Degranulation Responses Research Articles

Deciphering lipoprotein(a) atherogenicity with use of high-throughput proteomics

Abstract Background Accumulating observational and genetic evidence suggests that lipoprotein(a) [Lp(a)], is significantly more atherogenic than other apolipoprotein-B containing particles. Systemic inflammation is thought to mediate the atherogenic effects of Lp(a). Previous studies have predominantly focused on single inflammatory biomarkers, an approach that fails to capture the broader molecular response to elevated Lp(a) levels. Purpose The aim of this study was to derive a proteome-wide signature of plasma Lp(a) concentrations and subsequently identify the pathways through which Lp(a) influences the risk of coronary artery disease (CAD). Methods This study included 41,123 UK Biobank participants with baseline Lp(a) measurements who also underwent a proteomic assessment. Relative concentration of 2,920 proteins was quantified in EDTA plasma samples using a high-throughput proximity extension assay. Lp(a)-associated proteins were identified in linear regression models, adjusting for age, sex, body mass index, race, smoking status, estimated glomerular filtration rate, medication use, and apolipoprotein B. Proteins linked with Lp(a) concentration were then evaluated for their association with incident CAD risk using Cox proportional hazards models. Significant traits were further included in pathway enrichment analysis. Results Out of 2,920 analyzed proteins (Figure 1), 140 showed a positive association with Lp(a) concentration, while 336 exhibited a negative association after adjustment for multiple testing (False discovery rate < 0.05). The strongest positive associations were observed for apolipoprotein F, group 10 secretory phospholipase A, and C4b-binding protein beta chain. The strongest negative associations were observed for asporin, aminoacylase-1, and retinol-binding protein 5. Among 140 proteins positively associated with Lp(a), 49 were associated with an increased risk of CAD. Conversely, among the 336 proteins negatively associated with Lp(a), 10 were associated with a decreased risk of CAD. Pathway enrichment analysis (Figure 2) indicated that proteins linked with both Lp(a) levels and CAD risk predominantly upregulated pathways related to peptide-ligand receptor signalling, platelet degranulation, neutrophil degranulation, and cytosolic calcium response. Conversely, pathways related to HDL remodeling, PI3K/AKT, KIT, and nuclear receptor signalling were downregulated. Conclusions The greater atherogenic potential of Lp(a) may be attributable to the modulation of several molecular pathways, particularly those involving platelet and neutrophil responses, cell signalling, and lipoprotein metabolism.

Topiramate Inhibits Capsaicin-Induced Mast Cell Degranulation and CGRP Release in Rat Dura Mater

Background/Objectives: Migraine is a disease that stands out for its high prevalence and socioeconomic costs. It involves the entire trigeminovascular system, the signaling substances, and their targets. However, the role of meningeal mast cells in migraine is still unclear. To better understand one of the components of neurogenic inflammation underlying migraine pathophysiology, we developed an in vivo rat model in which the dura mater was exposed bilaterally to investigate the influence of topiramate on capsaicin-induced mast cell degranulation and CGRP release from dura mater. Methods: On the day of the experiment, rats were anesthetized, and a craniectomy was performed on each parietal bone. Test substances were applied in situ over the dura mater using the right and left sides of the dura mater for the test and control, respectively. After exposure, the dura mater was processed for mast cell staining and counting. Using this setup, the effect of capsaicin (10−3 M) was evaluated in rats of both sexes, and subsequently the effect of in situ (10−3 M, 20 µL) and (20 mg/kg/day for 10 days) topiramate treatment on mast cell degranulation and CGRP release were evaluated. Results: In both female and male rats, there was a greater amount of degranulated mast cells in the side stimulated by capsaicin compared to the control side in both females (18 ± 3% vs. 74 ± 3%; p = 0.016) and males (28 ± 2% vs. 74 ± 3%, p = 0.016). In the group treated with topiramate for 10 days prior to the experiments, capsaicin did not induce mast cell degranulation (control 20 ± 1% vs. capsaicin 22 ± 1%, p = 0.375) in contrast to animals treated for 10 days with gavage control (control 25 ± 1% vs. capsaicin 76 ± 1%, p = 0.016). Topiramate applied in situ concomitant with capsaicin did not protect the mast cells from degranulation in response to capsaicin (38 ± 2% vs. 44 ± 1%, p = 0.016). There was a significant reduction in CGRP release from the dura mater in the group treated with topiramate for 10 days compared to the control. Conclusions: This study demonstrates a novel experimental model wherein systemic administration of topiramate is observed to modulate the impact of capsaicin on meningeal mast cell degranulation.

NK cell subsets define sustained remission in rheumatoid arthritis.

Rheumatoid Arthritis (RA) is an immune-mediated, chronic inflammatory condition. With modern therapeutics and evidence-based management strategies, achieving sustained remission is increasingly common. To prevent complications associated with prolonged use of immunosuppressants, drug tapering or withdrawal is recommended. However, due to the lack of tools that define immunological remission, disease flares are frequent, highlighting the need for a more precision medicine-based approach. Utilising high dimensional phenotyping platforms, we set out to define peripheral blood immunological signatures of sustained remission in RA. We identified that CD8+CD57+KIR2DL1+ NK cells are associated with sustained remission. Functional studies uncovered an NK cell subset characterized by normal degranulation responses and reduced pro-inflammatory cytokine expression, which was elevated in sustained remission. Furthermore, flow cytometric analysis of NK cells from synovial fluid combined with interrogation of a publicly available single cell RNA-seq dataset of synovial tissue from active RA identified a deficiency of the phenotypic characteristics associated with this NK cell remission signature. In summary, we have uncovered a novel RA remission signature associated with compositional changes in NK cell phenotype and function that has implications for understanding the impact of sustained remission on host immunity and distinct features which may define operational tolerance in RA.

Impact of Hypoxia on Neutrophil Degranulation and Inflammatory Response in Alpha-1 Antitrypsin Deficiency Patients.

Alpha-1 antitrypsin deficiency (AATD) is an inflammatory disorder where neutrophils play a key role. Excessive neutrophil activation leads to local hypoxia and tissue damage. Most research on neutrophil function has been conducted under atmospheric conditions (21% O2), which may not represent physiological or pathological conditions. This study aimed to determine the effects of hypoxia on neutrophil degranulation and cytokine production in AATD patients. Neutrophils isolated from 54 AATD patients (31 MZ; 8 SZ; 15 ZZ) and 7 controls (MM) were exposed to hypoxia (1% O2) for 4 h. Neutrophil degranulation was assessed by measuring elastase (NE), myeloperoxidase (MPO), lactoferrin, and matrix metalloproteinase-9 (MMP-9) levels using immunoassay-based methods. Pro-inflammatory (IL-8, IL-1 beta, IL-6, and TNF-alpha) and anti-inflammatory (IL-4 and IL-10) cytokine levels were assessed by a Luminex-based method. Our results indicate a significantly increased release of NE (p = 0.015), MPO (p = 0.042), lactoferrin (p = 0.015), and MMP-9 (p = 0.001) compared to controls. Pro-inflammatory cytokines show a significant rise in IL-8 (p = 0.019), a trend towards increased IL-1 beta (p = 0.3196), no change in IL-6 (p = 0.7329), and reduced TNF-alpha (p = 0.006). Anti-inflammatory cytokines show increased IL-4 (p = 0.057) and decreased IL-10 (p = 0.05703). Increased neutrophil degranulation and inflammatory phenotype are observed in AATD neutrophils under physiological hypoxia.

Kir6.1, a component of an ATP-sensitive potassium channel, regulates natural killer cell development.

Involved in immunity and reproduction, natural killer (NK) cells offer opportunities to develop new immunotherapies to treat infections and cancer or to alleviate pregnancy complications. Most current strategies use cytokines or antibodies to enhance NK-cell function, but none use ion channel modulators, which are widely used in clinical practice to treat hypertension, diabetes, epilepsy, and other conditions. Little is known about ion channels in NK cells. We show that Kcnj8, which codes for the Kir6.1 subunit of a certain type of ATP-sensitive potassium (K ATP ) channel, is highly expressed in murine splenic and uterine NK cells compared to other K + channels previously identified in NK cells. Kcnj8 expression is highest in the most mature subset of splenic NK cells (CD27 - CD11b + ) and in NKG2A + or Ly49C/I + educated uterine NK cells. Using patch clamping, we show that a subset of NK cells expresses a current sensitive to the Kir6.1 blocker PNU-37883A. Kcnj8 does not participate in NK cell degranulation in response to tumor cells in vitro or rejection of tumor cells in vivo . Transcriptomics show that genes previously implicated in NK cell development are amongst those differentially expressed in CD27 - CD11b + NK cells deficient of Kcnj8 . Indeed, we found that mice with NK-cell specific Kcnj8 gene ablation have fewer CD11b + CD27 - and KLRG-1 + NK cells in the bone barrow and spleen. These results show that the K ATP subunit Kir6.1 has a key role in NK-cell development.

Albumin reprograms the B cell transcriptional landscape and improves neutrophil antimicrobial function in patients with decompensated cirrhosis

Background&AimPatients with acutely decompensated (AD) cirrhosis are immunocompromised and particularly susceptible to infections. This study investigated the immunomodulatory actions of albumin by which this protein may lower the incidence of infections. MethodsBlood immunophenotyping was performed in 11 AD patients and 10 healthy volunteers (HV). Bulk and single-cell (sc) RNA sequencing (RNA-seq) and flow cytometry were performed in peripheral blood mononuclear cells (PBMCs) from 20 AD patients and 34 HV exposed to albumin. Albumin’s effects on degranulation, phagocytosis, chemotaxis, and swarming of neutrophils from 6 AD patients and 9 HV were assessed by myeloperoxidase enzymatic activity, engulfment of fluorescent-labeled Escherichia coli and zymosan and interactions at single-cell resolution of neutrophils with Candida albicans in microfluidic chambers, respectively. Whole blood RNA-seq analyses were performed in 45 patients admitted for severe AD of whom 30 received albumin during hospitalization. ResultsCompared to HV, AD patients showed severe lymphopenia and defective neutrophil anti-microbial function. Bulk and scRNA-seq analyses revealed significantly (false discovery rate (FDR)<0.05) increased signatures related to B cells, myeloid cells and CD4+ T cells in PBMCs incubated with albumin. Changes in the B cell population were confirmed by flow cytometry. Neutrophils exposed to albumin also exhibited augmented chemotactic and degranulation responses, enhanced phagocytosis, and increased pathogen-restrictive swarming. Analysis of RNA-seq data in patients who had received albumin revealed specific upregulation of signatures related to B cells and neutrophils together with transcriptional changes in CD4+ T cells (FDR<0.05). ConclusionsThe finding that albumin promotes the transcriptional reprogramming and expansion of the B cell compartment and improves neutrophil antimicrobial functions indicates mechanisms that may lower the incidence of infections in patients with severe AD receiving albumin therapy.

Vaccinia virus Tiantan strain blocks host antiviral innate immunity and programmed cell death by disrupting gene expression

The vaccinia virus Tiantan (VTT) is widely utilized as a smallpox vaccine in China and holds significant importance in the prevention of diseases stemming from poxvirus infections. Nevertheless, few studies have investigated the influence of VTT infection on host gene expression. In this study, we constructed time series transcriptomic profiles of HeLa cells infected with both VTT and western reserve (WR) strains. We observed similar patterns of viral gene expression, while the expression levels of host genes varied between the two strains. There was an immediate and significant repression of host gene expression, particularly in genes associated with oxidative phosphorylation. Conversely, genes involved in nerve growth factor (NGF)-stimulated transcription were significantly activated. The upregulation of genes linked to the ribonucleic acid (RNA)-induced silencing complex (RISC) suggested a potential role for posttranscriptional regulation in the interaction between the vaccinia virus and the host. In the later stages of infection, pathways such as extracellular matrix organization, neutrophil degranulation, complement and interferon responses, translation, and programmed cell death are largely inhibited. A significant number of host genes exhibit correlations with changes in the expression levels of viral genes. The host genes that are negatively correlated with viral genes are mainly enriched in pathways associated with translation and the response to viral infection. This study significantly contributes to advancing our understanding of the dynamics between the vaccinia virus and the host, improving the application of VTTs and facilitating the development of effective vaccines against diseases such as smallpox and monkeypox.

Identifying Key Genes and Their Associated Molecular Pathways in Lupus Nephritis-Osteoporosis: An In-Silico Analysis

Nephritis and osteoporosis are debilitating medical conditions that significantly impact human health and reduce quality of life. To develop potential therapeutic strategies for these disorders necessitates understanding the genetic and molecular mechanisms. Here, we employed bioinformatics techniques purposed to find key genes and associated pathways responsible for nephritis-osteoporosis comorbidity. Six microarray datasets of systemic lupus erythematosus (SLE) and osteoporosis were retrieved from the Gene Expression Omnibus (GEO) database. Post normalization of data sets LIMMA package was utilized for differential expression analysis, among the datasets 44 differentially expressed genes (DEGs) were identified. The identified 44 genes were further analyzed for gene ontology (GO) where it was found that these genes are involved in defense response, organism interactions, and response to external stimuli. In predicting the molecular function, they were involved in several biological processes including binding to lipopolysaccharides and having peptidase and hydrolase activities. Firstly, the identified genes were primarily associated with certain granules such as specific granules and secretory granules in the aspect of cellular components. Enrichment analysis pointed out the potential pathways linked to the immune system, neutrophil degranulation, innate immunity, and immune response to tuberculosis. To examine interactions among DEGs, a complex protein-protein interaction (PPI) network was built, resulting in the identification of seven hub genes, CXCL8, ELANE, LCN2, MMP8, IFIT1, MX1, and ISG15. The study suggests that these elucidated hub genes might have high potential to be exploited as promising biomarkers and therapeutic targets in nephritis-osteoporosis. Taken together, this study provided deeper insights into the genetic and molecular basis for the comorbidity of nephritis and osteoporosis.

Combinatorial Genomic Biomarkers Associated with High Response in IgE-Dependent Degranulation in Human Mast Cells.

Mast cells are the major effector cells that mediate IgE-dependent allergic reactions. We sought to use integrated network analysis to identify genomic biomarkers associated with high response in IgE-mediated activation of primary human mast cells. Primary human mast cell cultures derived from 262 normal donors were categorized into High, Average and Low responder groups according to their activation response profiles. Transcriptome analysis was used to identify genes that were differentially expressed in different responder cultures in their baseline conditions, and the data were analyzed by constructing a personalized perturbed profile (PEEP). For upregulated genes, the construction of PEEP for each individual sample of all three responder groups revealed that High responders exhibited a higher percentage of "perturbed" samples whose PEEP values lay outside the normal range of expression. Moreover, the integration of PEEP of four selected upregulated genes into distinct sets of combinatorial profiles demonstrated that the specific pattern of upregulated expression of these four genes, in a tandem combination, was observed exclusively among the High responders. In conclusion, this combinatorial approach was useful in identifying a set of genomic biomarkers that are associated with high degranulation response in human mast cell cultures derived from the blood of a cohort of normal donors.

Red cell exchange modulates neutrophil degranulation responses in sickle cell disease.

Neutrophils in sickle cell disease (SCD) are activated, contributing to disease. Red cell exchange (RCE), with the goal of lowering hemoglobin S (HbS), is an important part of therapy for many SCD patients. Whether RCE impacts neutrophil reactivity is unknown. To determine the effect of RCE on neutrophil activation, SCD patients undergoing RCE in steady-state were enrolled. Neutrophil degranulation responses were examined before/after RCE. Kinetic studies were completed to determine the duration of the effect of RCE on neutrophil function. Degranulation results were examined in relation to white blood cell count, neutrophil count, and HbS levels. The effect of RCE on RBC phosphatidylserine (PS) exposure was examined as a possible contributor to modulation of neutrophil function by RCE. Twenty-two patients with SCD, genotype SS, who underwent RCE (average pre-RCE HbS 33 ± 14%) were included for the study. RCE significantly decreased neutrophil degranulation responses. The effect of RCE on neutrophil activation was unrelated to cell count and instead directly correlated with HbS. The effect of RCE on neutrophil activation was sustained over several days post-apheresis. Furthermore, while increased RBC PS exposure results in increased neutrophil degranulation, RCE decreases RBC PS exposure. To our knowledge, this is the first study demonstrating that RCE significantly decreases neutrophil activation in a sustained HbS-dependent manner. Modulation of PS exposure by RCE may be a contributing mechanism by which RCE modulates neutrophil activation. These studies raise the possibility that modulation of neutrophil activation contributes significantly to the therapeutic effect of RCE.

Expression of Concern: Pyk2 Is Required for Neutrophil Degranulation and Host Defense Responses to Bacterial Infection.

Expression of Concern: Pyk2 Is Required for Neutrophil Degranulation and Host Defense Responses to Bacterial Infection.

Degranulation of RBL-2H3 rat basophilic leukemia cells is synergistically inhibited by combined treatment with nobiletin and lactoferrin.

The aim of this study was to elucidate the anti-allergic effects of polymethoxyflavonoids in combination with milk proteins and the mechanism of inhibition. Three polymethoxyflavonoids and two milk proteins were exposed to the rat basophilic leukemia cell line RBL-2H3. β-hexosaminidase was used as an indicator of degranulation inhibition. The mechanism of inhibition was examined by measuring intracellular Ca2+ levels and western blot method. In the degranulation inhibition test with polymethoxyflavonoids and milk proteins alone, nobiletin was the strongest inhibitor in the polymethoxyflavonoid group and lactoferrin in the milk protein group. Next, co-stimulation with nobiletin and lactoferrin showed stronger synergistic degranulation inhibition than treatment with nobiletin or lactoferrin alone. Western blot analysis showed that co-stimulation with nobiletin and lactoferrin significantly downregulated the induction of phospholipase Cγ 1 phosphorylation. The degranulation response in RBL-2H3 cells was synergistically suppressed by co-stimulation of nobiletin and lactoferrin acting on both Ca2+-dependent and Ca2+-independent pathways.

Texture Analysis as a Discriminating Tool: Unmasking Rodlet Cell Degranulation in Response to a Contaminant of Emerging Concern.

Contaminants of emerging concern (CECs) have garnered significant attention due to their potential impacts on ecology, wildlife, and human health. The interest in these contaminants arises from their inadequate regulation or lack of routine monitoring in natural environments. Among them, per- and polyfluoroalkyl substances (PFAS) are of particular concern due to their notable propensity to accumulate within the kidney, significantly influencing the excretion of these pollutants. Rodlet cells (RCs) have emerged as promising indicators of immunotoxicity in response to chemical stressors. A prior comprehensive study extensively detailed the effects of sub-chronic exposure to perfluorooctanoic acid (PFOA), a well-known PFAS compound, on RCs located in the hematopoietic tissue of the common carp kidney. Even at concentrations commonly found in the environment, PFOA exhibited a significant impact on the distribution patterns of RCs, concurrently enhancing exocytosis activity. The assessment of PFOA-induced RC degranulation employed texture analysis combined with linear discriminant analysis (LDA) to differentiate between various experimental exposure groups. The investigation encompassed three fish groups: an unexposed group, a group exposed to an environmentally relevant PFOA concentration (200 ng L-1), and a group exposed to a higher PFOA concentration (2 mg L-1). Texture analysis was conducted on high-resolution color (RGB) images obtained from light microscopy of ultrathin sections from five fish per experimental group, stained with toluidine blue. This analysis facilitated the quantification of potential cytoplasmic alterations associated with degranulation, encompassing all three RGB channels. The data subjected to LDA enabled the identification of the most distinctive texture characteristics, providing a reliable, objective, and reproducible method to differentiate between experimental groups. Remarkably, 98.0% of both the original and cross-validated cases were correctly classified. However, only one unexposed case was misclassified as a fish exposed to a 200 ng L-1 PFOA concentration, constituting the single false positive in the analysis. Utilizing texture analysis and LDA to quantify RC degranulation offers a dependable approach for assessing immunotoxicity within experimental models of toxicological and environmental pathology. This underscores the scientific significance of employing a morphological approach in such investigations.

CD11B/CD18 SIALYLATION REGULATES NEUTROPHIL TRAFFICKING AND INFLAMMATORY FUNCTION IN THE INTESTINE

Abstract Pathogen-triggered neutrophil (PMN) recruitment is critical for innate immunity, but excessive PMN influx and associated mucosal tissue damage is implicated in the pathogenesis of numerous human inflammatory disorders including inflammatory bowel disease (IBD). Critically in both ulcerative colitis and Crohn’s disease, disease flares requiring medical intervention are associated with migration of large numbers of PMNs across colonic epithelium resulting in mucosal injury/ulceration. Recent studies have shown that specific PMN glycans can be targeted to reduce transepithelial migration (TEpM) the critical final step in PMN intestinal trafficking. However the role of Sialic acid (Sia), the most abundant PMN expressed terminal glycan, in regulating PMN migration and inflammatory function in the gut is not well understood. Using sophisticated models of human and murine PMN intestinal migration, we show that blocking sialidase-mediated removal of alpha 2-3 linked sialic acid from CD11b/CD18 inhibits PMN TEpM in vitro and in vivo.Measurement of cytochrome C reduction revealed that inhibition of sialidases reduced bacterial peptide (fMLF) stimulated superoxide release by human and murine PMN. Flow cytometry analyses revealed that sialidase inhibition decreased fMLF mediated PMN degranulation and fMLF mediated CD11b/CD18 conformational activation. Highlighting the functional importance of individual Sia residues, inhibition of alpha 2-3 sialidase activity with 3’ Sialyllactose (3’SL) was found to inhibit PMN intestinal trafficking in vitro and in vivo and reduce PMN degranulation responses. Immunoblotting studies showed that sialidase inhibition deactivates spleen tyrosine kinase (Syk) and p38 MAP kinase, key intracellular mediators that signal downstream of PMN CD11b/CD18. Finally, inhibition of sialidase activity reduced adhesion of PMN to ICAM-1 (a major physiological substrate of CD11b/CD18) demonstrating that endogenous PMN sialidases regulate binding interactions between migrating PMN and intestinal epithelial receptors. Taken together data show that upon activation PMN sialidases remove alpha 2-3 Sia from CD11b/CD18 which leads to integrin activation and subsequent outside in signaling mediated by Syk to drive PMN inflammatory effector functions including migration, degranulation, and superoxide release. As such targeting CD11b/CD18 sialylation represents a promising new therapeutic strategy for reducing dysregulated PMN influx and associated mucosal tissue damage in IBD and other inflammatory disorders.

IgG in the control of FcεRI activation: a battle on multiple fronts.

The rising global incidence of IgE-mediated allergic reactions poses a significant challenge to the quality of life of affected individuals and to healthcare systems, with current treatments being limited in effectiveness, safety, and disease-modifying capabilities. IgE acts by sensitizing the high-affinity IgE receptor FcεRI expressed by mast cells and basophils, tuning these cells for inflammatory degranulation in response to future allergen encounters. In recent years, IgG has emerged as an essential negative regulator of IgE-dependent allergic inflammation. Mechanistically, studies have proposed different pathways by which IgG can interfere with the activation of IgE-mediated inflammation. Here, we briefly summarize the major proposed mechanisms of action by which IgG controls the IgE-FcεRI inflammatory axis and how those mechanisms are currently applied as therapeutic interventions for IgE-mediated inflammation.

The Underlying Rab Network of MRGPRX2-Stimulated Secretion Unveils the Impact of Receptor Trafficking on Secretory Granule Biogenesis and Secretion.

MRGPRX2, the human member of the MAS-related G-protein-coupled receptors (GPCRs), mediates the immunoglobulin E (IgE)-independent responses of a subset of mast cells (MCs) that are associated with itch, pain, neurogenic inflammation, and pseudoallergy to drugs. The mechanisms underlying the responses of MRGPRX2 to its multiple and diverse ligands are still not completely understood. Given the close association between GPCR location and function, and the key role played by Rab GTPases in controlling discrete steps along vesicular trafficking, we aimed to reveal the vesicular pathways that directly impact MRGPRX2-mediated exocytosis by identifying the Rabs that influence this process. For this purpose, we screened 43 Rabs for their functional and phenotypic impacts on MC degranulation in response to the synthetic MRGPRX2 ligand compound 48/80 (c48/80), which is often used as the gold standard of MRGPRX2 ligands, or to substance P (SP), an important trigger of neuroinflammatory MC responses. Results of this study highlight the important roles played by macropinocytosis and autophagy in controlling MRGPRX2-mediated exocytosis, demonstrating a close feedback control between the internalization and post-endocytic trafficking of MRGPRX2 and its triggered exocytosis.

An optimized method for IgE-mediated degranulation of human lung mast cells.

Mast cells are critically involved in IgE-mediated diseases, e.g., allergies and asthma. Human mast cells are heterogeneous, and mast cells from different anatomical sites have been shown to respond differently to certain stimuli and drugs. The origin of the mast cells is therefore of importance when setting up a model system, and human lung mast cells are highly relevant cells to study in the context of asthma. We therefore set out to optimize a protocol of IgE-mediated activation of human lung mast cells. Human lung mast cells were extracted from lung tissue obtained from patients undergoing pulmonary resection by enzyme digestion and mechanical disruption followed by CD117 magnetic-activated cell sorting (MACS) enrichment. Different culturing media and conditions for the IgE-mediated degranulation were tested to obtain an optimized method. IgE crosslinking of human lung mast cells cultured in serum-free media gave a stronger response compared to cells cultured with 10% serum. The addition of stem cell factor (SCF) did not enhance the degranulation. However, when the cells were put in fresh serum-free media 30 minutes prior to the addition of anti-IgE antibodies, the cells responded more vigorously. Maximum degranulation was reached 10 minutes after the addition of anti-IgE. Both CD63 and CD164 were identified as stable markers for the detection of degranulated mast cells over time, while the staining with anti-CD107a and avidin started to decline 10 minutes after activation. The levels of CD203c and CD13 did not change in activated cells and therefore cannot be used as degranulation markers of human lung mast cells. For an optimal degranulation response, human lung mast cells should be cultured and activated in serum-free media. With this method, a very strong and consistent degranulation response with a low donor-to-donor variation is obtained. Therefore, this model is useful for further investigations of IgE-mediated mast cell activation and exploring drugs that target human lung mast cells, for instance, in the context of asthma.

γδ T cells mediate robust anti-HIV functions during antiretroviral therapy regardless of immune checkpoint expression.

Although antiretroviral therapy (ART) efficiently suppresses HIV viral load, immune dysregulation and dysfunction persist in people living with HIV (PLWH). γδ T cells are functionally impaired during untreated HIV infection, but the extent to which they are reconstituted upon ART is currently unclear. Utilising a cohort of ART-treated PLWH, we assessed the frequency and phenotype, characterised in vitro functional responses and defined the impact of immune checkpoint marker expression on effector functions of both Vδ1 and Vδ2 T cells. We additionally explore the in vitro expansion of Vδ2 T cells from PLWH on ART and the mechanisms by which such expanded cells may sense and kill HIV-infected targets. A matured NK cell-like phenotype was observed for Vδ1 T cells among 25 ART-treated individuals (PLWH/ART) studied compared to 17 HIV-uninfected controls, with heightened expression of 2B4, CD160, TIGIT and Tim-3. Despite persistent phenotypic perturbations, Vδ1 T cells from PLWH/ART exhibited strong CD16-mediated activation and degranulation, which were suppressed upon Tim-3 and TIGIT crosslinking. Vδ2 T cell degranulation responses to the phosphoantigen (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate at concentrations up to 2 ng mL-1 were significantly impaired in an immune checkpoint-independent manner among ART-treated participants. Nonetheless, expanded Vδ2 T cells from PLWH/ART retained potent anti-HIV effector functions, with the NKG2D receptor contributing substantially to the elimination of infected cells. Our findings highlight that although significant perturbations remain within the γδ T cell compartment throughout ART-treated HIV, both subsets retain the capacity for robust anti-HIV effector functions.

HIV vaccines induce CD8+ T cells with low antigen receptor sensitivity.

Current HIV vaccines designed to stimulate CD8+ T cells have failed to induce immunologic control upon infection. The functions of vaccine-induced HIV-specific CD8+ T cells were investigated here in detail. Cytotoxic capacity was significantly lower than in HIV controllers and was not a consequence of low frequency or unaccumulated functional cytotoxic proteins. Low cytotoxic capacity was attributable to impaired degranulation in response to the low antigen levels present on HIV-infected targets. The vaccine-induced T cell receptor (TCR) repertoire was polyclonal and transduction of these TCRs conferred the same reduced functions. These results define a mechanism accounting for poor antiviral activity induced by these vaccines and suggest that an effective CD8+ T cell response may require a vaccination strategy that drives further TCR clonal selection.

Is Wheat Glutenin Extract Intrinsically Allergenic? Evaluation Using a Novel Adjuvant-Free Mouse Model of Systemic Anaphylaxis.

Wheat is a prominent allergenic food that can trigger life-threatening anaphylaxis. Presently, it remains unclear whether wheat glutenin (WG) extract possesses inherent sensitization potential independently, without the use of adjuvants, and whether it can sensitize mice to the extent of inducing life-threatening systemic anaphylaxis. In this study, we tested the hypothesis that repeated skin exposures to WG extract without adjuvant will sensitize mice with the resultant anaphylactic reaction upon systemic WG challenge. Balb/c mice were bred and maintained on a strict plant protein-free diet and were repeatedly exposed to a WG extract or vehicle once a week for 9 weeks. WG-specific (s)IgE and total (t)IgE levels were quantified. Mice were challenged with WG extract to induce anaphylactic reactions as measured by hypothermic shock response (HSR) and mucosal mast cell degranulation response (MMCR). We also conducted proteomic analysis of 120 spleen immune markers. These skin-sensitized mice exhibited exposure-dependent IgE responses and near-fatal anaphylaxis upon challenge. Proteomic analysis identified seven dramatically elevated immune biomarkers in anaphylactic mice. These data reveal that WG is intrinsically allergenic, and that chronic skin exposure to WG extract can prime the mice for potentially fatal anaphylaxis.