Correlation analysis of intracellular and secreted cytokines via the generalized integrated mean fluorescence intensity

Immunologic Profiling of CSF in Subarachnoid Neurocysticercosis Reveals Specific Interleukin-10-Producing Cell Populations During Treatment

BACKGROUND AND OBJECTIVES

Subarachnoid neurocysticercosis (SANCC) is the most severe form of Taenia solium CNS infection and accounts for the majority of neurocysticercosis-associated mortality. Inflammation is important in the treatment of SANCC because overactivity can lead to serious complications, but excessive suppression may be counterproductive toward parasite eradication. A relative abundance of CSF IL-10 to IL-12 has been associated with increased treatment duration for patients with SANCC, suggesting that IL-10 plays an important role in this disease process. To better understand SANCC immunology and the major sources of IL-10 during anthelmintic treatment, we took an unbiased and comprehensive approach to phenotype the immune cell populations in the CSF and peripheral blood of patients with SANCC.

METHODS

Eight samples of CSF cells collected from 5 patients with SANCC during treatment were evaluated using single-cell RNA sequencing. Matched CSF and peripheral blood mononuclear cells from 4 patients were assessed using flow cytometry. Staining for extracellular and intracellular markers allowed for the characterization of IL-10-producing T cells.

RESULTS

The CSF during SANCC contains a diversity of immune cell populations including multiple myeloid and lymphoid populations. Although there were changes in the composition of CSF cells during treatment, the largest population at both early and late time points was CD4+ T cells. Within this population, we identified 3 sources of IL-10 unique to SANCC CSF compared with controls: natural regulatory T cells (nTregs), induced regulatory T cells (iTregs), and Th17 cells. The abundance and phenotype of these IL-10-producing populations differed between CSF and blood in patients with SANCC, but iTregs were the single most productive population in the CSF. During treatment, these IL-10 producers persisted in consistent proportions despite decreases in parasite antigen over time.

DISCUSSION

This profile of immune cell populations in the CSF provides a comprehensive blueprint of the local and systemic immunology associated with SANCC. The identification of IL-10-producing cells in the CSF and peripheral blood deepens our understanding of the immunosuppressive phenotype that deters SANCC treatment success. Finally, the discovery that these IL-10 producers persist throughout treatment highlights the endurance of these populations in the CNS.

Shedding Light on Intracellular Proteins using Flow Cytometry

Intracellular protein abundance is routinely measured in mammalian cells using population-based techniques such as western blotting which fail to capture single cell protein levels or using fluorescence microscopy which is although suitable for single cell protein detection but not for rapid analysis of large no. of cells. Flow cytometry offers rapid, high-throughput, multiparameter-based analysis of intracellular protein expression in statistically significant no. of cells at single cell resolution. In past few decades, customized assays have been developed for flow cytometric detection of specific intracellular proteins. This review discusses the scope of flow cytometry for intracellular protein detection in mammalian cells along with specific applications. Technological advancements to overcome the limitations of traditional flow cytometry for the same are also discussed.

Alteration of gene expression and protein solubility of the PI 5-phosphatase SHIP2 are correlated with Alzheimer's disease pathology progression

A recent large genome-wide association study has identified EGFR (encoding the epidermal growth factor EGFR) as a new genetic risk factor for late-onset AD. SHIP2, encoded by INPPL1, is taking part in the signalling and interactome of several growth factor receptors, such as the EGFR. While INPPL1 has been identified as one of the most significant genes whose RNA expression correlates with cognitive decline, the potential alteration of SHIP2 expression and localization during the progression of AD remains largely unknown. Here we report that gene expression of both EGFR and INPPL1 was upregulated in AD brains. SHIP2 immunoreactivity was predominantly detected in plaque-associated astrocytes and dystrophic neurites and its increase was correlated with amyloid load in the brain of human AD and of 5xFAD transgenic mouse model of AD. While mRNA of INPPL1 was increased in AD, SHIP2 protein undergoes a significant solubility change being depleted from the soluble fraction of AD brain homogenates and co-enriched with EGFR in the insoluble fraction. Using FRET-based flow cytometry biosensor assay for tau-tau interaction, overexpression of SHIP2 significantly increased the FRET signal while siRNA-mediated downexpression of SHIP2 significantly decreased FRET signal. Genetic association analyses suggest that some variants in INPPL1 locus are associated with the level of CSF pTau. Our data support the hypothesis that SHIP2 is an intermediate key player of EGFR and AD pathology linking amyloid and tau pathologies in human AD.

Aminopeptidase N/CD13 Crosslinking Promotes the Activation and Membrane Expression of Integrin CD11b/CD18

The β2 integrin CD11b/CD18, also known as complement receptor 3 (CR3), and the moonlighting protein aminopeptidase N (CD13), are two myeloid immune receptors with overlapping activities: adhesion, migration, phagocytosis of opsonized particles, and respiratory burst induction. Given their common functions, shared physical location, and the fact that some receptors can activate a selection of integrins, we hypothesized that CD13 could induce CR3 activation through an inside-out signaling mechanism and possibly have an influence on its membrane expression. We revealed that crosslinking CD13 on the surface of human macrophages not only activates CR3 but also influences its membrane expression. Both phenomena are affected by inhibitors of Src, PLCγ, Syk, and actin polymerization. Additionally, after only 10 min at 37 °C, cells with crosslinked CD13 start secreting pro-inflammatory cytokines like interferons type 1 and 2, IL-12p70, and IL-17a. We integrated our data with a bioinformatic analysis to confirm the connection between these receptors and to suggest the signaling cascade linking them. Our findings expand the list of features of CD13 by adding the activation of a different receptor via inside-out signaling. This opens the possibility of studying the joint contribution of CD13 and CR3 in contexts where either receptor has a recognized role, such as the progression of some leukemias.

Six-month immune responses to mRNA-1273 vaccine in combination antiretroviral therapy treated late presenter people with HIV according to previous SARS-CoV-2 infection

OBJECTIVE

Immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines in people with HIV (PWH) with a history of late presentation (LP) and their durability have not been fully characterized.

DESIGN

In this prospective, longitudinal study, we sought to assess T-cell and humoral responses to SARS-CoV-2 mRNA vaccination up to 6 months in LP-PWH on effective combination antiretroviral therapy (cART) as compared to HIV-negative healthcare workers (HCWs), and to evaluate whether previous SARS-CoV-2 infection modulates immune responses to vaccine.

METHODS

SARS-CoV-2 spike (S)-specific T-cell responses were determined by two complementary flow cytometry methodologies, namely activation-induced marker (AIM) assay and intracellular cytokine staining (ICS), whereas humoral responses were measured by ELISA [anti-receptor binding domain (RBD) antibodies) and receptor-binding inhibition assay (spike-ACE2 binding inhibition activity), before vaccination (T0), 1 month (T1) and 5 months (T2) after the second dose.

RESULTS

LP-PWH showed at T1 and T2 significant increase of: S-specific memory and circulating T follicular helper (cTfh) CD4 + T cells; polyfunctional Th1-cytokine (IFN-γ, TNF-α, IL-2)- and Th2-cytokine (IL-4)-producing S-specific CD4 + T cells; anti-RBD antibodies and spike-ACE2 binding inhibition activity. Immune responses to vaccine in LP-PWH were not inferior to HCWs overall, yet S-specific CD8 + T cells and spike-ACE2 binding inhibition activity correlated negatively with markers of immune recovery on cART. Interestingly, natural SARS-CoV-2 infection, while able to sustain S-specific antibody response, seems less efficacious in inducing a T-cell memory and in boosting immune responses to vaccine, possibly reflecting an enduring partial immunodeficiency.

CONCLUSIONS

Altogether, these findings support the need for additional vaccine doses in PWH with a history of advanced immune depression and poor immune recovery on effective cART.

Influence of Testosterone in Neglected Tropical Diseases: Clinical Aspects in Leprosy and In Vitro Experiments in Leishmaniasis

Neglected tropical diseases encompass a group of chronic and debilitating infectious diseases that primarily affect marginalized populations. Among these diseases, leprosy and leishmaniasis are endemic in numerous countries and can result in severe and disfiguring manifestations. Although there have been reports indicating a higher incidence of leprosy and leishmaniasis in males, the underlying factors contributing to this observation remain unclear. Therefore, the objective of this study was to examine both clinical and experimental evidence regarding the role of testosterone in leprosy and leishmaniasis. A prospective clinical study was conducted to compare the clinical forms of leprosy and assess circulating testosterone levels. Additionally, the impact of testosterone on Leishmania amazonensis-infected macrophages was evaluated in vitro. The findings demonstrated that serum testosterone levels were higher in women with leprosy than in the control group, irrespective of the multi- or pauci-bacillary form of the disease. However, no differences in testosterone levels were observed in men when comparing leprosy patients and controls. Interestingly, increasing doses of testosterone in macrophages infected with L. amazonensis resulted in a higher proportion of infected cells, decreased CD40 expression on the cell surface, elevated expression of SOCS1, and decreased expression of IRF5. These findings provide biological evidence to support the influence of testosterone on intracellular infections, though the interpretation of clinical evidence remains limited.

Mucosal immunization with lipopeptides derived from conserved regions of SARS-CoV-2 antigens induce robust cellular and cross-variant humoral immune responses in mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, has infected >600 million people in the ongoing global pandemic. Several variants of the SARS-CoV-2 have emerged in the last >2 years, challenging the continued efficacy of current COVID vaccines. Therefore, there is a crucial need to investigate a highly cross-protective vaccine effective against variants of SARS-CoV-2. In this study, we examined seven lipopeptides derived from highly conserved, immunodominant epitopes from the S, N, and M proteins of SARS-CoV-2, that are predicted to contain epitopes for clinically protective B cells, helper T cells (TH) and cytotoxic T cells (CTL). Intranasal immunization of mice with most of the lipopeptides led to significantly higher splenocyte proliferation and cytokine production, mucosal and systemic antibody responses, and induction of effector B and T lymphocytes in both lungs and spleen, compared to immunizations with the corresponding peptides without lipid. Immunizations with Spike-derived lipopeptides led to cross-reactive IgG, IgM and IgA responses against Alpha, Beta, Delta, and Omicron Spike proteins as well as neutralizing antibodies. These studies support their potential for development as components of a cross-protective SARS-CoV-2 vaccine.

Efficacy and Synergy with Cisplatin of an Adenovirus Vectored Therapeutic E1E2E6E7 Vaccine against HPV Genome-Positive C3 Cancers in Mice

Human papillomavirus (HPV) infections are the main cause of cervical and oropharyngeal cancers. As prophylactic vaccines have no curative effect, an efficient therapy would be highly desired. Most therapeutic vaccine candidates target only a small subset of HPV regulatory proteins, namely, E6 and E7, and are therefore restricted in the breadth of their immune response. However, research has suggested E1 and E2 as promising targets to fight HPV+ cancer. Here, we report the design of adenoviral vectors efficiently expressing HPV16 E1 and E2 in addition to transformation-deficient E6 and E7. Vaccination elicited vigorous CD4+ and CD8+ T-cell responses against all encoded HPV16 proteins in outbred mice and against E1 and E7 in C57BL/6 mice. Therapeutic vaccination of C3 tumor-bearing mice led to significantly reduced tumor growth and enhanced survival for both small and established tumors. Tumor biopsies revealed increased numbers of tumor-infiltrating CD8+ T cells in treated mice. Cisplatin enhanced the effect of therapeutic vaccination, accompanied by enhanced infiltration of dendritic cells into the tumor. CD8+ T cells were identified as effector cells in T-cell depletion assays, seemingly under regulation by FoxP3+CD4+ regulatory T cells. Finally, therapeutic vaccination with Ad-Ii-E1E2E6E7 exhibited significantly enhanced survival compared with vaccination with two peptides each harboring a known E6/E7 epitope. We hypothesize that this difference could be due to the induction of additional T-cell responses against E1. These results support the use of this novel vaccine candidate targeting an extended set of antigens (Ad-Ii-E1E2E6E7), in combination with cisplatin, as an advanced strategy to combat HPV+ cancers.

TOLLIP Optimizes Dendritic Cell Maturation to Lipopolysaccharide and Mycobacterium tuberculosis

TOLLIP is a central regulator of multiple innate immune signaling pathways, including TLR2, TLR4, IL-1R, and STING. Human TOLLIP deficiency, regulated by single-nucleotide polymorphism rs5743854, is associated with increased tuberculosis risk and diminished frequency of bacillus Calmette-Guérin vaccine-specific CD4+ T cells in infants. How TOLLIP influences adaptive immune responses remains poorly understood. To understand the mechanistic relationship between TOLLIP and adaptive immune responses, we used human genetic and murine models to evaluate the role of TOLLIP in dendritic cell (DC) function. In healthy volunteers, TOLLIP single-nucleotide polymorphism rs5743854 G allele was associated with decreased TOLLIP mRNA and protein expression in DCs, along with LPS-induced IL-12 secretion in peripheral blood DCs. As in human cells, LPS-stimulated Tollip -/- bone marrow-derived murine DCs secreted less IL-12 and expressed less CD40. Tollip was required in lung and lymph node-resident DCs for optimal induction of MHC class II and CD40 expression during the first 28 d of Mycobacterium tuberculosis infection in mixed bone marrow chimeric mice. Tollip -/- mice developed fewer M. tuberculosis-specific CD4+ T cells after 28 d of infection and diminished responses to bacillus Calmette-Guérin vaccination. Furthermore, Tollip -/- DCs were unable to optimally induce T cell proliferation. Taken together, these data support a model where TOLLIP-deficient DCs undergo suboptimal maturation after M. tuberculosis infection, impairing T cell activation and contributing to tuberculosis susceptibility.

Successive Site Translocating Inoculation Improved T Cell Responses Elicited by a DNA Vaccine Encoding SARS-CoV-2 S Protein

A variety of methods have been explored to increase delivery efficiencies for DNA vaccine. However, the immunogenicity of DNA vaccines has not been satisfactorily improved. Unlike most of the previous attempts, we provided evidence suggesting that changing the injection site successively (successively site-translocated inoculation, SSTI) could significantly enhance the immunogenicity of DNA vaccines in a previous study. To simplify the strategy and to evaluate its impact on candidate SARS-CoV-2 vaccines, we immunized mice with either a SARS-CoV-2 spike-based DNA vaccine or a spike protein subunit vaccine via three different inoculation strategies. Our data demonstrated that S protein specific antibody responses elicited by the DNA vaccine or the protein subunit vaccine showed no significant difference among different inoculation strategies. Of interest, compared with the conventional site fixed inoculation (SFI), both successive site-translocating inoculation (SSTI) and the simplified translocating inoculation (STI) strategy improved specific T cell responses elicited by the DNA vaccine. More specifically, the SSTI strategy significantly improved both the monofunctional (IFN-γ+IL-2-TNF-α-CD8+) and the multifunctional (IFN-γ+IL-2-TNF-α+CD8+, IFN-γ+IL-2-TNF-α+CD4+, IFN-γ+IL-2+TNF-α+CD4+) T cell responses, while the simplified translocating inoculation (STI) strategy significantly improved the multifunctional CD8+ (IFN-γ+IL-2-TNF-α+CD8+, IFN-γ+IL-2+TNF-α+CD8+) and CD4+ (IFN-γ+IL-2-TNF-α+CD4+, IFN-γ+IL-2+TNF-α+CD4+) T cell responses. The current study confirmed that changing the site of intra muscular injection can significantly improve the immunogenicity of DNA vaccines.

Considerations for user consultation in a flow cytometry shared resource laboratory

User consultation is an essential first step in assuring high-quality flow cytometric data. A central challenge to shared resource laboratory (SRL) staff is how to best guide new and current users to meet each projects' needs. One solution to this challenge is to follow a standard user consultation platform addressing all critical steps between the conception of the experiment and the actual acquisition of samples. Here we describe considerations to help an SRL understand the researcher's goals and how best the SRL staff can provide expert advice in a structured manner. User consultation has an educational nature, informing users about current best practices in cytometry that apply to their specific utilization. A consultation report also improves communication between the SRL, principal investigator, and lab members of the collaborating researcher. Development of best SRL practices is spearheaded by the ISAC SRL committee and this communication sets the foundation to initiate such report for user consultation. Implementation of best practices during user consultation will improve rigor and reproducibility in cytometry.

Development of novel reagents to chicken FLT3, XCR1 and CSF2R for the identification and characterization of avian conventional dendritic cells

Conventional dendritic cells (cDC) are bone marrow-derived immune cells that play a central role in linking innate and adaptive immunity. cDCs efficiently uptake, process and present antigen to naïve T cells, driving clonal expansion of antigen-specific T-cell responses. In chicken, vital reagents are lacking for the efficient and precise identification of cDCs. In this study, we have developed several novel reagents for the identification and characterization of chicken cDCs. Chicken FLT3 cDNA was cloned and a monoclonal antibody to cell surface FLT3 was generated. This antibody identified a distinct FLT3^HI splenic subset which lack expression of signature markers for B cells, T cells or monocyte/macrophages. By combining anti-FLT3 and CSF1R-eGFP transgenic expression, three major populations within the mononuclear phagocyte system were identified in the spleen. The cDC1 subset of mammalian cDCs express the chemokine receptor XCR1. To characterize chicken cDCs, a synthetic chicken chemokine (C motif) ligand (XCL1) peptide conjugated to Alexa Fluor 647 was developed (XCL1^AF647 ). Flow cytometry staining of XCL1^AF647 on splenocytes showed that all chicken FLT3^HI cells exclusively express XCR1, supporting the hypothesis that this population comprises bona fide chicken cDCs. Further analysis revealed that chicken cDCs expressed CSF1R but lacked the expression of CSF2R. Collectively, the cell surface phenotypes of chicken cDCs were partially conserved with mammalian XCR1⁺ cDC1, with distinct differences in CSF1R and CSF2R expression compared with mammalian orthologues. These original reagents allow the efficient identification of chicken cDCs to investigate their important roles in the chicken immunity and diseases.

TNF-α Carried by Plasma Extracellular Vesicles Predicts Knee Osteoarthritis Progression

Objectives

To identify plasma extracellular vesicles (EVs) associated with radiographic knee osteoarthritis (OA) progression.

Methods

EVs of small (SEV), medium (MEV) and large (LEV) sizes from plasma of OA participants (n=30) and healthy controls (HCs, n=22) were profiled for surface markers and cytokine cargo by high-resolution flow cytometry. The concentrations of cytokines within (endo-) and outside (exo-) EVs were quantified by multiplex ELISA. EV associations with knee radiographic OA (rOA) progression were assessed by multivariable linear regression (adjusted for baseline clinical variables of age, gender, BMI and OA severity) and receiver operating characteristic (ROC) curve analysis.

Results

Based on integrated mean fluorescence intensity (iMFI), baseline plasma MEVs carrying CD56 (corresponding to natural killer cells) predicted rOA progression with highest area under the ROC curve (AUC) 0.714 among surface markers. Baseline iMFI of TNF-α in LEVs, MEVs and SEVs, and the total endo-EV TNF-α concentration, predicted rOA progression with AUCs 0.688, 0.821, 0.821, 0.665, respectively. In contrast, baseline plasma exo-EV TNF-α (the concentration in the same unit of plasma after EV depletion) did not predict rOA progression (AUC 0.478). Baseline endo-EV IFN-γ and exo-EV IL-6 concentrations were also associated with rOA progression, but had low discriminant capacity (AUCs 0.558 and 0.518, respectively).

Conclusions

Plasma EVs carry pro-inflammatory cargo that predict risk of knee rOA progression. These findings suggest that EV-associated TNF-α may be pathogenic in OA. The sequestration of pathogenic TNF-α within EVs may provide an explanation for the lack of success of systemic TNF-α inhibitors in OA trials to date.

In-Depth Profiling of T-Cell Responsiveness to Commonly Recognized CMV Antigens in Older People Reveals Important Sex Differences

The impact of biological sex on T-cell immunity to Cytomegalovirus (CMV) has not been investigated in detail with only one published study comparing CMV-specific T-cell responses in men and women. Many studies, however, have shown an association between CMV infection and immunosenescence, with broad effects on peripheral blood lymphocyte subsets as well as the T and B-cell repertoires. Here, we provide a detailed analysis of CMV-specific T-cell responses in (n=94) CMV+ older people, including 47 women and 47 men aged between 60 and 93 years. We explore sex differences with respect to 16 different CMV proteins arranged in 14 peptide pools (overlapping peptides). Following ex vivo stimulation, CD4 and CD8 T-cells producing IFN-γ, TNF, and IL-2 were enumerated by flow-cytometry (intracellular cytokine staining). T-cell responses were evaluated in terms of each cytokine separately or in terms of cytokines produced simultaneously (polyfunctionality). Surface memory phenotype and CD3 downmodulation were assessed in parallel. The polyfunctionality index and a memory subset differentiation score were used to identify associations between response size, cytokine production, polyfunctionality, and memory subset distribution. While no significant sex differences were found with respect to overall CMV target protein selection, the T-cell response in men appeared more focused and accompanied by a more prominent accumulation of CMV-specific memory CD4 and CD8 T-cells. T-cell polyfunctionality and differentiation were similar in the sexes, however, CMV-specific T-cells in men produced more pro-inflammatory cytokines. Particularly, TNF production by CD4 T-cells was stronger in men than in women. Also, compared with women, men had larger responses to CMV proteins with immediate-early/early kinetics than women, which might have been driven by CMV reactivation. In conclusion, the CMV-specific T-cell response in men was larger and more pro-inflammatory than in women. Our findings may help explain sex differences in CMV-associated pathologies.

Prenatal maternal infection promotes tissue-specific immunity and inflammation in offspring

The immune system has evolved in the face of microbial exposure. How maternal infection experienced at distinct developmental stages shapes the offspring immune system remains poorly understood. Here, we show that during pregnancy, maternally restricted infection can have permanent and tissue-specific impacts on offspring immunity. Mechanistically, maternal interleukin-6 produced in response to infection can directly impose epigenetic changes on fetal intestinal epithelial stem cells, leading to long-lasting impacts on intestinal immune homeostasis. As a result, offspring of previously infected dams develop enhanced protective immunity to gut infection and increased inflammation in the context of colitis. Thus, maternal infection can be coopted by the fetus to promote long-term, tissue-specific fitness, a phenomenon that may come at the cost of predisposition to inflammatory disorders.

ABO haemolytic disease of the newborn: Improved prediction by novel integration of causative and protective factors in newborn and mother

BACKGROUND AND OBJECTIVES

Prediction of haemolytic disease of the foetus and newborn (HDFN) caused by maternal anti-A/-B enables timely therapy, thereby preventing the development of kernicterus spectrum disorder. However, previous efforts to establish accurate prediction methods have been only modestly successful.

MATERIALS AND METHODS

In a case-control study, we examined 76 samples from mothers and 76 samples from their newborns; 38 with and 38 without haemolysis. The IgG subclass profile of maternal anti-A and anti-B was determined by flow cytometry. Samples from newborns were genetically analysed for the A² subgroup, secretor and FcγRIIa receptor alleles.

RESULTS

Surprisingly, we found a correlation between the newborn secretor allele and haemolysis (p = 0.034). No correlation was found for FcγRIIa alleles. The A² subgroup was found only in newborns without haemolysis. Unexpectedly, different reaction patterns were found for maternal anti-A and anti-B; consequently, the results were treated separately. For the prediction of haemolysis in A-newborns, the maternal IgG1 subclass determination resulted in an accuracy of 83% at birth. For B-newborns, an accuracy of 91% was achieved by the maternal IgG2 subclass determination.

CONCLUSION

We improved the prediction of ABO-HDFN by characterizing maternal anti-A and anti-B by flow cytometry and we presented genetic traits in newborns with correlation to haemolysis. We propose a new understanding of A- and B-substances as immunogens that enhance the maternal immune response and protect the newborn, and we suggest that the development of ABO-HDFN is different when caused by maternal anti-A compared to maternal anti-B.

Extracellular Vesicles as Biological Indicators and Potential Sources of Autologous Therapeutics in Osteoarthritis

Along with cytokines, extracellular vesicles (EVs) released by immune cells in the joint contribute to osteoarthritis (OA) pathogenesis. By high-resolution flow cytometry, we characterized 18 surface markers and 4 proinflammatory cytokines carried by EVs of various sizes in plasma and synovial fluid (SF) from individuals with knee OA, with a primary focus on immune cells that play a major role in OA pathogenesis. By multiplex immunoassay, we also measured concentrations of cytokines within (endo) and outside (exo) EVs. EVs carrying HLA-DR, -DP and -DQ were the most enriched subpopulations in SF relative to plasma (25–50-fold higher depending on size), suggesting a major contribution to the SF EV pool from infiltrating immune cells in OA joints. In contrast, the CD34⁺ medium and small EVs, reflecting hematopoietic stem cells, progenitor cells, and endothelial cells, were the most significantly enriched subpopulations in plasma relative to SF (7.3- and 7.7-fold higher). Ratios of EVs derived from neutrophils and lymphocytes were highly correlated between SF and plasma, indicating that plasma EVs could reflect OA severity and serve as systemic biomarkers of OA joint pathogenesis. Select subsets of plasma EVs might also provide next generation autologous biological products for intra-articular therapy of OA joints.

A cross-reactive antibody protects against Ross River virus musculoskeletal disease despite rapid neutralization escape in mice

Arthritogenic alphaviruses cause debilitating musculoskeletal disease and historically have circulated in distinct regions. With the global spread of chikungunya virus (CHIKV), there now is more geographic overlap, which could result in heterologous immunity affecting natural infection or vaccination. Here, we evaluated the capacity of a cross-reactive anti-CHIKV monoclonal antibody (CHK-265) to protect against disease caused by the distantly related alphavirus, Ross River virus (RRV). Although CHK-265 only moderately neutralizes RRV infection in cell culture, it limited clinical disease in mice independently of Fc effector function activity. Despite this protective phenotype, RRV escaped from CHK-265 neutralization in vivo, with resistant variants retaining pathogenic potential. Near the inoculation site, CHK-265 reduced viral burden in a type I interferon signaling-dependent manner and limited immune cell infiltration into musculoskeletal tissue. In a parallel set of experiments, purified human CHIKV immune IgG also weakly neutralized RRV, yet when transferred to mice, resulted in improved clinical outcome during RRV infection despite the emergence of resistant viruses. Overall, this study suggests that weakly cross-neutralizing antibodies can protect against heterologous alphavirus disease, even if neutralization escape occurs, through an early viral control program that tempers inflammation.

The induction of broadly neutralizing antibodies is a goal of many antiviral vaccine programs. In this study, we show that cross-reactive monoclonal and polyclonal antibodies developed after CHIKV infection or immunization with relatively weak cross-neutralizing activity can protect against RRV-induced musculoskeletal disease in mice. Even though RRV rapidly escaped from neutralization, antibody therapy reduced inflammation in musculoskeletal tissues and decreased viral burden near the site of infection in a manner that required type I interferon signaling. These studies in mice show that broadly reactive antibodies with limited neutralizing activity still can confer protection against heterologous alphaviruses.

Innate immunity to malaria-The role of monocytes

Monocytes are innate immune cells essential for host protection against malaria. Upon activation, monocytes function to help reduce parasite burden through phagocytosis, cytokine production, and antigen presentation. However, monocytes have also been implicated in the pathogenesis of severe disease through production of damaging inflammatory cytokines, resulting in systemic inflammation and vascular dysfunction. Understanding the molecular pathways influencing the balance between protection and pathology is critical. In this review, we discuss recent data regarding the role of monocytes in human malaria, including studies of innate sensing of the parasite, immunometabolism, and innate immune training. Knowledge gained from these studies may guide rational development of novel antimalarial therapies and inform vaccine development.

An Nfil3-Zeb2-Id2 pathway imposes Irf8 enhancer switching during cDC1 development

Classical type 1 dendritic cells (cDC1s) are required for antiviral and antitumor immunity, which necessitates an understanding of their development. Development of the cDC1 progenitor requires an E-protein-dependent enhancer located 41 kilobases downstream of the transcription start site of the transcription factor Irf8 (+41-kb Irf8 enhancer), but its maturation instead requires the Batf3-dependent +32-kb Irf8 enhancer. To understand this switch, we performed single-cell RNA sequencing of the common dendritic cell progenitor (CDP) and identified a cluster of cells that expressed transcription factors that influence cDC1 development, such as Nfil3, Id2 and Zeb2. Genetic epistasis among these factors revealed that Nfil3 expression is required for the transition from Zeb2hi and Id2lo CDPs to Zeb2lo and Id2hi CDPs, which represent the earliest committed cDC1 progenitors. This genetic circuit blocks E-protein activity to exclude plasmacytoid dendritic cell potential and explains the switch in Irf8 enhancer usage during cDC1 development.

Transcriptional and Functional Programming of Decidual Innate Lymphoid Cells

A successful pregnancy requires many physiological adaptations from the mother, including the establishment of tolerance toward the semiallogeneic fetus. Innate lymphoid cells (ILCs) have arisen as important players in immune regulation and tissue homeostasis at mucosal and barrier surfaces. Dimensionality reduction and transcriptomic analysis revealed the presence of two novel CD56^Bright decidual ILCs that express low T-bet and divergent Eomes levels. Transcriptional correlation with recently identified first trimester decidual dNKs suggests that these novel decidual ILCs might be present throughout pregnancy. Functional testing with permutation analysis revealed production of multiple factors by individual cells, with a preference for IFNγ and VEGF. Overall, our data suggests continuity of a unique decidual innate lymphocytes across pregnancy with a polyfunctional functional profile conducive for pregnancy.

Rosuvastatin alleviates high-salt and cholesterol diet-induced cognitive impairment in rats via Nrf2-ARE pathway

OBJECTIVE

The objectives of our study were to investigate the possible effect of rosuvastatin in ameliorating high salt and cholesterol diet (HSCD)-induced cognitive impairment and to also investigate its possible action via the Nrf2-ARE pathway.

METHODS

In silico studies were performed to check the theoretical binding of rosuvastatin to the Nrf2 target. HSCD was used to induce cognitive impairment in rats and neurobehavioral studies were performed to evaluate the efficacy of rosuvastatin in enhancing cognition. Biochemical analyses were used to estimate changes in oxidative markers. Western blot and immunohistochemical analyses were done to check Nrf2 translocation. TUNEL and caspase 3 tests were performed to evaluate reversal of apoptosis by rosuvastatin.

RESULTS

Rosuvastatin showed good theoretical affinity to Nrf2, significantly reversed changes in oxidative biomarkers which were induced by HSCD, and also improved the performance of rats in the neurobehavioral test. A rise in nuclear translocation of Nrf2 was revealed through immunohistochemical analysis and western blot. TUNEL staining and caspase 3 activity showed attenuation of apoptosis.

DISCUSSION

We have investigated a novel mechanism of action for rosuvastatin (via the Nrf2-ARE pathway) and demonstrated that it has the potential to be used in the treatment of cognitive impairment.

Alpha2beta1 Integrin (VLA-2) Protects Activated Human Effector T Cells From Methotrexate-Induced Apoptosis

β1 integrins are critical for T cell migration, survival and costimulation. The integrin α2β1, which is a receptor for collagen, also named VLA-2, is a major costimulatory pathway of effector T cells and has been implicated in arthritis pathogenesis. Herein, we have examined its ability to promote methotrexate (MTX) resistance by enhancing effector T cells survival. Our results show that attachment of anti-CD3-activated human polarized Th17 cells to collagen but not to fibronectin or laminin led to a significant reduction of MTX-induced apoptosis. The anti-CD3+collagen-rescued cells still produce significant amounts of IL-17 and IFNγ upon their reactivation indicating that their inflammatory nature is preserved. Mechanistically, we found that the prosurvival role of anti-CD3+collagen involves activation of the MTX transporter ABCC1 (ATP Binding Cassette subfamily C Member 1). Finally, the protective effect of collagen/α2β1 integrin on MTX-induced apoptosis also occurs in memory CD4⁺ T cells isolated from rheumatoid arthritis (RA) patients suggesting its clinical relevance. Together these results show that α2β1 integrin promotes MTX resistance of effector T cells, and suggest that it could contribute to the development of MTX resistance that is seen in RA.

Altered compensatory cytokine signaling underlies the discrepancy between Flt3-/- and Flt3l-/- mice

The receptor Flt3 and its ligand Flt3L are both critical for dendritic cell (DC) development, but DC deficiency is more severe in Flt3l^-/- mice than in Flt3^-/- mice. This has led to speculation that Flt3L binds to another receptor that also supports DC development. However, we found that Flt3L administration does not generate DCs in Flt3^-/- mice, arguing against a second receptor. Instead, Flt3^-/- DC progenitors matured in response to macrophage colony-stimulating factor (M-CSF) or stem cell factor, and deletion of Csf1r in Flt3^-/- mice further reduced DC development, indicating that these cytokines could compensate for Flt3. Surprisingly, Flt3^-/- DC progenitors displayed enhanced M-CSF signaling, suggesting that loss of Flt3 increased responsiveness to other cytokines. In agreement, deletion of Flt3 in Flt3l^-/- mice paradoxically rescued their severe DC deficiency. Thus, multiple cytokines can support DC development, and the discrepancy between Flt3^-/- and Flt3l^-/- mice results from the increased sensitivity of Flt3^-/- progenitors to these cytokines.

The role of HFE genotype in macrophage phenotype

Background

Iron regulation is essential for cellular energy production. Loss of cellular iron homeostasis has critical implications for both normal function and disease progression. The H63D variant of the HFE gene is the most common gene variant in Caucasians. The resulting mutant protein alters cellular iron homeostasis and is associated with a number of neurological diseases and cancer. In the brain, microglial and infiltrating macrophages are critical to maintaining iron homeostasis and modulating inflammation associated with the pathogenic process in multiple diseases. This study addresses whether HFE genotype affects macrophage function and the implications of these findings for disease processes.

Methods

Bone marrow macrophages were isolated from wildtype and H67D HFE knock-in mice. The H67D gene variant in mice is the human equivalent of the H63D variant. Upon differentiation, the macrophages were used to analyze iron regulatory proteins, cellular iron release, migration, phagocytosis, and cytokine expression.

Results

The results of this study demonstrate that the H67D HFE genotype significantly impacts a number of critical macrophage functions. Specifically, fundamental activities such as proliferation in response to iron exposure, L-ferritin expression in response to iron loading, secretion of BMP6 and cytokines, and migration and phagocytic activity were all found to be impacted by genotype. Furthermore, we demonstrated that exposure to apo-Tf (iron-poor transferrin) can increase the release of iron from macrophages. In normal conditions, 70% of circulating transferrin is unsaturated. Therefore, the ability of apo-Tf to induce iron release could be a major regulatory mechanism for iron release from macrophages.

Conclusions

These studies demonstrate that the HFE genotype impacts fundamental components of macrophage phenotype that could alter their role in degenerative and reparative processes in neurodegenerative disorders.

Neonatal immune response to rhinovirus A16 has diminished dendritic cell function and increased B cell activation

Background

Rhinovirus infections during infancy account for the majority of respiratory illness health care utilization and are an associated risk factor for subsequent development of allergic asthma. Neonatal type I interferon production is diminished compared to adults after stimulation with TLR agonists. However, broad profiling of immune cell responses to infectious rhinovirus has not been undertaken and we hypothesized that additional immune differences can be identified in neonates. In this study, we undertook a comparative analysis of neonatal and adult blood immune cell responses after in vitro incubation with infectious RV-A16 for 6 and 24 hours.

Methods

Intracellular proinflammatory and type I interferon cytokines along with expression of surface co-stimulatory and maturation markers were measured using multi-parameter flow cytometry.

Results

Both circulating myeloid dendritic cell (mDC) and plasmacytoid dendritic cell (pDC) frequency were lower in cord blood. Qualitative and quantitative plasmacytoid dendritic cell IFN-alpha + TNF- alpha responses to rhinovirus were significantly lower in cord pDCs. In cord blood samples, the majority of responsive pDCs were single-positive TNF-alpha producing cells, whereas in adult samples rhinovirus increased double-positive TNF-alpha+IFN-alpha+ pDCs. Rhinovirus upregulated activation and maturation markers on monocytes, mDCs, pDCs, and B cells, but CD40+CD86+ monocytes, mDCs, and pDCs cells were significantly higher in adult samples compared to cord samples. Surprisingly, rhinovirus increased CD40+CD86+ B cells to a significantly greater extent in cord samples compared to adults.

Conclusions

These findings define a number of cell-specific differences in neonatal responses to rhinovirus. This differential age-related immune response to RV may have implications for the immune correlates of protection to viral respiratory illness burden and determination of potential biomarkers for asthma risk.

Analyses of a Mutant Foxp3 Allele Reveal BATF as a Critical Transcription Factor in the Differentiation and Accumulation of Tissue Regulatory T Cells

Foxp3 controls the development and function of regulatory T (Treg) cells, but it remains elusive how Foxp3 functions in vivo. Here, we established mouse models harboring three unique missense Foxp3 mutations that were identified in patients with the autoimmune disease IPEX. The I363V and R397W mutations were loss-of-function mutations, causing multi-organ inflammation by globally compromising Treg cell physiology. By contrast, the A384T mutation induced a distinctive tissue-restricted inflammation by specifically impairing the ability of Treg cells to compete with pathogenic T cells in certain non-lymphoid tissues. Mechanistically, repressed BATF expression contributed to these A384T effects. At the molecular level, the A384T mutation altered Foxp3 interactions with its specific target genes including Batf by broadening its DNA-binding specificity. Our findings identify BATF as a critical regulator of tissue Treg cells and suggest that sequence-specific perturbations of Foxp3-DNA interactions can influence specific facets of Treg cell physiology and the immunopathologies they regulate.

Quality of TCR signaling determined by differential affinities of enhancers for the composite BATF-IRF4 transcription factor complex

Variable strengths of T cell receptor (TCR) signaling can produce divergent outcomes, but the mechanism remains obscure. The abundance of the transcription factor IRF4 increases with TCR signal strength, but how this would induce distinct types of responses is unclear. We compared T_H2 gene expression with BATF/IRF4 enhancer occupancy at varying strengths of TCR stimulation. BATF/IRF4-dependent genes clustered into distinct TCR-sensitivities. Enhancers exhibited a spectrum of occupancy by BATF/IRF4 ternary complex that correlated with TCR-sensitivity of gene expression. DNA sequences immediately flanking the previously defined AICE motif controlled the affinity for BATF/IRF4 for direct binding to DNA. ChIP-exo analysis allowed identification of a novel high-affinity AICE2 motif at a human SNP of CTLA4 associated with resistance to autoimmunity. Thus, the affinity of different enhancers for the BATF-IRF4 complex may underlie divergent signaling outcomes in response to various strengths of TCR signaling.

Inhibition of Interleukin 17-A but not Interleukin-17F Signaling Lowers Blood Pressure and Reduces End-organ Inflammation in Angiotensin II-induced Hypertension

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Hypertension is associated with an increase in T-cell–derived cytokines such IL-17A and IL-17F.

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Monoclonal antibodies to IL-17A, IL-17F, IL-17RA, or isotype control antibodies (IgG1) were administered twice weekly during the last 2 weeks of a 4-week angiotensin II infusion protocol in mice.

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Antibodies to IL-17A or IL-17RA, but not IL-17F, lowered blood pressure by 30 mm Hg, attenuated renal and vascular inflammation, and reduced renal transforming growth factor beta levels (a marker of renal fibrosis) compared with control IgG1 antibodies. All 3 experimental antibodies blunted the progression of albuminuria.

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Monoclonal antibodies to IL-17A or IL-17RA may be a useful adjunct treatment for hypertension and the associated end-organ dysfunction.

Inflammatory cytokines play a major role in the pathophysiology of hypertension. The authors previously showed that genetic deletion of interleukin (IL)-17A results in blunted hypertension and reduced renal/vascular dysfunction. With the emergence of a new class of monoclonal antibody–based drugs for psoriasis and related autoimmune disorders that target IL-17 signaling, the authors sought to determine whether these antibodies could also reduce blood pressure, renal/vascular inflammation, and renal injury in a mouse model of hypertension. The authors show that antibodies to IL-17A or the IL-17RA receptor subunit, but not IL-17F, may be a novel adjunct treatment for hypertension and the associated end-organ dysfunction.

Oxidative stress modulates the cytokine response of differentiated Th17 and Th1 cells

Reactive oxygen species (ROS) signaling is critical in T helper (Th) cell differentiation; however its role in differentiated Th cell functions is unclear. In this study, we investigated the role of oxidative stress on the effector functions of in vitro differentiated mouse Th17 and Th1 cells or CD4⁺ T cells from patients with Rheumatoid Arthritis using pro-oxidants plumbagin (PB) and hydrogen peroxide. We found that in mouse Th cells, non-toxic concentration of pro-oxidants inhibited reactivation induced expression of IL-17A in Th17 and IFN-γ in Th1 cells by reducing the expression of their respective TFs, RORγt and T-bet. Interestingly, in both the subsets, PB increased the expression of IL-4 by enhancing reactivation induced ERK1/2 phosphorylation. We further investigated the cytokine modulatory effect of PB on CD4⁺ T cells isolated from PBMCs of patients with Rheumatoid Arthritis, a well-known Th17 and or Th1 mediated disease. In human CD4⁺ T cells from Rheumatoid Arthritis patients, PB reduced the frequencies of IL-17A⁺ (Th17), IFN^-γ⁺ (Th1) and IL-17A⁺/IFN^-γ⁺ (Th17/1) cells and also inhibited the production of pro-inflammatory cytokines TNF-α and IL-6. N-Acetyl Cysteine (NAC) an antioxidant completely reversed PB mediated cytokine modulatory effects in both mouse and human cells indicating a direct role for ROS. Together our data suggest that oxidative microenvironment can alter cytokine response of terminally differentiated cells and thus altering intracellular ROS could be a potential way to target Th17 and Th1 cells in autoimmune disorders.

Batf3 maintains autoactivation of Irf8 for commitment of a CD8α(+) conventional DC clonogenic progenitor

The transcription factors Batf3 and IRF8 are required for the development of CD8α(+) conventional dendritic cells (cDCs), but the basis for their actions has remained unclear. Here we identified two progenitor cells positive for the transcription factor Zbtb46 that separately generated CD8α(+) cDCs and CD4(+) cDCs and arose directly from the common DC progenitor (CDP). Irf8 expression in CDPs required prior autoactivation of Irf8 that was dependent on the transcription factor PU.1. Specification of the clonogenic progenitor of CD8α(+) cDCs (the pre-CD8 DC) required IRF8 but not Batf3. However, after specification of pre-CD8 DCs, autoactivation of Irf8 became Batf3 dependent at a CD8α(+) cDC-specific enhancer with multiple transcription factor AP1-IRF composite elements (AICEs) within the Irf8 superenhancer. CDPs from Batf3(-/-) mice that were specified toward development into pre-CD8 DCs failed to complete their development into CD8α(+) cDCs due to decay of Irf8 autoactivation and diverted to the CD4(+) cDC lineage.

The cell-surface proteome of cultured adipose stromal cells

In this technical note we describe a method to evaluate the cell surface proteome of human primary cell cultures and cell lines. The method utilizes the BD Biosciences lyoplate, a system covering 242 surface proteins, glycoproteins, and glycosphingolipids plus relevant isotype controls, automated plate-based flow cytometry, conventional file-level analysis and unsupervised K-means clustering of markers on the basis of percent of positive events and mean fluorescence intensity of positive and total clean events. As an example, we determined the cell surface proteome of cultured adipose stromal cells (ASC) derived from 5 independent clinical isolates. Between-sample agreement of very strongly expressed (n = 32) and strongly expressed (n =16) markers was excellent, constituting a reliable profile for ASC identification and determination of functional properties. Known mesenchymal markers (CD29, CD44, CD73, CD90, CD105) were among the identified strongly expressed determinants. Among other strongly expressed markers are several that are potentially immunomodulatory including three proteins that protect from complement mediated effects (CD46, CD55, and CD59), two that regulate apoptosis (CD77 and CD95) and several with ectoenzymatic (CD10, CD26, CD13, CD73, and CD143) or receptor tyrosine kinase (CD140b (PDGFR), CD340 (Her-2), EGFR) activity, suggesting mechanisms for the anti-inflammatory and tissue remodeling properties of ASC. Because variables are standardized for K-means clustering, results generated using this methodology should be comparable between instrumentation platforms. It is widely generalizable to human primary explant cultures and cells lines and will prove useful to determine how cell passage, culture interventions, and gene expression and silencing affect the cell-surface proteome.

Novel role for NFAT3 in ERK-mediated regulation of CXCR4

The G-protein coupled chemokine (C-X-C motif) receptor CXCR4 is linked to cancer, HIV, and WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome. While CXCR4 is reported to be overexpressed in multiple human cancer types and many hematological cancer cell lines, we have observed poor in vitro cell surface expression of CXCR4 in many solid tumor cell lines. We explore further the possible factors and pathways involved in regulating CXCR4 expression. Here, we showed that MEK-ERK signaling pathway and NFAT3 transcriptional factor plays a novel role in regulating CXCR4 expression. When cultured as 3D spheroids, HeyA8 ovarian tumor cells showed a dramatic increase in surface CXCR4 protein levels as well as mRNA transcripts. Furthermore, HeyA8 3D spheroids showed a decrease in phospho-ERK levels when compared to adherent cells. The treatment of adherent HeyA8 cells with an inhibitor of the MEK-ERK pathway, U0126, resulted in a significant increase in surface CXCR4 expression. Additional investigation using the PCR array assay comparing adherent to 3D spheroid showed a wide range of transcription factors being up-regulated, most notably a > 20 fold increase in NFAT3 transcription factor mRNA. Finally, chromatin immunoprecipitation (ChIP) analysis showed that direct binding of NFAT3 on the CXCR4 promoter corresponds to increased CXCR4 expression in HeyA8 ovarian cell line. Taken together, our results suggest that high phospho-ERK levels and NFAT3 expression plays a novel role in regulating CXCR4 expression.

Antigenic composition of single nano-sized extracellular blood vesicles

Extracellular vesicles (EVs) are important in normal physiology and are altered in various pathologies. EVs produced by different cells are antigenically different. Since the majority of EVs are too small for routine flow cytometry, EV composition is studied predominantly in bulk, thus not addressing their antigenic heterogeneity. Here, we describe a nanoparticle-based technique for analyzing antigens on single nano-sized EVs. The technique consists of immuno-capturing of EVs with 15-nm magnetic nanoparticles, staining captured EVs with antibodies against their antigens, and separating them from unbound EVs and free antibodies in a magnetic field, followed by flow analysis. This technique allows us to characterize EVs populations according to their antigenic distribution, including minor EV fractions. We demonstrated that the individual blood EVs carry different sets of antigens, none being ubiquitous, and quantified their distribution. The physiological significance of antigenically different EVs and their correlation with different pathologies can now be directly addressed. From the clinical editor: This study reports a nanoparticle-based technique for analyzing antigens on single nano-sized extracellular vehicles (EV). The technique consists of immuno-capturing of EVs with 15-nm magnetic nanoparticles, followed by staining the captured EVs with antibodies and separating them via a magnetic field, followed by flow analysis. This technique enables studies of antigenic properties of individual EVs that conventionally can only be studied in bulk.

Protective and detrimental roles for regulatory T cells in a viral model for multiple sclerosis

Multiple sclerosis (MS) has been proposed to be an immune-mediated disease in the central nervous system (CNS) that can be triggered by virus infections. In Theiler's murine encephalomyelitis virus (TMEV) infection, during the first week (acute stage), mice develop polioencephalomyelitis. After 3 weeks (chronic stage), mice develop immune-mediated demyelination with virus persistence, which has been used as a viral model for MS. Regulatory T cells (Tregs) can suppress inflammation, and have been suggested to be protective in immune-mediated diseases, including MS. However, in virus-induced inflammatory demyelination, although Tregs can suppress inflammation, preventing immune-mediated pathology, Tregs may also suppress antiviral immune responses, leading to more active viral replication and/or persistence. To determine the role and potential translational usage of Tregs in MS, we treated TMEV-infected mice with ex vivo generated induced Tregs (iTregs) on day 0 (early) or during the chronic stage (therapeutic). Early treatment worsened clinical signs during acute disease. The exacerbation of acute disease was associated with increased virus titers and decreased immune cell recruitment in the CNS. Therapeutic iTreg treatment reduced inflammatory demyelination during chronic disease. Immunologically, iTreg treatment increased interleukin-10 production from B cells, CD4(+) T cells and dendritic cells, which may contribute to the decreased CNS inflammation.

Biological 2-input decoder circuit in human cells

Decoders are combinational circuits that convert information from n inputs to a maximum of 2ⁿ outputs. This operation is of major importance in computing systems yet it is vastly underexplored in synthetic biology. Here, we present a synthetic gene network architecture that operates as a biological decoder in human cells, converting 2 inputs to 4 outputs. As a proof-of-principle, we use small molecules to emulate the two inputs and fluorescent reporters as the corresponding four outputs. The experiments are performed using transient transfections in human kidney embryonic cells and the characterization by fluorescence microscopy and flow cytometry. We show a clear separation between the ON and OFF mean fluorescent intensity states. Additionally, we adopt the integrated mean fluorescence intensity for the characterization of the circuit and show that this metric is more robust to transfection conditions when compared to the mean fluorescent intensity. To conclude, we present the first implementation of a genetic decoder. This combinational system can be valuable toward engineering higher-order circuits as well as accommodate a multiplexed interface with endogenous cellular functions.

Matrix metalloproteinase-9 is involved in chronic lymphocytic leukemia cell response to fludarabine and arsenic trioxide

BACKGROUND

Matrix metalloproteinase-9 (MMP-9) contributes to chronic lymphocytic leukemia (CLL) pathology by regulating cell migration and preventing spontaneous apoptosis. It is not known if MMP-9 is involved in CLL cell response to chemotherapy and we address this in the present study, using arsenic trioxide (ATO) and fludarabine as examples of cytotoxic drugs.

METHODS

We used primary cells from the peripheral blood of CLL patients and MEC-1 cells stably transfected with an empty vector or a vector containing MMP-9. The effect of ATO and fludarabine was determined by flow cytometry and by the MTT assay. Expression of mRNA was measured by RT-PCR and qPCR. Secreted and cell-bound MMP-9 was analyzed by gelatin zymography and flow cytometry, respectively. Protein expression was analyzed by Western blotting and immunoprecipitation. Statistical analyses were performed using the two-tailed Student's t-test.

RESULTS

In response to ATO or fludarabine, CLL cells transcriptionally upregulated MMP-9, preceding the onset of apoptosis. Upregulated MMP-9 primarily localized to the membrane of early apoptotic cells and blocking apoptosis with Z-VAD prevented MMP-9 upregulation, thus linking MMP-9 to the apoptotic process. Culturing CLL cells on MMP-9 or stromal cells induced drug resistance, which was overcome by anti-MMP-9 antibodies. Accordingly, MMP-9-MEC-1 transfectants showed higher viability upon drug treatment than Mock-MEC-1 cells, and this effect was blocked by silencing MMP-9 with specific siRNAs. Following drug exposure, expression of anti-apoptotic proteins (Mcl-1, Bcl-xL, Bcl-2) and the Mcl-1/Bim, Mcl-1/Noxa, Bcl-2/Bax ratios were higher in MMP-9-cells than in Mock-cells. Similar results were obtained upon culturing primary CLL cells on MMP-9.

CONCLUSIONS

Our study describes for the first time that MMP-9 induces drug resistance by modulating proteins of the Bcl-2 family and upregulating the corresponding anti-apoptotic/pro-apoptotic ratios. This is a novel role for MMP-9 contributing to CLL progression. Targeting MMP-9 in combined therapies may thus improve CLL response to treatment.

Folate receptor-targeted aminopterin therapy is highly effective and specific in experimental models of autoimmune uveitis and autoimmune encephalomyelitis

EC0746 is a rationally designed anti-inflammatory drug conjugate consisting of a modified folic acid-based ligand linked to a γ-hydrazide analog of aminopterin. In this report, EC0746's effectiveness was evaluated against experimental retinal S-antigen (PDSAg) induced autoimmune uveitis (EAU) and myelin-basic-protein induced autoimmune encephalomyelitis (EAE). In both models, functional FR-β was detected on activated macrophages in local (retinal or central-nervous-system, respectively) and systemic (peritoneal cavity) sites of inflammation. In myelin-rich regions of EAE rats, an increased uptake of (99m)Tc-EC20 (etarfolatide; a FR-specific radioimaging agent) was also observed. EC0746 treatment at disease onset suppressed the clinical severity of both EAU and EAE, and it strongly attenuated progressive histopathological changes in the affected organs. In all parameters assessed, EC0746 activity was completely blocked by a benign folate competitor, suggesting that these therapeutic outcomes were specifically FR-β mediated. EC0746 may emerge as a useful macrophage-modulating agent for treating inflammatory episodes of organ-specific autoimmunity.

Flow cytometry for the analysis of α-dystroglycan glycosylation in fibroblasts from patients with dystroglycanopathies

α-dystroglycan (α-DG) is a peripheral membrane protein that is an integral component of the dystrophin-glycoprotein complex. In an inherited subset of muscular dystrophies known as dystroglycanopathies, α-DG has reduced glycosylation which results in lower affinity binding to several extracellular matrix proteins including laminins. The glycosylation status of α-DG is normally assessed by the binding of the α-DG antibody IIH6 to a specific glycan epitope on α-DG involved in laminin binding. Immunocytochemistry and immunoblotting are two of the most widely used methods to detect the amount of α-DG glycosylation in muscle. While the interpretation of the presence or absence of the epitope on muscle using these techniques is straightforward, the assessment of a mild defect can be challenging. In this study, flow cytometry was used to compare the amount of IIH6-reactive glycans in fibroblasts from dystroglycanopathy patients with defects in genes known to cause α-DG hypoglycosylation to the amount in fibroblasts from healthy and pathological control subjects. A total of twenty one dystroglycanopathy patient fibroblasts were assessed, as well as fibroblasts from three healthy controls and seven pathological controls. Control fibroblasts have clearly detectable amounts of IIH6-reactive glycans, and there is a significant difference in the amount of this glycosylation, as measured by the mean fluorescence intensity of an antibody recognising the epitope and the percentage of cells positive for the epitope, between these controls and dystroglycanopathy patient fibroblasts (p<0.0001 for both). Our results indicate that the amount of α-DG glycosylation in patient fibroblasts is comparable to that in patient skeletal muscle. This method could complement existing immunohistochemical assays in skeletal muscle as it is quantitative and simple to perform, and could be used when a muscle biopsy is not available. This test could also be used to assess the pathogenicity of variants of unknown significance in genes involved in dystroglycanopathies.

The average IFN-γ secreting capacity of specific CD8(+) T cells is compromised while increasing copies of a single T cell epitope encoded by DNA vaccine

Previous studies suggested that both the frequency and the mean fluorescence intensity (MFI) of cytokine secreting T cells could be of great value for immunogenicity evaluation of a vaccine. In this study, by constructing epitope-based DNA vaccines encoding a previously identified CD8⁺ T cell epitope, we investigated the influence of multiplying epitope copies on both the frequency and the MFI of specific IFN-γ secreting CD8⁺ T cells. We found that frequencies of specific CD8⁺ T cell could be improved by multiplying epitope copies, while the MFI of IFN-γ secreted by epitope-specific CD8⁺ T cells decreased synchronously. And further analysis showed that the decrease of MFI was not caused by the functional avidity variation of CD8⁺ T cell receptor.

Ontogeny of Toll-like receptor mediated cytokine responses of South African infants throughout the first year of life

The first year of life represents a time of marked susceptibility to infections; this is particularly true for regions in sub-Saharan Africa. As innate immunity directs the adaptive immune response, the observed increased risk for infection as well as a suboptimal response to vaccination in early life may be due to less effective innate immune function. In this study, we followed a longitudinal cohort of infants born and raised in South Africa over the first year of life, employing the most comprehensive analysis of innate immune response to stimulation published to date. Our findings reveal rapid changes in innate immune development over the first year of life. This is the first report depicting dramatic differences in innate immune ontogeny between different populations in the world, with important implications for global vaccination strategies.

Immune markers and correlates of protection for vaccine induced immune responses

Vaccines have been a major innovation in the history of mankind and still have the potential to address the challenges posed by chronic intracellular infections including tuberculosis, HIV and malaria which are leading causes of high morbidity and mortality across the world. Markers of an appropriate humoral response currently remain the best validated correlates of protective immunity after vaccination. Despite advancements in the field of immunology over the past few decades currently there are, however, no sufficiently validated immune correlates of vaccine induced protection against chronic infections in neither human nor veterinary medicine. Technological and conceptual advancements within cell-mediated immunology have led to a number of new immunological read-outs with the potential to emerge as correlates of vaccine induced protection. For T(H)1 type responses, antigen-specific production of interferon-gamma (IFN-γ) has been promoted as a quantitative marker of protective cell-mediated immune responses over the past couple of decades. More recently, however, evidence from several infections has pointed towards the quality of the immune response, measured through increased levels of antigen-specific polyfunctional T cells capable of producing a triad of relevant cytokines, as a better correlate of sustained protective immunity against this type of infections. Also the possibilities to measure antigen-specific cytotoxic T cells (CTL) during infection or in response to vaccination, through recombinant major histocompatibility complex (MHC) class I tetramers loaded with relevant peptides, has opened a new vista to include CTL responses in the evaluation of protective immune responses. Here, we review different immune markers and new candidates for correlates of a protective vaccine induced immune response against chronic infections and how successful they have been in defining the protective immunity in human and veterinary medicine.

Alcohol impairs the myeloid proliferative response to bacteremia in mice by inhibiting the stem cell antigen-1/ERK pathway

Enhancement of stem cell Ag-1 (Sca-1) expression by myeloid precursors promotes the granulopoietic response to bacterial infection. However, the underlying mechanisms remain unclear. ERK pathway activation strongly enhances proliferation of hematopoietic progenitor cells. In this study, we investigated the role of Sca-1 in promoting ERK-dependent myeloid lineage proliferation and the effects of alcohol on this process. Thirty minutes after i.p. injection of alcohol, mice received i.v. challenge with 5 × 10(7) Escherichia coli for 8 or 24 h. A subset of mice received i.v. BrdU injection 20 h after challenge. Bacteremia increased Sca-1 expression, ERK activation, and proliferation of myeloid and granulopoietic precursors. Alcohol administration suppressed this response and impaired granulocyte production. Sca-1 expression positively correlated with ERK activation and cell cycling, but negatively correlated with myeloperoxidase content in granulopoietic precursors. Alcohol intoxication suppressed ERK activation in granulopoietic precursors and proliferation of these cells during bacteremia. Granulopoietic precursors in Sca-1(-/-) mice failed to activate ERK signaling and could not increase granulomacrophagic CFU activity following bacteremia. These data indicate that Sca-1 expression promotes ERK-dependent myeloid cell proliferation during bacteremia. Suppression of this response could represent an underlying mechanism for developing myelosuppression in alcohol-abusing hosts with severe bacterial infection.

CD8+ T cell immunity to 2009 pandemic and seasonal H1N1 influenza viruses

A novel strain of H1N1 influenza A virus (pH1N1) emerged in 2009, causing a worldwide pandemic. Several studies suggest that this virus is antigenically more closely related to human influenza viruses that circulated prior to 1957 than viruses of more recent seasonal influenza varieties. The extent to which individuals who are naïve to the 2009 pH1N1 virus carry cross-reactive CD8+ T cells is not known, but a certain degree of reactivity would be expected since there is substantial conservation among the internal proteins of the virus. In the present study, we examined the production of multiple cytokines in response to virus from CD8+ T cells in healthy adult subjects, between 18 and 50 years of age (born post 1957), who had no evidence of exposure to the 2009 pH1N1 virus, and had blood collected prior to the emergence of the pandemic in April of 2009. Human peripheral blood mononuclear cells (PBMCs) were stimulated in vitro with a panel of live viruses, and assayed by intracellular cytokine staining and flow cytometry. Although results were variable, most subjects exhibited cytokine positive CD8+ T cells in response to pH1N1. Cytokine producing cells were predominantly single positive (IL2, IFNγ, or TNFα); triple-cytokine producing cells were relatively rare. This result suggests that although many adults carry cross-reactive T cells against the emergent pandemic virus, these cells are in a functionally limited state, possibly because these subjects have not had recent exposure to either seasonal or pandemic influenza strains.

Ontogeny of Toll-like receptor mediated cytokine responses of human blood mononuclear cells

Newborns and young infants suffer increased infectious morbidity and mortality as compared to older children and adults. Morbidity and mortality due to infection are highest during the first weeks of life, decreasing over several years. Furthermore, most vaccines are not administered around birth, but over the first few years of life. A more complete understanding of the ontogeny of the immune system over the first years of life is thus urgently needed. Here, we applied the most comprehensive analysis focused on the innate immune response following TLR stimulation over the first 2 years of life in the largest such longitudinal cohort studied to-date (35 subjects). We found that innate TLR responses (i) known to support Th17 adaptive immune responses (IL-23, IL-6) peaked around birth and declined over the following 2 years only to increase again by adulthood; (ii) potentially supporting antiviral defense (IFN-α) reached adult level function by 1 year of age; (iii) known to support Th1 type immunity (IL-12p70, IFN-γ) slowly rose from a low at birth but remained far below adult responses even at 2 years of age; (iv) inducing IL-10 production steadily declined from a high around birth to adult levels by 1 or 2 years of age, and; (v) leading to production of TNF-α or IL-1β varied by stimuli. Our data contradict the notion of a linear progression from an ‘immature’ neonatal to a ‘mature’ adult pattern, but instead indicate the existence of qualitative and quantitative age-specific changes in innate immune reactivity in response to TLR stimulation.