Analysis of chromatin data supports a role for CD14+ monocytes/macrophages in mediating genetic risk for juvenile idiopathic arthritis.

Introduction: Genome wide association studies (GWAS) have identified multiple regions that confer genetic risk for the polyarticular/oligoarticular forms of juvenile idiopathic arthritis (JIA). However, genome-wide scans do not identify the cells impacted by genetic polymorphisms on the risk haplotypes or the genes impacted by those variants. We have shown that genetic variants driving JIA risk are likely to affect both innate and adaptive immune functions. We provide additional evidence that JIA risk variants impact innate immunity. Materials and methods: We queried publicly available H3K4me1/H3K27ac ChIP-seq data in CD14+ monocytes to determine whether the linkage disequilibrium (LD) blocks incorporating the SNPs that tag JIA risk loci showed enrichment for these epigenetic marks. We also queried monocyte/macrophage GROseq data, a functional readout of active enhancers. We defined the topologically associated domains (TADs) encompassing enhancers on the risk haplotypes and identified genes within those TADs expressed in monocytes. We performed ontology analyses of these genes to identify cellular processes that may be impacted by these variants. We also used whole blood RNAseq data from the Genotype-Tissue Expression (GTEx) data base to determine whether SNPs lying within monocyte GROseq peaks influence plausible target genes within the TADs encompassing the JIA risk haplotypes. Results: The LD blocks encompassing the JIA genetic risk regions were enriched for H3K4me1/H3K27ac ChIPseq peaks (p=0.00021 and p=0.022) when compared to genome background. Eleven and sixteen JIA were enriched for resting and activated macrophage GROseq peaks, respectively risk regions (p=0.04385 and p=0.00004). We identified 321 expressed genes within the TADs encompassing the JIA haplotypes in human monocytes. Ontological analysis of these genes showed enrichment for multiple immune functions. Finally, we found that SNPs lying within the GROseq peaks are strongly associated with expression levels of plausible target genes in human whole blood. Conclusions: These findings support the idea that both innate and adaptive immunity are impacted by JIA genetic risk variants.

Inhibition of Borrelia Burgdorferi-Induced TLR2-NFκB Canonical Signaling by Gallic Acid through Targeting the CD14+ Adaptor Protein and p65 Molecule.

The cases of Lyme disease caused by Borrelia burgdorferi infection have been increasing throughout Northern America and Europe. This pathogen, if not treated in a timely manner with antibiotics, can cause persisting and debilitating health outcomes. In the search for novel agents against B. burgdorferi, we investigated a phenolic compound-gallic acid-for its anti-Borrelia and anti-inflammatory effects. Our results showed its biocidal effect starting from 100 µg/mL against active spirochetes, persisters/round-shaped bodies, and biofilm like aggregates of B. burgdorferi sensu stricto. Activation of macrophages by live B. burgdorferi also resulted in a robust NFκB-dependent proinflammatory responses seen in increased production of cytokines. Using human CD14+ macrophages in vitro, we showed that CD14+ adaptor and phosphorylated p65 molecule are impeded at nonbiocidal and noncytotoxic concentrations of gallic acid, resulting in the inhibition of both expression and secretion of cytokines IL1ß, IL6, and TNFα. Our findings demonstrate efficacy of gallic acid against B. burgdorferi and provide potential mechanistic insight into its TLR2/CD14+-NFκB mediated mode of action. Further studies on the potential of gallic acid as a safe and effective compound against Borrelia-caused infection are warranted.

LPS differentially affects expression of CD14 and CCR2 in monocyte subsets of Post-STEMI patients with hyperglycemia.

AIMS: Following ST-segment elevation myocardial infarction (STEMI), recruitment and activation of monocytes [classical (CD14++CD16-CCR2++), intermediate (CD14++CD16+CCR2+), non-classical (CD14LowCD16++CCR2Low)] are needed for myocardial wound healing. Monocyte surface receptor CC chemokine receptor type 2 (CCR2) is responsible for monocyte chemotaxis to sites of inflammation and the lipopolysaccharide (LPS)-binding protein co-receptor, CD14, is involved in pro-inflammatory monocyte activation. The purpose of this investigation was to determine the effects of ex-vivo LPS activation on monocyte subset CD14 and CCR2 expression in post-STEMI individuals with normal and elevated random blood glucose. METHODS: Post-STEMI subjects were identified as normal random glucose (NG, <98 mg/dL, n = 13) or impaired random glucose (IG, ≥98 mg/dL, n = 26) and monocytes were analyzed for non-activated and LPS-activated (1 µg/mL for 4 h) CCR2 and CD14 expression. RESULTS: Non-activated intermediate monocytes from IG showed decreased CD14 expression when compared to NG, which was maintained following LPS-activation. The NG group showed a larger absolute reduction in classical CCR2 expression, leading to a significant difference between NG and IG following LPS-activation. CONCLUSION: Results suggest a heightened response to pro-inflammatory activation in IG following STEMI, which may impair or delay post-STEMI myocardial healing, and thus increase the incidence of chronic heart failure. NIH 1R34HL121402.

Estrogen May Enhance Toll-Like Receptor 4-Induced Inflammatory Pathways in People With HIV: Implications for Transgender Women on Hormone Therapy.

Background: Transgender women (TW) are at increased risk for both human immunodeficiency virus (HIV) and cardiovascular disease (CVD). Antiretroviral therapy-treated HIV has been associated with a two-fold increased risk of CVD, potentially due to dysregulated Toll-like receptor (TLR)-induced immune activation. Use of estrogens in feminizing hormone therapy (FHT) may enhance inflammatory responses and the risk of cardiovascular mortality in TW. Despite this, the immunomodulatory effects of estrogen use in TW with HIV have been inadequately explored. Methods: As an in vitro model for FHT, cryopreserved PBMCs (cryoPBMCs) from HIV negative (HIV-), HIV+ ART-suppressed (HIV+SP), and HIV+ ART-unsuppressed (HIV+USP) cisgender men were cultured overnight in the presence of 17-ß estradiol or 17-α ethinylestradiol with and without the TLR4 agonist LPS or the TLR8 agonist ssPolyU. Monocyte activation (CD69, HLA-DR, CD38) was assessed by flow cytometry. Cytokine levels (IL-6, TNF-α, IL-1ß, and IL-10) were measured in cell culture supernatants by Legendplex. Levels of phosphorylated TLR signaling molecules (JNK, MAPK p38) were assessed by Phosflow. Plasma levels of immune activation biomarkers (LPS-binding protein, monocyte activation markers sCD14 and sCD163, and inflammatory molecules IL-6 and TNF-α receptor I) were measured by ELISA. Results: PBMCs from people with HIV (PWH) produced greater levels of inflammatory cytokines following exposure to LPS or ssPolyU compared to levels from cells of HIV- individuals. While estrogen exposure alone induced mild changes in immune activation, LPS-induced TLR4 activation was elevated with estrogen in cisgender men (CM) with HIV, increasing monocyte activation and inflammatory cytokine production (IL-6, TNF-α). Interestingly, testosterone inhibited LPS-induced cytokine production in CM regardless of HIV status. Plasma markers of immune activation and microbial translocation (e.g., sCD14, sCD163, LPS-binding protein) were generally higher in PWH compared to HIV- CM, and these markers were positively associated with in vitro responsiveness to estrogen and LPS in CM with HIV. Conclusions: Our in vitro data suggest that estrogen exposure may enhance innate immune activation in PWH. Further examination is needed to fully understand the complex interactions of FHT, HIV, and CVD in TW, and determine optimal FHT regimens or supplementary treatments aimed at reducing excess immune activation.

The CD36 and SR-A/CD204 scavenger receptors fine-tune Staphylococcus aureus-stimulated cytokine production in mouse macrophages.

The occurring in SR-A/CD204- or CD36-deficient mice increased susceptibility to infections with Staphylococcus aureus (Sa) had traditionally been ascribed to the impairment of macrophage-mediated phagocytosis, which is, however, inconsistent with low effectiveness of unopsonized Sa killing within macrophages and redundant roles of both receptors in this process. We have found that Sa-stimulated cytokine production in mouse macrophages seems to be exclusively mediated by TLR2, mainly from within endosomes in response to Sa-derived lipoteichoic acid. By driving endocytic trafficking of TLR2 and its ligands through the clathrin-dependent pathway, CD36 and SR-A sensitize macrophages to activation by Sa as well as regulate the type and amount of cytokines produced. Additionally, upon direct Sa binding, both receptors autonomously generate anti-inflammatory signaling. Consequently, the delayed induction of acute inflammation in knockout mice may allow for the initial, uncontrolled multiplication of bacteria, stimulating excessive, septic shock-inducing production of inflammatory cytokines in later stages of infection.

High CD14+ peripheral monocytes expression of ALX/FPR2 and BLT1 in low disease activity and remission status in rheumatoid arthritis: a piltot study.

OBJECTIVES: Specialised pro-resolving mediator (SPM) can dampen the acute inflammation through ERV1, ALX/FPR2 and BLT1 cell receptors and it is conceivable that their expression is dysregulated during chronic inflammation. The aim of this study was to evaluate the expression of ERV1, ALX/FPR2 and BLT1 on peripheral blood (PB) cells from rheumatoid arthritis (RA) patients. METHODS: At baseline, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), clinimetric indexes (28-joint disease activity score (DAS28) and clinical disease activity index (CDAI)), and PB samples were collected from 33 RA patients. Based on DAS28, patients were divided into high-moderate (H-Mo/RA, DAS28≥3.2) and low-remission (L-Rem/RA, DAS28<3.2) disease activity group. Cell membrane expression of ERV1, ALX/FPR2 and BLT1 on CD3pos, CD19pos, CD14pos cells and granulocytes was assessed by multi-parametric flow-cytometry analysis. Nine healthy controls (HC) were also studied. RESULTS: Sixteen H-Mo/RA and 17 L-Rem/RA patients were identified. The percentage of BLT1posCD14pos cells was significantly higher in L-Rem/RA (47.17%) than in H-Mo/RA (14.27%) group (p=0.005). Likewise, the percentage ALX/FPR2pos CD14pos cells was significantly higher in L-Rem/RA (33.02%) than in H-Mo/RA (8.77%; p=0.04) patients. An inverse correlation between BLT1posCD14pos cell percentage and DAS28 (r=-0.42; p=0.01), CDAI (r=-0.51; p=0.003), ESR (r=-0.39; p=0.025) and CRP (r=-0.40; p=0.02), ALX/FPR2posCD14pos cell percentage and CRP (r=-0.39; p=0.02) were found, while SPM-receptors mean fluorescence intensity (MFI) was not different between HC and L-Rem/RA patients. CONCLUSIONS: ALX/FPR2 and BLT1 receptors expression mirrors RA disease activity arising as potential biomarkers of inflammatory regulation.

Clinical and prognostic significance of CD14 (+) HLA-DR (-/low) myeloid-derived suppressor cells in patients with hepatocellular carcinoma received transarterial radioembolization with Yttrium-90.

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. For unresectable HCC, transarterial radioembolization (TARE) with Yttrium-90 is a widely used treatment. The aim of this study was to investigate whether monocytic myeloid-derived suppressor cells (M-MDSC) and CD39+ T cells can be non-invasive predictive biomarkers of radiological response and prognosis in patients with HCC treated with TARE. This study was conducted on 39 patients with HCC who were treated with TARE between August 2018 and December 2019 and the control group consisted of 23 healthy volunteers. CD4+, CD8+, CD39+ T cells, Natural killer (NK) cells, myeloid cells (MC) and M-MDSC parameters are examined in the course of TARE treatment with student t test and Kaplan-Meier method. There were statistically significant differences in M-MDSC, CD39+ T cells and MC values between healthy controls and HCC patients. A statistically significant difference was found in M-MDSC and CD4+ T cells values in the HCC patient group who responded to the treatment compared to those who did not. Survival analysis found that patients with lower frequencies (under 3.81%) of M-MDSC showed more prominent differences of overall survival (OS) compared to patients with all high groups. We found that M-MDSC in the peripheral blood might be a useful non-invasive biomarker to predict OS. We have shown for the first time that M-MDSC is correlated with treatment response in HCC patients treated with TARE. Additionally, we have found that the percentage of CD39+ T cells is high in HCC patients and these cells are positively correlated with M-MDSC.

Evolution-inspired redesign of the LPS receptor caspase-4 into an interleukin-1ß converting enzyme.

Innate immune signaling pathways comprise multiple proteins that promote inflammation. This multistep means of information transfer suggests that complexity is a prerequisite for pathway design. Herein, we test this hypothesis by studying caspases that regulate inflammasome-dependent inflammation. Several caspases differ in their ability to recognize bacterial LPS and cleave interleukin-1ß (IL-1ß). No caspase is known to contain both activities, yet distinct caspases with complementary activities bookend an LPS-induced pathway to IL-1ß cleavage. Using caspase-1/4 hybrid proteins present in canines as a guide, we identified molecular determinants of IL-1ß cleavage specificity within caspase-1. This knowledge enabled the redesign of human caspase-4 to operate as a one-protein signaling pathway, which intrinsically links LPS detection to IL-1ß cleavage and release, independent of inflammasomes. We identified caspase-4 homologues in multiple carnivorans which display the activities of redesigned human caspase-4. These findings illustrate natural signaling pathway diversity and highlight how multistep innate immune pathways can be condensed into a single protein.

Ovine CD14- an Immune Response Gene Has a Role Against Gastrointestinal Nematode Haemonchus contortus-A Novel Report.

CD14 (also known as the monocyte differentiation antigen) is an important immune response gene known to be primarily responsible for innate immunity against bacterial pathogens, and as a pattern recognition receptor (PRR), binds with LPS (endotoxin), lipoproteins, and lipotechoic acid of bacteria. So far very limited work has been conducted in parasitic immunology. In the current study, we reported the role of CD14 in parasitic immunology in livestock species (sheep) for the first time. Ovine CD14 is characterized as a horse-shoe shaped bent solenoid with a hydrophobic amino-terminal pocket for CD14 along with domains. High mutation frequency was observed, out of total 41 mutations identified, 23 mutations were observed to be thermodynamically unstable and 11 mutations were deleterious in nature, causing major functional alteration of important domains of CD14, an indication of variations in individual susceptibility for sheep against Haemonchus contortus infestations. In silico studies with molecular docking reveal a role of immune response against Haemonchus contortus in sheep, which is later confirmed with experimental evidence through differential mRNA expression analysis for sheep, which revealed better expression of CD14 in Haemonchus contortus infected sheep compared to that of non-infected sheep. We confirmed the above findings with supportive evidence through haematological and biochemical analyses. Phylogenetic analysis was conducted to assess the evolutionary relationship with respect to humans and it was observed that sheep may well be used as model organisms due to better genetic closeness compared to that of mice.

Leishmania infantum (syn. L. chagasi) parasites affect the release of soluble CD14 by infected macrophages.

Functionally, cluster of differentiation 14 (CD14) is a co-receptor of the complex formed by lipopolysaccharide (LPS) and LPS-binding protein expressed on the membrane of a variety of cells. However, CD14 can be shed from the cell membrane into the circulation as soluble CD14 (sCD14) upon cell activation. Previously, our group reported that elevated sCD14 serum levels were associated with the clinical and laboratory findings in the context of visceral leishmaniasis (VL), but not in the context of LPS stimulation or bacterial infection. In the present study, we investigated the secretion dynamics of sCD14 in the context of Leishmania infantum (syn. L. chagasi) in vitro infection. Macrophages from treated VL patients and delayed-type hypersensitivity positive (DTH+) subjects were infected with L. infantum (syn. L. chagasi) promastigotes, and the infection index was evaluated (number of amastigotes per 100 infected macrophages). Additionally, the levels of sCD14, Inteleukin (IL)10, IL-6 and tumour necrosis factor alpha (TNF-α) were measured in the culture supernatants using the Luminex assay. Interestingly, the release of sCD14 was inversely correlated with the L. infantum (syn. L. chagasi) infection index. Of note, the release of sCD14 was upregulated and downregulated in the context of infected macrophages from DTH+ subjects and treated VL patients, respectively. Additionally, we also observed that the levels of sCD14 in the culture supernatants were positively correlated with the levels of TNF-α, IL-6 and IL-10. Therefore, our data suggest that macrophages from treated VL patients and DTH+ subjects respond differently to L. infantum (syn. L. chagasi) infection in the context of the release of sCD14; therefore, the release of sCD14 may be associated with the outcome of VL.

Tree-aggregated predictive modeling of microbiome data.

Modern high-throughput sequencing technologies provide low-cost microbiome survey data across all habitats of life at unprecedented scale. At the most granular level, the primary data consist of sparse counts of amplicon sequence variants or operational taxonomic units that are associated with taxonomic and phylogenetic group information. In this contribution, we leverage the hierarchical structure of amplicon data and propose a data-driven and scalable tree-guided aggregation framework to associate microbial subcompositions with response variables of interest. The excess number of zero or low count measurements at the read level forces traditional microbiome data analysis workflows to remove rare sequencing variants or group them by a fixed taxonomic rank, such as genus or phylum, or by phylogenetic similarity. By contrast, our framework, which we call trac (tree-aggregation of compositional data), learns data-adaptive taxon aggregation levels for predictive modeling, greatly reducing the need for user-defined aggregation in preprocessing while simultaneously integrating seamlessly into the compositional data analysis framework. We illustrate the versatility of our framework in the context of large-scale regression problems in human gut, soil, and marine microbial ecosystems. We posit that the inferred aggregation levels provide highly interpretable taxon groupings that can help microbiome researchers gain insights into the structure and functioning of the underlying ecosystem of interest.

Changes in the Subpopulation Composition and Phagocytic Activity of Monocytes in Patients with Kidney Cancer under the Influence of Metabolites In Vitro.

We studied changes in the subpopulation composition and phagocytic activity of monocytes in patients with kidney cancer under the influence of metabolites of the tumor microenvironment in vitro (lactate, ADP, and glutamate). Incubation with metabolites caused similar shifts in the monocyte subsets in kidney cancer patients (an increase in the relative content of classical CD14++CD16- monocytes and a decrease in the content of the fraction of intermediate CD14++CD16+ monocytes), but different changes in their phagocytic activity. The regulatory effect of metabolites on cells is realized by various mechanisms: receptor, metabolic, and epigenomic. The reactions of monocytes to metabolites in vitro confirm the existence of a distant metabolic effect of the tumor on blood cells that should be taken into account when developing new immunotherapeutic methods.

Transcriptomic Analysis of Peripheral Monocytes upon Fingolimod Treatment in Relapsing Remitting Multiple Sclerosis Patients.

Fingolimod (FTY), a second-line oral drug approved for relapsing remitting Multiple Sclerosis (RRMS) acts in preventing lymphocyte migration outside lymph nodes; moreover, several lines of evidence suggest that it also inhibits myeloid cell activation. In this study, we investigated the transcriptional changes induced by FTY in monocytes in order to better elucidate its mechanism of action. CD14+ monocytes were collected from 24 RRMS patients sampled at baseline and after 6 months of treatment and RNA profiles were obtained through next-generation sequencing. We conducted pathway and sub-paths analysis, followed by centrality analysis of cell-specific interactomes on differentially expressed genes (DEGs). We investigated also the predictive role of baseline monocyte transcription profile in influencing the response to FTY therapy. We observed a marked down-regulation effect (60 down-regulated vs. 0 up-regulated genes). Most of the down-regulated DEGs resulted related with monocyte activation and migration like IL7R, CCR7 and the Wnt signaling mediators LEF1 and TCF7. The involvement of Wnt signaling was also confirmed by subpaths analyses. Furthermore, pathway and network analyses showed an involvement of processes related to immune function and cell migration. Baseline transcriptional profile of the HLA class II gene HLA-DQA1 and HLA-DPA1 were associated with evidence of disease activity after 2 years of treatment. Our data support the evidence that FTY induces major transcriptional changes in monocytes, mainly regarding genes involved in cell trafficking and immune cell activation. The baseline transcriptional levels of genes associated with antigen presenting function were associated with disease activity after 2 years of FTY treatment.

Monocyte subset distribution and surface expression of HLA-DR and CD14 in patients after cardiopulmonary resuscitation.

Systemic inflammation is a major feature of the post-cardiac arrest syndrome. The three monocyte subpopulations are thought to play an important role in this inflammatory state because they are endowed with numerous pattern recognition receptors, such as CD14, that have been associated with ischemia-reperfusion injury. By contrast, an exaggerated antiinflammatory response has also been described following cardiac arrest, which may be mediated by downregulation of antigen presentation receptor HLA-DR. We report the composition of monocyte subpopulations and the expression of CD14 and HLA-DR following cardiac arrest. Blood specimens were collected from 32 patients at three timepoints in the first 48 h after cardiac arrest. Monocyte subset composition was determined by flow cytometry based on the expression of CD14, CD16, and HLA-DR. Monocyte subset composition and the expression of CD14 and HLA-DR were correlated with patient outcomes. The results were compared to 19 patients with coronary artery disease. Cardiac arrest patients showed a significant decline in the percentage of nonclassical monocytes. Monocyte CD14 expression was upregulated after 24 h and correlated with the time to return of spontaneous circulation. Downregulation of HLA-DR expression was observed mainly among classical monocytes and significantly correlated with the dose of norepinephrine used to treat shock. Downregulation of HLA-DR among nonclassical and intermediate monocytes was significantly associated with disease severity. Our data demonstrate the disturbance of monocyte subset composition with a significant decline in nonclassical monocytes at an early stage following cardiac arrest. Our findings suggest the simultaneous presence of hyperinflammation, as evidenced by upregulation of CD14, and monocyte deactivation, characterized by downregulation of HLA-DR. The extent of monocyte deactivation was significantly correlated with disease severity.

The "Intermediate" CD14 + CD16 + monocyte subpopulation plays a role in IVIG responsiveness of children with Kawasaki disease.

BACKGROUND: Kawasaki disease (KD) is an acute, self-limited febrile illness of unknown cause. Intravenous immunoglobulin (IVIG)-resistance are related to greater risk for permanent cardiac complications. We aimed to determine the correlation between monocytes and the phenotype of KD in relation to IVIG responsiveness in children. MATERIALS AND METHODS: The study cohort included 62 patients who were diagnosed with KD, 20 non febrile healthy controls (NFC), and 15 other febrile controls (OFC). In all enrolled patients, blood was taken at least 4 times and laboratory tests were performed. In addition, subtypes of monocytes were characterized via flow cytometry. RESULTS: The numbers of intermediate monocytes were significantly lower in IVIG-resistant group compared to IVIG-responsive group before IVIG infusion (p < 0.0001). After infusion, intermediate monocytes decreased in the responsive group, while a trend of increase was observed in the resistant group. Only intermediate monocytes were significant in logistic regression with adjusted OR of 0.001 and p value of 0.03. CONCLUSIONS: CD14 + CD16 + intermediate monocyte may play an important role in IVIG responsiveness among KD children. Low starting levels of intermediate monocytes, followed by a dramatic increase post-IVIG infusion during acute phase of KD are associated with IVIG-resistance. Functional studies on intermediate monocyte may help to reveal the pathophysiology.

COVID-19 and RA share an SPP1 myeloid pathway that drives PD-L1+ neutrophils and CD14+ monocytes.

We explored the potential link between chronic inflammatory arthritis and COVID-19 pathogenic and resolving macrophage pathways and their role in COVID-19 pathogenesis. We found that bronchoalveolar lavage fluid (BALF) macrophage clusters FCN1+ and FCN1+SPP1+ predominant in severe COVID-19 were transcriptionally related to synovial tissue macrophage (STM) clusters CD48hiS100A12+ and CD48+SPP1+ that drive rheumatoid arthritis (RA) synovitis. BALF macrophage cluster FABP4+ predominant in healthy lung was transcriptionally related to STM cluster TREM2+ that governs resolution of synovitis in RA remission. Plasma concentrations of SPP1 and S100A12 (key products of macrophage clusters shared with active RA) were high in severe COVID-19 and predicted the need for Intensive Care Unit transfer, and they remained high in the post-COVID-19 stage. High plasma levels of SPP1 were unique to severe COVID-19 when compared with other causes of severe pneumonia, and IHC localized SPP1+ macrophages in the alveoli of COVID-19 lung. Investigation into SPP1 mechanisms of action revealed that it drives proinflammatory activation of CD14+ monocytes and development of PD-L1+ neutrophils, both hallmarks of severe COVID-19. In summary, COVID-19 pneumonitis appears driven by similar pathogenic myeloid cell pathways as those in RA, and their mediators such as SPP1 might be an upstream activator of the aberrant innate response in severe COVID-19 and predictive of disease trajectory including post-COVID-19 pathology.

Activated CD4+ T cells and CD14hiCD16+ monocytes correlate with antibody response following influenza virus infection in humans.

The failure to mount an antibody response following viral infection or seroconversion failure is a largely underappreciated and poorly understood phenomenon. Here, we identified immunologic markers associated with robust antibody responses after influenza virus infection in two independent human cohorts, SHIVERS and FLU09, based in Auckland, New Zealand and Memphis, Tennessee, USA, respectively. In the SHIVERS cohort, seroconversion significantly associates with (1) hospitalization, (2) greater numbers of proliferating, activated CD4+ T cells, but not CD8+ T cells, in the periphery during the acute phase of illness, and (3) fewer inflammatory monocytes (CD14hiCD16+) by convalescence. In the FLU09 cohort, fewer CD14hiCD16+ monocytes during early illness in the nasal mucosa were also associated with the generation of influenza-specific mucosal immunoglobulin A (IgA) and IgG antibodies. Our study demonstrates that seroconversion failure after infection is a definable immunological phenomenon, associated with quantifiable cellular markers that can be used to improve diagnostics, vaccine efficacy, and epidemiologic efforts.

Expression of VEGFA-mRNA in classical and MSX2-mRNA in non-classical monocytes in patients with spondyloarthritis is associated with peripheral arthritis.

Spondyloarthritis (SpA) is characterized by chronic inflammation and structural damage involving spine and peripheral joints. Monocytes, as part of innate immune system, following migration into affected tissue, may play a role in the pathogenesis of SpA. Here, potential associations between osteogenesis-linked gene expression profile in particular monocyte subpopulations and clinical signs of SpA were investigated. The 20 patients with axial and 16 with peripheral SpA were enrolled in the study. Monocyte subpopulations (classical-CD14++CD16-, intermediate-CD14++CD16+ and non-classical-CD14+CD16++) were isolated from blood using flow cytometry and gene expression analysis was performed using real-time PCR method and TaqMan Array, Human Osteogenesis, Fast 96-well plates. Next, the characteristic clinical features shared by axial and peripheral SpA were analyzed in the context of the expression of selected genes in the three subpopulations of monocytes. We demonstrated that expression of VEGFA in classical and MSX2 in non-classical monocytes were associated with the number of swollen and painful peripheral joints of SpA patients. We conclude that monocytes may contribute to the development of peripheral arthritis in SpA patients. This might be possible through subpopulation specific effects, linking number of inflamed joints with expression of VEGFA in classical monocytes and MSX2 in non-classical monocytes.

Th17 Immunity in the Colon Is Controlled by Two Novel Subsets of Colon-Specific Mononuclear Phagocytes.

Intestinal immunity is coordinated by specialized mononuclear phagocyte populations, constituted by a diversity of cell subsets. Although the cell subsets constituting the mononuclear phagocyte network are thought to be similar in both small and large intestine, these organs have distinct anatomy, microbial composition, and immunological demands. Whether these distinctions demand organ-specific mononuclear phagocyte populations with dedicated organ-specific roles in immunity are unknown. Here we implement a new strategy to subset murine intestinal mononuclear phagocytes and identify two novel subsets which are colon-specific: a macrophage subset and a Th17-inducing dendritic cell (DC) subset. Colon-specific DCs and macrophages co-expressed CD24 and CD14, and surprisingly, both were dependent on the transcription factor IRF4. Novel IRF4-dependent CD14+CD24+ macrophages were markedly distinct from conventional macrophages and failed to express classical markers including CX3CR1, CD64 and CD88, and surprisingly expressed little IL-10, which was otherwise robustly expressed by all other intestinal macrophages. We further found that colon-specific CD14+CD24+ mononuclear phagocytes were essential for Th17 immunity in the colon, and provide definitive evidence that colon and small intestine have distinct antigen presenting cell requirements for Th17 immunity. Our findings reveal unappreciated organ-specific diversity of intestine-resident mononuclear phagocytes and organ-specific requirements for Th17 immunity.

The Innate Immune Response Characterizes Posterior Reversible Encephalopathy Syndrome.

While posterior reversible encephalopathy syndrome (PRES) is often characterized by an inflammatory cerebrospinal-fluid (CSF) profile, knowledge of immune cell patterns in PRES is lacking. Thus, we retrospectively characterized CSF and peripheral blood (PB) from 15 PRES patients, which we analyzed by multidimensional flow cytometry (FC). Results were compared to 72 controls, as well as to 9 patients with progressive multifocal leukoencephalopathy (PML, as a relevant differential diagnosis) and 15 multiple sclerosis patients (MS, as a classical neuroinflammatory disorder), respectively. Total protein level in CSF from PRES patients was elevated compared to that in controls, but not to MS and PML. In-depth FC analysis revealed no differences for adaptive immune cells (B cells, plasma cells, CD4+, and CD8+ T cells) in PB or CSF of PRES compared to controls. In contrast, we observed alterations of the adaptive immune response in CSF of PML and MS compared to PRES, indicating that the adaptive immune response is not a driver of disease in PRES. Indeed, PRES was characterized by an innate immune response with CD14++/CD16+ (intermediate) monocytes elevated in PB and CSF, while CD14++/CD16- (classical) monocytes were decreased in PB from PRES patients as compared to controls. Levels of CD14++/CD16+ monocytes correlated with the duration of hospital stay as a surrogate marker for disease severity in PRES patients. Our findings argue for a role of innate rather than adaptive immunity in the pathophysiology of PRES. The observed shift in monocyte subsets might provide valuable diagnostic clues for the clinical management of these patients.