Role of CD86 on granulocyte in mediating the effect of Genus Roseburia on periodontitis.

OBJECTIVES: This study aimed to explore the causal link between the gut microbiota and periodontitis, and to delineate and quantify the intermediary role of immune cells, so as to provide new insights into the pathogenesis, prevention and treatment of periodontitis. MATERIALS AND METHODS: We employed a two-sample Mendelian randomization (MR) approach to analyze the genetic predictors of gut microbiota composition (covering 412 gut microbiota taxa and functions) and periodontitis (involving 4,784 cases and 272,252 controls) derived from genome-wide association study (GWAS) datasets. A subsequent two-step MR analysis was conducted to evaluate the extent to which immune cell traits (encompassing 731 immune cell characteristics) mediate the influence of gut microbiota on periodontitis risk. RESULTS: Our analysis implicated nine gut microbiota taxa as causal factors in periodontitis susceptibility (p < 0.05). Notably, the Genus Roseburia was identified as exerting a protective effect against periodontitis, partially mediated through the upregulation of CD86 expression on granulocytes, with an 8.15% mediation effect observed. CONCLUSIONS: Our findings establish a causal relationship between the gut microbiota and periodontitis, highlighting the protective role of Roseburia against this condition. A notable proportion of this protective effect is mediated via the upregulation of CD86 on granulocytes. CLINICAL RELEVANCE: It can provide new ideas for the pathogenesis, prevention and treatment for periodontitis through exploring the causal link between the gut microbiota and periodontitis, and describing and quantifying the intermediary role of immune cells.

CD11b/CD86 involved in the microenvironment of colorectal cancer by promoting Wnt signaling activation.

BACKGROUND: Colorectal cancer (CRC) is a malignancy that arises within the gastrointestinal tract. Despite ongoing research, the etiology and pathogenesis of CRC remain elusive; particularly, the distribution and characteristics of tumor-associated macrophages is currently an active area of investigation in understanding the pathological progression and prevention of CRC. METHODS: This study utilized CRC patient surgical samples, mouse models of colitis-associated cancer, colonic organoid, and co-culture cell line to examine the changes in CD11b/CD86 at different pathological region and detect the Wnt signaling pathway activity. RESULTS: Our findings revealed a sensitive and increased expression of CD11b from the early to the advanced CRC tissues and correlated with poor prognosis, while CD86 expression was reduced in advanced CRC tissues. CD133 expression was also elevated in advanced CRC tissues and mainly co-localized with CD11b, suggesting a positive regulatory effect of CD11b and CD133 expression that may contribute to CRC progression. In AOM/DSS mouse models, activation of the Wnt signaling pathway was associated with increased CD133 and CD11b expression. In vitro, THP-1 cell was induced to high expression of CD11b, and the above conditional cultural medium enhanced HCT116 cell colony number and CD133 protein expression. Furthermore, colonic crypts from AOM/DSS mouse models were isolated to culture, and the colonic organoids exhibited dilation and significant increases expression of CD133 and ß-Catenin/N-P-B-Catenin. CONCLUSIONS: CD11b might be an important factor to participate the progress of CRC. And the high CD11b of CRC microenviroment might potentially promote CD133 expression and associate with Wnt signal activation.

High-dose radiation-induced immunogenic cell death of bladder cancer cells leads to dendritic cell activation.

Radiotherapy is a commonly used method in the treatment of bladder cancers (BC). Radiation-induced immunogenic cell death (ICD) is related to the immune response against cancers and their prognoses. Even though dendritic cells (DC) act as powerful antigen-presenting cells in the body, their precise role in this ICD process remains unclear. Accordingly, an in vitro study was undertaken to ascertain whether high-dose radiation-induced ICD of BC cells could regulate the immune response of DC. The results indicated that high-dose radiation treatments of BC cells significantly increased their levels of apoptosis, blocked their cell cycle in the G2/M phase, increased their expression of ICD-related proteins, and upregulated their secretion of CCL5 and CCL21 which control the directed migration of DC. It was also noted that expression of CD80, CD86, CCR5, and CCR7 on DC was upregulated in the medium containing the irradiated cells. In conclusion, the present findings illustrate that high-dose radiation can induce the occurrence of ICD within BC cells, concomitantly resulting in the activation of DC. Such findings could be of great significance in increasing the understanding how radiotherapy of BC may work to bring about reductions in cell activity and how these processes in turn lead to immunoregulation of the function of DC.

Dendritic Cells Promote the Differentiation of ILCs into NCR-ILC3s in the Lungs of Mice Exposed to Cigarette Smoke.

The involvement of Group 3 innate lymphoid cells (ILC3s) and dendritic cells (DCs) in chronic lung inflammation has been increasingly regarded as the key to understand the inflammatory mechanisms of smoke-related chronic obstructive pulmonary disease (COPD). However, the mechanism underlying the engagement of both remains unclear. Our study aimed to explore NCR-ILC3 differentiation in the lungs of mice exposed to cigarette smoke (CS) and to further investigate whether DCs activated by CS exposure contribute to the differentiation of ILCs into NCR-ILC3s. The study involved both in vivo and in vitro experiments. In the former, the frequencies of lung NCR-ILC3s and NKp46-IL-17A+ ILCs and the expression of DCs, CD40, CD86, IL-23, and IL-1ß quantified by flow cytometry were compared between CS-exposed mice and air-exposed mice. In the latter, NKp46-IL-17A+ ILC frequencies quantified by flow cytometry were compared after two cocultures, one involving lung CD45+Lin-CD127+ ILCs sorted from air-exposed mice and DCs sifted by CD11c magnetic beads from CS-exposed mice and another including identical CD45+Lin-CD127+ ILCs and DCs from air-exposed mice. The results indicated significant increases in the frequencies of NCR-ILC3s and NKp46-IL-17A+ ILCs; in the expression of DCs, CD40, CD86, IL-23, and IL-1ß in CS-exposed mice; and in the frequency of NKp46-IL-17A+ ILCs after the coculture with DCs from CS-exposed mice. In conclusion, CS exposure increases the frequency of lung ILCs and NCR-ILC3s. CS-induced DC activation enhances the differentiation of ILCs into NCR-ILC3s, which likely acts as a mediating step in the involvement of NCR-ILC3s in chronic lung inflammation.

Spatiotemporal coordination of antigen presentation and co-stimulatory signal for enhanced anti-tumor vaccination.

Controlled-release systems enhance anti-tumor effects by leveraging local antigen persistence for antigen-presenting cells (APCs) recruitment and T cell engagement. However, constant antigen presentation alone tends to induce dysfunction in tumor-specific CD8+ T cells, neglecting the synergistic effects of co-stimulatory signal. To address this, we developed a soft particle-stabilized emulsion (SPE) to deliver lipopeptides with controlled release profiles by adjusting their hydrophobic chain lengths: C6-SPE (fast release), C10-SPE (medium release), and C16-SPE (slow release). Following administration, C6-SPE release antigen rapidly, inducing early antigen presentation, whereas C16-SPE's slow-release delays antigen presentation. Both scenarios missed the critical window for coordinating with the expression of CD86, leading to either T cell apoptosis or suboptimal activation. In contrast, C10-SPE achieved a spatiotemporally synergetic effect of the MHC-I-peptide complex and co-stimulatory signal (CD86), leading to effective dendritic cell (DC) activation, enhanced T cell activation, and tumor regression in EG7-OVA bearing mice. Additionally, co-delivery of cytosine-phosphate-guanine (CpG) with SPE provided a sustained expression of the CD86 window for DC activation, improving the immune response and producing robust anti-tumor effects with C6-SPE comparable to C10-SPE. These findings highlight that synchronizing the spatiotemporal dynamics of antigen presentation and APC activation may confer an optimal strategy for enhanced vaccinations.

Altered co-stimulatory and inhibitory receptors on monocyte subsets in patients with visceral leishmaniasis.

Visceral leishmaniasis (VL) is a neglected tropical disease caused by parasites from the Leishmania (L.) donovani complex. VL is characterised by uncontrolled parasite replication in spleen, liver and bone marrow, and by an impaired immune response and high systemic levels of inflammation. Monocytes have been poorly characterised in VL patients. The aim of this study was to evaluate the expression levels of markers involved in the regulation of T cell responses on different subsets of monocytes from the blood of VL patients and healthy non-endemic controls (HNEC). Monocytes can broadly be divided into three subsets: classical, intermediate and non-classical monocytes. Our results show that the percentages of all three subsets stayed similar at the time of VL diagnosis (ToD) and at the end of anti-leishmanial treatment (EoT). We first looked at co-stimulatory receptors: the expression levels of CD40 were significantly increased on classical and intermediate, but not non-classical monocytes, at ToD as compared to EoT and HNEC. CD80 expression levels were also increased on intermediate monocytes at ToD as compared to EoT and HNEC, and on classical monocytes only as compared to HNEC. The levels of CD86 were similar at EoT and ToD and in HNEC on classical and intermediate monocytes, but significantly higher at EoT on non-classical monocytes. We also looked at an inhibitory molecule, PD-L1. Our results show that the expression levels of PD-L1 were significantly higher on all three monocyte subsets at ToD as compared to HNEC, and to EoT on classical and intermediate monocytes. These results show that monocytes from the blood of VL patients upregulate both co-stimulatory and inhibitory receptors and that their expression levels are restored at EoT.

A novel costimulatory molecule gene-modified leukemia cell-derived exosome enhances the anti-leukemia efficacy of DC vaccine in mouse models.

OBJECTIVES: Leukemia cell-derived exosomes (LEXs), carrying leukemia cell-specific antigens, can serve as a source of antigen for dendritic cell (DC) vaccine loading. However, LEX-targeted DC-based vaccines have demonstrated limited antitumor immune effects in clinical trials, attributed to the low immunogenicity of LEXs and the scant levels of costimulatory molecules on DCs. The costimulatory molecules CD80 and CD86, which are crucial to DC function, play a significant role in enhancing immune efficacy. In this study, we explored the anti-leukemia immune response of costimulatory molecule gene-modified LEX-targeted DCs (LEX-8086) in vitro and in animal models. METHODS: DCs were incubated with LEX-8086 to produce LEX-8086-targeted DCs (DCsLEX-8086). ELISA, cytotoxicity assays and flow cytometry utilized to assess the antitumor efficacy of DCsLEX8086 in vitro. Flow cytometry was used to evaluate the immunomodulatory function of DCsLEX8086 in animal models. RESULTS: Our findings indicated that LEX-8086 enhanced the maturation and antigen-presenting ability of DCs. Immunization with DCsLEX8086 significantly activated CD8+ T cells and boosted the CTL response in vitro. More importantly, DCsLEX-8086 effectively suppressed tumor growth and exerted anti-leukemia effects in both prophylactic and therapeutic animal models. Furthermore, DCsLEX-8086 promoted the proportion of CD4+ T cells, CD8+ T cells and M1 macrophages in the tumor environments both prophylactically and therapeutically. Treatment with DCsLEX-8086 showed no significant difference in the levels of M2 macrophages but decreased the proportion of Tregs within the tumor bed during therapeutic experiments. CONCLUSION: The results suggested that DCsLEX-8086 induces a more effective anti-leukemia immunity compared to DCsLEX-null in vivo and in vitro. DCsLEX-8086 might achieve antitumor effects by elevating the numbers of CD4+ T cells, CD8+ T cells, and M1 macrophages in tumors. Our findings indicate that DCsLEX-8086 could be leveraged to develop a new, highly effective vaccine for anti-leukemia immunity.

Bacteriophages from treatment-naïve type 2 diabetes individuals drive an inflammatory response in human co-cultures of dendritic cells and T cells.

Individuals with type 2 diabetes (T2D) show signs of low-grade inflammation, which is related to the development of insulin resistance and beta-cell dysfunction. However, the underlying triggers remain unknown. The gut microbiota is a plausible source as it comprises pro-inflammatory bacteria, bacterial metabolites and viruses, including (bacterio)phages. These prokaryotic viruses have been shown to mediate inflammatory responses in gastrointestinal disease. Given the differences in phage populations in healthy individuals versus those with cardiometabolic diseases such as T2D, we here questioned whether phages from T2D individuals would have increased immunogenic potential. To address this, we isolated intestinal phages from a fresh stool sample of healthy controls and individuals with newly diagnosed, treatment-naive T2D. Phages were purified using cesium chloride ultracentrifugation and incubated with healthy donor dendritic cells (DCs) and autologous T cells. Donors with T2D had slightly higher free viral particle numbers compared to healthy controls (p = .1972), which has been previously associated with disease states. Further, phages from T2D induced a higher inflammatory response in DCs and T cells than phages from HC. For example, the expression of the co-stimulatory molecule CD86 on DCs (p < .001) and interferon-y secretion from T cells (p < .01) were increased when comparing the two groups. These results suggest that phages might play a role in low-grade inflammation in T2D individuals.

Blockade of CD80/CD86-CD28 co-stimulation augments the inhibitory function of peptide antigen-specific regulatory T cells.

Mixed lymphocyte culture under the blockade of CD80/CD86-CD28 co-stimulation induces anergic (completely hyporesponsive) T cells with immune suppressive function (inducible suppressing T cells: iTS cells). Previously, iTS cell therapy has demonstrated outstanding benefits in clinical trials for organ transplantation. Here, we examined whether peptide antigen-specific iTS cells are inducible. DO 11.10 iTS cells were obtained from splenocytes of BALB/c DO 11.10 mice by stimulation with OVA peptide and antagonistic anti-CD80/CD86 mAbs. When DO 11.10 iTS or Foxp3- DO 11.10 iTS cells were stimulated with OVA, these cells produced IL-13, but not IL-4. DO 11.10 iTS cells decreased IL-4 and increased IL-13 production from OVA-stimulated naïve DO 11.10 splenocytes. When Foxp3+ DO 11.10 iTS cells were prepared, these cells significantly inhibited the production of IL-4 and IL-13 compared with freshly isolated Foxp3+ DO 11.10 T cells. Moreover, an increase in the population expressing OX40, ICOS, and 4-1BB suggested activation of Foxp3+ DO 11.10 iTS cells. Thus, blockade of CD80/CD86-CD28 co-stimulation during peptide antigen stimulation augments the inhibitory function of Foxp3+ regulatory T cells, and does not induce anergic Foxp3- conventional T cells. Peptide-specific Foxp3+ regulatory iTS cells could be useful for the treatment of allergic and autoimmune diseases without adverse effects.

Development of Hsp90 inhibitor to regulate cytokine storms in excessive delayed- and acute inflammation.

BACKGROUND: The surplus cytokines remaining after use in the early stages of the inflammatory response stimulate immune cells even after the response is over, causing a secondary inflammatory response and ultimately damaging the host, which is called a cytokine storm. Inhibiting heat shock protein 90 (Hsp90), which has recently been shown to play an important role in regulating inflammation in various cell types, may help control excessive inflammatory responses and cytokine storms. METHODS: We discovered an anti-inflammatory compound by measuring the inhibitory effect of CD86 expression on spleen DCs (sDCs) using the chemical compounds library of Hsp90 inhibitors. Subsequently, to select the hit compound, the production of cytokines and expression of surface molecules were measured on the bone marrow-derived DCs (BMDCs) and peritoneal macrophages. Then, we analyzed the response of antigen-specific Th1 cells. Finally, we confirmed the effect of the compound using acute lung injury (ALI) and delayed-type hypersensitivity (DTH) models. RESULTS: We identified Be01 as the hit compound, which reduced CD86 expression the most in sDCs. Treatment with Be01 decreased the production of pro-inflammatory cytokines (IL-6, TNF-α, and IL-1ß) in BMDC and peritoneal macrophages stimulated by LPS. Under the DTH model, Be01 treatment reduced ear swelling and pro-inflammatory cytokines in the spleen. Similarly, Be01 treatment in the ALI model decreased neutrophil infiltration and lower levels of secreted cytokines (IL-6, TNF-α). CONCLUSIONS: Reduction of CD80 and CD86 expression on DCs by Be01 indicates reduced secondary inflammatory response by Th1 cells, and reduced release of pro-inflammatory cytokines by peritoneal macrophages may initially control the cytokine storm.

Targeting dendritic cell activation: the therapeutic impact of paeoniflorin in cortosteroid-dependent dermatitis management.

This study investigates the mechanism through which paeoniflorin inhibits TSLP expression to regulate dendritic cell activation in corticosteroid-dependent dermatitis treatment. Utilizing databases like TCMSP, we identified paeoniflorin's components, targets, and constructed networks. Molecular docking and gene enrichment analysis helped pinpoint key targets and pathways affected by paeoniflorin. In vitro and in vivo models were used to study CD80, CD86, cytokines, T-cell activation, skin lesions, histopathological changes, TSLP, CD80, and CD86 expression. Our study revealed paeoniflorin's active constituent targeting IL-6 in corticosteroid-dependent dermatitis. In vitro experiments demonstrated reduced TSLP expression, CD80, CD86, and cytokine secretion post-paeoniflorin treatment. In vivo, paeoniflorin significantly decreased skin lesion severity, cytokine levels, TSLP, CD80, and CD86 expression. The study highlights paeoniflorin's efficacy in inhibiting TSLP expression and suppressing dendritic cell activation in corticosteroid-dependent dermatitis, suggesting its potential as a therapeutic intervention. Additionally, it offers insights into the complex molecular mechanisms underlying paeoniflorin's anti-inflammatory properties in treating corticosteroid-dependent dermatitis.

Obesity induces PD-1 on macrophages to suppress anti-tumour immunity.

Obesity is a leading risk factor for progression and metastasis of many cancers1,2, yet can in some cases enhance survival3-5 and responses to immune checkpoint blockade therapies, including anti-PD-1, which targets PD-1 (encoded by PDCD1), an inhibitory receptor expressed on immune cells6-8. Although obesity promotes chronic inflammation, the role of the immune system in the obesity-cancer connection and immunotherapy remains unclear. It has been shown that in addition to T cells, macrophages can express PD-19-12. Here we found that obesity selectively induced PD-1 expression on tumour-associated macrophages (TAMs). Type I inflammatory cytokines and molecules linked to obesity, including interferon-γ, tumour necrosis factor, leptin, insulin and palmitate, induced macrophage PD-1 expression in an mTORC1- and glycolysis-dependent manner. PD-1 then provided negative feedback to TAMs that suppressed glycolysis, phagocytosis and T cell stimulatory potential. Conversely, PD-1 blockade increased the level of macrophage glycolysis, which was essential for PD-1 inhibition to augment TAM expression of CD86 and major histocompatibility complex I and II molecules and ability to activate T cells. Myeloid-specific PD-1 deficiency slowed tumour growth, enhanced TAM glycolysis and antigen-presentation capability, and led to increased CD8+ T cell activity with a reduced level of markers of exhaustion. These findings show that obesity-associated metabolic signalling and inflammatory cues cause TAMs to induce PD-1 expression, which then drives a TAM-specific feedback mechanism that impairs tumour immune surveillance. This may contribute to increased cancer risk yet improved response to PD-1 immunotherapy in obesity.

Saponin Esculeoside A and Aglycon Esculeogenin A from Ripe Tomatoes Inhibit Dendritic Cell Function by Attenuation of Toll-like Receptor 4 Signaling.

Dendritic cells (DCs) can initiate immune response through the presenting antigens to naïve T lymphocytes. Esculeoside A (EsA), a spirosolane glycoside, is reported as a major component in the ripe fruit of tomato. Little is known about the effect of tomato saponin on mice bone marrow-derived DCs. This study revealed that EsA and its aglycon, esculeogenin A (Esg-A), attenuated the phenotypic and functional maturation of murine DCs stimulated by lipopolysaccharide (LPS). We found that EsA/Esg-A down-regulated the expression of major histocompatibility complex type II molecules and costimulatory molecule CD86 after LPS stimulation. It was also determined that EsA-/Esg-A-treated DCs were poor stimulators of allogeneic T-cell proliferation and exhibited impaired interleukin-12 and TNF-α production. Additionally, EsA/Esg-A was able to inhibit TLR4-related and p-NFκB signaling pathways. This study shows new insights into the immunopharmacology of EsA/Esg-A, and represents a novel approach to controlling DCs for therapeutic application.

Development of a Protocol for Obtaining a Homologous Cell Product of Animal Origin Intended for Preclinical Studies of Antitumor Vaccine CaTeVac.

When developing a program of preclinical studies of human cell-based drugs intended for adoptive immunotherapy of cancer patients, the biological effect should be substantiated by data describing their immunological action. Administration and study of human autologous dendritic cell vaccine to immunocompetent animals are not adequate in terms of immunological compatibility. It is possible to use immunocompromised, knockout, or transgenic animals or to obtain a homologous cellular product, namely, a preparation based on animal cells using a technology similar to obtaining the original preparation for clinical practice in humans. Within the framework of this study, we have developed a protocol for obtaining a homologous cell product based on animal dendritic cells (mice, rats) according to a similar technology for obtaining human vaccine dendritic cells, and demonstrated the comparability of morphological characteristics and expression of differentiation antigens of dendritic cells (CD11c, CD80, CD86, and CD83) of animals (mice) and humans.

K33 only mutant ubiquitin augments bone marrow-derived dendritic cell-mediated CTL priming via PI3K-Akt pathway.

To explore the effect of K33 only mutant ubiquitin (K33O) on bone marrow-derived dendritic cells' (BMDCs') maturity, antigen uptake capability, surface molecule expressions and BMDC-mediated CTL priming, and further investigate the role of PI3K-Akt engaged in K33O-increased BMDC maturation, antigen uptake and presentation, surface molecule expressions and BMDC-based CTL priming. BMDCs were conferred K33O and other ubiquitin mutants (K33R, K48R, K63R-mutant ubiquitin) incubation or LY294002 and wortmannin pretreatment. PI3K-Akt phosphorylation, antigen uptake, antigenic presentation and CD86/MHC class I expression in BMDC were determined by western blot or flow cytometry. BMDC-based CTL proliferation and priming were determined by in vitro mixed lymphocyte reaction (MLR), ex vivo enzyme-linked immunospot assay (Elispot) and flow cytometry with intracellular staining, respectively. The treatment with K33O effectively augmented PI3K-Akt phosphorylation, BMDCs' antigen uptake, antigenic presentation, CD86/MHC class I and CD11c expressions. MLR, Elispot and flow cytometry revealed that K33O treatment obviously enhanced CTL proliferation, CTL priming and perforin/granzyme B expression. The pretreatment with PI3K-Akt inhibitors efficiently abrogated K33O's effects on BMDC. The replenishment of K33 only mutant ubiquitin augments BMDC-mediated CTL priming in bone marrow-derived dendritic cells via PI3K-Akt signalling.

Optimal conditions for adenoviral transduction of immature dendritic cells without affecting the tolerogenic activity of DC-based immunotherapy.

Dendritic cells (DCs) play a pivotal role in maintaining immune tolerance. Using recombinant adenovirus (rAd) to deliver vectors to immature dendritic cells (imDCs) is an important method for studying the tolerogenic function of DCs. We found that using RPMI medium and a higher MOI during transduction increased the expression of CD80, CD86, and MHC-II on the surface of imDCs. Our data reveal a significant increase in the secretion of the pro-inflammatory cytokine IL-6 in the group showing the most pronounced phenotypic changes. In the mouse heart transplant model, imDCs with unstable phenotype and function due to adenoviral transduction resulted in an increased proportion of Th1 and Th17 cells in recipients. However, these effects can be managed, and our proposed optimized transduction strategy significantly minimizes these adverse effects. Our study holds significant implications for the development and optimization of immunotherapy utilizing tolerogenic dendritic cells.

Co-stimulatory pathway competitive assay development using Liquid chromatography-tandem mass spectrometry (LC-MS/MS).

T-cells play a significant role in the development of autoimmune diseases. The CD28-B7 costimulatory pathway is crucial for activating T-cells, and blocking this pathway is essential for treating autoimmune diseases. Therapeutic antibodies and fusion proteins that target costimulatory molecules like CD80, CD86, CTLA-4, and CD28 have been developed to explore the costimulation process and as targeted treatments. To advance our understanding of costimulation in autoimmunity and the inhibition of the costimulatory pathway, it is crucial to have an accurate, precise, and direct method for detecting and quantifying the soluble form of these molecules in body fluids and various biological systems. Herein, we developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying the four costimulatory proteins depending on the signature peptides derived from the soluble isoform of these proteins in multiple reaction monitoring (MRM) mode. The method was validated using the US FDA guidelines. The LOQ was determined as ∼0.5 nM for the four analytes, with quantification extended to 20 nM with a correlation coefficient of R2>0.998. The developed MRM method was used to analyze on-bead digested protein mixtures to establish a competitive assay for the CD28-B7 costimulatory pathway using CTLA4-Ig (Abatacept ™) as an FDA-approved drug for rheumatoid arthritis. The IC50 was determined to be 2.99 and 159.8 nM for sCD80 and sCD86, respectively. A straightforward MRM-based competitive assay will advance the knowledge about the costimulatory role in autoimmunity and the autoimmune therapeutic drug discovery, with the need for broad application on different in vitro and in vivo models to discover new targeted inhibitors.

A better understanding of the role of the CTLA-CD80/86 axis in the treatment of autoimmune diseases.

Autoimmune diseases are diseases in which the regulatory mechanisms of the immune response are disturbed. As a result, the body loses self-tolerance. Since one of the main regulatory mechanisms of the immune response is the CTLA4-CD80/86 axis, this hypothesis suggests that autoimmune diseases potentially share a similar molecular basis of pathogenesis. Hence, investigating the CTLA4-CD80/86 axis may be helpful in finding an appropriate treatment strategy. Therefore, this study aims to investigate the molecular basis of the CTLA4-CD80/86 axis in the regulation of the immune response, and then its role in developing some autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. As well, the main therapeutic strategies affecting the CTLA4-CD80/86 axis have been summarized to highlight the importance of this axis in management of autoimmune diseases.

Quantitative analysis of soluble costimulatory molecules as potential diagnostic biomarkers for rheumatoid arthritis using LC-MS/MS in MRM mode.

BACKGROUND AND AIMS: Rheumatoid arthritis (RA) is a chronic autoimmune disease. RA-induced immunological responses are coordinated by T-cell stimulation. The costimulatory signal CD28-B7 is essential for T-cell activation by interacting CD28 with CD80 and CD86 costimulatory proteins. CTLA4 is another costimulatory protein that binds to CD80 and CD86 to inhibit T-cell activity. The soluble costimulatory proteins: sCD80, sCD86, sCD28, and sCTLA-4 were detected and quantified in human plasma and correlated with RA development. As potential diagnostic biomarkers for RA, developing a sensitive, specific, and reproducible method for quantifying these costimulatory molecules in human plasma and establishing quantitative ranges for each protein in healthy and RA patients' plasma is essential for advancing the clinical diagnostic and health outcomes. MATERIALS AND METHODS: A novel quantitative liquid chromatography-tandem spectrometry (LC-MS/MS) technique using multiple reaction monitoring (MRM) modes was developed and validated to measure soluble costimulatory molecules sCTLA4, sCD28, sCD80, and sCD86 in human plasma samples. Furthermore, the method was applied to determine sCTLA4, sCD28, sCD80, and sCD86 levels in plasma samples from RA patients (n = 23) and healthy controls (n = 21). RESULTS: The method was successfully developed and validated according to international inter- and intra-assay precision and accuracy guidelines. The linearity of the method was achieved between 0.5 nM and 100 nM for each protein with a correlation coefficient of > 0.998. The plasma level of sCTLA4, sCD80, and sCD86 in RA patients was significantly elevated compared to controls. RA patients had 63.32 ± 17.63 nM sCTLA4 and controls 36.05 ± 18.83 nM; p < 0.0001. The performance of the four proteins was determined using ROC curves, where sCTLA4 showed the highest diagnostic and clinical performance compared to the others. CONCLUSIONS: This study reports the first use of LC-MS/MS in MRM mode to accurately quantify soluble costimulatory molecules in plasma samples as potential RA diagnostic biomarkers. Determination of the reference range for each protein with high selectivity and sensitivity increases the potential for utilizing this method as a clinical diagnostic.

cis-B7:CD28 interactions at invaginated synaptic membranes provide CD28 co-stimulation and promote CD8+ T cell function and anti-tumor immunity.

B7 ligands (CD80 and CD86), expressed by professional antigen-presenting cells (APCs), activate the main co-stimulatory receptor CD28 on T cells in trans. However, in peripheral tissues, APCs expressing B7 ligands are relatively scarce. This raises the questions of whether and how CD28 co-stimulation occurs in peripheral tissues. Here, we report that CD8+ T cells displayed B7 ligands that interacted with CD28 in cis at membrane invaginations of the immunological synapse as a result of membrane remodeling driven by phosphoinositide-3-kinase (PI3K) and sorting-nexin-9 (SNX9). cis-B7:CD28 interactions triggered CD28 signaling through protein kinase C theta (PKCθ) and promoted CD8+ T cell survival, migration, and cytokine production. In mouse tumor models, loss of T cell-intrinsic cis-B7:CD28 interactions decreased intratumoral T cells and accelerated tumor growth. Thus, B7 ligands on CD8+ T cells can evoke cell-autonomous CD28 co-stimulation in cis in peripheral tissues, suggesting cis-signaling as a general mechanism for boosting T cell functionality.