Megakaryocytic differentiation of HIMeg-1 cells induced by interferon gamma and tumour necrosis factor alpha but not by thrombopoietin

Biomarkers and Predictive Factors for Treatment Response to Tumor Necrosis Factor-α Inhibitors in Patients with Psoriasis

We performed a retrospective and observational study of patients with psoriasis. The aim of this study was to define the laboratory indicators reflecting the treatment response to tumor necrosis factor (TNF)-α inhibitors and the predictors for the treatment response. From January 2010 to June 2022, 28, 15 and 12 patients with psoriasis were treated with infliximab (IFX), adalimumab (ADA) and certolizumab pegol (CZP), respectively. The values of C-reactive protein (CRP), platelet to lymphocyte ratio (PLR), neutrophil to lymphocyte ratio and monocyte to lymphocyte ratio decreased in parallel with psoriasis area and severity index (PASI) at weeks 12 and 52 of treatment. The percentage reduction of the CRP was correlated with that of the PASI at week 52 in all patients and subgroups treated with IFX. The percentage reduction of the PLR was correlated with that of the PASI at week 52 in all patients. Linear multivariate regression analyses revealed that the presence of scalp lesions was associated with a high percentage reduction of the PASI at week 52 in the ADA subgroup. The CRP and PLR might act as biomarkers reflecting the treatment response to TNF-α inhibitors in patients with psoriasis. The presence of scalp lesions might be a predictive factor for a high treatment response to ADA in patients with psoriasis.

The effect of inflammatory factors and their inhibitors on the hematopoietic stem cells fate

Inflammatory cytokines exert different effects on hematopoietic stem cells (HSCs), lead to the development of various cell lineages in bone marrow (BM) and are thus a differentiation axis for HSCs. The content used in this article has been obtained by searching PubMed database and Google Scholar search engine of English-language articles (1995-2020) using "Hematopoietic stem cell," "Inflammatory cytokine," "Homeostasis," and "Myelopoiesis." Inflammatory cytokines are involved in the differentiation and proliferation of hematopoietic progenitors to compensate for cellular death due to inflammation. Since each of these cytokines differentiates HSCs into a specific cell line, the difference in the effect of these cytokines on the fate of HSC progenitors can be predicted. Inhibitors of these cytokines can also control the inflammatory process as well as the cells involved in leukemic conditions. In general, inflammatory signaling can specify the dominant cell line in BM to counteract inflammation and leukemic condition via stimulating or inhibiting hematopoietic progenitors. Therefore, detection of the effects of inflammatory cytokines on the differentiation of HSCs can be an appropriate approach to check inflammatory and leukemic conditions and the suppression of these cytokines by their inhibitors allows for control of homeostasis in stressful conditions.

Associations of Platelet Count with Inflammation and Response to Anti-TNF-α Therapy in Patients with Ankylosing Spondylitis

Background: Increased platelet count has been reported in ankylosing spondylitis (AS) patients, but its clinical significance is still largely elusive. The objective of this study was to evaluate the clinical role of platelet count in AS patients, especially its impact on treatment outcomes.

Methods: A case-control study containing 35 AS patients receiving anti-tumor necrosis factor-α (anti-TNF-α) therapy and 45 healthy controls was performed, and AS patients were followed at least 6 months after anti-TNF-α therapy. A systematic review and meta-analysis of studies containing relevant data on outcomes of interest was also performed.

Results: AS patients had significantly higher platelet count than controls (p = 0.0001), and the significantly increased platelet count in AS patients was confirmed in a meta-analysis of 14 studies involving 1,223 AS patients and 913 controls (mean difference = 39.61, 95% CI 27.89–51.34, p < 0.001). Besides, platelet count was significantly correlated with ESR (p < 0.001) and was moderately correlated with ASDAS-CRP score (p = 0.002). Moreover, anti-TNF-α therapy could reduce platelet count in AS patients at the first month and the effect was maintained through the treatment duration. In the prospective follow-up study of those 35 AS patients, those responders to anti-TNF-α therapy had significantly lower platelet count than nonresponders (p = 0.015). Logistic regression analysis suggested that lower platelet count was associated with higher possibility of achieving good response to anti-TNF-α therapy in AS patients (odds ratio = 2.26; 95% CI = 1.06–4.82; p = 0.035).

Conclusion: This study suggested that platelet count was associated with inflammation severity and treatment outcomes in AS patients, and elevated platelet count was a promising biomarker of poorer response to anti-TNF-α therapy. The findings above need to be validated in more future studies.

STAT1 promotes megakaryopoiesis downstream of GATA-1 in mice

Thrombocytosis is associated with inflammation, and certain inflammatory cytokines, including IFN-gamma, stimulate megakaryocyte and platelet production. However, the roles of IFN-gamma and its downstream effector STAT1 in megakaryocyte development are poorly understood. We previously reported that STAT1 expression was significantly downregulated in Gata1-knockdown murine megakaryocytes, which also have impaired terminal maturation. Here, we show that ectopic expression of STAT1, or its target effector IRF-1, rescued multiple defects in Gata1-deficient megakaryopoiesis in mice, inducing polyploidization and expression of a subset of platelet-expressing genes. Enforced expression of STAT1, IRF-1, or GATA-1 enhanced phosphorylation of STAT1, STAT3, and STAT5 in cultured Gata1-deficient murine megakaryocytes, with concomitant megakaryocyte maturation. In contrast, enhanced thrombopoietin signaling, conferred by enforced expression of constitutively active JAK2 or c-MPL, induced phosphorylation of STAT3 and STAT5, but not STAT1, and failed to rescue megakaryocyte maturation. Finally, megakaryocytes from Stat1(-/-) mice were defective in polyploidization. Together, these findings reveal a unique role for STAT1 in megakaryopoiesis and provide new insights into how GATA-1 regulates this process. Our studies elucidate potential mechanisms by which various inflammatory disorders can cause elevated platelet counts.

Functional role of CCCTC binding factor (CTCF) in stress-induced apoptosis

CTCF, a nuclear transcriptional factor, is a multifunctional protein and involves regulation of growth factor- and cytokine-induced cell proliferation/differentiation. In the present study, we investigated the role of CTCF in protecting stress-induced apoptosis in various human cell types. We found that UV irradiation and hyper-osmotic stress induced human corneal epithelial (HCE) and hematopoietic myeloid cell apoptosis detected by significantly increased caspase 3 activity and decreased cell viability. The stress-induced apoptotic response in these cells requires down-regulation of CTCF at both mRNA and protein levels, suggesting that CTCF may play an important role in downstream events of stress-induced signaling pathways. Inhibition of NFkappaB activity prevented stress-induced down-regulation of CTCF and increased cell viability against stress-induced apoptosis. The anti-apoptotic effect of CTCF was further studied by manipulating CTCF activities in HCE and hematopoietic cells. Transient transfection of cDNAs encoding full-length human CTCF markedly suppressed stress-induced apoptosis in these cells. In contrast, knocking down of CTCF mRNA using siRNA specific to CTCF significantly promoted stress-induced apoptosis. Thus, our results reveal that CTCF is a down stream target of stress-induced signaling cascades and it plays a significant anti-apoptotic role in regulation of stress-induced cellular responses in HCE and hematopoietic myeloid cells.

Phagocytosis of codeveloping megakaryocytic progenitors by dendritic cells in culture with thrombopoietin and tumor necrosis factor-α and its possible role in hemophagocytic syndrome

Tumor necrosis factor-α (TNF-α) and thrombopoietin (TPO) have been shown to induce the differentiation and proliferation of CD34+ cells toward dendritic cells (DCs) in the presence of multiacting cytokines. We hypothesized that the costimulation of TPO and TNF-α generates megakaryocytic progenitors and DCs together from human CD34+ cells and that the interaction of these cells may indicate a physiologic and/or a pathologic role of DCs in megakaryopoiesis. When highly purified human CD34+ cells were cultured for 7 days with TPO alone, the generated cells expressed megakaryocytic markers, such as CD41, CD42b, and CD61. The addition of TNF-α with TPO remarkably decreased the number of megakaryocytic progenitor cells without affecting the cell yield. Almost half of the cells thus generated expressed CD11c, and most of them were positive for CD4 and CD123. Furthermore, CD11c+ cells were found to capture damaged CD61+ cells and to induce autologous T-cell proliferation, although the cytokine productions were low. We also confirmed an engulfment of CD61+ cells and their fragment by CD11c+ cells in bone marrow cells from patients with hemophagocytic syndrome. These findings suggest that DCs generated under megakaryocytic and inflammatory stimuli are involved in megakaryopoiesis and the subsequent immune responses to self-antigens.

Involution of thymus and lymphoid depletion in mice expressing the hTNF transgene

Tumour necrosis factor (TNF) is involved in the pathogenesis of several diseases. In mice, human TNF signals only through p55, one of two murine TNF receptors. We here report a study of growth, viability and morphological alterations in transgenic mice expressing a low constitutive and tissue-restricted level of human TNF in vivo. The transgene was expressed solely in T cells. The transgenic mice showed a marked failure to thrive and a rapid cellular depletion in spleen and thymus. Slight fibrosis was seen in most tissues investigated, in addition to immature adipose tissue and irregular lymphocytic areas. Serum levels of hTNF were only slightly increased in the transgenic mice, enough, however, to cause an inflammatory reaction. All the symptoms were abrogated by an inhibitory hTNF antibody, demonstrating the essential role of hTNF in this phenotype. Transgenic mice constitute a multidimensional system allowing observation of disease processes over time in all tissues. The effects of hTNF were seen first and foremost in the lymphoid organs of the transgenic mice, verifying their cells as major targets at low levels of hTNF expression in the T-cell compartments. Chronic, low levels of TNF expression cause profound disturbances in lymphoid tissue development resulting in cachexia and premature death.

Risk factors for visual loss in giant cell (temporal) arteritis: a prospective study of 174 patients

OBJECTIVE

To determine the risk factors--especially the effects of thrombocytosis--for permanent visual loss in patients with temporal arteritis.

METHODS

One hundred seventy-four patients with temporal arteritis (147 biopsy proven) were prospectively observed for the development of permanent visual loss. We used multivariate logistic regression analysis to determine which of 17 pretreatment characteristics were associated with visual loss.

RESULTS

Visual ischemic manifestations occurred in 48 (28%) patients, including permanent visual loss in 23 (13%) patients. The independent predictors associated with an increased risk of permanent visual loss were a history of transient visual ischemic symptoms (odds ratio [OR] = 6.3; 95% confidence interval [CI]: 1.4 to 29; P = 0.02) and a higher platelet count (OR = 3.7 per SD; 95% CI: 1.8 to 7.9; P = 0.001). The presence of constitutional symptoms (OR = 0.14; 95% CI: 0.02 to 0.77, P = 0.01), polymyalgia rheumatica (OR = 0.04; 95% CI: 0.01 to 0.48, P = 0.02), and C-reactive protein level (OR = 0.35 per SD; 95% CI: 0.13 to 0.92, P = 0.03) were associated with a reduced risk. Upper limb artery involvement was excluded from the multivariate model, as no patients with that problem developed permanent visual loss. Of the 87 patients who presented with thrombocytosis (platelet count >400 x 10(9)/L), 32 (37%) developed ischemic visual symptoms, compared with 16 (18%) of those without thrombocytosis.

CONCLUSIONS

An elevated platelet count is a risk factor for permanent visual loss in temporal arteritis. The finding of thrombocytosis in a patient with suspected temporal arteritis should emphasize the need for urgent treatment, with consideration of using inhibitors of platelet aggregation or anticoagulation therapy.

[Risk factors for irreversible cerebral ischemia complications from Horton's disease: prospective study of 178 patients]

PURPOSE

To search for risk factors of developing irreversible cranial ischemic complications (ICIC) in patients with giant cell arteritis (GCA) and to explore whether two subsets of patients (high risk and low risk of developing ICIC) can be defined.

METHODS

One-hundred seventy-eight consecutive patients with temporal arteritis (149 biopsy-proven) were diagnosed and followed up in a department of Internal Medicine between 1976 and 1999. The patients were separated into two groups, according to the presence or absence of ICIC, with comparison of 17 clinical and biological parameters prospectively recorded for each patient using a pre-established comprehensive questionnaire.

RESULTS

ICIC occurred in 25 patients (14%), with amaurosis in 22 cases. Suggestive symptoms and/or signs of temporal arteritis were present in 92% of the patients, lasting 50 days (median) before the onset of ICIC. Forty-three patients (24%) complained of transient visual ischemic symptoms (TVIS), which preceded acute blindness in 11 cases. A multivariate logistic regression, from which 28 cases with upper limb artery involvement were excluded for technical reasons (no CCII in any case, thus predicting perfectly the lack of ischemic risk, P = 0.02), indicated that the only independent variables associated with the ischemic risk were: a history of TVIS (P = 0.05), the lack of signs of polymyalgia rheumatica (PMR; P = 0.02), lower blood levels of fibrinogen (P = 0.024) and higher mean blood platelets levels (P = 0.006). However, these five variables predicted only 30% of the variability of the model. Sensitivity, specificity, positive and negative predictive values of the model reached respectively 36, 96, 64 and 88%. Overall, 86% of the cases were correctly classified with respect to the ischemic risk.

CONCLUSION

The rate of ICIC should be reduced by an earlier recognition of the usual signs of temporal arteritis. Several independent risk factors of ICIC have been identified. However, the logistic model failed to predict accurately the ischemic risk in 14% of the cases, indicating that as yet unrecognised factors probably exist that play a role in the occurrence of ICIC. Nevertheless, regarding the strong association between platelet levels and ICIC, patients with thrombocytosis should receive initially both corticosteroids and antiplatelet agents.