Decreased plasma cytokines are associated with low platelet counts in aplastic anemia and immune thrombocytopenic purpura

Translating mechanisms into therapeutic strategies for immune thrombocytopenia (ITP): Lessons from clinical trials

Immune thrombocytopenia (ITP) is an autoimmune disorder that causes a significant reduction in peripheral blood platelet count. Fortunately, due to an increased understanding of ITP, there have been significant improvements in the diagnosis and treatment of these patients. Over the past decade, there have been a variety of proven therapeutic options available for ITP patients, including intravenous immunoglobulins (IVIG), Rituximab, corticosteroids, and thrombopoietin receptor agonists (TPO-RAs). Although the effectiveness of current therapies in treating more than two-thirds of patients, still some patients do not respond well to conventional therapies or fail to achieve long-term remission. Recently, a significant advancement has been made in identifying various mechanisms involved in the pathogenesis of ITP, leading to the development of novel treatments targeting these pathways. It seems that new agents that target plasma cells, Bruton tyrosine kinase, FcRn, platelet desialylation, splenic tyrosine kinase, and classical complement pathways are opening new ways to treat ITP. In this study, we reviewed the pathophysiology of ITP and summarized updates in this population's management and treatment options. We also took a closer look at the 315 ongoing trials to investigate their progress status and compare the effectiveness of interventions. May our comprehensive view of ongoing clinical trials serve as a guiding beacon, illuminating the path towards future trials of different drugs in the treatment of ITP patients.

Current Understanding of Immune Thrombocytopenia: A Review of Pathogenesis and Treatment Options

The management of immune thrombocytopenia (ITP) and the prediction of patient response to therapy still represent a significant and constant challenge in hematology. ITP is a heterogeneous disease with an unpredictable evolution. Although the pathogenesis of ITP is currently better known and its etiology has been extensively studied, up to 75% of adult patients with ITP may develop chronicity, which represents a significant burden on patients' quality of life. A major risk of ITP is bleeding, but knowledge on the exact relationship between the degree of thrombocytopenia and bleeding symptoms, especially at a lower platelet count, is lacking. The actual management of ITP is based on immune suppression (corticosteroids and intravenous immunoglobulins), or the use of thrombopoietin receptor agonists (TPO-RAs), rituximab, or spleen tyrosine kinase (Syk) inhibitors. A better understanding of the underlying pathology has facilitated the development of a number of new targeted therapies (Bruton's tyrosine kinase inhibitors, neonatal Fc receptors, strategies targeting B and plasma cells, strategies targeting T cells, complement inhibitors, and newer TPO-RAs for improving megakaryopoiesis), which seem to be highly effective and well tolerated and result in a significant improvement in patients' quality of life. The disadvantage is that there is a lack of knowledge of the predictive factors of response to treatments, which would help in the development of an optimized treatment algorithm for selected patients.

STAT1 overexpression triggers aplastic anemia: a pilot study unravelling novel pathogenetic insights in bone marrow failure

We identified STAT1 gain of function (GOF) in a 32-year-old female with pallor, weakness, cough, and dyspnea admitted to our Division of Medicine. She had severe oral ulcers (OU), type 1 diabetes (T1DM), and pancytopenia. Bone marrow (BM) biopsy showed the absence of erythroid precursors. Peripheral blood parameters such as neutrophils < 500/mL, reticulocytes < 2%, and BM hypo-cellularity allowed to diagnose severe aplastic anemia. A heterozygous variant (p.520T>C, p.Cys174Arg) of STAT1 was uncovered. Thus, p.Cys174Arg mutation was investigated as potentially responsible for the patient's inborn immunity error and aplastic anemia. Although STAT1 GOF is rare, aplastic anemia is a more common condition; therefore, we explored STAT1 functional role in the pathobiology of BM failure. Interestingly, in a cohort of six patients with idiopathic aplastic anemia, enhanced phospho-STAT1 levels were observed on BM immunostaining. Next, the most remarkable features associated with STAT1 signaling dysregulation were examined: in both pure red cell aplasia and aplastic anemia, CD8+ T cell genetic variants and mutations display enhanced signaling activities related to the JAK-STAT pathway. Inborn errors of immunity may represent a paradigmatic condition to unravel crucial pathobiological mechanisms shared by common pathological conditions. Findings from our case-based approach and the phenotype correspondence to idiopathic aplastic anemia cases prompt further statistically powered prospective studies aiming to elucidate the exact role and theragnostic window for JAK/STAT targeting in this clinical context. Nonetheless, we demonstrate how a comprehensive study of patients with primary immunodeficiencies can lead to pathophysiologic insights and potential therapeutic approaches within a broader spectrum of aplastic anemia cases.

Aplastic anemia, cellular and molecular aspects

Aplastic anemia (AA) is an autoimmune disorder characterized by bone marrow and peripheral blood pancytopenia. Different environmental and genetical conditions could be effective in an outbreak of this disease. The exact pathogenesis of this disease, however, is still idiopathic. The present study is based on Pubmed database information (2002-2021) using the words "Aplastic Anemia," "Hematopoietic Stem Cells niche," "Signaling pathway," "Cytokines," and "Immuno cells." In this disease, both hematopoietic stem cells and mesenchymal stromal cells are impaired, which is associated with impaired hematopoiesis and decreased hematopoietic cells. Inflammatory cytokines increase, which changes the ratio of T lymphocytes and leads to disease progression. In addition, the most common mechanism of AA is damage by the immune system, which leads to increased apoptosis in progenitor cells. We have shown in this review that the disease involves quantitative defects in stem cell numbers and qualitative abnormalities in the function of these cells and the activity of many different cellular and molecular factors can damage hematopoietic cells and the protective substrate of these cells in this disease.

Platelets Fuel the Inflammasome Activation of Innate Immune Cells

The inflammasomes control the bioactivity of pro-inflammatory cytokines of the interleukin (IL)-1 family. The inflammasome assembled by NLRP3 has been predominantly studied in homogeneous cell populations in vitro, neglecting the influence of cellular interactions that occur in vivo. Here, we show that platelets boost the inflammasome capacity of human macrophages and neutrophils and are critical for IL-1 production by monocytes. Platelets license NLRP3 transcription, thereby enhancing ASC oligomerization, caspase-1 activity, and IL-1β secretion. Platelets influence IL-1β production in vivo, and blood platelet counts correlate with plasmatic IL-1β levels in malaria. Furthermore, we reveal an enriched platelet gene signature among the highest-expressed transcripts in IL-1β-driven autoinflammatory diseases. The platelet effect is independent of cell-to-cell contact, platelet-derived lipid mediators, purines, nucleic acids, and a host of platelet cytokines, and it involves the triggering of calcium-sensing receptors on macrophages. Hence, platelets provide an additional layer of regulation of inflammasomes and IL-1-driven inflammation.

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Platelets license NLRP3 for inflammasome activattion in innate immune cells

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Platelets are required for optimal monocyte inflammasome activation

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Platelets shape IL-1β in vivo, and platelet counts correlate with IL-1β in plasma

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A constitutive, heat-sensitive soluble platelet-factor boost IL-1β in macrophages

Analysis of the expression profile of long non-coding RNAs MALAT1 and THRIL in children with immune thrombocytopenia

BACKGROUND/AIMS

Pediatric immune thrombocytopenia (ITP) is an autoimmune disease; whose etiology is not exactly understood and seems to be highly multifactorial. Long non-coding RNAs (lncRNAs) are key regulators of different actions, which contribute to the development of many autoimmune diseases. To gain a further understanding, we estimated the relative expression of lncRNAs Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and tumor necrosis factor-α (TNF-α) and heterogeneous nuclear ribonucleoprotein L (hnRNPL) immune-regulatory lncRNA (THRIL) in pediatric ITP.

METHODS

In this case-control study, analysis of the expression profiles of these lncRNAs in blood samples from children with ITP and healthy controls (HCs) using quantitative real-time PCR was done. The association of MALAT1 and THRIL with ITP clinical features and their potential usage as non-invasive circulating biomarkers for ITP diagnosis was also evaluated. The receiver operating characteristic curve was constructed, and an area under the curve was analyzed.

RESULTS

Both lncRNAs MALAT1 and THRIL were significantly upregulated in ITP patients in comparison to HCs ( p < .0001 and = .001 respectively). In addition, there was a positive significant correlation between the expression level of both biomarkers among patients (r = 0.745, p < .0001). At cutoff points of 1.17 and 1.27 for lncRNAs MALAT1and THRIL, respectively, both biomarkers had an excellent specificity (100% for both) and fair sensitivity (63.6 and 73.3% for lncRNAs MALAT1and THRIL, respectively). Improvement of biomarkers specificity was obtained by evaluation of the combined expression of both biomarkers. Serum lncRNAs MALAT1 and THRIL could be used as potential biomarkers in differentiating childhood ITP patients and HCs.

Increased levels of IL-10 and IL-1Ra counterbalance the proinflammatory cytokine pattern in acute pediatric immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease which leads to accelerated platelet clearance. We investigated the plasma cytokine, chemokine and growth factor signatures and their clinical significance in pediatric ITP patients during acute, chronic and follow-up stages as well as the effects of intravenous immunoglobulin (IVIg) treatment, by using the Multiplex technology. In acute ITP before and/or after IVIg treatment we found significantly increased plasma levels of the pro- (tumour necrosis factor-α (TNF-α), interleukin IL-15) and anti- (IL-1 receptor antagonist (Ra), IL-10 and the growth factor interferon γ-induced protein (IP-10)) inflammatory cytokines, compared to healthy controls. Except for IL1-Ra, these cytokines decreased to normal levels in chronic patients. In contrast, growth-regulated α protein (GRO) and soluble CD40 ligand (sCD40L), known as platelet-derived molecules, were found to be significantly decreased in acute and increased in chronic ITP patients compared to healthy controls. GRO levels positively correlated with the platelet counts in the follow-up and chronic cohort. Monocyte counts showed a significant positive correlation only with IP-10 levels in acute ITP after IVIg treatment and follow-up patients. Expression levels of mRNAs for macrophage inflammatory protein MIP1-β, IL-1Ra and GRO determined in peripheral blood mononuclear cells (PBMCs) were significantly reduced in both acute and chronic ITP compared to controls. Our findings suggest that the different clinical presentation of acute and chronic pediatric ITP and to a lesser extent the IVIg treatment effects are characterized overall by a counterbalanced cytokine, chemokine and growth factor pattern response that might exert a pathogenic role in this disease.

Epidemiological, clinical and genetic characterization of aplastic anemia patients in Pakistan

Aplastic anemia (AA) is the most serious non-malignant blood disorder in Pakistan, ranked second in prevalence, after thalassemia. We investigated various epidemiological, clinical, and genetic factors of AA in a Pakistani cohort of 214 patients reporting at our hospital between June 2014 and December 2015. A control group of 214 healthy subjects was included for comparison of epidemiological and clinical features. Epidemiological data revealed 2.75-fold higher frequency of AA among males. A single peak of disease onset was observed between ages 10 and 29 years followed by a steady decline. AA was strongly associated with lower socioeconomic profile, rural residence, and high rate of consanguineous marriages. Serum granulocyte colony-stimulating factor and thrombopoietin levels were significantly elevated in AA patients, compared to healthy controls (P < 0.0001), while there was no statistical significance in other nine cytokine levels screened. Allele frequencies of DRB1*15 (56.8%) and DQB1*06 (70.3%) were predominantly high in AA patients. Ten mutations were found in TERT and TERC genes, including two novel mutations (Val526Ala and Val777Met) in exons 3 and 7 of TERT gene. Despite specific features of the AA cohort, this study suggests that epidemiologic and etiologic factors as well as host genetic predisposition exclusively or cooperatively trigger AA in Pakistan.

Ticagrelor Improves Endothelial Function by Decreasing Circulating Epidermal Growth Factor (EGF)

Ticagrelor is one of the most powerful P2Y₁₂ inhibitor. We have recently reported that, in patients with concomitant Stable Coronary Artery Disease (SCAD) and Chronic Obstructive Pulmonary Disease (COPD) undergoing percutaneous coronary intervention (PCI), treatment with ticagrelor, as compared to clopidogrel, is associated with an improvement of the endothelial function (Clinical Trial NCT02519608). In the present study, we showed that, in the same population, after 1 month treatment with ticagrelor, but not with clopidogrel, there is a decrease of the circulating levels of epidermal growth factor (EGF) and that these changes in circulating levels of EGF correlate with on-treatment platelet reactivity. Furthermore, in human umbilical vein endothelial cells (HUVEC) incubated with sera of the patients treated with ticagrelor, but not with clopidogrel there is an increase of p-eNOS levels. Finally, analyzing the changes in EGF and p-eNOS levels after treatment, we observed an inverse correlation between p-eNOS and EGF changes only in the ticagrelor group. Causality between EGF and eNOS activation was assessed in vitro in HUVEC where we showed that EGF decreases eNOS activity in a dose dependent manner. Taken together our data indicate that ticagrelor improves endothelial function by lowering circulating EGF that results in the activation of eNOS in the vascular endothelium.

Alterations in hematologic indices during long-duration spaceflight

BACKGROUND

Although a state of anemia is perceived to be associated with spaceflight, to date a peripheral blood hematologic assessment of red blood cell (RBC) indices has not been performed during long-duration space missions.

METHODS

This investigation collected whole blood samples from astronauts participating in up to 6-months orbital spaceflight, and returned those samples (ambient storage) to Earth for analysis. As samples were always collected near undock of a returning vehicle, the delay from collection to analysis never exceeded 48 h. As a subset of a larger immunologic investigation, a complete blood count was performed. A parallel stability study of the effect of a 48 h delay on these parameters assisted interpretation of the in-flight data.

RESULTS

We report that the RBC and hemoglobin were significantly elevated during flight, both parameters deemed stable through the delay of sample return. Although the stability data showed hematocrit to be mildly elevated at +48 h, there was an in-flight increase in hematocrit that was ~3-fold higher in magnitude than the anticipated increase due to the delay in processing.

CONCLUSIONS

While susceptible to the possible influence of dehydration or plasma volume alterations, these results suggest astronauts do not develop persistent anemia during spaceflight.

Pathogenesis and Therapeutic Mechanisms in Immune Thrombocytopenia (ITP)

Immune thrombocytopenia (ITP) is a complex autoimmune disease characterized by low platelet counts. The pathogenesis of ITP remains unclear although both antibody-mediated and/or T cell-mediated platelet destruction are key processes. In addition, impairment of T cells, cytokine imbalances, and the contribution of the bone marrow niche have now been recognized to be important. Treatment strategies are aimed at the restoration of platelet counts compatible with adequate hemostasis rather than achieving physiological platelet counts. The first line treatments focus on the inhibition of autoantibody production and platelet degradation, whereas second-line treatments include immunosuppressive drugs, such as Rituximab, and splenectomy. Finally, third-line treatments aim to stimulate platelet production by megakaryocytes. This review discusses the pathophysiology of ITP and how the different treatment modalities affect the pathogenic mechanisms.

Effects of the nephrilin peptide on post-burn glycemic control, renal function, fat and lean body mass, and wound healing

The mechanisms underlying the effects of severe burn trauma are not well understood. We previously demonstrated the ability of nephrilin peptide (an iron-binding peptide believed to enter cells through iron-uptake pathways) to suppress aspects of the neuroinflammatory response in a rat scald model, as well as sepsis mortality in a mouse model. This study explores the effect of nephrilin on other clinically relevant outcomes in the rat scald model. In a rat scald model, animals were treated with nephrilin either in week 1 or week 2 post-burn. Measurements were made of serum glucose and creatinine as well as wound area by planimetry and body composition by DEXA. Given the potential role of iron, results were analyzed both for the entire cohort of animals and for the normoferremic (>100 ug/dL serum iron) subset of animals. Nephrilin improved body composition, wound healing, kidney function, and glycemic control. The first two effects were significant in normoferremic but not in hypoferremic animals suggesting an effect of iron status on burn injury outcomes. Nephrilin treatment modulates a number of relevant variables in the rat scald model.

Pulsed high-dose dexamethasone modulates Th1-/Th2-chemokine imbalance in immune thrombocytopenia

Background

Chemokines and chemokine receptors play important roles in autoimmune diseases; however, their role in immune thrombocytopenia (ITP) is unclear. High-dose dexamethasone (HD-DXM) may become a first-line therapy for adult patients with ITP, but the effect of HD-DXM on chemokines in ITP patients is unknown. Our aim was to investigate the mechanism of pulsed HD-DXM for management of ITP, specifically regarding the chemokine pathways.

Methods

Th1-/Th2-associated chemokine and chemokine receptor profiles in ITP patients before and after pulsed HD-DXM was studied. Plasma levels of CCL5 and CXCL11 (Th1-associated) and of CCL11 (Th2-associated) were determined by ELISA. Gene expression of these three chemokines and their corresponding receptors CCR5, CXCR3, and CCR3, in peripheral blood mononuclear cells (PBMCs) was determined by quantitative RT-PCR.

Results

Thirty-three of the thirty-eight ITP patients responded effectively to HD-DXM (oral, 40 mg/day, 4 days). In ITP patients, plasma CXCL11 levels increased, while CCL11 and CCL5 decreased compared to controls (P < 0.05). Similarly, gene expression of CXCL11 and its receptor CXCR3 increased, while CCL11 and CCR3 decreased (P < 0.05). CCL5 expression did not significantly change; however, expression of its receptor CCR5 increased (P < 0.05). Interestingly, in the patients who responded to pulsed HD-DXM, CXCL11 and CXCR3 expression was down-regulated, while CCL11 and CCR3 expression was up-regulated (P < 0.05). Meanwhile, CCL5 expression was up-regulated and CCR5 was down-regulated by HD-DXM (P < 0.05).

Conclusions

The abnormal profiles of Th1-/Th2-associated chemokines and chemokine receptors may play important roles in the pathogenesis of ITP. Importantly, regulating Th1 polarization by pulsed HD-DXM may represent a novel approach for immunoregulation in ITP.

Identification and Validation of Gene Expression Pattern and Signature in Patients with Immune Thrombocytopenia

In the present study, we sought to define genes associated with immune thrombocytopenia (ITP). Microarray analysis revealed that of 1002 genes associated with ITP, 309 genes had downregulated expression and 693 genes had upregulated expression in patients with ITP. Gene set enrichment analysis revealed that 11 pathways were positively correlated to ITP, such as type I diabetes mellitus, intestinal immune network for IgA production, and oxidative phosphorylation. The messenger RNA expression levels of the indicated genes, including HLA-DRB5, IGHV3-66, IFI27, FAM212A, PLD5, tumor necrosis factor (TNF)–α, interferon-γ, interleukin (IL)–1β, and IL-4, were significantly increased in patients with ITP compared with healthy humans, while MMP8, SLC1A3, CRISP3, THBS1, FMN1, and IL-10 were decreased. In conclusion, the gene expression profile of patients with ITP has established a foundation to study the gene mechanism of ITP progression.

Evaluation of simple blood counts as inflammation markers for brain tumor patients

AIMS

Hemogram parameters in routine blood panels have been proposed as inflammation markers. These parameters, especially the red cell distribution width (RDW) and mean platelet volume (MPV), were evaluated as surrogate inflammatory markers in brain tumor patients. We aimed to observe RDW and MPV values of tumor patients and compare to those in healthy population.

METHODS

We recorded white blood cell count, neutrophil count, lymphocyte count, hemoglobin, hematocrit, RDW, platelet count, and MPV of the study group at the time of diagnosis and compared to those of the control subjects.

RESULTS

The RDW was significantly elevated in study group compared to that of the control subjects (p=0.001). The MPV was significantly lower in study group than that of the control group (p=0.01).

CONCLUSION

Decreased MPV and increased RDW were both associated with brain tumor. However, prospective studies with larger sample sizes are needed to support the results and expose MPV and RDW variations between metastatic and primary brain tumors.

Is There a Relationship Between CXCR4 Gene Expression and Prognosis of Immune Thrombocytopenia in Children?

Immune thrombocytopenia (ITP) is a common autoimmune disorder characterized by decreased platelet count (thrombocytopenia) and bleeding symptoms due to production of autoantibodies against platelets. Chemokines are molecules inducing chemotaxis and play an important role in megakaryopoiesis, including CXCR4 chemokine receptor. CXCR4 is expressed on cells of megakaryocytic series, especially platelets, and triggers several mechanisms in these cells. The purpose of this study was to evaluate the pattern of CXCR4 gene changes upon diagnosis and after treatment and its comparison with laboratory findings in peripheral blood samples from newly diagnosed ITP patients. 35 newly diagnosed patients with ITP and 35 healthy controls were enrolled in this study. CXCR4 gene expression was investigated before and after treatment using real-time PCR. HPRT gene was used as the reference gene to calculate the expression rate of CXCR4 as CXCR4/HPRT ratio. CXCR4 gene expression upon diagnosis and after treatment in peripheral blood plasma of ITP patients showed a significant decrease in comparison with the control group while its expression did not change before and after treatment. No significant correlation was found between the expression of this gene and laboratory parameters. Due to unpredictable course of ITP in patients and the possibility of its progress to refractory form, accurate choice of a biomarker is essential for evaluating prognosis and detection of resistant forms.

2-Arachidonoylglycerol enhances platelet formation from human megakaryoblasts

Platelets modulate vascular system integrity, and their loss is critical in haematological pathologies and after chemotherapy. Therefore, identification of molecules enhancing platelet production would be useful to counteract thrombocytopenia. We have previously shown that 2-arachidonoylglycerol (2-AG) acts as a true agonist of platelets, as well as it commits erythroid precursors toward the megakaryocytic lineage. Against this background, we sought to further interrogate the role of 2-AG in megakaryocyte/platelet physiology by investigating terminal differentiation, and subsequent thrombopoiesis. To this end, we used MEG-01 cells, a human megakaryoblastic cell line able to produce in vitro platelet-like particles. 2-AG increased the number of cells showing ruffled surface and enhanced surface expression of specific megakaryocyte/platelet surface antigens, typical hallmarks of terminal megakaryocytic differentiation and platelet production. Changes in cytoskeleton modeling also occurred in differentiated megakaryocytes and blebbing platelets. 2-AG acted by binding to CB1 and CB2 receptors, because specific antagonists reverted its effect. Platelets were split off from megakaryocytes and were functional: they contained the platelet-specific surface markers CD61 and CD49, whose levels increased following stimulation with a natural agonist like collagen. Given the importance of 2-AG for driving megakaryopoiesis and thrombopoiesis, not surprisingly we found that its hydrolytic enzymes were tightly controlled by classical inducers of megakaryocyte differentiation. In conclusion 2-AG, by triggering megakaryocyte maturation and platelet release, may have clinical efficacy to counteract thrombocytopenia-related diseases.

Immune status of patients with inherited bone marrow failure syndromes

Immune function abnormalities have been reported in patients with Fanconi anemia (FA), dyskeratosis congenita (DC) and, rarely, in Shwachman-Diamond syndrome (SDS), and Diamond-Blackfan anemia (DBA), but large systematic studies are lacking. We assessed immunological parameters in 118 patients with these syndromes and 202 unaffected relatives. We compared the results in patients with reference values, and with values in relatives after adjusting for age, sex, corticosteroid treatment, and severe bone marrow failure (BMF). Adult patients (≥18 years) with FA had significantly lower immunoglobulins (IgG, IgA and IgM), total lymphocytes, and CD4 T cells than reference values or adult relatives (P < 0.001); children with FA had normal values. Both children and adults with FA had lower B- and NK cells (P < 0.01) than relatives or reference values. Patients with DC had essentially normal immunoglobulins but lower total lymphocytes than reference values or relatives, and lower T-, B-, and NK-cells; these changes were more marked in children than adults (P < 0.01). Most patients with DBA and SDS had normal immunoglobulins and lymphocytes. Lymphoproliferative responses, serum cytokine levels, including tumor necrosis factor-α and interferon-γ, and cytokine levels in supernatants from phytohemagglutinin-stimulated cultures were similar across patient groups and relatives. Only patients with severe BMF, particularly those with FA and DC, had higher serum G-CSF and Flt3-ligand and lower RANTES levels compared with all other groups or relatives (P < 0.05). Overall, immune function abnormalities were seen mainly in adult patients with FA, which likely reflects their disease-related progression, and in children with DC, which may be a feature of early-onset severe disease phenotype.

Association of haemolytic uraemic syndrome with dysregulation of chemokine receptor expression in circulating monocytes

Haemolytic uraemic syndrome (HUS) is the major complication of Escherichia coli gastrointestinal infections that are Shiga toxin (Stx) producing. Monocytes contribute to HUS evolution by producing cytokines that sensitize endothelial cells to Stx action and migration to the injured kidney. As CC chemokine receptors (CCRs) are involved in monocyte recruitment to injured tissue, we analysed the contribution of these receptors to the pathogenesis of HUS. We analysed CCR1, CCR2 and CCR5 expression in peripheral monocytes from HUS patients during the acute period, with healthy children as controls. We observed an increased expression of CCRs per cell in monocytes from HUS patients, accompanied by an increase in the absolute number of monocytes CCR1+, CCR2+ and CCR5+. It is interesting that prospective analysis confirmed that CCR1 expression positively correlated with HUS severity. The evaluation of chemokine levels in plasma showed that regulated on activation of normal T-cell-expressed and -secreted (RANTES) protein was reduced in plasma from patients with severe HUS, and this decrease correlated with thrombocytopenia. Finally, the expression of the higher CCRs was accompanied by a loss of functionality which could be due to a mechanism for desensitization to compensate for altered receptor expression. The increase in CCR expression correlates with HUS severity, suggesting that the dysregulation of these receptors might contribute to an increased risk of renal damage. Activated monocytes could be recruited by chemokines and then receptors could be dysregulated. The dysregulation of CCRs and their ligands observed during the acute period suggests that a chemokine pathway would participate in HUS development.

New frontiers for platelet CD154

The role of platelets extends beyond hemostasis. The pivotal role of platelets in inflammation has shed new light on the natural history of conditions associated with acute or chronic inflammation. Beyond the preservation of vascular integrity, platelets are essential to tissue homeostasis and platelet-derived products are already used in the clinics. Unanticipated was the role of platelets in the adaptative immune response, allowing a renewed conceptual approach of auto-immune diseases. Platelets are also important players in cancer growth and dissemination. Platelets fulfill most of their functions through the expression of still incompletely characterized membrane-bound or soluble mediators. Among them, CD154 holds a peculiar position, as platelets represent a major source of CD154 and as CD154 contributes to most of these new platelet attributes. Here, we provide an overview of some of the new frontiers that the study of platelet CD154 is opening, in inflammation, tissue homeostasis, immune response, hematopoiesis and cancer.

Treatment with Evasin-3 abrogates neutrophil-mediated inflammation in mouse acute pancreatitis

BACKGROUND

Acute pancreatitis is characterized by inflammatory processes affecting not only the pancreas, but also the lung. Here, we investigated timing of leucocyte infiltration and chemokine expression within lung and pancreas during pancreatitis and whether treatments selectively inhibiting chemokines (using Evasins) could improve organ injury.

MATERIAL AND METHODS

C57Bl/6 mice were submitted in vivo to 10-h intraperitoneal injections of cerulein and followed for up to 168 h. Five minutes after the first cerulein injection, a single intraperitoneal injection of 10 μg Evasin-3, 1 μg Evasin-4 or an equal volume of vehicle (PBS) was performed. Leucocytes, reactive oxygen species (ROS), necrosis and chemokine/cytokine mRNA expression were assessed in different organs by immunohistology and real-time RT-PCR, respectively.

RESULTS

In the lung, neutrophil infiltration and macrophage infiltration peaked at 12 h and were accompanied by increased CXCL2 mRNA expression. CCL2, CXCL1 and TNF-alpha significantly increased after 24 h as compared to baseline. No increase in CCL3 and CCL5 was observed. In the pancreas, neutrophil infiltration peaked at 6 h, while macrophages increased only after 72 h. Treatment with Evasin-3 decreased neutrophil infiltration, ROS production and apoptosis in the lung and reduced neutrophils, macrophages apoptosis and necrosis in the pancreas. Evasin-4 only reduced macrophage content in the lung and did not provide any benefit at the pancreas level.

CONCLUSION

Chemokine production and leucocyte infiltration are timely regulated in lung and pancreas during pancreatitis. CXC chemokine inhibition with Evasin-3 improved neutrophil inflammation and injury, potentially interfering with damages in acute pancreatitis and related pulmonary complications.

Platelet count predicts cardiovascular mortality in very elderly patients with myocardial infarction

BACKGROUND

The prognosis of elderly patients with acute myocardial infarction (AMI) is poor, and information on specific risk factors remains scarce. The aim of our study was to assess the influence of platelet count on cardiovascular mortality in very elderly patients with acute myocardial infarction (≥ 85 years of age).

METHODS

We identified 208 elderly AMI patients and compared the platelet count with 208 matched young AMI patients (≤ 65 years) and 208 matched intermediate age AMI patients (66-84 years) who derived from the same cohort.

RESULTS

During a median follow-up of 4·7 years, 25% of patients (n = 156) died of cardiovascular causes (97 very elderly, 46 intermediate age and 13 young age patients). We detected a mean platelet count of 227G/l (SD ± 83) in very elderly AMI patients, of 236G/l (SD ± 78) in the intermediate AMI group and of 254G/l (SD ± 79) in 208 young AMI patients (ANOVA P = 0·002). We revealed a significant interaction between age and platelet count with regard to cardiovascular mortality (p for interaction = 0·014). Platelet count displayed a significant risk transformation from an independent risk factor for cardiovascular mortality in very elderly AMI patients (adj. hazard ratio (HR) per 1-SD increase 1·25;95%CI 1·02-1·54;P = 0·028), via displaying no association with mortality in the intermediate age group (P = 0·10), to a strong inverse association in young patients (adj. HR 0·36;95%CI 0·18-0·68;P = 0·002).

CONCLUSION

Our study demonstrates an independent association between elevated platelet count and long-term cardiovascular mortality in the growing and vulnerable group of very elderly AMI patients. Nevertheless, the pathophysiologic mechanisms underlying this age-dependent effect have to be further clarified.

Pathogenesis in immune thrombocytopenia: new insights

Idiopathic (immune) thrombocytopenic purpura (ITP) is a common autoimmune disorder resulting in isolated thrombocytopenia. ITP can present either alone (primary) or in the setting of other conditions (secondary) such as infections or altered immune states. ITP is associated with a loss of tolerance to platelet antigens and a phenotype of accelerated platelet destruction and impaired platelet production. Although the etiology of ITP remains unknown, complex dysregulation of the immune system is observed in ITP patients. Antiplatelet antibodies mediate accelerated clearance from the circulation in large part via the reticuloendothelial (monocytic phagocytic) system. In addition, cellular immunity is perturbed and T-cell and cytokine profiles are significantly shifted toward a type 1 and Th17 proinflammatory immune response. Further clues into immune dysregulation in ITP may be gleaned from studies of secondary ITP. Some infections can induce antiplatelet Abs by molecular mimicry, and there may be common elements involved in breaking tolerance with other autoimmune disorders. There is also evidence for a genetic predisposition to both ITP and responsiveness to therapy, which may in part lie within immune-related genes. Lastly, treatment with immunomodulatory agents remains the mainstay of ITP therapies.