single prostaglandin, PGD
2
, through its DP1 receptor on myeloid cells is critical for optimal immune responses in infected mice. Here, we demonstrate that the specific ablation of the DP1 receptor on macrophages and microglia had markedly different effects on outcomes. DP1
−/−
macrophages exhibited greater phagocytic properties than controls, resulting in enhanced kinetics of virus clearance, while DP1 absence on microglia resulted in increased lethality. Microglia were still required for protection, even when DP1 was not expressed on macrophages. These results suggest that therapeutic strategies directed at specific myeloid subsets in the brain may be useful in the context of viral infections.
The prime function of nucleoli is ribogenesis, however, several other, non-canonical functions have recently been identified, including a role in genotoxic stress response. Upon DNA damage, numerous ...proteins shuttle dynamically between the nucleolus and the nucleoplasm, yet the underlying molecular mechanisms are incompletely understood. Here, we demonstrate that PARP1 and PARylation contribute to genotoxic stress-induced nucleolar-nucleoplasmic shuttling of key genome maintenance factors in HeLa cells. Our work revealed that the RECQ helicase, WRN, translocates from nucleoli to the nucleoplasm upon treatment with the oxidizing agent H
O
, the alkylating agent 2-chloroethyl ethyl sulfide (CEES), and the topoisomerase inhibitor camptothecin (CPT). We show that after treatment with H
O
and CEES, but not CPT, WRN translocation was dependent on PARP1 protein, yet independent of its enzymatic activity. In contrast, nucleolar-nucleoplasmic translocation of the base excision repair protein, XRCC1, was dependent on both PARP1 protein and its enzymatic activity. Furthermore, gossypol, which inhibits PARP1 activity by disruption of PARP1-protein interactions, abolishes nucleolar-nucleoplasmic shuttling of WRN, XRCC1 and PARP1, indicating the involvement of further upstream factors. In conclusion, this study highlights a prominent role of PARP1 in the DNA damage-induced nucleolar-nucleoplasmic shuttling of genome maintenance factors in HeLa cells in a toxicant and protein-specific manner.
Plasmodium berghei ANKA (PbA) infection of C57BL/6 mice leads to experimental cerebral malaria (ECM) that is commonly associated with serious T cell mediated damage. In other parasitic infection ...models, inflammatory monocytes have been shown to regulate Th1 responses but their role in ECM remains poorly defined, whereas neutrophils are reported to contribute to ECM immune pathology. Making use of the recent development of specific monoclonal antibodies (mAb), we depleted in vivo Ly6C(hi) inflammatory monocytes (by anti-CCR2), Ly6G+ neutrophils (by anti-Ly6G) or both cell types (by anti-Gr1) during infection with Ovalbumin-transgenic PbA parasites (PbTg). Notably, the application of anti-Gr1 or anti-CCR2 but not anti-Ly6G antibodies into PbTg-infected mice prevented ECM development. In addition, depletion of Ly6C(hi) inflammatory monocytes but not neutrophils led to decreased IFNγ levels and IFNγ+CD8+ T effector cells in the brain. Importantly, anti-CCR2 mAb injection did not prevent the generation of PbTg-specific T cell responses in the periphery, whereas anti-Gr1 mAb injection strongly diminished T cell frequencies and CTL responses. In conclusion, the specific depletion of Ly6C(hi) inflammatory monocytes attenuated brain inflammation and immune cell recruitment to the CNS, which prevented ECM following Plasmodium infection, pointing out a substantial role of Ly6C+ monocytes in ECM inflammatory processes.
Humoral immune responses initiate in the lymph node draining the site of viral infection (dLN). Some viruses subvert LN B cell activation; however, our knowledge of viral hindrance of B cell ...responses of important human pathogens is lacking. Here, we define mechanisms whereby chikungunya virus (CHIKV), a mosquito-transmitted RNA virus that causes outbreaks of acute and chronic arthritis in humans, hinders dLN antiviral B cell responses. Infection of WT mice with pathogenic, but not acutely cleared CHIKV, induced MyD88-dependent recruitment of monocytes and neutrophils to the dLN. Blocking this influx improved lymphocyte accumulation, dLN organization, and CHIKV-specific B cell responses. Both inducible nitric oxide synthase (iNOS) and the phagocyte NADPH oxidase (Nox2) contributed to impaired dLN organization and function. Infiltrating monocytes expressed iNOS through a local IRF5- and IFNAR1-dependent pathway that was partially TLR7-dependent. Together, our data suggest that pathogenic CHIKV triggers the influx and activation of monocytes and neutrophils in the dLN that impairs virus-specific B cell responses.
Resolving inflammation is thought to return the affected tissue back to homoeostasis but recent evidence supports a non-linear model of resolution involving a phase of prolonged immune activity. Here ...we show that within days following resolution of Streptococcus pneumoniae-triggered lung inflammation, there is an influx of antigen specific lymphocytes with a memory and tissue-resident phenotype as well as macrophages bearing alveolar or interstitial phenotype. The transcriptome of these macrophages shows enrichment of genes associated with prostaglandin biosynthesis and genes that drive T cell chemotaxis and differentiation. Therapeutic depletion of post-resolution macrophages, inhibition of prostaglandin E2 (PGE
) synthesis or treatment with an EP4 antagonist, MF498, reduce numbers of lung CD4
/CD44
/CD62L
and CD4
/CD44
/CD62L
/CD27
T cells as well as their expression of the α-integrin, CD103. The T cells fail to reappear and reactivate upon secondary challenge for up to six weeks following primary infection. Concomitantly, EP4 antagonism through MF498 causes accumulation of lung macrophages and marked tissue fibrosis. Our study thus shows that PGE
signalling, predominantly via EP4, plays an important role during the second wave of immune activity following resolution of inflammation. This secondary immune activation drives local tissue-resident T cell development while limiting tissue injury.
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