Mononuclear Phagocytic Cells Research Articles

Peptide ligands on the PEGylated nanoparticle surface and human serum composition are key factors for the interaction between immune cells and nanoparticles

The architecture of a nanoparticles’ surface formed due to a modification with a ligand and protein corona formation in biofluids is critical for interactions with cells in vivo. Here we studied interactions of immune cells with magnetic nanoparticles (MNPs) covalently modified with polyethylene glycol (PEG) and their counterparts conjugated with peptides: a pH (low) insertion peptide (pHLIP) and cycloRGD as a targeting ligand in human serum. The conjugation of MNPs-PEG with pHLIP, but not with cycloRGD, enhanced the association of these particles with mononuclear phagocytic cells in vitro and in vivo. We did not find a clear difference in protein corona composition between the pHLIP-modified and parental PEGylated nanoparticles. Analysis of the effect of autologous human serum on MNP uptake by monocytes showed that the efficiency of endocytosis varies among healthy donors and depends on intrinsic properties of serum. Nevertheless, using classic blood, coagulation, biochemical tests, and anti-PEG IgG serum level, we failed to identify the cause of the observed interdonor variation. These individual differences should be taken into consideration during testing of nanotherapeutics.

Toll-like receptor 2 signaling pathway activation contributes to a highly efficient inflammatory response in Japanese encephalitis virus-infected mouse microglial cells by proteomics.

Thousands of people die each year from Japanese encephalitis (JE) caused by the Japanese encephalitis virus (JEV), probably due to exacerbation of the inflammatory response that impairs the course of the disease. Microglia are mononuclear phagocytic cells located within the parenchyma of the central nervous system; these play a key role in the innate immune response against JEV infections. However, the involvement of toll-like receptor 2 (TLR2) in the inflammatory response during the early stages of JEV infection in BV2 cells remains. Here, we evaluated protein profiles and determined the role of TLR2 in the inflammatory response of JEV-infected BV2 cells. High-depth tandem mass tags labeling for quantitative proteomics was used to assess JEV infected-BV2 cells and compare immune response profiles at 6, 12, and 24 h post-infection (hpi). In total, 212 upregulated proteins were detected at 6 hpi, 754 at 12 h, and 191 at 24 h. According to GO and KEGG enrichment analysis, the upregulated proteins showed enrichment for proteins related to the immune response. Parallel reaction monitoring tests, western blotting, and qPCR results showed that the adaptor protein MyD88 was not activated. The expression levels of key proteins downstream of MyD88, such as IRAK1, IRAK4, and TRAF6 did not increase; however, the expression levels of PI3K-AKT did increase. By inhibiting key proteins (TLR2, PI3K, and AKT) we confirmed that JEV activated TLR2, thus resulting in a robust inflammatory response. Consequently, the TLR2-PI3K-AKT signaling axis was proven to play a critical in the early stages of the JEV infection-induced inflammatory response in microglia.

Human Pluripotent Stem Cell-Derived Alveolar Organoid with Macrophages.

Alveolar organoids (AOs), derived from human pluripotent stem cells (hPSCs) exhibit lung-specific functions. Therefore, the application of AOs in pulmonary disease modeling is a promising tool for understanding disease pathogenesis. However, the lack of immune cells in organoids limits the use of human AOs as models of inflammatory diseases. In this study, we generated AOs containing a functional macrophage derived from hPSCs based on human fetal lung development using biomimetic strategies. We optimized culture conditions to maintain the iMACs (induced hPSC-derived macrophages) AOs for up to 14 days. In lipopolysaccharide (LPS)-induced inflammatory conditions, IL-1β, MCP-1 and TNF-α levels were significantly increased in iMAC-AOs, which were not detected in AOs. In addition, chemotactic factor IL-8, which is produced by mononuclear phagocytic cells, was induced by LPS treatment in iMACs-AOs. iMACs-AOs can be used to understand pulmonary infectious diseases and is a useful tool in identifying the mechanism of action of therapeutic drugs in humans. Our study highlights the importance of immune cell presentation in AOs for modeling inflammatory pulmonary diseases.

Histopathologic and Immunohistochemical Evaluation of Induced Lesions, Tissue Tropism and Host Responses following Experimental Infection of Egyptian Rousette Bats (Rousettus aegyptiacus) with the Zoonotic Paramyxovirus, Sosuga Virus.

Ecological and experimental infection studies have identified Egyptian rousette bats (ERBs; Rousettus aegyptiacus: family Pteropodidae) as a reservoir host for the zoonotic rubula-like paramyxovirus Sosuga virus (SOSV). A serial sacrifice study of colony-bred ERBs inoculated with wild-type, recombinant SOSV identified small intestines and salivary gland as major sites of viral replication. In the current study, archived formalin-fixed paraffin-embedded (FFPE) tissues from the serial sacrifice study were analyzed in depth—histologically and immunohistochemically, for SOSV, mononuclear phagocytes and T cells. Histopathologic lesion scores increased over time and viral antigen persisted in a subset of tissues, indicating ongoing host responses and underscoring the possibility of chronic infection. Despite the presence of SOSV NP antigen and villus ulcerations in the small intestines, there were only mild increases in mononuclear phagocytes and T cells, a host response aligned with disease tolerance. In contrast, there was a statistically significant, robust and targeted mononuclear phagocyte cell responses in the salivary glands at 21 DPI, where viral antigen was sparse. These findings may have broader implications for chiropteran–paramyxovirus interactions, as bats are hypothesized to be the ancestral hosts of this diverse virus family and for ERB immunology in general, as this species is also the reservoir host for the marburgviruses Marburg virus (MARV) and Ravn virus (RAVV) (family Filoviridae).

Белок InlB, секретируемый Listeria monocytogenes, контролирует взаимодействие возбудителя с макрофагами

The virulence of gram-positive bacterium Listeria monocytogenes depends on its capacity to infect non-professional phagocytes and proliferate inside them. Listerias monocytogenes captured by mononuclear phagocytic cells during the infectious process are resistant to lysosomal digestion and can proliferate inside macrophages. Internalin B (InlB), one of the key pathogenicity factors of L. monocytogenes, interacts with mammalian receptors c-Met and gC1q-R. For epithelial cells, such interactions with surface receptors promote activation of these receptors and cytoskeletal remodeling, which leads to massive bacterial invasion into nonprofessional phagocytes. For macrophages, by contrast, nothing is known about the role of InlB in their interactions with L. monocytogenes apart from the fact that both receptors are abundantly expressed by macrophages and participate in the development of immune reactions. This study aimed at determination of the potential role of InlB in the interactions between L. monocytogenes and macrophages. We found that 1) InlB expression promoted a significant 3.5-fold increase in the rates of L. monocytogenes capture by macrophages; 2) the 24 h fold increase in bacterial number inside macrophages constituted 182.5 ± 16.7, 96 ± 12 and 13.3 ± 3 for EGDe∆inlB, EGDe and EGDe∆inlB::pInlB strains, respectively; 3) the EGDe∆inlB::pInlB strain, complemented with a plasmid copy of inlB, produced InlB at 3.3fold higher rates than the type strain EGDe. We conclude that InlB negatively affects the survival of listeria inside macrophages. The results enable advanced understanding of the host-pathogen interactions for L. monocytogenes.

Deep immunophenotyping reveals endometriosis is marked by dysregulation of the mononuclear phagocytic system in endometrium and peripheral blood

BackgroundEndometriosis is a chronic, estrogen-dependent disorder where inflammation contributes to disease-associated symptoms of pelvic pain and infertility. Immune dysfunction includes insufficient immune lesion clearance, a pro-inflammatory endometrial environment, and systemic inflammation. Comprehensive understanding of endometriosis immune pathophysiology in different hormonal milieu and disease severity has been hampered by limited direct characterization of immune populations in endometrium, blood, and lesions. Simultaneous deep phenotyping at single-cell resolution of complex tissues has transformed our understanding of the immune system and its role in many diseases. Herein, we report mass cytometry and high dimensional analyses to study immune cell phenotypes, abundance, activation states, and functions in endometrium and blood of women with and without endometriosis in different cycle phases and disease stages.MethodsA case-control study was designed. Endometrial biopsies and blood (n = 60 total) were obtained from women with (n = 20, n = 17, respectively) and without (n = 14, n = 9) endometriosis in the proliferative and secretory cycle phases of the menstrual cycle. Two mass cytometry panels were designed: one broad panel and one specific for mononuclear phagocytic cells (MPC), and all samples were multiplexed to characterize both endometrium and blood immune composition at unprecedented resolution. We combined supervised and unsupervised analyses to finely define the immune cell subsets with an emphasis on MPC. Then, association between cell types, protein expression, disease status, and cycle phase were performed.ResultsThe broad panel highlighted a significant modification of MPC in endometriosis; thus, they were studied in detail with an MPC-focused panel. Endometrial CD91+ macrophages overexpressed SIRPα (phagocytosis inhibitor) and CD64 (associated with inflammation) in endometriosis, and they were more abundant in mild versus severe disease. In blood, classical and intermediate monocytes were less abundant in endometriosis, whereas plasmacytoid dendritic cells and non-classical monocytes were more abundant. Non-classical monocytes were higher in severe versus mild disease.ConclusionsA greater inflammatory phenotype and decreased phagocytic capacity of endometrial macrophages in endometriosis are consistent with defective clearance of endometrial cells shed during menses and in tissue homeostasis, with implications in endometriosis pathogenesis and pathophysiology. Different proportions of monocytes and plasmacytoid dendritic cells in blood from endometriosis suggest systemically aberrant functionality of the myeloid system opening new venues for the study of biomarkers and therapies for endometriosis.

Temporal and Spatial Characterization of Mononuclear Phagocytes in Circulating, Pulmonary Alveolar, and Interstitial Compartments in LPS-Induced Acute Lung Injury.

Peripheral circulating monocytes and resident macrophages are heterogeneous effector cells that play a critical role in the maintenance and restoration of pulmonary integrity. However, their detailed dynamic changes in lipopolysaccharide (LPS)-induced acute lung injury (ALI) remain unclear. Here, we investigated the impact of mononuclear phagocyte cells in the development of LPS-induced ALI/Acute respiratory distress syndrome (ARDS) and described the relations between the dynamic phenotypic changes and pulmonary pathological evolution. In this study, mice were divided into two groups and intraperitoneally injected with normal saline (NS) or LPS, respectively. A series of flow cytometry assay was performed for the quantification of peripheral circulating monocyte subpopulations, detection of the polarization state of bronchoalveolar lavage fluid (BALF)-isolated alveolar macrophages (AMϕ) and pulmonary interstitial macrophages (IMϕ) separated from lung tissues. Circulating Ly6Clo monocytes expanded rapidly after the LPS challenge on day 1 and then decreased to day 7, while Ly6Chi monocytes gradually increased and returned to normal level on the 7th day. Furthermore, the expansion of M2-like AMϕ (CD64+CD206+) was peaked on day 1 and remained high on the third day, while the polarization state of IMϕ (CD64+ CD11b+) was not influenced by the LPS challenge at all the time points. Taken together, our findings show that Ly6Clo monocytes and M2-like AMϕ form the major peripheral circulation and pulmonary immune cell populations, respectively. The dynamic changes of mononuclear phagocyte in three compartments after the LPS challenge may provide novel protective strategies for mononuclear phagocytes.

Antigen cross-presentation in young tumor-bearing hosts promotes CD8+ T cell terminal differentiation.

The immune system undergoes a progressive functional remodeling with age. Understanding how age bias shapes antitumor immunity is essential in designing effective immunotherapies, especially for pediatric patients. Here, we explore antitumor CD8+ T cell responses generated in young (prepubescent) and adult (presenescent) mice. Using an MHCI-deficient tumor model, we observed that tumor-reactive CD8+ T cells expanded in young tumor-bearing (TB) mice acquired a terminally differentiated phenotype characterized by overexpression of inhibitory receptors and the transcription factor Tox1. Furthermore, tumor-infiltrating CD8+ T cells from young tumors yielded a poor cytokine response compared with CD8+ T cells infiltrating adult tumors. Young migratory dendritic cells (migDCs) from the draining lymph nodes (dLNs), and mononuclear phagocytic cells (MPCs) infiltrating young tumors, were more competent in capturing and cross-presenting tumor antigen, leading to enhanced priming of CD8+ T cells in dLNs and their subsequent terminal differentiation in the tumors. Single-cell transcriptional profiling of tumor-infiltrating MPCs demonstrated that young MPCs are polarized toward an inflammatory, effector phenotype. Consistent with our observations in young versus adult TB mice, analysis of immune infiltrates from pediatric solid tumors showed a correlation between tumor-infiltrating CD8+ T cells with an exhaustion phenotype and the frequency of PD-L1-expressing monocytes/macrophages. Collectively, these data indicate that a young tissue microenvironment contributes to the generation of an immune response skewed toward a less pliable terminal effector state, thus narrowing the window for immunotherapeutic interventions.

Urinary immune cell phenotype of severe AKI in critically ill patients.

Cellular mechanisms involved in human renal recovery after an episode of acute kidney injury (AKI) are understudied. We aim to characterize the urinary immune cell phenotype of patients with AKI and evaluate its ability to predict renal recovery. A prospective study of critically ill patients with stage ≥ 2 AKI by KDIGO and sterile leukocyturia at admission was performed. Urine samples were collected fresh at day 0 and 2 and samples were analyzed by flow cytometry for different leukocytes. Patients were categorized in renal recovery or no-recovery groups. 28 patients were included, all with sepsis, 60.7% of which recovered renal function. The main urinary leukocytes present were neutrophils, followed by mononuclear phagocytic cells and B cells. Patients who recovered renal function had more M2 macrophages at day 2 (p = 0.043) and less B cells at admission (p = 0.006). M2 macrophages had an AUC-ROC of 0.796 (0.601-0.990) for recovery prediction and B cells an AUC-ROC of 0.743 (0.560-0.926) for no recovery. B regulatory cells were found in the urine of AKI patients. The urinary immune cell phenotype of severe AKI patients was composed essentially of neutrophils, mononuclear phagocytic cells and B cells. Our data suggest that M2 macrophages may promote and B cells preclude renal recovery. More studies are needed to validate our results and further explore the role of immune cells in renal recovery.

B7-H3 blockade decreases macrophage inflammatory response and alleviates clinical symptoms of arthritis

Objective. The costimulatory molecule B7-H3 is an immunoregulatory protein, which is highly expressed in peripheral blood monocytes of rheumatoid arthritis (RA) patients and its expression is closely related to the clinical parameters of the disease. In this study we aimed to determine what the implication of high B7-H3 expression for the disease severity, and whether targeting this molecule could constitute a new therapeutic approach. Methods. In this study we analyzed B7-H3 expression on macrophage in human RA and mouse model of arthritis and assessed the function of B7-H3 in relation with the pro-inflammatory role of macrophage through small RNA interference. Then we studied the molecular pathways liking B7-H3 with TNF-α. The therapeutic benefit of anti-B7-H3 blocking was probed in mouse with CIA. Results. We found a positive correlation between expression of B7-H3 on macrophages and disease activities, pathological evaluation and pro-inflammatory cytokine TNF-α. Knocking down B7-H3 expression weakened the inflammatory response of the mouse mononuclear phagocytic cell. Further molecular analyses indicated that the regulation of the inflammatory response through B7-H3 involved NF-κB signaling. Treatment of CIA mice with anti-B7-H3 reduced the clinical manifestation of arthritis and downregulated the expression of pro-inflammatory cytokines. Conclusion. We confirmed increased expression of B7-H3 in arthritis and established a positive correlation between disease severity and expression of B7-H3 on macrophages. Through functional approaches in vitro and in vivo, we also demonstrated the therapeutic benefits of targeting B7-H3 for dampening macrophages’ inflammatory responses in RA.

COVID-19 tissue atlases reveal SARS-CoV-2 pathology and cellular targets.

COVID-19,which is caused by SARS-CoV-2, can result in acute respiratory distress syndrome and multiple organ failure1-4, but little is known about its pathophysiology. Here we generated single-cell atlases of 24 lung, 16 kidney, 16 liver and 19 heart autopsy tissue samples and spatial atlases of 14 lung samplesfrom donors who died ofCOVID-19. Integrated computational analysis uncovered substantial remodelling in the lung epithelial, immune and stromal compartments, with evidence of multiple paths of failed tissue regeneration, including defective alveolar type 2 differentiation and expansion of fibroblasts and putative TP63+ intrapulmonary basal-like progenitor cells. Viral RNAs were enriched in mononuclear phagocytic and endothelial lung cells, which induced specific host programs. Spatial analysis in lung distinguished inflammatory host responses in lung regions with and without viral RNA. Analysis of the other tissue atlases showed transcriptional alterations in multiple cell types in heart tissue from donors with COVID-19, and mapped cell types and genes implicated with disease severity based on COVID-19 genome-wide association studies. Our foundational dataset elucidates the biological effect of severe SARS-CoV-2 infection across the body, a key step towards new treatments.

Prenatal Development and Function of Human Mononuclear Phagocytes.

The human mononuclear phagocyte (MP) system, which includes dendritic cells, monocytes, and macrophages, is a critical regulator of innate and adaptive immune responses. During embryonic development, MPs derive sequentially in yolk sac progenitors, fetal liver, and bone marrow haematopoietic stem cells. MPs maintain tissue homeostasis and confer protective immunity in post-natal life. Recent evidence – primarily in animal models – highlight their critical role in coordinating the remodeling, maturation, and repair of target organs during embryonic and fetal development. However, the molecular regulation governing chemotaxis, homeostasis, and functional diversification of resident MP cells in their respective organ systems during development remains elusive. In this review, we summarize the current understanding of the development and functional contribution of tissue MPs during human organ development and morphogenesis and its relevance to regenerative medicine. We outline how single-cell multi-omic approaches and next-generation ex-vivo organ-on-chip models provide new experimental platforms to study the role of human MPs during development and disease.

Effect of Cytochalasin B on Human Monocyte Binding and Sphering of IgG-coated Human Erythrocytes

The ability of human mononuclear phagocytic cells to bind IgG-coated human erythrocytes (EA) and to cause bound EA to become osmotically fragile (sphered) was investigated in the presence of cytochalasin B, a known inhibitor of phagocytosis. Cytochalasin B inhibited the binding of EA to mononuclear cells in a dose-dependent fashion; 80% inhibition of binding was observed at a concentration of 5 mug/ml. This profound effect on EA binding together with presently available data suggested a role for IgG receptor mobility in the macrophage binding of IgG-coated erythrocytes. Cytochalasin B, however, had a minimal effect on the capacity of mononuclear cells to sphere adherent EA, suggesting that the processes involved in macrophage-induced spherocytosis may differ from those operable in phagocytosis.

Macrophages in Organ Transplantation

Current immunosuppressive therapy has led to excellent short-term survival rates in organ transplantation. However, long-term graft survival rates are suboptimal, and a vast number of allografts are gradually lost in the clinic. An increasing number of animal and clinical studies have demonstrated that monocytes and macrophages play a pivotal role in graft rejection, as these mononuclear phagocytic cells recognize alloantigens and trigger an inflammatory cascade that activate the adaptive immune response. Moreover, recent studies suggest that monocytes acquire a feature of memory recall response that is associated with a potent immune response. This form of memory is called “trained immunity,” and it is retained by mechanisms of epigenetic and metabolic changes in innate immune cells after exposure to particular ligands, which have a direct impact in allograft rejection. In this review article, we highlight the role of monocytes and macrophages in organ transplantation and summarize therapeutic approaches to promote tolerance through manipulation of monocytes and macrophages. These strategies may open new therapeutic opportunities to increase long-term transplant survival rates in the clinic.

A Uromodulin Mutation Drives Autoimmunity and Kidney Mononuclear Phagocyte Endoplasmic Reticulum Stress

We identified a family with a UMOD gene mutation (C106F) resulting in glomerular inflammation and complement deposition. To determine if the observed phenotype is due to immune system activation by mutant uromodulin, a mouse strain with a homologous cysteine to phenylalanine mutation (C105F) in the UMOD gene was generated using CRISPR-Cas9 gene editing and the effect of this mutation on mononuclear phagocytic cells was examined. Mutant mice developed high levels of intracellular and secreted aggregated uromodulin, resulting in anti-uromodulin antibodies and circulating uromodulin containing immune complexes with glomerular deposition and kidney fibrosis with aging. F4/80+ and CD11c+kidney cells phagocytize uromodulin. Differential gene expression analysis by RNA sequencing of F4/80+ phagocytic cells revealed activation of the activating transcription factor 5 (ATF5)-mediated stress response pathway in mutant mice. Phagocytosis of mutant uromodulin by cultured dendritic cells resulted in activation of the endoplasmic reticulum stress response pathway and markers of cell inactivation, an effect not seen with wild-type protein. Mutant mice demonstrate a twofold increase in T-regulatory cells, consistent with induction of immune tolerance, resulting in decreased inflammatory response and improved tissue repair following ischemia-reperfusion injury. The C105F mutation results in autoantibodies against aggregated misfolded protein with immune complex formation and kidney fibrosis. Aggregated uromodulin may induce dendritic cell tolerance following phagocytosis through an unfolded protein/endoplasmic reticulum stress response pathway, resulting in decreased inflammation following tissue injury.

Autoantibody-dependent amplification of inflammation in SLE

Anti-double stranded DNA antibodies (anti-dsDNA) are a hallmark of SLE but their role in disease pathogenesis is not fully resolved. Anti-dsDNA in serum are highly heterogeneous therefore in this study, we aimed to dissect the functional specificities of anti-dsDNA using a panel of human monoclonal antibodies (humAbs) generated from patients with active lupus nephritis. A total of 46 ANA reactive humAbs were isolated and divided into four broad classes based on their reactivity to histones, DNA and Crithidia. Functional analysis indicated that one subclass of antibodies bound strongly to decondensed DNA areas in neutrophil extracellular traps (NETs) and protected NETs from nuclease digestion, similar to the sera from active SLE patients. In addition, these anti-dsDNA antibodies could stimulate type I interferon responses in mononuclear phagocytic cells, or NF-kB activity in endothelial cells, by uptake of NETs-anti-NETs immune complexes and subsequently trigging inflammatory responses in an Fc-gamma receptor (Fcg-R)-dependant manner. Together our data suggest that only a subset of anti-dsDNA antibodies is capable to amplify inflammatory responses by deposit in the nephritic kidney in vivo, protecting NETs digestion as well as uptake of NETs immune complexes into Fcg-R-expressing cells in vitro.

Abstract 971: Effects of tumor cryo-ablation on cGAS-STING pathway and antitumor immunity in syngeneic murine rhabdomyosarcoma

Abstract Even with current improvement in cancer therapy, tumor immunosuppressive microenvironment and metastatic tumors are important factors which have shown to be a challenge for cancer treatment. Thus, targeting the tumor microenvironment (TME) locally are required to modify the activation of innate immunity, which can provoke subsequent global adaptive anti-tumor immunity. Tumor cryo-ablation, a medical procedure that utilizes ultra-cold temperatures to destroy in situ local tumor tissues, has the capability to induce the release of immune danger signals that activate antigen-presenting cells to initiate the anti-tumor immunity. To understand the mechanism of immune activation by cryo-ablation, we performed comprehensive analyses on the effects of tumor cryo-ablation on mononuclear phagocytic lineage cells and the antitumor immunity. Here, we show that cryo-ablation of syngeneic Rhabdomyosarcoma (RMS) tumor, an aggressive sarcoma affecting children and young adults, was able to induce both the regression of tumor and the upregulation of the critical immune cytokines and chemokines profile. Moreover, cryo-ablation of RMS tumor initiates cGAS-STING signaling activation and type I interferon production in dendritic cells, which are consequential in pro-inflammatory TME. We also report that antitumor effects of cryo-ablation was more inhibitive, but not completely abrogated, in STING-deficient mice comparing with wild-type mice, demonstrating that both host-derived and tumor-intrinsic cGAS-STING signaling plays an important role in antitumor effects of tumor cryo-ablation. Ongoing experiments will address the efficacy of RMS tumor cryo-ablation on systemic anti-tumor immune activation leading to an abscopal effect on tumor regression at metastatic tumor. Taken together, our results demonstrate that tumor cryo-ablation affects antitumor immunity and cGAS-STING signaling in RMS tumor, and this approach may help guide future immunotherapy to improve cancer treatment outcomes. Citation Format: Mohammad Abdulaziz Alshebremi, Jay T. Myers, Daniel T. Kingsley, Alex Y. Huang. Effects of tumor cryo-ablation on cGAS-STING pathway and antitumor immunity in syngeneic murine rhabdomyosarcoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 971.

Characteristics and Intracellular Life of Brucella Organism: A Review

Brucella is a Gram-negative, facultative intracellular bacteria that causes zoonotic brucellosis in humans and various animals. These pathogens are affecting domestic animals (cattle, goat, sheep, pig, dogs and camel), human and wild animals. Humans are accidental hosts of brucellosis acquiring the infection commonly from contact with infected animals, aborted materials and consumption raw milk. Brucella do not produce classical virulence factors, and their capacity to successfully replicate within a variety of host cells, to persist for prolonged periods within host cells and to evade the host immune response at the same time underlies their pathogenicity. The virulence factors of Brucella are involved in intracellular survival and replication within mononuclear phagocytic cells, preferentially macrophages in the host and hampers the intracellular trafficking and ability to prevent recognition by the host defense system. All these comprehensions of Brucella can inhabit inside the phagocytes of infected host to promote their survival, persistence and multiplication.

CGAS-STING pathway mediates antitumor immunity of tumor cryoablation in syngeneic murine Rhabdomyosarcoma

Abstract Tumor cryoablation, a medical procedure that utilizes ultra-cold temperatures to destroy in situ local tumor tissues, has been established for cure of many tumor types and for stimulation of the immune system. The mechanism of immune response to tumor cryoabltion are not well defined. To understand the molecular pathway of immune activation by cryoablation, we performed comprehensive analyses on the impact of tumor cryoablation on mononuclear phagocytic lineage cells and the antitumor immunity. Here, we show that cryoablation of a murine Rhabdomyosarcoma (RMS) tumor, an aggressive sarcoma affecting children and young adults, was able to induce the regression of tumor and the upregulation of the critical immune cytokines/chemokines profile and maturation markers of CD11c+ DCs. Moreover, cryoablation of RMS tumor initiates cGAS-STING signaling activation and type I interferon production in CD11c+ DCs, which are consequential in pro-inflammatory tumor microenvironment (TME). We also report that antitumor effects of cryoablation were more inhibitive, but not completely abrogated, in STING-deficient mice comparing with wild-type mice, indicating that both host-derived and tumor-intrinsic cGAS-STING signaling plays an important role in antitumor effects of tumor cryoablation. Taken together, our results demonstrate that tumor cryoablation induces antitumor immunity via cGAS-STING signaling in syngeneic Rhabdomyosarcoma (RMS) tumor, and this approach may help guide future immunotherapy to improve cancer treatment outcomes.

Precision cut lung slices: a novel versatile tool to examine host\u2013pathogen interaction in the chicken lung

The avian respiratory tract is a common entry route for many pathogens and an important delivery route for vaccination in the poultry industry. Immune responses in the avian lung have mostly been studied in vivo due to the lack of robust, relevant in vitro and ex vivo models mimicking the microenvironment. Precision-cut lung slices (PCLS) have the major advantages of maintaining the 3-dimensional architecture of the lung and includes heterogeneous cell populations. PCLS have been obtained from a number of mammalian species and from chicken embryos. However, as the embryonic lung is physiologically undifferentiated and immunologically immature, it is less suitable to examine complex host–pathogen interactions including antimicrobial responses. Here we prepared PCLS from immunologically mature chicken lungs, tested different culture conditions, and found that serum supplementation has a detrimental effect on the quality of PCLS. Viable cells in PCLS remained present for ≥ 40 days, as determined by viability assays and sustained motility of fluorescent mononuclear phagocytic cells. The PCLS were responsive to lipopolysaccharide stimulation, which induced the release of nitric oxide, IL-1β, type I interferons and IL-10. Mononuclear phagocytes within the tissue maintained phagocytic activity, with live cell imaging capturing interactions with latex beads and an avian pathogenic Escherichia coli strain. Finally, the PCLS were also shown to be permissive to infection with low pathogenic avian influenza viruses. Taken together, immunologically mature chicken PCLS provide a suitable model to simulate live organ responsiveness and cell dynamics, which can be readily exploited to examine host–pathogen interactions and inflammatory responses.