Immune asynchrony in COVID-19 pathogenesis and potential immunotherapies

The outbreak of coronavirus disease 2019 (COVID-19) is an unprecedented global health crisis. Tissue and peripheral blood analysis indicate profound, aberrant myeloid cell activation, cytokine storm, and lymphopenia, with unknown immunopathological mechanisms. Spatiotemporal control of the quality and quantity of the antiviral immune responses involves synchronized cellular and molecular cascades and cross-talk between innate and adaptive immunity. Dysregulated responses in immunity, such as at the stages of immune sensing, alarming, polarization, and resolution, may contribute to disease pathology. Herein, we approach SARS-CoV-2 through an immunomodulatory lens, discussing possible mechanisms of the asynchronized antiviral immune response and proposing potential therapeutic strategies to correct the dysregulation.

Download Full-text

Murine myeloid cell MCPIP1 suppresses autoimmunity by regulating B-cell expansion and differentiation

Disease Models & Mechanisms ◽

10.1242/dmm.047589 ◽

2021 ◽

Vol 14 (3) ◽

pp. dmm047589

Author(s):

Ewelina Dobosz ◽

Georg Lorenz ◽

Andrea Ribeiro ◽

Vivian Würf ◽

Marta Wadowska ◽

...

Keyword(s):

Autoimmune Disease ◽

Immune Responses ◽

Cell Activation ◽

Plasma Cells ◽

Myeloid Cell ◽

Skin Inflammation ◽

Adaptive Immune ◽

Systemic Autoimmunity ◽

Key Factor ◽

Old Mice

ABSTRACTMyeloid-derived cells, in particular macrophages, are increasingly recognized as critical regulators of the balance of immunity and tolerance. However, whether they initiate autoimmune disease or perpetuate disease progression in terms of epiphenomena remains undefined.Here, we show that depletion of MCPIP1 in macrophages and granulocytes (Mcpip1fl/fl-LysMcre+ C57BL/6 mice) is sufficient to trigger severe autoimmune disease. This was evidenced by the expansion of B cells and plasma cells and spontaneous production of autoantibodies, including anti-dsDNA, anti-Smith and anti-histone antibodies. Consequently, we document evidence of severe skin inflammation, pneumonitis and histopathologic evidence of glomerular IgG deposits alongside mesangioproliferative nephritis in 6-month-old mice. These phenomena are related to systemic autoinflammation, which secondarily induces a set of cytokines such as Baff, Il5, Il9 and Cd40L, affecting adaptive immune responses. Therefore, abnormal macrophage activation is a key factor involved in the loss of immune tolerance.Overall, we demonstrate that deficiency of MCPIP1 solely in myeloid cells triggers systemic lupus-like autoimmunity and that the control of myeloid cell activation is a crucial checkpoint in the development of systemic autoimmunity.

Download Full-text

Membrane-associated and secreted forms of the Rhesus macaque rhadinovirus-encoded CD200 homologue and cellular CD200 demonstrate differential effects on Rhesus Macaque CD200 Receptor signaling and regulation of myeloid cell activation

Journal of Virology ◽

10.1128/jvi.01654-20 ◽

2020 ◽

pp. JVI.01654-20

Author(s):

Ryan D. Estep ◽

Aparna N. Govindan ◽

Kristin Fitzpatrick ◽

Tiffany C. Blair ◽

S.A. Rahim Rezaee ◽

...

Keyword(s):

Immune Responses ◽

Rhesus Macaque ◽

Cell Activation ◽

Myeloid Cell ◽

Functional Protein ◽

Dna Viruses ◽

Cd200 Receptor ◽

First Time

The CD200-CD200R pathway is involved in inhibition of immune responses, and the importance of this pathway to infectious disease is highlighted by the fact that viral CD200 (vCD200) molecules have been found to be encoded by several DNA viruses, including the human gammaherpesvirus Kaposi’s sarcoma-associated herpesvirus (KSHV), and the closely related rhesus macaque rhadinovirus (RRV). KSHV vCD200 is the most extensively studied vCD200 molecule, however, the only herpesvirus vCD200 molecule to be examined in vivo is that encoded by RRV. Our prior studies have demonstrated that RRV vCD200 is a functional CD200 homologue that is capable of affecting immune responses in vivo, and further, that RRV can express a secreted form of vCD200 (vCD200-Sec) during infection. Despite this information, RRV vCD200 has not been examined specifically for effects on RM CD200R signaling, and the functionality of vCD200-Sec has not been examined in any context. Thus, we developed an in vitro model system in which B cells expressing vCD200 were utilized to assess the effects of this molecule on the regulation of myeloid cells expressing RM CD200R, mimicking interactions that are predicted to occur in vivo. Our findings suggest that RRV vCD200 can bind and induce functional signals through RM CD200R, while vCD200-Sec represents a non-functional protein incapable of affecting CD200R signaling. We also provide the first demonstration of the function of RM CD200, which appears to possess more robust signaling capabilities than RRV vCD200, and also show that KSHV vCD200 does not efficiently induce signaling via RM CD200R.IMPORTANCE Viral CD200 homologues are encoded by KSHV and the closely related RRV. Though RRV vCD200 has been examined, questions still exist in regard to the ability of this molecule to induce signaling via rhesus macaque CD200R, as well as the potential function of a secreted form of vCD200. Further, all previous in vitro studies of RRV vCD200 have utilized an Fc fusion protein to examine functionality, which does not replicate the structural properties of the membrane-associated form of vCD200 that is naturally produced during RRV infection. In this study, we demonstrate for the first time that membrane-expressed RRV vCD200 is capable of inducing signal transduction via RM CD200R, while the secreted form of vCD200 appears to be non-functional. Further, we also demonstrate that RM CD200 induces signaling via RM CD200R, and is more robust than RRV vCD200, while KSHV vCD200 does not appear to induce efficient signaling via RM CD200R.

Download Full-text

Functional and genomic adaptations of blood monocytes to pregravid obesity during pregnancy

10.1101/2020.12.02.409185 ◽

2020 ◽

Author(s):

Suhas Sureshchandra ◽

Nicole E. Marshall ◽

Norma Mendoza ◽

Allen Jankeel ◽

Michael Z. Zulu ◽

...

Keyword(s):

Immune Responses ◽

Cell Activation ◽

Immune Cell ◽

Cell Subset ◽

Myeloid Cell ◽

Chromatin Accessibility ◽

Blood Monocytes ◽

Increased Risk ◽

Th1 And Th2 Cytokines ◽

The Impact

ABSTRACTPre-pregnancy obesity is associated with several adverse maternal health outcomes, notably increased risk of infection as well as the incidence of gestational diabetes, preeclampsia, and preterm birth. However, the mechanisms by which pregravid obesity disrupts the pregnancy associated “immune clock” are still unknown. To address this question, we collected blood samples from women during the first and third trimesters and determined the impact of both pregnancy and pregravid obesity on circulating immune mediators, immune cell subset frequencies, and peripheral immune responses. While regardless of BMI, pregnancy was associated with an elevation in both Th1 and Th2 cytokines, pregravid obesity was associated with a dysregulation in circulating myeloid factors at term. Moreover, pregnancy in lean subjects was associated with enhanced monocyte activation, augmented chromatin accessibility at inflammatory loci, and heightened responses to LPS. Pregravid obesity disrupted this trajectory and was accompanied by a lack of transcriptional and epigenetic changes and alterations in metabolic status strongly suggesting a skewing towards immunotolerance. These findings provide novel insight into the increased susceptibility to infections observed with obesity during pregnancy.SUMMARYA healthy pregnancy is associated with progressive innate immune activation. Maternal factors such as obesity compromise this myeloid cell activation trajectory at genomic, epigenomic, functional, and metabolic levels, resulting in stagnant immune responses, suggestive of a state of tolerance.

Download Full-text

Differential and sequential immunomodulatory role of neutrophils and Ly6Chi inflammatory monocytes during antiviral antibody therapy

10.1101/2020.04.22.055533 ◽

2020 ◽

Author(s):

Jennifer Lambour ◽

Mar Naranjo-Gomez ◽

Myriam Boyer-Clavel ◽

Mireia Pelegrin

Keyword(s):

Immune Responses ◽

Antibody Therapy ◽

Myeloid Cell ◽

Cell Types ◽

Retroviral Infection ◽

Antiviral Immune Response ◽

Inflammatory Monocytes ◽

Cytokines And Chemokines

AbstractAntiviral monoclonal antibodies (mAbs) can generate protective immunity through Fc-Fcγ Rs interactions. Using a mouse model of retroviral infection, we previously showed a crucial role for immune complexes (ICs) in the enhancement of T-cell responses through FcγR-mediated activation of dendritic cells (DCs). However, IC-FcγR interactions involve different cells of the immune system other than DCs such as neutrophils and monocytes. These two myeloid cell-types are innate effector cells rapidly recruited to sites of infection. In addition to being key cells to fight against invading pathogens, they are also endowed with immunomodulatory properties. While the role of DCs in enhancing antiviral immune responses upon mAb treatment has been addressed in several studies, the role of neutrophils and monocytes has been much less studied. Here we addressed how mAb therapy affects the functional activation of neutrophils and inflammatory monocytes in retrovirus-infected mice. We found that both cell-types activated in vitro by viral ICs secreted high levels of chemokines able to recruit monocytes and neutrophils themselves. Moreover, inflammatory cytokines potentiated chemokines and cytokines release by IC-activated cells and induced FcγRIV upregulation. Similarly, infection and mAb-treatment upregulated FcγRIV expression on neutrophils and inflammatory monocytes and enhanced their cytokines and chemokines secretion. Notably, upon antibody therapy neutrophils and inflammatory monocytes displayed distinct functional activation states and sequentially modulated the antiviral immune response through the secretion of Th1-type polarizing cytokines and chemokines. Our work provides novel findings on the immunomodulatory role of neutrophils and monocytes in the enhancement of immune responses upon antiviral mAb therapy.

Download Full-text

Synergistic cancer immunotherapy combines MVA-CD40L induced innate and adaptive immunity with tumor targeting antibodies

Nature Communications ◽

10.1038/s41467-019-12998-6 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 5

Author(s):

José Medina-Echeverz ◽

Maria Hinterberger ◽

Marco Testori ◽

Marlene Geiger ◽

Raphael Giessel ◽

...

Keyword(s):

Immune Responses ◽

Tumor Targeting ◽

Cell Activation ◽

Nk Cell ◽

Cancer Therapies ◽

Antitumor Effects ◽

Innate And Adaptive Immunity ◽

Adaptive Immune ◽

Modified Vaccinia Virus Ankara ◽

Cell Immunity

Abstract Virus-based vaccines and appropriate costimulation potently enhance antigen-specific T cell immunity against cancer. Here we report the use of recombinant modified vaccinia virus Ankara (rMVA) encoding costimulatory CD40L against solid tumors. Therapeutic treatment with rMVA-CD40L-expressing tumor-associated antigens results in the control of established tumors. The expansion of tumor-specific cytotoxic CD8+ T cells is essential for the therapeutic antitumor effects. Strikingly, rMVA-CD40L also induces strong natural killer (NK) cell activation and expansion. Moreover, the combination of rMVA-CD40L and tumor-targeting antibodies results in increased therapeutic antitumor efficacy relying on the presence of Fc receptor and NK cells. We describe a translationally relevant therapeutic synergy between systemic viral vaccination and CD40L costimulation. We show strengthened antitumor immune responses when both rMVA-CD40L-induced innate and adaptive immune mechanisms are exploited by combination with tumor-targeting antibodies. This immunotherapeutic approach could translate into clinical cancer therapies where tumor-targeting antibodies are employed.

Download Full-text

Homeostatic MyD88-dependent signals cause lethal inflamMation in the absence of A20

Journal of Experimental Medicine ◽

10.1084/jem.20071108 ◽

2008 ◽

Vol 205 (2) ◽

pp. 451-464 ◽

Cited By ~ 201

Author(s):

Emre E. Turer ◽

Rita M. Tavares ◽

Erwan Mortier ◽

Osamu Hitotsumatsu ◽

Rommel Advincula ◽

...

Keyword(s):

Immune Responses ◽

Cell Activation ◽

Interleukin 1 ◽

Critical Role ◽

Tumor Necrosis Factor Receptor ◽

Intestinal Flora ◽

Myeloid Cell ◽

Nuclear Factor Κb ◽

Host Cells

Toll-like receptors (TLRs) on host cells are chronically engaged by microbial ligands during homeostatic conditions. These signals do not cause inflammatory immune responses in unperturbed mice, even though they drive innate and adaptive immune responses when combating microbial infections. A20 is a ubiquitin-modifying enzyme that restricts exogenous TLR-induced signals. We show that MyD88-dependent TLR signals drive the spontaneous T cell and myeloid cell activation, cachexia, and premature lethality seen in A20-deficient mice. We have used broad spectrum antibiotics to demonstrate that these constitutive TLR signals are driven by commensal intestinal flora. A20 restricts TLR signals by restricting ubiquitylation of the E3 ligase tumor necrosis factor receptor–associated factor 6. These results reveal both the severe proinflammatory pathophysiology that can arise from homeostatic TLR signals as well as the critical role of A20 in restricting these signals in vivo. In addition, A20 restricts MyD88-independent TLR signals by inhibiting Toll/interleukin 1 receptor domain–containing adaptor inducing interferon (IFN) β–dependent nuclear factor κB signals but not IFN response factor 3 signaling. These findings provide novel insights into how physiological TLR signals are regulated.

Download Full-text

Faculty Opinions recommendation of Promotion of B cell immune responses via an alum-induced myeloid cell population.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1019734.222544 ◽

2004 ◽

Author(s):

Richard Locksley

Keyword(s):

Immune Responses ◽

B Cell ◽

Cell Population ◽

Myeloid Cell

Download Full-text

188 Novel Anti-SIRpalpha antibodies with differentiated characteristics as promising cancer therapeutics

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0188 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A202-A202

Author(s):

Swati Jalgaonkar ◽

George Huang ◽

Erin Filbert ◽

Christine Tan ◽

Ryan Alvarado ◽

...

Keyword(s):

T Cell ◽

Tumor Immunity ◽

Cell Activation ◽

Regulatory Protein ◽

Cancer Therapeutics ◽

Myeloid Cell ◽

Therapeutic Window ◽

Close Relative ◽

Cell Functions ◽

Tumor Clearance

BackgroundTherapeutically targeting tumor myeloid cells has emerged as a novel and complementary strategy to existing cancer immunotherapy approaches. The interaction of tumor expressed CD47 with SIRP alpha (signal regulatory protein-alphaa, SIRPA) on macrophages, dendritic cells and neutrophils inhibits key immune effector mechanisms. Targeting SIRPa-CD47 represents a novel approach to enhance anti-tumor immunity by augmenting or reactivating critical tumor clearance mechanisms.H5F9, an antibody against CD47, has shown promising therapeutic activities in patients with MSD, AML and NHL. However, agents targeting CD47 present hematological toxicities and present a huge antigen sink leading to not achieving an optimum therapeutic window. Our approach is to target SIRP alpha, the receptor of CD47 and focus therapeutic targeting to relevant mechanisms related to phagocytosis and myeloid cell activation and at the same time avoid undesired effects of blocking CD47. SIRP gamma, a very close relative of SIRP alpha is expressed on T cells and also binds to CD47. It has been shown that blockade of SIRP gamma-CD47 interaction inhibits T cell proliferation and blocks trans-endothelial T cell migration. Hence, our aim is to generate SIRP alpha selective antibodies that do not cross-react with SIRP gamma and have minimal impact on T cell functions.MethodsUsing Apexigen’s APXiMAB™ proprietary antibody discovery platform, we have generated two novel anti-SIRP alpha antibodies (APX701 & APX702) with differentiated properties as compared to other approaches targeting the CD47/SIRP alpha axis. We have used ELISA, FACS based cell binding and blocking assays, and functional assays including in vitro phagocytosis and antibody-dependent cell phagocytosis (ADCP) in combination with tumor-opsonizing antibody to select APX701 & APX702.ResultsOur novel preclinical-stage APX701 & APX702 antibodies have demonstrated the following attributes: high binding affinity to human SIRP alpha (APX701 Kd = 0.95nM, APX702 Kd = 0.88nM), no binding to SIRP gamma, efficient blockade of SIRP alpha binding to CD47(APX701 IC50 = 1.04nM, APX702 IC50 = 0.80nM), potent macrophage mediated phagocytosis, enhancement of ADCP mediated by tumor-opsonizing antibody and favorable developability CMC profiles. In comparison with the benchmark antibody OSE-172, APX701 & APX702 showed potent phagocytosis activity and ADCP enhancement in all donors tested while OSE-172 induced phagocytosis in only 50% of the donors. This may result from the fact that APX701 and APX702 bind to all major SIRP alpha variants (V1, V2 & V8; covering ~92% population) while OSE 172 only binds to SIRPalpha V1 (~50% population).ConclusionsAPX701 and APX702 demonstrate differentiated anti-SIRPalpha activities by enhancing myeloid cell-mediated anti-tumor immunity and reactivating critical tumor clearance mechanisms within the tumor microenvironment.

Download Full-text

Differences in TCR repertoire and T cell activation underlie the divergent outcomes of antitumor immune responses in tumor-eradicating versus tumor-progressing hosts

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-001615 ◽

2021 ◽

Vol 9 (1) ◽

pp. e001615

Author(s):

Rachel A Woolaver ◽

Xiaoguang Wang ◽

Alexandra L Krinsky ◽

Brittany C Waschke ◽

Samantha M Y Chen ◽

...

Keyword(s):

T Cell ◽

Mouse Model ◽

Immune Responses ◽

Single Cell ◽

T Cell Activation ◽

Antitumor Immunity ◽

Cell Activation ◽

Tcr Repertoire ◽

Underlying Mechanisms ◽

Personalized Cancer

BackgroundAntitumor immunity is highly heterogeneous between individuals; however, underlying mechanisms remain elusive, despite their potential to improve personalized cancer immunotherapy. Head and neck squamous cell carcinomas (HNSCCs) vary significantly in immune infiltration and therapeutic responses between patients, demanding a mouse model with appropriate heterogeneity to investigate mechanistic differences.MethodsWe developed a unique HNSCC mouse model to investigate underlying mechanisms of heterogeneous antitumor immunity. This model system may provide a better control for tumor-intrinsic and host-genetic variables, thereby uncovering the contribution of the adaptive immunity to tumor eradication. We employed single-cell T-cell receptor (TCR) sequencing coupled with single-cell RNA sequencing to identify the difference in TCR repertoire of CD8 tumor-infiltrating lymphocytes (TILs) and the unique activation states linked with different TCR clonotypes.ResultsWe discovered that genetically identical wild-type recipient mice responded heterogeneously to the same squamous cell carcinoma tumors orthotopically transplanted into the buccal mucosa. While tumors initially grew in 100% of recipients and most developed aggressive tumors, ~25% of recipients reproducibly eradicated tumors without intervention. Heterogeneous antitumor responses were dependent on CD8 T cells. Consistently, CD8 TILs in regressing tumors were significantly increased and more activated. Single-cell TCR-sequencing revealed that CD8 TILs from both growing and regressing tumors displayed evidence of clonal expansion compared with splenic controls. However, top TCR clonotypes and TCR specificity groups appear to be mutually exclusive between regressing and growing TILs. Furthermore, many TCRα/TCRβ sequences only occur in one recipient. By coupling single-cell transcriptomic analysis with unique TCR clonotypes, we found that top TCR clonotypes clustered in distinct activation states in regressing versus growing TILs. Intriguingly, the few TCR clonotypes shared between regressors and progressors differed greatly in their activation states, suggesting a more dominant influence from tumor microenvironment than TCR itself on T cell activation status.ConclusionsWe reveal that intrinsic differences in the TCR repertoire of TILs and their different transcriptional trajectories may underlie the heterogeneous antitumor immune responses in different hosts. We suggest that antitumor immune responses are highly individualized and different hosts employ different TCR specificities against the same tumors, which may have important implications for developing personalized cancer immunotherapy.

Download Full-text