The prediction value of Treg cell subtype alterations for glucocorticoid treatment in newly diagnosed primary immune thrombocytopenia patients

Autoimmune effector mechanisms associated with a defective immunosuppressive axis in immune thrombocytopenia (ITP)

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by an isolated thrombocytopenia and variable phenotype as some patients suffer no bleeding whilst others have bleeding from mild to severe, which may be fatal. This variability probably reflects the disease's complex pathophysiology; a dysregulated hyperreactive immune effector cell response involving the entire adaptive immune system (e.g. B and T cell subsets) that leads to platelet and megakaryocyte (MK) destruction. It appears that these effector responses are due to a breakdown in immune tolerance, and this is characterized by defects in several immunosuppressive cell types. These include defective T regulatory cells (Tregs), B regulatory cells (Bregs) and Myeloid-derived suppressor cells (MDSC), all of which are all intimately associated with antigen presenting cells (APC) such as dendritic cells (DC). The loss of this immunosuppressive axis allows for the activation of unchecked autoreactive T cells and B cells, leading to the development of autoantibodies and cytotoxic T cells (CTL), which can directly destroy platelets in the periphery and inhibit MK platelet production in the bone marrow (BM). This review will focus on the effector cell mechanisms in ITP and highlight the defective immunosuppressive axis that appears responsible for this platelet-specific immune hyperreactivity.

HIF-1α induced by hypoxic condition regulates Treg/Th17 axis polarization in chronic immune thrombocytopenia

Immune thrombocytopenia (ITP) is an acquired immune disorder characterized by increased platelet destruction and reduced platelet (Plt) production. Hypoxia-inducible factor-1α (HIF-1α) have regulatory effects on Treg/Th17 axis balance and may represent relevant factors in the pathogenesis of ITP. Treg/Th17 ratio, serum levels and gene expression were investigated in new diagnosed ITP (NITP) and chronic ITP (CITP). The Treg/Th17 ratio obviously decreased in CITP (P = 0.001). The ratio of Treg/Th17 was correlated with the level of HIF-1α level both in mRNA (r = 0.49, P < 0.0001) and serum level (r = 0.50, P < 0.0001). However, none statistical upregulation of HIF-1α was observed in CITP. In vitro, There was significant polarization difference of Treg/Th17 axis (P = 0.042) and Foxp3-MFI/IL17-MFI (P = 0.0003) in hypoxic condition between NITP and CITP. These findings suggest that HIF-1α induced by hypoxia plays a crucial role in the chronicity of ITP by mediating the imbalance of the Treg/Th17 axis.

Trimethylamine-N-oxide (TMAO) and basic fibroblast growth factor (bFGF) are possibly involved in corticosteroid resistance in adult patients with immune thrombocytopenia

PURPOSE

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by accelerated platelet clearance. Gut dysbiosis was associated with its pathogenesis, but the underlying mechanisms have not been fully elucidated. Patients with ITP exhibit varying degrees of responsiveness to corticosteroid treatment. Therefore, prognostic indexes for corticosteroid responsiveness in ITP could offer valuable guidance for clinical practices.

METHODS

The present study examined the signature of six types of gut-microbiota metabolites and forty-eight types of cytokines, chemokines, and growth factors and their clinical significance in patients with ITP.

RESULTS

Both patients with good and poor corticosteroid responsiveness exhibited significantly elevated/suppressed secretion of twenty-two cyto(chemo)kins/growth factors in comparison to healthy controls. Additionally, patients with ITP demonstrated a significant decrease in plasma levels of trimethylamine-N-oxide (TMAO), which was found to be negatively correlated to circulating platelet counts, and positively correlated with Interleukin (IL)-1β and IL-18. Notably, patients who exhibited poor response to corticosteroid treatment displayed elevated levels of TMAO and basic fibroblast growth factor (bFGF) in comparison to responders. Additionally, we found that the amalgamation of TMAO, bFGF and interleukin (IL)-13 could serve as a valuable prognostic tool for predicting CS responsiveness.

CONCLUSION

Patients with ITP were characterized overall by an imbalanced secretion of cyto(cheo)kins/growth factors and inadequate levels of TMAO. The varying degrees of responsiveness to corticosteroid treatment can be attributed to different profiles of basic FGF and TMAO that might be related to overburdened oxidative stress and inflammasome overactivation, and ultimately mediate corticosteroid resistance.

Genome-wide DNA methylation profiling of CD4+ T lymphocytes identifies differentially methylated loci associated with adult primary refractory immune thrombocytopenia

BACKGROUND

DNA methylation played a crucial role in the pathogenesis of immune thrombocytopenia (ITP). However, genome-wide DNA methylation analysis has not been applied thus far. The present study aimed to provide the first DNA methylation profiling for ITP.

METHODS

Peripheral blood CD4+ T lymphocytes samples were collected from 4 primary refractory ITP cases and 4 age-matched healthy controls, and DNA methylome profiling was performed using Infinium MethylationEPIC BeadChip. Differentially methylated CpG sites were further validated in another independent cohort of 10 ITP patients and 10 healthy controls using qRT-PCR.

RESULTS

The DNA methylome profiling identified a total of 260 differentially methylated CpG sites mapping to 72 hypermethylated and 64 hypomethylated genes. These genes were mainly enriched in the actin nucleation of the Arp2/3 complex, vesicle transport, histone H3-K36 demethylation, Th1 and Th2 cell differentiation, and Notch signaling pathway according to the GO and KEGG databases. The mRNA expression of CASP9, C1orf109, and AMD1 were significantly different.

CONCLUSIONS

Given the altered DNA methylation profiling of ITP, our study provides new insights into its genetic mechanism and suggests candidate biomarkers for the diagnosis and treatment of ITP.

Proinflammatory plasticity towards Th17 paradigm of regulatory T cells consistent with elevated prevalence of TGFBR2 variants in elderly patients with primary immune thrombocytopenia

BACKGROUND

Primary immune thrombocytopenia (ITP) is characterized for the skewed Th differentiation towards Th1 and Th17 cells as well as the impaired number and function of regulatory T cells (Tregs). Tregs are capable of co-expressing effector Th markers in different inflammatory milieu, which probably indicates Treg dysfunction and incompetence to counter over-activated immune responses.

METHODS

Ninety-two primary ITP patients from March 2013 to December 2018 were included, and proinflammatory plasticity in different Treg compartments, age groups, and TGFBR2 variant carrier status were investigated.

RESULTS

Patients were categorized into elderly (n = 44) and younger (n = 48) groups according to an age of 50 years at disease onset. The overall remission rate was 82.6% after first-line regimens, including 47.8% complete remission. TGFBR2 variants were found in 7 (7.6%) patients with three V216I and four T340M heterozygote carriers. ITP patients demonstrated elevated co-expression of IL-17 and decreased co-expression of both IFN-γ and IL-13 than health control (all p < 0.01). The elderly group demonstrated elevated prevalence of TGFBR2 variants (p = 0.037) and elevated co-expression of IL-17 (p = 0.017) in Tregs, while female predominance was found in the younger group (p = 0.037). In the elderly group, TGFBR2 variant carriers demonstrated further elevated co-expression of IL-17 (p = 0.023) and decreased co-expression of both IFN-γ (p = 0.039) and IL-13 (p = 0.046) in the aTreg compartment.

CONCLUSIONS

Our findings revealed additional aberrations of Treg proinflammatory plasticity in elderly primary ITP patients, and highlighted the potential role of Treg dysfunction and senescence in the pathogenesis and management among these patients.

A bibliometric analysis of primary immune thrombocytopenia from 2011 to 2021

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia. This bibliometric analysis was applied to identify the characteristics of global scientific output, the hotspots, and frontiers of ITP over the past 10 years. We retrieved publications from 2011 to 2021 from the Web of Science Core Collection (WoSCC). Bibliometrix package, VOSviewer, and Citespace were used to analyse and visualize the trend, distribution, and hotspots of research on ITP. Altogether, there were 2084 papers, written by 9080 authors from 410 organizations in 70 countries/regions, published in 456 journals with 37 160 co-cited references. In the last decades, the most productive journal was British Journal of Haematology, China was the most productive country. and the most cited journal was Blood. Shandong University was the most productive institution in the field of ITP. NEUNERT C, 2011, BLOOD, CHENG G, 2011, LANCET, and PATEL VL, 2012, BLOOD were the top three most cited documents. "Thrombopoietin receptor agonist", "regulatory T cell" and "sialic acid" were three hotspots of the last decade. And "immature platelet fraction", "Th17", and "fostamatinib" would be research frontiers in the feature. The present study provided a novel insight for future research directions and scientific decision-making.

Special Issue "Advances in Thrombocytopenia"

Thrombocytopenia is a commonly encountered hematologic challenge in medicine [...].

Impaired mitochondria of Tregs decreases OXPHOS-derived ATP in primary immune thrombocytopenia with positive plasma pathogens detected by metagenomic sequencing

Background

Primary immune thrombocytopenia (ITP) is an autoimmune disease. Some ITP patients are associated with pathogen infection undetected with conventional technologies. Investigating the changes of T cells and potential metabolic mechanism are important for better understanding of ITP.

Methods

The study enrolled 75 newly diagnosed ITP patients. The pathogens of patients were detected by metagenomic next-generation sequencing (mNGS). Plasma lipids were measured by liquid chromatography-mass spectrometry (LC–MS). CD4 T cell and CD8 T cell were analyzed using flow cytometry. Mitochondrial reactive oxygen species (ROS) and mitochondrial membrane potential were measured by flow cytometry. Seahorse XF real-time ATP rate assay was used to investigate the change of cellular metabolism.

Results

Positive plasma pathogens were detected in seven ITP patients. Of them, 5 (71.4%) positive pathogen-ITP patients were no response (NR) after first-line treatment with corticosteroids. Regulatory T cells (Tregs) increased significantly in positive pathogen-ITP patients compared to negative pathogen-ITP patients and healthy controls (HC). Mitochondrial membrane potential of Th17 and Tregs were decreased in positive pathogen-ITP and negative pathogen-ITP patients, compared to HC (all p < 0.05). The overall metabolism flux of positive pathogen-ITP patients was decreased, as compared to HC (p = 0.004), of them a higher proportion of glycolysis-derived ATP and a smaller proportion of oxidative phosphorylation (OXPHOS)-derived ATP were found in Tregs. The ATP rate index of Tregs was decreased significantly in positive pathogen-ITP patients compared to negative pathogen-ITP patients and HC (p < 0.05).

Conclusions

Impaired mitochondria function of Tregs in positive pathogen-ITP patients caused a decrease of OXPHOS-derived ATP and overall metabolism flux that might be the cause of steroid resistance in ITP patients.

The short-term predictive value of CD4+ cells for combination therapy with high-dose dexamethasone and immunoglobulin in newly diagnosed primary immune thrombocytopenia patients

INTRODUCTION

Dexamethasone (DXM) or immunoglobulin (IVIg) are first-line therapies for primary immune thrombocytopenia (ITP), with an effective rate of 80 %. Some patients with both severe bleeding symptoms and platelet counts of <30 × 10⁹/L received a combination of DXM and IVIg. Autoimmune disorders, especially involving CD4⁺ T-cells, play a key role in the pathogenesis of ITP. We assumed that variations in the immune status of CD4⁺ T-cells will lead to different treatment responses. Until now, there have been few relevant clinical studies on CD4⁺ T-cells and the outcome of first-line therapies.

METHODS

A prospective study enrolling 42 newly diagnosed ITP patients and 30 normal control volunteers was performed. The profiles of major CD4⁺ T-cells, including T helper (Th)1, Th2, Th17, and regulatory T (Treg) cells, and the related levels of interleukin (IL)-2, IL-17, and IL-23 were examined. The platelet number was recorded at the time point of day 0, day 14, and day 30.

RESULTS

Greater concentrations of Th1 and Th17 cells and lower relative numbers of Treg cells were found in the ITP group. As for the treatment outcome on day 14, the profiles of Th2 and IL-2 were significantly greater in the NR group, while the expression of IL-17 was elevated in the CR group. As for the treatment outcome on day 30, higher levels of Th2 cells were observed in those patients who needed 2× pulses of HD DXM compared to those who needed only 1× pulse of HD DXM and IVIg, and receiver operating characteristic curve analysis showed that lower Treg cell may predict favorable values. Meanwhile, the higher IL-23 value may predict a poor early response.

CONCLUSIONS

Our results indicate that Th1, Th17, and Treg cells and IL-2 and IL-23 participate in the onset of ITP. Higher profiles of Th2, IL-2 and IL-23 may predict poor treatment outcomes. Higher levels of IL-17 and lower profile of Treg may predict sensitivity to HD DXM and IVIg combination therapy.

A Nomogram Model for Individualized Prediction of the Risk of Respiratory Tract Infection within Six Months after Diagnosis in Patients with Primary Immune Thrombocytopenia

The risk factors of upper respiratory tract infection (URI) within 6 months after diagnosis in patients with idiopathic thrombocytopenic purpura (ITP) were analyzed, and the nomogram model was established and verified, with 242 and 50 ITP patients as the training and validation set, respectively. The patients were followed up for six months after the diagnosis of ITP. The clinical data of patients were collected, and the risk factors of URI in ITP patients within six months after diagnosis were analyzed using univariable, followed by multivariable logistic regression. Among the 242 ITP patients in the training set, 52 cases (21.49%) had URI, including 24 cases of viral infection, 11 cases of Mycoplasma pneumoniae infection, and 17 cases of bacterial infection. Logistic regression analysis showed that advanced age, use of glucocorticoid, smoking history, platelet count, serum CRP level, and lymphocyte subsets CD₄⁺ and CD₈⁺ were all risk factors for ITP patients to develop symptoms within six months after diagnosis (P < 0.05). Using the above five indicators, a nomogram prediction model was built for URI occurrence in patients with ITP within half a year after diagnosis, and the results showed an AUC, a sensitivity, and a specificity of 0.936 (95% CI: 0.878-0.983), 0.942, and 0.865, respectively. The nomogram model was internally verified by the bootstrap method for 500 self-sampling times, and the prediction of the calibration curve was in high consistency with the real results. External validation of the nomogram model resulted in an AUC, a sensitivity, and a specificity of 0.890 (95% CI: 0.757-0.975), 0.949, and 0.727, respectively. The nomogram model of URI in ITP patients within half a year after diagnosis based on logistic regression analysis has good discrimination and prediction accuracy. This provides important guidance value for individualized prediction of URI in ITP patients.

Comparison of Peripheral Blood Regulatory T Cells and Functional Subsets Between Ocular and Generalized Myasthenia Gravis

Purpose

This study aims to discuss the function mechanism of regulatory T cells and its subsets in the pathogenic process of myasthenia gravis by contracting the activation levels of those cells in peripheral blood among healthy people, patients with ocular myasthenia gravis (oMG) and patients with generalized myasthenia gravis (gMG).

Method

Healthy people, newly diagnosed oMG patients, and gMG patients were enrolled in this study. The percentage of the CD3⁺CD4⁺CD25⁺ Treg cells, CD3⁺CD4⁺CD25⁺Foxp3⁺ Treg cells, CD3⁺CD4⁺CD25⁺Foxp3^hi CD45RA^–aTreg cells, CD3⁺CD4⁺CD25⁺Foxp3^loCD45RA^–n-sTreg cells, and CD3⁺CD4⁺CD25⁺ Foxp3^loCD45RA⁺rTreg cells in the peripheral blood were examined by flow cytometry. And then analyzed the differences of Treg cells and its subsets among the study members.

Results

The percentage of the CD4⁺CD25⁺Treg cells in the peripheral blood of oMG patients and gMG patients were both lower than that of healthy people (p < 0.05), the percentage of patients with oMG had no distinct difference with that of patients with gMG (p = 0.475), however. Also, the percentage of CD3⁺CD4⁺CD25⁺Foxp3⁺Treg cells in the oMG and gMG patients’ group were both lower than that of healthy group. And the percentage of CD25⁺Foxp3⁺Treg cells in the peripheral blood of patients with oMG and healthy people were both higher than that of patients with gMG (p < 0.05). The percentage of rTreg in the CD3⁺CD4⁺CD25⁺Treg of the peripheral blood for both gMG and oMG patients’ group were lower than healthy group (p < 0.05), but there was no statistical significance between the oMG and gMG patients’ group (p = 0.232). The percentage of the aTreg cells in the CD3⁺CD4⁺CD25⁺Treg cells of the peripheral blood for the oMG patients was higher than that of gMG patients (p < 0.05), but both of them were lower than healthy group (p < 0.05). The percentage of n-sTreg cells in the peripheral blood descended among the gMG patients’ group, oMG patients’ group, and healthy group (p < 0.05).

Conclusion

The changes in the number and function of Treg cells and its subsets can cause the impairment of negative immune regulation, which may mediate the triggering of oMG and its progression to gMG.

[Expression of miR-106b-5p in children with primary immune thrombocytopenia and its correlation with T cells]

OBJECTIVES

To study the expression level of plasma miR-106b-5p in primary immune thrombocytopenia (ITP) and its correlation with the levels of T helper 17 cell (Th17) and regulatory T cell (Treg) and the Th17/Treg ratio.

METHODS

A total of 79 children with ITP (ITP group) and 40 healthy children (control group) were selected as subjects. According to the treatment response, the 79 children with ITP were divided into three groups: complete response (n=40), partial response (n=18), and non-response (n=21). Quantitative real-time PCR was used to measure the expression level of miR-106b-5p. Flow cytometry was used to measure the frequencies of Th17 and Treg, and the Th17/Treg ratio was calculated. The correlation of the expression level of plasma miR-106b-5p with the frequencies of Th17 and Treg and the Th17/Treg ratio was analyzed.

RESULTS

Compared with the control group, the ITP group had significantly higher levels of miR-106b-5p, Th17, and Th17/Treg ratio (P<0.05) and a significantly lower level of Treg (P<0.05). After treatment, the ITP group had significant reductions in the levels of miR-106b-5p, Th17, and Th17/Treg ratio (P<0.05) and a significant increase in the level of Treg (P<0.05). Compared with the partial response and non-response groups, the complete response group had significantly lower levels of miR-106b-5p, Th17, and Th17/Treg ratio (P<0.05) and a significantly higher level of Treg (P<0.05). The correlation analysis showed that in the children with ITP, the expression level of plasma miR-106b-5p was positively correlated with the Th17 level and the Th17/Treg ratio (r=0.730 and 0.816 respectively; P<0.001) and was negatively correlated with the Treg level (r=-0.774, P<0.001).

CONCLUSIONS

A higher expression level of miR-106b-5p and Th17/Treg imbalance may be observed in children with ITP. The measurement of miR-106b-5p, Th17, Treg, and Th17/Treg ratio during treatment may be useful to the evaluation of treatment outcome in children with ITP.

HUWE1 Causes an Immune Imbalance in Immune Thrombocytopenic Purpura by Reducing the Number and Function of Treg Cells Through the Ubiquitination Degradation of Ets-1

Background: Immune thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder and the decreased number and immunosuppressive dysfunction of Treg cells are key promoters of ITP. However, their mechanisms in ITP development have not been fully clarified.

Methods: HUWE1 mRNA and protein levels in CD4⁺ T cells in peripheral blood from ITP patients were assessed by quantitative real-time PCR and Western blot. HUWE1 function in ITP was estimated using flow cytometry, enzyme-linked immunosorbent assay and immunosuppression assay. Besides, the HUWE1 mechanism in reducing the number and function of Treg cells in ITP was investigated by immunoprecipitation, cycloheximide-chase assay, ubiquitin experiment and immunofluorescence assay.

Results: HUWE1 expression was elevated in CD4⁺ T cells in peripheral blood from ITP patients and HUWE1 mRNA level was negatively correlated with platelet counts and Treg cell percentage. Moreover, the interference with HUWE1 increased the number of Treg cells and enhanced its immunosuppressive function, and the HUWE1 overexpression produced the opposite results. For the exploration of mechanism, HUWE1 interacted with E26 transformation-specific-1 (Ets-1) and this binding was dependent on the negative regulation of the phosphorylation level of Ets-1 (Thr38) and HUWE1 facilitated the ubiquitin degradation of Ets-1 protein to restrain Treg cell differentiation and weaken their immunosuppressive functions. The in vivo assay confirmed that the HUWE1 inhibitor alleviated ITP in mice.

Conclusion: HUWE1 induced the immune imbalance in ITP by decreasing the number and weakening the function of Treg cells through the ubiquitination degradation of Ets-1.

Decreasing lncRNA PVT1 causes Treg/Th17 imbalance via NOTCH signaling in immune thrombocytopenia

Objectives: Immune thrombocytopenia (ITP) is an autoimmune disease. T helper cell 17 (Th17) cells are increased in peripheral blood of ITP patients. NOTCH signaling is involved in Th17 cell differentiation and function. Besides, lncRNA Plasmacytoma variant translocation 1 (PVT1) was decreased in experimental autoimmune encephalomyelitis, and overexpressing PVT1 inhibited Th17 cell differentiation. Here, we aimed to investigate the effect of lncRNA PVT1 on ITP and its related mechanism.Methods: The number of Th17 cells and Treg cells was carried out using flow cytometry. PVT1 levels were detected by quantitative real-time PCR. Interleukin-17 (IL-17) levels and transforming growth factor-β (TGF-β) levels were detected by enzyme-linked immunosorbent assay. Protein levels of retinoid acid-related orphan receptor γ t (RORγt), forkhead box P3 (Foxp3), and NOTCH1 were carried out by western blot. NOTCH1 ubiquitylation was detected by ubiquitination assay.Results: PVT1 was down-regulated and Th17 cells were up-regulated in ITP patients. Overexpression of PVT1 decreased the number of Th17 cells, and also decreased the levels of IL-17, RORγt, and NOTCH1. Besides, PVT1 could bind to NOTCH1 and mediated NOTCH1 degradation by increasing its ubiquitination. Additionally, excessive expression of PVT1 could increase the levels of PVT1, reduce the amount of Th17 cells, as well as the levels of IL-17, RORγt, and NOTCH1, while co-overexpressing NOTCH1 reversed the results.Conclusion: PVT1 was down-regulated in ITP patients. Overexpressing PVT1 might reduce Th17 cell differentiation by down-regulating NOTCH1, and further alleviated the development of ITP.

Decreased levels of immune-regulatory cytokines in patients with immune thrombocytopenia and long-lasting overexpression of these cytokines in the splenectomized patients

Immune thrombocytopenia (ITP) is an autoimmune-mediated disease characterized by decreased platelet counts. Cytokines play important roles in modulating the immune response and are involved in the pathogenesis of many autoimmune diseases. This study aimed at exploring the serum levels of a core set of cytokines that exert immune-regulatory functions in newly diagnosed ITP patients (both before and after treatment) and splenectomized ITP patients. Using the Bio-Plex suspension array system and ELISA, the serum levels of IL-10, IL-21, IL-27, IL-33, IL-35, IL-37, and TGF-β₁ were detected. The data showed that the serum levels of the immune regulatory cytokines IL-10, IL-35, and TGF-β₁ were significantly lower in newly diagnosed ITP patients. Decreased cytokine levels could be improved in patients with a complete response or a response after steroid-based treatment(s). The serum concentrations of TGF-β₁ were positively correlated with the platelet counts both before and after treatment. All the detected immune-regulatory cytokines, except IL-37, showed significantly higher levels in splenectomized ITP patients than pretreatment ITP patients and healthy controls. In conclusion, these data suggest that lower levels of immune-regulatory cytokines are involved in the pathogenesis of ITP and that there is a long-lasting overexpression of immune-regulatory cytokines in ITP patients with splenectomy.

Potential Diagnostic Approaches for Prediction of Therapeutic Responses in Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder in which, via unresolved mechanisms, platelets and megakaryocytes (MKs) are targeted by autoantibodies and/or T cells resulting in increased platelet destruction and impairment of MK function. Over the years, several therapeutic modalities have become available for ITP, however, therapeutic management has proven to be very challenging in several cases. Patients refractory to treatment can develop a clinically worsening disease course, treatment-induced toxicities and are predisposed to development of potentially life-endangering bleedings. It is therefore of critical importance to timely identify potential refractory patients, for which novel diagnostic approaches are urgently needed in order to monitor and predict specific therapeutic responses. In this paper, we propose promising diagnostic investigations into immune functions and characteristics in ITP, which may potentially be exploited to help predict platelet count responses and thereby distinguish therapeutic responders from non-responders. This importantly includes analysis of T cell homeostasis, which generally appears to be disturbed in ITP due to decreased and/or dysfunctional T regulatory cells (Tregs) leading to loss of immune tolerance and initiation/perpetuation of ITP, and this may be normalized by several therapeutic modalities. Additional avenues to explore in possible prediction of therapeutic responses include examination of platelet surface sialic acids, platelet apoptosis, monocyte surface markers, B regulatory cells and platelet microparticles. Initial studies have started evaluating these markers in relation to response to various treatments including glucocorticosteroids (GCs), intravenous immunoglobulins (IVIg) and/or thrombopoietin receptor agonists (TPO-RA), however, further studies are highly warranted. The systematic molecular analysis of a broad panel of immune functions may ultimately help guide and improve personalized therapeutic management in ITP.

An update on the pathophysiology of immune thrombocytopenia

: Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder mediated by antiplatelet autoantibodies and antigen-specific T cells that either destroy platelets peripherally in the spleen or impair platelet production in the bone marrow. There have been a plethora of publications relating to the pathophysiology of ITP and since January of 2019, at least 50 papers have been published on ITP pathophysiology.

PURPOSE OF REVIEW

To summarize the literature relating to the pathophysiology of ITP including the working mechanisms of therapies, T-cell and B-cell physiology, protein/RNA/DNA biochemistry, and animal models in an attempt to unify the perceived abnormal immune processes.

RECENT FINDINGS

The most recent pathophysiologic irregularities associated with ITP relate to abnormal T-cell responses, particularly, defective T regulatory cell activity and how therapeutics can restore these responses. The robust literature on T cells in ITP points to the notion that ITP is a disease initiated by faulty self-tolerance mechanisms very much like that of other organ-specific autoimmune diseases. There is also a large literature on new and existing animal models of ITP and these will be discussed. It appears that understanding how to specifically modulate T cells in patients with ITP will undoubtedly lead to effective antigen-specific therapeutics.

CONCLUSIONS

ITP is predominately a T cell disorder which leads to a breakdown in self tolerance mechanisms and allows for the generation of anti-platelet autoantibodies and T cells. Novel therapeutics that target T cells may be the most effective way to perhaps cure this disorder.

Insights on chronic immune thrombocytopenia pathogenesis: A bench to bedside update

Immune thrombocytopenia (ITP) is a heterogeneous disease with an unpredictable course. Chronicity can develop in up to two-thirds of adults and 20-25% of children, representing a significant burden on patients' quality of life. Despite acceptable responses to treatment, precise etiology and pathophysiology phenomena driving evolution to chronicity remain undefined. We analyzed reported risk factors for chronic ITP and associated them with proposed underlying mechanisms in its pathogenesis, including bone marrow (BM) microenvironment disturbances, clinical features, and immunological markers. Their understanding has diagnostic implications, such as screening for the presence of specific antibodies or BM examination employing molecular tools, which could help predict prognosis and recognize main pathogenic pathways in each patient. Identifying these underlying mechanisms could guide the use of personalized therapies such as all-trans retinoic acid, mTor inhibitors, FcRn inhibitors, oseltamivir, and others. Further research should lead to tailored treatments and chronic course prevention, improving patients' quality of life.

Interleukin (IL)-1 family cytokines could differentiate primary immune thrombocytopenia from systemic lupus erythematosus-associated thrombocytopenia

Background

Primary immune thrombocytopenia (ITP) is an autoimmune-mediated disorder characterized by a decreased platelet count. Systemic lupus erythematosus (SLE) is also an autoimmune disease in which thrombocytopenia is a common hematologic manifestation. Interleukin (IL)-1 family cytokines are major proinflammatory and immunoregulatory mediators. This study aimed to investigate the role of IL-1 cytokines in patients with ITP and SLE and the potential pathophysiologic mechanism to differentiate SLE-associated thrombocytopenia (SLE-TP) from ITP.

Methods

Multiplex cytokine assay and real-time polymerase chain reaction (RT-PCR) were used to measure IL-1 cytokines in 17 newly diagnosed ITP patients, 17 SLE-TP patients, 19 SLE patients without thrombocytopenia (SLE-NTP), and 10 healthy controls.

Results

The serum levels of IL-1β, IL-18, IL-36α, IL-36β, IL-36γ, and IL-33 were decreased significantly in ITP patients compared with SLE-TP patients, SLE-NTP patients, and healthy controls (P<0.05). While there was no significant difference in the serum level of IL-37 between ITP and SLE-TP patients, there was a positive correlation between the platelet count and IL-37 level in ITP patients. Our data suggested that serum IL-1β, IL-18, IL-36α, IL-36β, IL-36γ, IL-33, and IL-37 could be considered biomarkers in the diagnosis of ITP.

Conclusions

Serum IL-1β, IL-18, IL-36α, IL-36β, IL-36γ, and IL-33 could be considered biomarkers to differentiate SLE-TP from ITP patients.

IL-10 and IL-17 expression by CD4+ T cells is altered in corticosteroid refractory immune thrombocytopenia (ITP)

BACKGROUND

Corticosteroids remain the first-line treatment for patients with immune thrombocytopenia (ITP). However, 20% to 30% of patients do not respond to treatment at tolerable doses. This variation in corticosteroid efficacy is replicated in other autoimmune diseases and may have an adaptive immune basis.

OBJECTIVE

To test the hypothesis that CD4+ T-cell responses to corticosteroids are different in patients with clinically defined corticosteroid refractory ITP.

METHODS

In this prospective cohort study, CD4+ T cells from patients with ITP were cultured in the presence or absence of dexamethasone (Dex). Intracellular cytokine expression was then quantified by flow cytometry and compared with patients' clinical response to corticosteroid treatment. A control cohort of patients with autoimmune uveitis was also studied to evaluate whether our findings were limited to ITP or are potentially generalizable across autoimmune diseases.

RESULTS

The ratio of interleukin (IL)-10 to IL-17 expression following CD4+ T cell culture with Dex was able to discriminate between ITP patients with a clinically defined complete (n = 33), partial (n = 12) or nonresponse (n = 11) to corticosteroid treatment (P = .002). These findings were replicated in patients with autoimmune uveitis (complete response n = 14, nonresponse n = 22; P = .01).

CONCLUSIONS

There is a relative abrogation of IL-10 and persistence of IL-17 expression in the CD4+ T cells of patients who clinically fail corticosteroid therapy. This observation has potential to inform both our mechanistic understanding of the action of corticosteroids in the treatment of ITP, and as a biomarker for steroid refractory disease, with potential application across a range of hematological and nonhematological conditions.

[Effect and mechanism of low-dose chidamide on the treatment of primary immune thrombocytopenia]

Objective: To explore the effect and mechanism of low-dose chidamide on the treatment of primary immune thrombocytopenia (ITP) . Methods: Passive ITP animal model and active ITP animal model were established by C57BL/6J mice. Different doses of chidamide (0, 0.01, 0.1, 0.5, and 5 mg/kg) were orally administrated twice a week for 120 hours in passive ITP mice. Secondly, low-dose chidamine (0.1 mg/kg) was given intragastrically administrated twice a week in active ITP mice. The platelet counts in the peripheral blood before and after treatment were detected. Four weeks later, mice were executed to prepare splenocyte suspension; natural regulatory T cells (CD4(+)CD25(+)Foxp3(+) nTreg cells) in splenocyte suspension were detected by flow cytometry. Serum IL-6 was measured by ELISA. Peripheral blood mononuclear cells from ITP patients were co-cultured with low-dose chidamide in vitro. After incubation for 72 hours, CD4(+)CD25(+)Foxp3(+) Treg cells of mononuclear cells was detected. CD4(+)CD25(+) Treg cells and CD4(+)CD25(-) effector T cells were separated by immunomagnetic beads. The Treg cells and effector T cells were co cultured in a ratio of 1∶4, and treated with low-dose chidamide. The proliferation of effector T cells was detected. Results: Chidamide with low dose (0.1 mg/kg) significantly improved platelet counts in passive ITP mouse model, as well as in the ITP active mouse model and reduced the mortality related to bleeding. Low-dose chidamide significantly increased the number and proportion of nTreg cells in mouse splenocytes, and decreased serum IL-6 level in active ITP mice. In ITP patients, low-dose chidamide also significantly expanded Treg cells in the PBMC culture system. Besides, the proliferation of effector T cells was suppressed. Conclusion: Low-dose chidamide enhances the proliferation of CD4(+)CD25(+)Foxp3(+) regulatory T cells to mediate immunosuppressive function. Serum IL-6 is inhibited for further immune tolerance. In vivo animal study suggestes that low-dose chidamide has a novel therapeutic effect on ITP.

Intestinal microbiota dysbiosis play a role in pathogenesis of patients with primary immune thrombocytopenia

BACKGROUND

The intestinal microbiota is essential for the maintenance of the physiology of immune homeostasis. Dysbiosis has been described in some autoimmune diseases, however its role is still elusive in primary immune thrombocytopenia (ITP), which is one kind of autoimmune diseases. This study aimed to characterize the phylogenetic diversity of the fecal microbiota and its relationship with the platelet activation status in patients with ITP.

METHODS

The platelet activation status was assessed by 2 platelet markers, PAC-1 (antibody that recognizes the activated GPIIb/IIIa complex) and CD62p (Platelet surface P-selectin) by flow cytometry. Total DNA was extracted from fecal samples of ITP patients and healthy controls (HC). Sequencing the V4 hypervariable region of bacterial 16S rRNA genes was used to identify the changes in phylogenetic diversity and composition of the intestinal flora. The obtained sequencing reads were assigned to operational taxonomic units (OTUs, 97% sequence identity) and taxonomically classified to assess composition and diversity.

RESULTS

The percentage of PAC-1+ platelets in ITP patients was higher than that in control group (p < 0.001), The percentage of CD62p+ and PAC-1+CD62p+ platelets in ITP patients both higher than those in control group (p < 0.001). At the phylum level, eight different phyla were identified in ITP individuals, with a majority of Bacteroidetes (45.96%) and Firmicutes (38.59%), followed by Proteobacteria (11.43%), Fusobacteria(1.29%), and Actinobacteria (1.22%). While in the Healthy volunteers, ten phyla were detected, with a predominance of Firmicutes (50.92%) and Bacteroidetes (34.26%), came before Proteobacteria (13.60%), and Actinobacteria (0.90%). The gut microbiota was skewed in ITP, with an increased proportion of Proteobacteria, Bacteroidetes and Bacteroidetes/Firmicutes ratio, a decreased proportion of Firmicutes compared with HC. Disease specific alterations in diversity was also identified, especially the potential markers (Anaerorhabdus, sutterella, Peptostreptococcaceae, Clostridium_XI and carnobacteriaceae, p < 0.05) for ITP.

CONCLUSIONS

The results suggested that the distinct microbiota dysbiosis in ITP characterized by alterations in biodiversity and composition, which could provide insights for diet therapy and fecal microbiota transplantation treatment to cure ITP. There might be somehow compensatory enhancement of platelet activation in ITP patients. And there is associate between platelet activation and intestinal microbiota in patients with ITP.