Neutrophil progenitor populations of rhesus macaques

Immune Activation Profiles Elicited by Distinct, Repeated TLR Agonist Infusions in Rhesus Macaques

TLR agonists are a promising class of immune system stimulants investigated for immunomodulatory applications in cancer immunotherapy and viral diseases. In this study, we sought to characterize the safety and immune activation achieved by different TLR agonists in rhesus macaques (Macaca mulatta), a useful preclinical model of complex immune interactions. Macaques received one of three TLR agonists, followed by plasma cytokine, immune cell subset representation, and blood cell activation measurements. The TLR4 agonist LPS administered i.v. induced very transient immune activation, including TNF-α expression and monocyte activation. The TLR7/8 agonist 2BXy elicited more persistent cytokine expression, including type I IFN, IL-1RA, and the proinflammatory IL-6, along with T cell and monocyte activation. Delivery of 2BXy i.v. and i.m. achieved comparable immune activation, which increased with escalating dose. Finally, i.v. bacillus Calmette-Guérin (BCG) vaccination (which activates multiple TLRs, especially TLR2/4) elicited the most pronounced and persistent innate and adaptive immune response, including strong induction of IFN-γ, IL-6, and IL-1RA. Strikingly, monocyte, T cell, and NK cell expression of the proliferation marker Ki67 increased dramatically following BCG vaccination. This aligned with a large increase in total and BCG-specific cells measured in the lung. Principal component analysis of the combined cytokine expression and cellular activation responses separated animals by treatment group, indicating distinct immune activation profiles induced by each agent. In sum, we report safe, effective doses and routes of administration for three TLR agonists that exhibit discrete immunomodulatory properties in primates and may be leveraged in future immunotherapeutic strategies.

Claire M, Vannella KM, Holbrook MR, Chertow DS. Clinical and Immunologic Correlates of Vasodilatory Shock Among Ebola Virus-Infected Nonhuman Primates in a Critical Care Model

BACKGROUND

Existing models of Ebola virus infection have not fully characterized the pathophysiology of shock in connection with daily virologic, clinical, and immunologic parameters. We implemented a nonhuman primate critical care model to investigate these associations.

METHODS

Two rhesus macaques received a target dose of 1000 plaque-forming units of Ebola virus intramuscularly with supportive care initiated on day 3. High-dimensional spectral cytometry was used to phenotype neutrophils and peripheral blood mononuclear cells daily.

RESULTS

We observed progressive vasodilatory shock with preserved cardiac function following viremia onset on day 5. Multiorgan dysfunction began on day 6 coincident with the nadir of circulating neutrophils. Consumptive coagulopathy and anemia occurred on days 7 to 8 along with irreversible shock, followed by death. The monocyte repertoire began shifting on day 4 with a decline in classical and expansion of double-negative monocytes. A selective loss of CXCR3-positive B and T cells, expansion of naive B cells, and activation of natural killer cells followed viremia onset.

CONCLUSIONS

Our model allows for high-fidelity characterization of the pathophysiology of acute Ebola virus infection with host innate and adaptive immune responses, which may advance host-targeted therapy design and evaluation for use after the onset of multiorgan failure.

The double-edged role of neutrophil heterogeneity in inflammatory diseases and cancers

Neutrophils are important immune cells act as the body's first line of defense against infection and respond to diverse inflammatory cues. Many studies have demonstrated that neutrophils display plasticity in inflammatory diseases and cancers. Clarifying the role of neutrophil heterogeneity in inflammatory diseases and cancers will contribute to the development of novel treatment strategies. In this review, we have presented a review on the development of the understanding on neutrophil heterogeneity from the traditional perspective and a high-resolution viewpoint. A growing body of evidence has confirmed the double-edged role of neutrophils in inflammatory diseases and tumors. This may be due to a lack of precise understanding of the role of specific neutrophil subsets in the disease. Thus, elucidating specific neutrophil subsets involved in diseases would benefit the development of precision medicine. Thusly, we have summarized the relevance and actions of neutrophil heterogeneity in inflammatory diseases and cancers comprehensively. Meanwhile, we also discussed the potential intervention strategy for neutrophils. This review is intended to deepen our understanding of neutrophil heterogeneity in inflammatory diseases and cancers, while hold promise for precise treatment of neutrophil-related diseases.

Systemic and mucosal mobilization of granulocyte subsets during lentiviral infection

Granulocytes mediate broad immunoprotection through phagocytosis, extracellular traps, release of cytotoxic granules, antibody effector functions and recruitment of other immune cells against pathogens. However, descriptions of granulocytes in HIV infection and mucosal tissues are limited. Our goal was to characterize granulocyte subsets in systemic, mucosal and lymphoid tissues during lentiviral infection using the rhesus macaque (RM) model. Mononuclear cells from jejunum, colon, cervix, vagina, lymph nodes, spleen, liver and whole blood from experimentally naïve and chronically SHIVsf162p3-infected RM were analysed by microscopy and polychromatic flow cytometry. Granulocytes were identified using phenotypes designed specifically for RM: eosinophils-CD45+  CD66+  CD49d+ ; neutrophils-CD45+  CD66+  CD14+ ; and basophils-CD45+  CD123+  FcRε+ . Nuclear visualization with DAPI staining and surface marker images by ImageStream (cytometry/microscopy) further confirmed granulocytic phenotypes. Flow cytometric data showed that all RM granulocytes expressed CD32 (FcRγII) but did not express CD16 (FcRγIII). Additionally, constitutive expression of CD64 (FcRγI) on neutrophils and FcRε on basophils indicates the differential expression of Fc receptors on granulocyte subsets. Granulocytic subsets in naïve whole blood ranged from 25·4% to 81·5% neutrophils, 0·59% to 13·3% eosinophils and 0·059% to 1·8% basophils. Interestingly, elevated frequencies of circulating neutrophils, colorectal neutrophils and colorectal eosinophils were all observed in chronic lentiviral disease. Conversely, circulating basophils, jejunal eosinophils, vaginal neutrophils and vaginal eosinophils of SHIVsf162p3-infected RM declined in frequency. Overall, our data suggest modulation of granulocytes in chronic lentiviral infection, most notably in the gastrointestinal mucosae where a significant inflammation and disruption occurs in lentivirus-induced disease. Furthermore, granulocytes may migrate to inflamed tissues during infection and could serve as targets of immunotherapeutic intervention.

Functional Homology for Antibody-Dependent Phagocytosis Across Humans and Rhesus Macaques

Analyses of human clinical HIV-1 vaccine trials and preclinical vaccine studies performed in rhesus macaque (RM) models have identified associations between non-neutralizing Fc Receptor (FcR)-dependent antibody effector functions and reduced risk of infection. Specifically, antibody-dependent phagocytosis (ADP) has emerged as a common correlate of reduced infection risk in multiple RM studies and the human HVTN505 trial. This recurrent finding suggests that antibody responses with the capability to mediate ADP are most likely a desirable component of vaccine responses aimed at protecting against HIV-1 acquisition. As use of RM models is essential for development of the next generation of candidate HIV-1 vaccines, there is a need to determine how effectively ADP activity observed in RMs translates to activity in humans. In this study we compared ADP activity of human and RM monocytes and polymorphonuclear leukocytes (PMN) to bridge this gap in knowledge. We observed considerable variability in the magnitude of monocyte and PMN ADP activity across individual humans and RM that was not dependent on FcR alleles, and only modestly impacted by cell-surface levels of FcRs. Importantly, we found that for both human and RM phagocytes, ADP activity of antibodies targeting the CD4 binding site was greatest when mediated by human IgG3, followed by RM and human IgG1. These results demonstrate that there is functional homology between antibody and FcRs from these two species for ADP. We also used novel RM IgG1 monoclonal antibodies engineered with elongated hinge regions to show that hinge elongation augments RM ADP activity. The RM IgGs with engineered hinge regions can achieve ADP activity comparable to that observed with human IgG3. These novel modified antibodies will have utility in passive immunization studies aimed at defining the role of IgG3 and ADP in protection from virus challenge or control of disease in RM models. Our results contribute to a better translation of human and macaque antibody and FcR biology, and may help to improve testing accuracy and evaluations of future active and passive prevention strategies.

What Is the Evolutionary Fingerprint in Neutrophil Granulocytes?

Over the years of evolution, thousands of different animal species have evolved. All these species require an immune system to defend themselves against invading pathogens. Nevertheless, the immune systems of different species are obviously counteracting against the same pathogen with different efficiency. Therefore, the question arises if the process that was leading to the clades of vertebrates in the animal kingdom-namely mammals, birds, amphibians, reptiles, and fish-was also leading to different functions of immune cells. One cell type of the innate immune system that is transmigrating as first line of defense in infected tissue and counteracts against pathogens is the neutrophil granulocyte. During the host-pathogen interaction they can undergo phagocytosis, apoptosis, degranulation, and form neutrophil extracellular traps (NETs). In this review, we summarize a wide spectrum of information about neutrophils in humans and animals, with a focus on vertebrates. Special attention is kept on the development, morphology, composition, and functions of these cells, but also on dysfunctions and options for cell culture or storage.