Dragana Marković

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.

Chronic psychological stress activates BMP4-dependent extramedullary erythropoiesis

Psychological stress affects different physiological processes including haematopoiesis. However, erythropoietic effects of chronic psychological stress remain largely unknown. The adult spleen contains a distinct microenvironment favourable for rapid expansion of erythroid progenitors in response to stressful stimuli, and emerging evidence suggests that inappropriate activation of stress erythropoiesis may predispose to leukaemic transformation. We used a mouse model to study the influence of chronic psychological stress on erythropoiesis in the spleen and to investigate potential mediators of observed effects. Adult mice were subjected to 2 hrs daily restraint stress for 7 or 14 consecutive days. Our results showed that chronic exposure to restraint stress decreased the concentration of haemoglobin in the blood, elevated circulating levels of erythropoietin and corticosterone, and resulted in markedly increased number of erythroid progenitors and precursors in the spleen. Western blot analysis revealed significantly decreased expression of both erythropoietin receptor and glucocorticoid receptor in the spleen of restrained mice. Furthermore, chronic stress enhanced the expression of stem cell factor receptor in the red pulp. Moreover, chronically stressed animals exhibited significantly increased expression of bone morphogenetic protein 4 (BMP4) in the red pulp as well as substantially enhanced mRNA expression levels of its receptors in the spleen. These findings demonstrate for the first time that chronic psychological stress activates BMP4‐dependent extramedullary erythropoiesis and leads to the prolonged activation of stress erythropoiesis pathways. Prolonged activation of these pathways along with an excessive production of immature erythroid cells may predispose chronically stressed subjects to a higher risk of leukaemic transformation.

A biased Gm haplotype and Gm paraprotein allotype in multiple myeloma suggests a role for the Gm system in myeloma development

The association between a particular Gm haplotype and susceptibility to multiple myeloma (MM) is not clear. The reason is probably because no investigations have so far been carried out on the relationship between the Gm haplotype, which represents the inherited combination of IgG Gm allotypes, and the Gm allotype expressed at the IgG paraprotein (M‐component), which reflects the enhanced gene expression within the haplotype in MM. We studied the incidence of Gm allotypic markers present in IgG subclasses in the serum from 52 patients with MM and in parallel with the isolated IgG paraproteins. The results showed that 84.6% of the patients were heterozygous for haplotypes Gm(a; z; n−; g;)/Gm(f; n+/n–; b1; b0; b5) and 15.3% were homozygous for Gm(f; n/n–; b1; b0; b5), while no homozygous Gm(a; z; n–; g) individuals were found among the studied patients. The incidence of these combinations in the healthy population in Serbia is 34%, 66% and < 1%, respectively. Subjects with Gm(a; z; n–; g)/Gm(f; n+/n–; b1; b0; b5) combination are over 10 times [odds ratio (OR) = 10.69; 95% confidence interval 1.67–68] as likely to be affected by the disease as the subjects with homozygous Gm(f; n+/n–; b1; b0; b5) combination (OR = 0.35, 95% confidence interval 0.06–2.23). However, despite the Gm heterozygosity, most of the Gm(a; z; n–; g;)/Gm(f; n+/n–; b1; b0; b5) positive patients with MM (86.3%) had IgG paraprotein with the allotypic marker from the Gm(f; n+/n–; b1; b0; b5) haplotype. Together with patients homozygous for this haplotype, the relative number of patients with serum IgG paraprotein carrying allotypic marker from the Gm(f; n/n–; b1; b0; b5) haplotype was 88.5%. These results suggest that the development of an M‐component could be related to a disturbance on chromosome 14q32 carrying the Gm (f; n+/n–; b1; b0; b5) set of genes.

Glycosylation of IgG B cell receptor (IgG BCR) in multiple myeloma: relationship between sialylation and the signal activity of IgG BCR

Little is known about the glycosylation of the isotype switched B cell receptor (BCR) in multiple myeloma, and the way it might affect receptor function. In this work IgG BCRs isolated from the individual lysates of peripheral blood lymphocytes (PBL) of 32 patients with IgG multiple myeloma and healthy controls were investigated for the expression of sialic acid (SA), galactose (Gal) and N-acetylglucosamine (GlcNAc), the sugars known to specify the glycoforms of human serum IgG. The degree of glycosylation and signaling status of all 32 isolated myeloma IgG BCRs were correlated and compared with the glycosylation of the IgG paraproteins isolated from sera of the same patients. It was shown that BCR IgG in myeloma is more heavily sialylated when compared with normal controls, that the increased sialylation of IgG BCR is associated with higher levels of tyrosine phosphorylation (signaling activity) of the IgG BCR supramolecular complex and that BCR IgG and serum IgG paraprotein from the same patient differed in all cases in the levels of terminal sugar expression. The results suggest that the development of the malignant clone in MM from post-switch B cells expressing IgG BCR at their surfaces to plasma cells secreting IgG paraprotein may be followed by permanent glycosylation changes in the IgG molecules.

Angiogenic factors are increased in circulating granulocytes and CD34+ cells of myeloproliferative neoplasms

It has been shown that angiogenesis and inflammation play an important role in development of most hematological malignancies including the myeloproliferative neoplasm (MPN). The aim of this study was to investigate and correlate the levels of key angiogenic molecules such as hypoxia‐inducible factor‐1α (HIF‐1α), vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) in peripheral blood and bone marrow cells of MPN patients, along with JAK2V617F mutation allele burden and effects of therapy. HIF‐1α and VEGF gene expression were decreased, while eNOS mRNA levels were increased in granulocytes of MPN patients. Furthermore, positively correlated and increased VEGF and eNOS protein levels were in negative correlation with HIF‐1α levels in granulocytes of MPN patients. According to immunoblotting, the generally augmented angiogenic factors demonstrated JAK2V617F allele burden dependence only in granulocytes of PMF. The angiogenic factors were largely reduced after hydroxyurea therapy in granulocytes of MPN patients. Levels of eNOS protein expression were stimulated by Calreticulin mutations in granulocytes of essential thrombocythemia. Immunocytochemical analyses of CD34+ cells showed a more pronounced enhancement of angiogenic factors than in granulocytes. Increased gene expression linked to the proinflammatory TGFβ and MAPK signaling pathways were detected in CD34+ cells of MPN patients. In conclusion, the angiogenesis is increased in several cell types of MPN patients supported by the transcriptional activation of inflammation‐related target genes, and is not limited to bone marrow stroma cells. It also appears that some of the benefit of hydroxyurea therapy of the MPN is mediated by effects on angiogenic factors.

Ixodes ricinus immunogenic saliva protein, homologue to Amblyomma americanum AV422: Determining its potential for use in tick bite confirmation

Tick bites often go unnoticed, so specific reliable tests are needed to confirm them for prompt diagnosis and treatment of tick-borne diseases. One of the promising candidates for developing such a test is AV422, a tick saliva protein that has been conserved across tick genera. In this study, we demonstrate the potential of the AV422 homologue from Ixodes ricinus to be used for tick bite detection for both Prostriata and Metastriata. We expressed recombinant (r) I. ricinus (Ir) AV422 in E. coli and subjected it to Western blot analysis using rat antibodies to saliva proteins of both I. ricinus (Prostriata) and Dermacentor reticulatus (Metastriata) larvae. Our data demonstrate that rIrAV422 specifically bound to antibodies from sera of rats used for both I. ricinus and D. reticulatus larvae feeding, but not to antibodies from control serum, emphasizing its specificity since tick bites were the sole cause of sera reactivity.

Natural radionuclides in cigarette tobacco from Serbian market and effective dose estimate from smoke inhalation

The activity concentrations of natural radionuclides ((40)K, (210)Pb, (210)Po, (226)Ra and (228)Ra) in 17 most frequently used cigarette brands in Serbia and corresponding effective doses due to smoke inhalation are presented. The mean annual effective doses for (210)Pb and (210)Po were estimated to be 47.3 and 724 µSv y(-1) for (210)Pb and (210)Po, respectively. Serbia currently has the highest smoking rate in the world. The results of this study indicate the high contribution of the annual effective dose due to smoke inhalation to the total inhalation dose from natural radionuclides. The more effective implementation of actions for reducing smoking prevalence in Serbia is highly needed.

Macrophage migration inhibitory factor is an endogenous regulator of stress-induced extramedullary erythropoiesis

Macrophage migration inhibitory factor is a well-known proinflammatory cytokine that is released during systemic stress response. Although MIF can affect erythrocyte production, the role of this cytokine in stress-induced erythropoiesis is completely unknown. To extend our previous findings showing that chronic psychological stress stimulates extramedullary erythropoiesis, here we examined whether MIF is involved in the control of stress-induced erythropoietic response. Adult male C57BL/6 wild-type (WT) and MIF-KO (knock-out) mice were subjected to 2-h daily restraint stress for either 7 or 14 consecutive days. The number of erythroid progenitors and CD71/Ter119 profile of erythroid precursors were analyzed in the bone marrow and spleen. Additionally, MIF protein expression was assessed in WT mice. Our results demonstrated that chronic restraint stress enhanced the number of both erythroid progenitors and precursors in the spleen. Stress-induced increase in the number of splenic late erythroid progenitors as well as in the percentage of CD71+Ter119+-double-positive precursors was significantly more pronounced in MIF-KO mice compared to WT animals. Furthermore, repeatedly stressed WT animals demonstrated an augmented MIF expression in the spleen. Unlike the spleen, the bone marrow of chronically stressed WT mice exhibited less prominent changes in erythropoietic stress response and no significant alteration in MIF expression. In addition, MIF deficiency did not influence the bone marrow erythropoiesis in stressed animals. These findings suggest that MIF regulates extramedullary erythropoiesis by inhibiting an overexpansion of splenic immature erythroid cells during chronic stress and indicate a novel role for this cytokine under chronic stress conditions.

Vaccination and autoimmunity: Influenza vaccination and association with multiple sclerosis

Influenza, generally known as the flu, is one of the most common viral respiratory infections with the capacity to disseminate around the world, one could say at lightning speed, in seasonal epidemics, reaching its summit over the course of winter. Influenza is a serious infectious disease caused by RNA viruses which belong to the Orthomyxoviridae family. The first influenza pandemic was documented in 1580 and it has remained a viral disease of global dimension ever since . The four researchers analyzed medical literature reported during the Spanish Flu pandemic from 1918 to 1920. The metaanalysis of these data showed that treatment of new victims of the virus in 1918 with convalescent whole blood, plasma or serum collected from patients who had recovered from Spanish Influenza resulted in reduced case-fatality rate of severely ill patients by 50% . In 1931, Goodpasture was the first who discovered a viral growth in embryonated hen’s egg, and in the 1940s, the US military developed the first approved inactivated vaccines for influenza, used during World War II . Unlike other viral vaccines, annual influenza vaccination is recommended due to fast evolution of influenza viruses, evolve one million times faster than mammals, which results in high mutation rates and antigenic variations known as antigenic drift, a minor change such as amino acid substitution in virus surface proteins hemagglutinin (HA) and/or neuraminidase (NA), and antigenic shift, a new combination of different flu genes emerged to infect people . Traditional influenza vaccine composition

Postvaccination Accumulation of the Influenza Virus Antigen in the Rat Choroid Plexus

We examined the accessibility of influenza virus and diphtheria-tetanus toxin (DiTe) antigens to the choroid plexus (CP) within the postvaccination period and the expression of CD11b molecules (by immunohistochemistry). Eighteen Dark Agouti (DA) rats were divided into three groups: (i) animals administered with influenza vaccine (Flu), (ii) animals administered with DiTe vaccine (DiTe), and (iii) nontreated (Contr) animals. The serum antibody titers following influenza and diphtheria-tetanus vaccination were detected by the ELISA test. Immunohistochemical staining revealed a great number of viral antigen-positive and CD11b-positive brain cells in Flu rats compared to a very small number of the respective cells in DiTe animals and no staining in the Contr group. DiTe- and Flu-rats showed significant increases in the serum anti-tetanus toxoid and anti-influenza virus antibody levels compared to those in the Contr group. The results obtained attract attention towards the dynamic role of the CP in the immunosurveillance of the CNS. Based on the viral antigen deposits accumulated in the CP, it has been proposed that the latter can play an active role in modulation of the immune response after influenza vaccine immunization.