Intracellular signal transduction of interferon on the suppression of haematopoietic progenitor cell growth

Interferon-α2b induced anemia in severe coronavirus disease 2019 patients: a single centered, retrospective study

BACKGROUND

The current outbreak of coronavirus disease 2019 (COVID-19) has rapidly spread throughout the world. During treatment, we found that the majority of patients had a decrease in hemoglobin (Hb). Interferon-α2b (IFN-α2b) was the primary suspected drug that was related to Hb reduction. Thus, the study aimed to investigate whether IFN-α2b could induce Hb reduction in severe patients with COVID-19 and its potential mechanism.

MATERIAL AND METHODS

A total of 50 patients who were admitted to the First Affiliated Hospital of Harbin Medical University with severe COVID-19 infection were enrolled from February 12^th to 24^th, 2020. The demographics, baseline characteristics, clinical data, and therapeutic regimen were collected retrospectively. The patients were divided into two groups according to the declined use of IFN-α2b on day 14. The Hb levels on admission, day 7, day14, and day 21 were collected and analyzed. The primary endpoint was the level of Hb on day 21.

RESULTS

A total of 31 patients in the IFN-stop group and 19 patients in the non-IFN-stop group were reviewed. The age, gender, comorbidities, clinical symptoms, nutritional status, disease severity, complications, and other factors of the patients were compared, no difference was found between the IFN-stop group and the non-IFN-stop group. The Hb levels of all patients significantly decreased on day 7 compared with that on admission (p < .0001). In the IFN-stop group, the Hb level was increased in 7 days after IFN-α2b was stopped (p = .0008), whereas no difference was found between day 14 and day 21 in the non-IFN-stop group (p = .3152).

CONCLUSIONS

IFN-α2b was associated with Hb reduction in the treatment of severe patients of COVID-19. Clinicians should be aware of the high incidence of Hb reduction for patients treated by IFN-α2b.

Interferon gamma induces protective non-canonical signaling pathways in primary neurons

The signal transduction molecule, Stat1, is critical for the expression of type I and II interferon (IFN)-responsive genes in most cells; however, we previously showed that primary hippocampal mouse neurons express low basal Stat1, with delayed and attenuated expression of IFN-responsive genes. Moreover, IFNγ-dependent resolution of a neurotropic viral challenge in permissive mice is Stat1-independent. Here, we show that exogenous IFNγ has no deleterious impact on neuronal viability, and staurosporine-induced apoptosis in neurons is significantly blunted by the addition of IFNγ, suggesting that IFNγ confers a pro-survival signal in neurons. To identify the pathways induced by IFNγ in neurons, the activation of alternative signal transducers associated with IFNγ signaling was assessed. Rapid and pronounced activation of extracellular signal regulated kinase (Erk1/2) was observed in neurons, compared to a modest response in fibroblasts. Moreover, the absence of Stat1 in primary fibroblasts led to enhanced Erk activation following IFNγ addition, implying that the cell-specific availability of signal transducers can diversify the cellular response following IFN engagement.

Agranulocytosis at first presentation of autoimmune hepatitis type-1

Autoimmune hepatitis (AIH) is a progressive, chronic disease of unknown cause with varying presenting symptoms, ranging from no symptoms through nonspecific symptoms to fulminant hepatic failure. Although nonspecific hematologic abnormalities in AIH may occur, a case of agranulocytosis (<100 neutrophils/microL) associated with a flare of AIH and suspected to be of autoimmune origin was recently reported. Increased levels of suppressing cytokines had been previously reported in bone marrow samples of patients with AIH type-1 (AIH-1). These changes could be related to induction of apoptosis or interference with differentiation and proliferation of the myeloid lineage, hence, playing a meaningful role in the pathogenesis of agranulocytosis in patients with AIH-1. Here, we report a patient with agranulocytosis at first presentation of AIH-1. On the basis of the patient's diagnostic evaluation, response to administered therapy, and the review of the literature, we suggest several possible mechanisms relating to bone marrow cytokine milieu changes, in addition to autoimmune pathogenesis, that could explain this phenomenon.

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.

Directed evolution of gene-shuffled IFN-alpha molecules with activity profiles tailored for treatment of chronic viral diseases

Type I IFNs are unusually pleiotropic cytokines that bind to a single heterodimeric receptor and have potent antiviral, antiproliferative, and immune modulatory activities. The diverse effects of the type I IFNs are of differential therapeutic importance; in cancer therapy, an enhanced antiproliferative effect may be beneficial, whereas in the therapy of viral infections (such as hepatitis B and hepatitis C), the antiproliferative effects lead to dose limiting bone marrow suppression. Studies have shown that various members of the natural IFN-alpha family and engineered variants, such as IFN-con1, vary in the ratios between various IFN-mediated cellular activities. We used DNA shuffling to explore and confirm the hypothesis that one could simultaneously increase the antiviral and Th1-inducing activity and decrease the antiproliferative activity. We report IFN-alpha hybrids wherein the ratio of antiviral:antiproliferative and Th1-inducing: antiproliferative potencies are markedly increased with respsect to IFN-con1 (75- and 80-fold, respectively). A four-residue motif that overlaps with the IFNAR1 binding site and is derived by cross breeding with a pseudogene contributes significantly to this phenotype. These IFN-alphas have an activity profile that may result in an improved therapeutic index and, consequently, better clinical efficacy for the treatment of chronic viral diseases such as hepatitis B virus, human papilloma virus, HIV, or chronic hepatitis C.

Gangliosides of the stroma layer participate in the interferon-gamma receptor-dependent controls of myelopoiesis

Stroma-mediated myelopoiesis depends upon growth-factors and an appropriate intercellular microenvironment, whose polarity is relevant for granulocyte-macrophage colony stimulating factor (GM-CSF) mediated myeloid cell proliferation. Here we have studied qualitative and quantitative aspects of ganglioside participation in controls of the microenvironment required to sustain myelopoiesis. We analysed ganglioside synthesis, expression and shedding by two primary liver stromal cell cultures isolated from wild type and interferon-gamma (IFNgamma) receptor knockout mice. The latter one has a higher capacity to sustain myelopoiesis. FDC-P1 myeloid growth factor-dependent cell line was used as the reporter system, monitoring the cell survival and proliferation that reflect the bio-availability and the activity of GM-CSF. Although the two stromal cells synthesised the same gangliosides their relative content was quite different. FDC-P1 proliferation decreased in cultures in which ganglioside synthesis was inhibited in the stroma, as well as in presence of stroma cell supernatants in which GM3 was neutralised by the anti-GM3 monoclonal antibody. Addition of exogenous GM3 reverted the inhibition and sustained proliferation of FDC-P1 cells. FDC-P1 cells do not accumulate GM3, but they are able to take up the stroma-produced sphingolipids. Thus, stroma has a double role in sustaining myelopoiesis, providing both growth factor(s) and ganglioside(s) required for the optimal stimulation of the myeloid cell proliferation, and the IFNgamma mediated stroma-dependent controls of myelopoiesis are determinant for this cell interaction.

Dynamics of immature subsets of dendritic cells during antiviral therapy in HLA-A24-positive chronic hepatitis C patients

BACKGROUND

The cellular immune response is important in chronic hepatitis C (CHC). To better understand its mechanism, we examined dendritic cells (DCs) and hepatitis C virus (HCV)-specific cytotoxic T cells (CTLs), which are thought to contribute to liver injury and viral clearance.

METHODS

CHC patients received 24 weeks of interferon-alpha-based antiviral therapy. We analyzed time-sequential frequencies of peripheral DCs, classified as myeloid DCs (mDCs) or plasmacytoid DCs (pDCs), together with peptide major histocompatibility class I tetramers, epitope specific for HCV core 129-137 (t*24/c129) or HCV NS3 1296-1304 (t*24/ns1294), directly ex vivo.

RESULTS

The mDC and pDC populations changed in parallel (P < 0.05), showing a significant transient decrease at weeks 12 and 16 during the therapy, and then recovering. However, neither of the tetramer results showed a direct correlation with the kinetics of peripheral DCs.

CONCLUSIONS

There is an apparent effect of antiviral therapy or a subsequent reduction of HCV on host immunity, but the effect may not include the induction of CTLs in CHC.

Defective Synthesis of Granulocyte-Colony Stimulating Factor in Pegylated Interferon-α Treated Chronic Hepatitis C Patients with Declining Leukocyte Counts

Background

Pegylated-interferon-α (peg-IFN-α) is the mainstay of treatment for chronic hepatitis C (CHC). Treatment is often complicated by neutropaenia due to inhibition of haematopoiesis. However, there are no data on the kinetics of granulocyte-colony stimulating factor (G-CSF), a major neutrophil growth factor, in this setting. We therefore evaluated G-CSF synthesis in CHC patients on peg-IFN-α treatment.

Methods

A total of 40 CHC patients were studied. None had pre-existing haematological disorders, or hepatitis B virus or HIV coinfection. For controls, 30 healthy subjects were used. Laboratory examinations, including liver function tests, were performed at baseline and monthly over treatment and follow-up. Serum G-CSF was measured in all patients and controls at baseline and in a subgroup of 20 CHC patients also at weeks 2, 4, 24, 48 and 72 after treatment start.

Results

CHC patients had a significantly lower pre-treatment neutrophil count (3,256 ±1,197 versus 3,804 ±859; P=0.03). Notwithstanding, they showed lower baseline G-CSF serum levels than healthy controls (16.1 ±6.2 versus 19.4 ±7.5; P=0.048). Consistently, baseline G-CSF levels were poorly correlated with the neutrophil count in CHC patients (r=-0.2; P=0.2). Moreover, serum G-CSF levels did not increase in any of the 20 CHC patients during peg-IFN-α treatment, despite declining neutrophil counts.

Conclusions

The lower neutrophil counts observed in CHC might be related to an absolute deficiency in G-CSF production. In the human model of neutropaenia induced by peg-IFN-α, we show that endogenous G-CSF levels are not physiologically up-regulated to overcome the decline in neutrophil counts. Our study provides a rationale for the evaluation of recombinant human G-CSF treatment in peg-IFN-α-induced neutropaenia.

Antigen-presenting property of mesenchymal stem cells occurs during a narrow window at low levels of interferon-gamma

Mesenchymal stem cells (MSCs) are mostly found around the vasculature system of the adult bone marrow (BM). They function as immune suppressors, express MHC-II, are phagocytic, and support T-cell cytotoxicity. We hypothesize that these contradictory properties of MSCs are important for BM homeostasis and occur partly through antigen presentation (antigen-presenting cells [APCs]) within a narrow window. Indeed, we have verified APC functions of MSCs to recall antigens, Candida albicans and Tetanus toxoid. The target cells have been identified to be CD4(+) T cells. APC assays with IFNgamma-knockdown MSCs and with anti-IFNgamma receptor confirmed that MHC-II expression requires autocrine stimulation by IFNgamma. During APC functions, as IFNgamma levels become elevated, there was a concomitant decrease in MHC-II on MSCs. This observation was correlated with flow cytometry studies showing a gradual decrease in MHC-II expression as IFNgamma levels were increased. The reduced levels of MHC-II correlated with losses in their allogeneic potential, as indicated in mixed lymphocyte reaction. In summary, endogenous and low levels of IFNgamma are required for MHC-II expression on MSCs, and for APC functions. APC functions occur during a narrow window before IFNgamma levels are increased. The study has implications for BM protection against infection and exacerbated inflammatory responses.

Autoimmune hepatitis type 1 and primary biliary cirrhosis have distinct bone marrow cytokine production

We have recently reported differences in the hematopoiesis between autoimmune hepatitis type 1 (AIH-1) and primary biliary cirrhosis (PBC). In view of the notion that cytokines are regulators of hematopoiesis, we investigated in our tertiary center the cytokine production in the bone marrow (BM) of the same consecutive cohort of patients (13 AIH-1, 13 PBC, 10 healthy and 7 patients with cirrhosis due to chronic hepatitis B). Interferon-gamma (IFN-gamma), interleukin-4 (IL-4), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) were determined in the supernatants of long-term BM cultures by ELISAs. IL-4, TNF-alpha and TGF-beta were found significantly increased in the BM of PBC patients compared to AIH-1 and both control groups. AIH-1 patients had significantly higher BM IL-10 compared to PBC patients and higher IL-10, IL-4 and TNF-alpha compared to controls. BM IFN-gamma was significantly higher in PBC and AIH-1 patients compared to controls. In AIH-1 patients, IL-10 was positively correlated with CD34+, CD34+/CD38- and CD34+/CD38+ cell proportions. In conclusion, the BM cytokine microenvironment of PBC and AIH-1 patients differs significantly compared to that of healthy individuals and cirrhotic patients of non-autoimmune etiology. Differences were also found between patients with PBC and AH-1. The implication of BM in the pathogenesis of autoimmune liver diseases is possible and needs further investigation.

Interferons, interferon-like cytokines, and their receptors

Recombinant interferon-alpha (IFN-alpha) was approved by regulatory agencies in many countries in 1986. As the first biotherapeutic approved, IFN-alpha paved the way for the development of many other cytokines and growth factors. Nevertheless, understanding the functions of the multitude of human IFNs and IFN-like cytokines has just touched the surface. This review summarizes the history of the purification of human IFNs and the key aspects of our current state of knowledge of human IFN genes, proteins, and receptors. All the known IFNs and IFN-like cytokines are described [IFN-alpha, IFN-beta, IFN-epsilon, IFN-kappa, IFN-omega, IFN-delta, IFN-tau, IFN-gamma, limitin, interleukin-28A (IL-28A), IL-28B, and IL-29] as well as their receptors and signal transduction pathways. The biological activities and clinical applications of the proteins are discussed. An extensive section on the evolution of these molecules provides some new insights into the development of these proteins as major elements of innate immunity. The overall structure of the IFNs is put into perspective in relation to their receptors and functions.

Roles of Stat3 and ERK in G-CSF Signaling

G-CSF specifically stimulates the proliferation and differentiation of cells that are committed to the neutrophil-granulocyte lineage. Although Stat3 was thought to be essential for the transduction of G-CSF-induced cell proliferation and differentiation signals, mice deficient for Stat3 in hematopoietic cells show neutrocytosis and infiltration of cells into the digestive tract. The number of progenitor cells in the neutrophil lineage is not changed, and G-CSF-induced proliferation of progenitor cells and prolonged neutrophil survival were observed in Stat3-deficient mice. In hematopoietic cells from Stat3-deficient mice, trace levels of SOCS3, a negative regulator of granulopoiesis, were observed, and SOCS3 expression was not induced by G-CSF stimulation. Stat3-null bone marrow cells displayed a significant activation of extra-cellular regulated kinase 1 (ERK1)/ERK2 under basal conditions, and the activation of ERK was enhanced and sustained by G-CSF stimulation. Furthermore, the augmented proliferation of Stat3-deficient bone marrow cells in response to G-CSF was dramatically decreased by addition of a MEK1 inhibitor. These results indicate that Stat3 functions as a negative regulator of G-CSF signaling by inducing SOCS3 expression and that ERK activation is the major factor responsible for inducing the proliferation of hematopoietic cells in response to G-CSF.

Hematologic side effects of interferon and ribavirin therapy

Pegylated (PEG)-interferon and ribavirin combination therapy are the standard of care for the treatment of chronic hepatitis C and are associated with a high rate of sustained virologic response. However, there is a high incidence of hematologic side effects with this therapeutic regimen. Hematologic side effects are particularly common; bone marrow suppression caused by interferon may result in neutropenia and thrombocytopenia. Ribavirin is directly toxic to red blood cells and is associated with hemolysis, which is usually dose-related but self-limited. Historically, the traditional management of hematologic side effects of interferon therapy has been dose reduction. However, recent studies have shown that response to therapy is strongly influenced by adherence to optimal doses of interferon and particularly ribavirin. Therefore, there is increasing emphasis on the use of growth factors such as filgrastim and erythropoietin to stimulate bone marrow production of erythrocytes and leukocytes to allow patients to receive the optimal doses of interferon and ribavirin. The incidence, magnitude, and possible mechanisms of hematologic complications associated with interferon and ribavirin are described in this review.

Transcriptional down-regulation of the platelet ADP receptor P2Y(12) and clusterin in patients with systemic lupus erythematosus

Cardiovascular complications are common in systemic lupus erythematosus (SLE) and myocardial infarctions are the leading cause of increased mortality. The ADP receptor P2Y(12) plays a central role in platelet activation and the P2Y(12) blocker clopidogrel reduces the incidence of cardiovascular events. Clusterin, a complement inhibitory protein suggested to be involved in the pathogenesis of SLE, has been found recently in a microarray study to be expressed at very high levels in platelets. Using a new protocol for mRNA quantification in platelets we set out to study if gene expression is altered in SLE patients compared with a healthy control group. Quantitative assay based on real-time PCR was used to measure mRNA expression, Western blot for P2 receptor protein expression and PFA-100 for platelet aggregation. The P2Y(12) receptor expression was decreased in SLE compared to the controls (P < 0.05), while expression of P2Y(1) and P2X(1) were unaltered. These findings were consistent at the protein level. The clusterin mRNA expression was very high. However, SLE patients had significantly lower levels than controls (P < 0.05). Platelet aggregation was similar in both groups. It may be suggested that a decreased level of P2Y(12) receptors could represent a protective response in SLE against thrombotic complications. Lowered clusterin levels could be involved in the pathogenesis of SLE due to decreased protective effects. These findings could help to achieve a better understanding of the platelet function in SLE and serve as a guide for further research and drug use.

A novel role for STAT1 in regulating murine erythropoiesis: deletion of STAT1 results in overall reduction of erythroid progenitors and alters their distribution

Erythropoietin (EPO) activates many distinct signal transduction cascades on engagement of its receptor. Deletion of the EPO, EPO receptor (EPO-R), or JAK2 genes in mice results in embryonic lethality due to a fatal anemia. EPO activates signal transducer and activator of transcription 1 (STAT1), STAT3, and STAT5a/b transcription factors in erythroid cell lines. Studies have focused on STAT5 as the primary target of EPO-dependent JAK2 activation. However, STAT5a/b(-/-) mice are viable, displaying a nonfatal anemia during embryogenesis, and delayed differentiation in adult erythropoiesis. Importantly, EPO-R cytoplasmic tyrosines are dispensable for viability in vivo. Interestingly, no cytoplasmic tyrosines are required for phosphorylation of STAT1. This led us to examine whether STAT1-deficient mice have altered erythropoiesis. A shift in erythropoiesis was observed in STAT1(-/-) mice, with reduced bone marrow-derived erythroid colony-forming units (CFU-Es) and a compensatory increase in splenic burst-forming units (BFU-Es) and CFU-Es. Both types of splenic-derived cells displayed EPO hyperresponsiveness. A 1.6-fold reduction in total CFU-Es was observed in STAT1-deficient mice, whereas total BFU-Es were comparable. Flow cytometry of STAT1-deficient erythroid cells revealed a less differentiated phenotype, associated with increased apoptosis of early erythroblasts. STAT1-deficient erythroblasts from phenylhydrazine-primed mice displayed enhanced phosphorylation of STAT5a/b, Erk1/2, and protein kinase B (PKB)/Akt. These results illustrate that STAT1 plays an important role in the regulation of erythropoiesis.