Haploinsufficiency in PTPN2 leads to early-onset systemic autoimmunity from Evans syndrome to lupus.

An exome sequencing strategy employed to identify pathogenic variants in patients with pediatric-onset systemic lupus or Evans syndrome resulted in the discovery of six novel monoallelic mutations in PTPN2. PTPN2 is a phosphatase that acts as an essential negative regulator of the JAK/STAT pathways. All mutations led to a loss of PTPN2 regulatory function as evidenced by in vitro assays and by hyperproliferation of patients' T cells. Furthermore, patients exhibited high serum levels of inflammatory cytokines, mimicking the profile observed in individuals with gain-of-function mutations in STAT factors. Flow cytometry analysis of patients' blood cells revealed typical alterations associated with autoimmunity and all patients presented with autoantibodies. These findings further supported the notion that a loss of function in negative regulators of cytokine pathways can lead to a broad spectrum of autoimmune manifestations and that PTPN2 along with SOCS1 haploinsufficiency constitute a new group of monogenic autoimmune diseases that can benefit from targeted therapy.

Excessive expressions of T cell activation markers in pediatric immune thrombocytopenia.

BACKGROUND: Immune thrombocytopenia (ITP) is an immune-mediated bleeding disorder in children. Activated T cells have been shown to play important roles in ITP. The aims of this study were to evaluate whether these T cell activation markers could be used as indicators to differentiate ITP patients from controls, and to assess whether they could be used as predictors of IVIG response in ITP patients. METHODS: A cohort of 92 hospitalized ITP patients, 49 unrelated healthy children, and 48 thrombocytosis patients were enrolled in this retrospective study between February 2013 and September 2018. Expression of CD25, HLA-DR, and CD69 on the surfaces of CD4+ and CD8+ T cells were detected by flow cytometry. All statistical analyses were performed using SPSS 20.0 software. RESULTS: Compared to the healthy controls, ITP patients had higher percentages of CD4 + CD25+ T cells, CD4 + HLA-DR+ T cells, CD8 + HLA-DR+ T cells, and CD8 + CD69+ T cells. Compared to the thrombocytosis patients, ITP patients had higher percentages of CD4 + HLA-DR+ T cells and CD8 + HLA-DR+ T cells, and lower CD4 + CD69+ T cells and CD8 + CD69+ T cells. Platelet count at admission had a negative correlation with CD4 + CD25+ T cells in ITP. CD4 + CD69+ T cells were decreased in chronic compared to the newly diagnosed and persistent ITP patients. Activated T cell markers had no predictive value for IVIG response in ITP patients. CONCLUSIONS: T cell activation markers were excessively expressed in pediatric ITP, and those markers had no predictive value for IVIG response in ITP patients.

Platelets expressing IgG receptor FcγRIIA/CD32A determine the severity of experimental anaphylaxis.

Platelets are key regulators of vascular integrity; however, their role in anaphylaxis, a life-threatening systemic allergic reaction characterized by the loss of vascular integrity and vascular leakage, remains unknown. Anaphylaxis is a consequence of inappropriate cellular responses triggered by antibodies to generally harmless antigens, resulting in a massive mediator release and rapidly occurring organ dysfunction. Human platelets express receptors for immunoglobulin G (IgG) antibodies and can release potent mediators, yet their contribution to anaphylaxis has not been previously addressed in mouse models, probably because mice do not express IgG receptors on platelets. We investigated the contribution of platelets to IgG-dependent anaphylaxis in human IgG receptor-expressing mouse models and a cohort of patients suffering from drug-induced anaphylaxis. Platelet counts dropped immediately and markedly upon anaphylaxis induction only when they expressed the human IgG receptor FcγRIIA/CD32A. Platelet depletion attenuated anaphylaxis, whereas thrombocythemia substantially worsened its severity. FcγRIIA-expressing platelets were directly activated by IgG immune complexes in vivo and were sufficient to restore susceptibility to anaphylaxis in resistant mice. Serotonin released by activated platelets contributed to anaphylaxis severity. Data from a cohort of patients suffering from drug-induced anaphylaxis indicated that platelet activation was associated with anaphylaxis severity and was accompanied by a reduction in circulating platelet numbers. Our findings identify platelets as critical players in IgG-dependent anaphylaxis and provide a rationale for the design of platelet-targeting strategies to attenuate the severity of anaphylactic reactions.

Neutrophil-derived S100 calcium-binding proteins A8/A9 promote reticulated thrombocytosis and atherogenesis in diabetes.

Platelets play a critical role in atherogenesis and thrombosis-mediated myocardial ischemia, processes that are accelerated in diabetes. Whether hyperglycemia promotes platelet production and whether enhanced platelet production contributes to enhanced atherothrombosis remains unknown. Here we found that in response to hyperglycemia, neutrophil-derived S100 calcium-binding proteins A8/A9 (S100A8/A9) interact with the receptor for advanced glycation end products (RAGE) on hepatic Kupffer cells, resulting in increased production of IL-6, a pleiotropic cytokine that is implicated in inflammatory thrombocytosis. IL-6 acts on hepatocytes to enhance the production of thrombopoietin, which in turn interacts with its cognate receptor c-MPL on megakaryocytes and bone marrow progenitor cells to promote their expansion and proliferation, resulting in reticulated thrombocytosis. Lowering blood glucose using a sodium-glucose cotransporter 2 inhibitor (dapagliflozin), depleting neutrophils or Kupffer cells, or inhibiting S100A8/A9 binding to RAGE (using paquinimod), all reduced diabetes-induced thrombocytosis. Inhibiting S100A8/A9 also decreased atherogenesis in diabetic mice. Finally, we found that patients with type 2 diabetes have reticulated thrombocytosis that correlates with glycated hemoglobin as well as increased plasma S100A8/A9 levels. These studies provide insights into the mechanisms that regulate platelet production and may aid in the development of strategies to improve on current antiplatelet therapies and to reduce cardiovascular disease risk in diabetes.

Hyper IgM Syndrome with low IgM and thrombocytosis: an unusual case of immunodeficiency.

We report a 5 years old male child with low serum IgG, IgA and IgM levels, who presented with recurrent perianal and oral ulcers, intermittent fever, and protracted diarrhea. Despite the lack of typical respiratory symptoms, low serum IgM level and persistent thrombocytosis, an X-linked hyper-IgM syndrome (X-HIGM) was considered. Laboratory investigations revealed a diagnosis of hyper-IgM syndrome caused by CD40L deficiency.

Complement inhibition in biomaterial- and biosurface-induced thromboinflammation.

Therapeutic medicine today includes a vast number of procedures involving the use of biomaterials, transplantation of therapeutic cells or cell clusters, as well as of solid organs. These treatment modalities are obviously of great benefit to the patient, but also present a great challenge to the innate immune system, since they involve direct exposure of non-biological materials, cells of non-hematological origin as well as endothelial cells, damaged by ischemia-perfusion in solid organs to proteins and cells in the blood. The result of such an exposure may be an inappropriate activation of the complement and contact/kallikrein systems, which produce mediators capable of triggering the platelets and PMNs and monocytes, which can ultimately result in thrombotic and inflammatory (i.e., a thrombo-inflammatory) response to the treatment modality. In this concept review, we give an overview of the mechanisms of recognition within the innate immunity system, with the aim to identify suitable points for intervention. Finally, we discuss emerging and promising techniques for surface modification of biomaterials and cells with specific inhibitors in order to diminish thromboinflammation and improve clinical outcome.

Proinflammatory Cytokine IL-6 and JAK-STAT Signaling Pathway in Myeloproliferative Neoplasms.

The recent JAK1/2 inhibitor trial in myeloproliferative neoplasms (MPNs) showed that reducing inflammation can be more beneficial than targeting gene mutants. We evaluated the proinflammatory IL-6 cytokine and JAK-STAT signaling pathway related genes in circulating CD34(+) cells of MPNs. Regarding laboratory data, leukocytosis has been observed in polycythemia vera (PV) and JAK2V617F mutation positive versus negative primary myelofibrosis (PMF) patients. Moreover, thrombocytosis was reduced by JAK2V617F allele burden in essential thrombocythemia (ET) and PMF. 261 significantly changed genes have been detected in PV, 82 in ET, and 94 genes in PMF. The following JAK-STAT signaling pathway related genes had augmented expression in CD34(+) cells of MPNs: CCND3 and IL23A regardless of JAK2V617F allele burden; CSF3R, IL6ST, and STAT1/2 in ET and PV with JAK2V617F mutation; and AKT2, IFNGR2, PIM1, PTPN11, and STAT3 only in PV. STAT5A gene expression was generally reduced in MPNs. IL-6 cytokine levels were increased in plasma, as well as IL-6 protein levels in bone marrow stroma of MPNs, dependent on JAK2V617F mutation presence in ET and PMF patients. Therefore, the JAK2V617F mutant allele burden participated in inflammation biomarkers induction and related signaling pathways activation in MPNs.

Severe neutrophil-dominated inflammation and enhanced myelopoiesis in IL-33-overexpressing CMV/IL33 mice.

IL-33 is a cytokine of the IL-1 family, which signals through the ST2 receptor. Previous studies emphasized a role for IL-33 in shaping innate and adaptive immune responses. IL-33 was also reported to modulate myelopoiesis and myeloid cell activity. In this article, we describe IL-33-overexpressing CMV/IL33 and LysM/IL33 mice, which display an inflammatory phenotype associated with growth retardation and paw swelling. The phenotype of CMV/IL33 mice is dependent on activation of the ST2 receptor and is characterized by extensive neutrophil infiltration into different organs, including the paws. Local or systemic levels of proinflammatory mediators such as IL-1ß, Cxcl-1, G-CSF, and IL-6 are increased. CMV/IL-33 mice also suffer from anemia, thrombocytosis, and a marked dysregulation of myelopoiesis, leading to an important increase in myeloid cell production or accumulation in bone marrow (BM), spleen, and peripheral blood. Consistently, recombinant IL-33 induced proliferation of myeloid lineage cells in BM-derived granulocyte cultures, whereas IL-33 knockout mice exhibited minor deficiencies in spleen and BM myeloid cell populations. Our observations reveal a neutrophil-dominated inflammatory phenotype in IL-33-overexpressing CMV/IL33 and LysM/IL33 mice, and highlight important regulatory effects of IL-33 on myelopoiesis in vitro and in vivo, where excessive IL-33 signaling can translate into the occurrence of a myeloproliferative disorder.

CD44 antibodies and immune thrombocytopenia in the amelioration of murine inflammatory arthritis.

Antibodies to CD44 have been used to successfully ameliorate murine models of autoimmune disease. The most often studied disease model has been murine inflammatory arthritis, where a clear mechanism for the efficacy of CD44 antibodies has not been established. We have recently shown in a murine passive-model of the autoimmune disease immune thrombocytopenia (ITP) that some CD44 antibodies themselves can induce thrombocytopenia in mice, and the CD44 antibody causing the most severe thrombocytopenia (IM7), also is known to be highly effective in ameliorating murine models of arthritis. Recent work in the K/BxN serum-induced model of arthritis demonstrated that antibody-induced thrombocytopenia reduced arthritis, causing us to question whether CD44 antibodies might primarily ameliorate arthritis through their thrombocytopenic effect. We evaluated IM7, IRAWB14.4, 5035-41.1D, KM201, KM114, and KM81, and found that while all could induce thrombocytopenia, the degree of protection against serum-induced arthritis was not closely related to the length or severity of the thrombocytopenia. CD44 antibody treatment was also able to reverse established inflammation, while thrombocytopenia induced by an anti-platelet antibody targeting the GPIIbIIIa platelet antigen, could not mediate this effect. While CD44 antibody-induced thrombocytopenia may contribute to some of its therapeutic effect against the initiation of arthritis, for established disease there are likely other mechanisms contributing to its efficacy. Humans are not known to express CD44 on platelets, and are therefore unlikely to develop thrombocytopenia after CD44 antibody treatment. An understanding of the relationship between arthritis, thrombocytopenia, and CD44 antibody treatment remains critical for continued development of CD44 antibody therapeutics.

[Neonatal alloimmune neutropenia is a frequently overlooked diagnosis in neonates]. / Neonatal alloimmun neutropeni er en overset diagnose.

Neonatal alloimmune neutropenia (NIN) results from the destruction of foetal neutrophils by maternal immunoglobulin G-class neutrophil-reactive antibodies crossing the foeto-placental barrier. We report two cases of neonatal patients presenting with unspecific symptoms and persisting neutropenia accompanied by thrombocytosis. Both were subsequently diagnosed with NIN. These two cases of persisting neutropenia highlight the diversity of symptoms and the diagnostic challenges remaining in NIN. Furthermore, the cases remind us that neutropenia in neonates may be rooted in several different pathophysiological mechanisms.

Clinicohematological study of thrombocytosis.

OBJECTIVE: To find out etiology and clinical course of thrombocytosis in Indian pediatric population. METHODS: A total of 250 patients having thrombocytosis (defined as platelet count >500 x 10(9)/L) on haematological investigations were studied over one yr period. All patients were evaluated clinically and were subjected to investigations, including complete blood counts (CBC) with peripheral smear examination. To elucidate the possible role of inflammatory cytokines in pathogenesis of RT, levels of Interleukin-6 (IL-6) and C - reactive protein (CRP) were estimated. RESULTS: Infants and young children (<2 yr age) were most common group, contributing 60% of total cases. Out of total 250 cases, only 3 (1.2%) cases were found to have primary thrombocytosis and remaining 98.8% cases were having RT. Among RT patients, infections (alone or in association with iron deficiency anemia) were most common cause, accounting for 65% cases, while iron deficiency anemia (IDA) was second most common cause accounting for 41.3% cases (12.6% IDA alone and 28.7 % in association with infections). Other causes included nutritional dimorphic anemia and patients on treatment for megaloblastic anemia, acute lymphoblastic leukemia (during treatment) and lymphoma. Among various groups of RT, IL-6 and CRP levels were higher in patients with infection with or without IDA than IDA alone. One child with essential thrombocytosis and one child with RT had thrombotic complications. On follow up, platelet counts normalized in most of the patients with treatment of underlying conditions. CONCLUSIONS: Results of this study suggest that essential thrombocytosis is extremely rare in children. Infections and IDA (alone or in association with infections) are common causes of RT. IL-6 and CRP levels are increased in patients with RT, to a higher level in patients with infections than in patients with IDA. Most patients with RT have uneventful recovery of platelet counts to normal range with treatment for underlying condition.

Granulocytosis and thrombocytosis in renal cell carcinoma: a pro-inflammatory cytokine response originating in the tumour.

BACKGROUND: In up to 20% of patients with renal cell cancer (RCC) an inflammatory response consisting of low-grade fever, weight loss and an elevated ESR and CRP may occur with modest granulocytosis and thrombocytosis. Clinical and experimental data suggest a pathogenic role for tumour-derived cytokine production, especially interleukin-6. CASE REPORT: A 79-year-old female with RCC presented with low-grade fever, weight loss and overt granulocytosis and thrombocytosis. Radiological examination revealed a right-sided renal tumour. During nephrectomy a gradient between the IL-6 levels in the renal artery and vein was demonstrated, providing direct evidence for in vivo production of IL-6 by the tumour affected kidney, which was confirmed by the demonstration of IL -6 in the tumour cells by immunohistochemical staining and in the supernatant of the homogenised tumour. Cytogenetic examination revealed complex abnormalities including a gain of chromosome 7. In addition we demonstrated production of IL-1alpha, IL-1beta, IL-8 and ICAM-1 in the tumour with systemic elevated levels of IL-6 and IL-8 with secondary increased serum G-CSF and TPO levels. CONCLUSION: We have provided direct evidence for the production of pro-inflammatory cytokines by renal cancer cells in a patient with RCC and a profound inflammatory response, with a central role of IL-6, probably due to a gain of chromosome 7. The extreme granulocytosis and thrombocytosis may have resulted from the secondary systemic production of G-CSF and TPO.

Caffey disease with raised immunoglobulin levels and thrombocytosis.

Infantile cortical hyperostosis (Caffey disease) is characterized by radiological evidence of cortical hyperostosis, soft tissue swellings, fever and irritability. We report a case of Caffey disease highlighting its presentation with thrombocytosis and high serum immunoglobulin level to alert physicians to use steroids cautiously in view of the known thrombocythemic effect of the drug. Raised Immunoglobulin also suggests that this syndrome could be infectious in origin.

Anti-endothelial cell antibodies in antineutrophil cytoplasmic antibodies negative pauci-immune crescentic glomerulonephritis.

AIM: Pauci-immune crescentic glomerulonephritis (CrGN) is frequently associated with circulating anti-neutrophil cytoplasmic antibodies (ANCA). However, in patients with ANCA-negative pauci-immune CrGN, the pathogenesis is not clear. Anti-endothelial cell antibodies (AECA) have been implicated in the pathogenesis of vasculitis. The purpose of this study is to investigate the prevalence of AECA and their possible clinical significance in ANCA-negative pauci-immune CrGN. METHODS: Sera from 19 patients with ANCA-negative pauci-immune CrGN, 26 patients with ANCA-positive pauci-immune CrGN and 10 healthy blood donors were collected. Soluble proteins extracted from cultured human umbilical vein endothelial cells were used as antigens and western blot analysis was carried out to detect AECA. RESULTS: In ANCA-negative pauci-immune CrGN, 10 of 19 patients were serum IgG-AECA positive and seven bands reactive with endothelial antigens could be blotted. The prevalence of skin rash and thrombocytosis was significantly higher in patients with anti-76 kDa and anti-123 kDa autoantibodies than in patients without, respectively. Birmingham Vasculitis Activity Scores of patients with anti-200 kDa AECA were significantly higher than in patients without. In the sera of 26 ANCA-positive cases, 23 were AECA positive and 11 bands could be recognized. The prevalence of total AECA and anti-90 kDa AECA was significantly lower in patients with ANCA-negative pauci-immune CrGN than in patients with ANCA-positive pauci-immune CrGN. CONCLUSION: Anti-endothelial cell antibodies could be found in sera of patients with ANCA-negative pauci-immune CrGN; some AECA might have some clinical significance. The discrepancies of AECA might be a possible contributor to the differences between ANCA-negative and ANCA-positive pauci-immune CrGN.

Thrombocytosis in pediatric patients is associated with severe lower respiratory tract inflammation.

BACKGROUND: Secondary thrombocytosis is associated with a variety of clinical conditions. The aim of this study was to determine the incidence and to analyze the clinical significance and prognostic value of thrombocytosis in lower respiratory tract infection. METHODS: A total of 102 pediatric patients were hospitalized with lower respiratory tract infection during a period of 30 months. RESULTS: Forty nine (48%) of those patients had platelet counts >500 x 10(9)/L. The median age of the thrombocytotic patients was 31 months as opposed to 61 months for the non-thrombocytotic ones. The patients with thrombocytosis had more serious illness. This is indicated by three factors: more severe clinical condition on admission, presence of respiratory distress and longer hospitalization. Sedimentation rate >70 mm/h was observed in 44.4% patients of the thrombocytotic group compared to only 27.7% of the non-thrombocytotic ones. Almost all patients with pleural effusion were thrombocytotic. The children with very high platelet counts >650 x 10(9)/L presented with respiratory distress on admission and required longer hospitalization time. No other significant clinical or laboratory differences were demonstrated between these patients and the remainder of the thrombocytotic patients. CONCLUSIONS: Thrombocytosis is a common finding among patients with lower respiratory tract infection. Thrombocytotic patients have a more severe clinical condition. Importantly, thrombocytosis occurs almost exclusively in patients with pleural effusion. The platelet count may be a useful clinical marker associated with the severity of the lower respiratory tract infection.

Antiphospholipid antibodies and platelet activation as risk factors for thrombosis in thrombocythaemia.

INTRODUCTION: Risk factors for thrombosis (TB) in thrombocythaemia (TC) associated with myeloproliferative disorder (MPD) are not well defined. METHODS: We measured antiphospholipid antibodies (APLA) in 35 patients with TC associated with MPD. Fourteen had TB and 21 did not. We assayed IgG and IgM APLA by ELISA for 6 antigens: beta2GP1, cardiolipin (CL), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylethanolamine (PE) and FVII/VIIa, together with markers of activation of platelets (CD62P) and endothelium [endothelial microparticles (EMP)]. RESULTS: At least one positive APLA was detected in 66% of TC patients overall. The incidence was significantly higher in the TB subgroup (92.8%) than non-TB (47.6%, p < 0.05). Multiple APLA (positive for more than one antigen) were also more frequent in TB, for both IgG and IgM, for all 6 antigens tested (p < 0.05). However, IgM APLA predominated, being about 2-fold more frequently positive than IgG for all 6 antigens. Platelet CD62P was significantly higher in the TB group (p < 0.05). EMP did not differ between TB and non-TB. The most frequent thrombotic complication was recurring ischemic cerebral vascular accidents (ICVA), leading to progressive cognitive impairment. Venous TB often developed at unusual sites. Recurring and reversible TB were common features in TC. SUMMARY: This study suggests that APLA and platelet activation are risk factors for TB in TC. APLA are prevalent in TC, and IgM APLA predominated over IgG. Activation of platelets but not of endothelium may be consistent with the reversible and recurrent features of TB in TC.

[Correlation between platelet count and CA-125 in ovarian cancer]. / Znaczenie kliniczne poziomu plytek krwi w raku jajnika.

OBJECTIVE: To determine whether a correlation between platelet count and CA-125 exists, and to compare the mean levels of CA-125 in groups with normal and elevated platelet counts. DESIGN: A retrospective analysis of the medical records concerning to 31 ovarian cancer inpatients, treated 1998-2002 with primary surgery and subsequent platinum-based chemotherapy at the Division of Gynecology, Department of Perinatology and Gynecology, University Medical School Poznan. MATERIALS AND METHODS: 137 serum and whole blood samples collected from 31 ovarian cancer patients during their consecutive hospital stays. RESULTS: There was a positive, moderate (r = 0.49) and highly significant (p < 0.0000001) correlation between platelet count and CA-125 levels. Thrombocytosis occurred in 45% patients before treatment, and in none when the 6th course of chemotherapy was given. In the thrombocytosis group, an average CA-125 level (913.5 U/ml) was significantly higher (p < 0.00001) then in the group with normal platelet count (103.7 U/ml). CONCLUSIONS: Platelet count and CA-125 levels do correlate in blood samples taken from ovarian cancer patients at the same time.

Leukocyte-platelet interaction in patients with essential thrombocythemia and polycythemia vera.

OBJECTIVE: Circulating polymorphonuclear leukocyte (PMN) activation occurs in patients with essential thrombocythemia (ET) and polycythemia vera (PV). We want to define whether this phenomenon plays a role in the formation of circulating PMN-platelet aggregates in these conditions. METHODS: In 80 patients (46 ET and 34 PV) and 50 control subjects, we conducted a flow cytometric analysis to evaluate the levels of PMN-platelet aggregates (defined as the percentage of CD11b-positive PMN coexpressing a platelet-specific marker, i.e., CD42b or CD62P) and the levels of activated PMN and activated platelets. In addition, the in vitro PMN-platelet aggregate formation in response to N-formyl-methionyl-leucyl-phenylalanine (f-MLP)-induced activation of PMN was studied. RESULTS: Significantly high PMN-platelet aggregates in ET and PV patients were found and were associated with increased PMN surface CD11b and surface platelet CD62P expression. In vitro f-MLP stimulation upregulated PMN-CD11b expression and simultaneously increased CD11b/CD42b and CD11b/CD62P aggregates, without affecting platelet surface antigens. In ET patients receiving aspirin, the increments in f-MLP-induced PMN-CD11b and in PMN-platelet aggregates were significantly lower versus ET subjects not treated with aspirin. CONCLUSION: Our data show that in ET and PV patients PMN activation plays an important role in increasing circulating PMN-platelet aggregates and suggest that aspirin treatment may decrease their formation.