Christianna Choulaki

Genetic, immunologic, and immunohistochemical analysis of the programmed death 1/programmed death ligand 1 pathway in human systemic lupus erythematosus

OBJECTIVE A putative regulatory intronic polymorphism (PD1.3) in the programmed death 1 (PD-1) gene, a negative regulator of T cells involved in peripheral tolerance, is associated with increased risk for systemic lupus erythematosus (SLE). We undertook this study to determine the expression and function of PD-1 in SLE patients. METHODS We genotyped 289 SLE patients and 256 matched healthy controls for PD1.3 by polymerase chain reaction-restriction fragment length polymorphism analysis. Expression of PD-1 and its ligand, PDL-1, was determined in peripheral blood lymphocytes and in renal biopsy samples by flow cytometry and immunohistochemistry. A crosslinker of PD-1 was used to assess its effects on anti-CD3/anti-CD28-induced T cell proliferation and cytokine production. RESULTS SLE patients had an increased frequency of the PD1.3 polymorphism (30.1%, versus 18.4% in controls; P=0.006), with the risk A allele conferring decreased transcriptional activity in transfected Jurkat cells. Patients homozygous for PD1.3-but not patients heterozygous for PD1.3-had reduced basal and induced PD-1 expression on activated CD4+ T cells. In autologous mixed lymphocyte reactions (AMLRs), SLE patients had defective PD-1 induction on activated CD4+ cells; abnormalities were more pronounced among homozygotes. PD-1 was detected within the glomeruli and renal tubules of lupus nephritis patients, while PDL-1 was expressed by the renal tubules of both patients and controls. PD-1 crosslinking suppressed proliferation and cytokine production in both normal and lupus T cells; addition of serum from patients with active SLE significantly ameliorated this effect on proliferation. CONCLUSION SLE patients display aberrant expression and function of PD-1 attributed to both direct and indirect effects. The expression of PD-1/PDL-1 in renal tissue and during AMLRs suggests an important role in regulating peripheral T cell tolerance.

A common SNP in the CD40 region is associated with systemic lupus erythematosus and correlates with altered CD40 expression: implications for the pathogenesis

Background In systemic lupus erythematosus (SLE) sustained CD40L expression by T cells and platelets activates a variety of cells via its receptor CD40 contributing to disease pathogenesis. Although CD40 has recently been identified in genome-wide association study as a novel rheumatoid arthritis susceptibility gene such an association has not been documented for SLE. Objective To investigate whether the rs4810485 CD40 single nucleotide polymorphism (SNP) is associated with increased risk for SLE and its impact on CD40 expression. Materials and methods The primary sample set consisted of 351 patients with SLE and 670 matched healthy controls of Greek origin. 158 patients with SLE and 155 controls from Turkey were used as a replication sample. Genotyping of rs4810485 was performed by restriction fragment length polymorphism and the Sequenom MassArray technology. The expression of CD40 mRNA and protein was assessed in unstimulated and lipopolysaccharide-stimulated peripheral blood mononuclear cells by quantitative real time PCR and flow cytometry, respectively. Results The minor allele T of CD40 rs4810485 SNP was significantly under-represented in Greek patients with SLE compared with healthy controls (OR=0.65, 95% CI 0.54 to 0.79). The association was replicated in the Turkish cohort (OR=0.57, 95% CI 0.41 to 0.80; meta-analysis of 509 patients with SLE and 825 healthy controls: OR=0.63, 95% CI 0.53 to 0.74, p = 2×10−8). In both cases and controls, the rs4810485 G/T and T/T genotypes were associated with significantly reduced CD40 mRNA and protein expression in peripheral blood CD14+ monocytes and CD19+ B cells compared with G/G genotype, both under basal conditions and following stimulation. Conclusions CD40 has been identified as a new susceptibility locus in Greek and Turkish patients with SLE. The rs4810485 minor allele T is under-represented in SLE and correlates with reduced CD40 expression in peripheral blood monocytes and B cells, with potential implications for the regulation of aberrant immune responses in the disease.

Enhanced activity of NLRP3 inflammasome in peripheral blood cells of patients with active rheumatoid arthritis

IntroductionInterleukin-1β (IL-1β) is a major inflammatory cytokine, produced predominantly by innate immune cells through NLRP3-inflammasome activation. Both intrinsic and extrinsic danger signals may activate NLRP3. Genetic variations in NLRP3-inflammasome components have been reported to influence rheumatoid arthritis (RA) susceptibility and severity. We sought to assess the activity of NLRP3-inflammasome in patients with active RA compared to healthy individuals.MethodIntracellular protein expression of NLRP3, ASC, pro- and active caspase-1, pro- and active IL-1β was assessed by immunoblotting both at baseline and upon inflammasome activation. NLRP3 function (IL-1β secretion) was assessed upon priming of TLR2 (Pam(3)CysSK(4), TLR3 (poly(I:C)) or TLR4 (LPS) and ATP sequential treatment. We used caspase inhibitors (casp-1, 3/7 and 8) to assess their contribution to IL-1β maturation. All experiments were performed in whole blood cells.ResultsActive RA patients (n = 11) expressed higher basal intracellular levels of NLRP3 (p < 0.008), ASC (p < 0.003), active caspase-1 (p < 0.02) and pro-IL-1β (p < 0.001). Upon priming with TLR4 (LPS) and ATP, RA-derived cell extracts (n = 7) displayed increased expression of NLRP3 (p < 0.01) and active caspase-1 (p < 0.001). Secreted IL-1β in culture supernatants from whole blood cells activated with TLR4 (LPS) or TLR3 agonist (poly(I:C)) plus ATP was higher in RA patients (n = 20) versus controls (n = 18) (p < 0.02 for both). Caspase-1 inhibition significantly reduced IL-1β secretion induced by all stimuli, whereas caspase-8 inhibition affected only TLR4 and TLR3 cell priming.ConclusionPatients with active RA have increased expression of NLRP3 and NLRP3-mediated IL-1β secretion in whole blood cells upon stimulation via TLR3 and TLR4 but not TLR2. In these patients, IL-1β secretion seems to be predominately driven by caspase-1 and caspase-8. Targeting NLRP3 or downstream caspases may be of benefit in suppressing IL-1β production in RA.

Mannose-binding Lectin MBL2 Gene Polymorphisms and Outcome of Hepatitis C Virus-infected Patients

IntroductionMannose-binding lectin (MBL) is involved in host’s response to several infections including hepatitis B but little is known about MBL and hepatitis C virus (HCV) infection. The present study attempts to investigate whether MBL2 genotype and serum MBL levels affect the course of HCV infection.Results and DiscussionsWe investigated the variant alleles in MBL2 gene promoter and exon-1 regions in 80 Caucasian HCV-infected patients. Mutations in MBL2 were determined by polymerase chain reaction and restriction fragment length polymorphisms analysis. Serum MBL levels were measured by ELISA. Polymorphism homozygosity in exon-1 region was significantly related to lower serum MBL levels (p < 0.001), to liver inflammation (p = 0.034, OR = 11.7) and, in a lesser degree, to fibrosis. Polymorphisms in promoter sites −221nt and −550nt were not shown to be related with serum MBL levels or progress to liver inflammation and fibrosis. Serum MBL levels were adversely associated with progression to fibrosis (p = 0.037). Response to antiviral treatment was related to hepatitis C virus genotype (p < 0.001, OR = 10.9), but not to MBL2 genotype or serum MBL levels.ConclusionThese findings suggest that polymorphisms in MBL2 gene exon-1 region are related to low serum MBL levels and progression of HCV infection to liver inflammation and fibrosis.

Adult Onset Still’s Disease: A Case Report with a Rare Clinical Manifestation and Pathophysiological Correlations

Adult-onset Stills disease is an inflammatory multisystemic disease of unknown etiology. Pleuritis is the most common pulmonary manifestation and pleural effusions are usually exudates with a predominance of neutrophils. We report a case of an eosinophilic pleural effusion as a novel and hitherto unrecognized manifestation of active adult-onset Stills disease. We also observed a marked NLRP3 inflammasome activation with increased production of IL-1β which coincided with the development and resolved upon remission of the pleural effusion suggesting a possible novel pathogenetic pathway for the development of pleural effusions in the context of the auto-inflammatory disorders.

An open label, single dose study to evaluate the safety, efficacy, and effects on CD25 expression of ciclosporin in patients with active rheumatoid arthritis despite treatment with methotrexate and infliximab

Objective: To explore the safety, efficacy, and lymphocyte activation of a triple therapeutic regimen with infliximab, methotrexate (MTX), and ciclosporin A (CsA) by an open label, pilot study. Patients and methods: 19 patients (mean age 52.9 years) with active rheumatoid arthritis (mean DAS28 7.3) after a mean of 16.8 infliximab infusions and dose adjustments of both infliximab and MTX were enrolled. CsA was added to a stable therapeutic regimen. Disease activity was evaluated by the DAS28. Lymphocyte activation was evaluated by assessing CD25 expression on peripheral blood mononuclear cells (PBMCs). Primary end points were safety and efficacy according to the EULAR response criteria at 24 weeks. Results: Eight patients (42%) discontinued treatment: adverse events (3), inefficacy (2) or non-compliance (2). One patient had a stroke and died. 5/11 (45%) patients who completed 24 weeks’ treatment were moderate responders. CD25 expression, both on unstimulated and phytohaemagglutinin stimulated PBMCs in five patients assessed, was reduced (mean (SD) values from 37 (34)% to 15 (10)% and from 50 (15)% to 29 (20)%, respectively). Conclusion: In this group of patients with refractory, highly active disease, addition of CsA reduced lymphocyte activation, and resulted in a modest response and a high rate of discontinuation. In such patients, other new approaches need to be explored.

Similar Metabolic, Innate Immunity, and Adipokine Profiles in Adult and Pediatric Sepsis Versus Systemic Inflammatory Response Syndrome—a Pilot Study

Objectives: To examine whether the septic profiles of heat shock protein 72, heat shock protein 90&agr;, resistin, adiponectin, oxygen consumption, CO2 production, energy expenditure, and metabolic pattern, along with illness severity, nutritional, and inflammatory indices, differ between adult and pediatric patients compared with systemic inflammatory response syndrome and healthy controls. To evaluate whether these biomolecules may discriminate sepsis from systemic inflammatory response syndrome in adult and pediatric patients. Design: Prospective cohort study. Setting: University ICU and PICU. Patients: Seventy-eight adults (sepsis/23; systemic inflammatory response syndrome/23; healthy controls/33), 67 children (sepsis/18; systemic inflammatory response syndrome/23; controls/27), mechanically ventilated. Interventions: None. Measurements and Main Results: Flow cytometry determined mean fluorescence intensity for monocyte or neutrophil heat shock protein expression. Resistin, adiponectin, and extracellular heat shock proteins were measured using enzyme-linked immunosorbent assay; energy expenditure by E-COVX (GE Healthcare). Genomic DNA was extracted with PureLink Genomic DNA kit (Invitrogen, Carlsbad, CA) to detect heat shock protein 72 single nucleotide polymorphisms. Similarly, in adult and pediatric patients, Acute Physiology and Chronic Evaluation-II/Acute Physiology and Pediatric Risk of Mortality-III, Simplified Acute Physiology Score-III, C-reactive protein, lactate, and resistin were higher and myocardial contractility, monocyte heat shock protein 72, oxygen consumption, CO2 production, energy expenditure, metabolic pattern, glucose, and albumin lower in sepsis compared with systemic inflammatory response syndrome or controls (p < 0.05). For discriminating sepsis from systemic inflammatory response syndrome, resistin, extracellular heat shock protein 90&agr;, and lactate achieved a receiver operating characteristic curve greater than 0.80 in children and greater than 0.75 in adults (p < 0.05). In both, adults and children, genotype heat shock protein 72 analysis did not disclose any diagnosis or mortality group differences regarding either rs6457452 or rs1061581 haplotypes. Conclusions: Sepsis presents with similar profiles in adult and pediatric patients, characterized by enhanced inflammatory hormonal response and by repressed innate immunity, metabolism, and myocardial contractility. These features early distinguish sepsis from systemic inflammatory response syndrome across all age groups.

Expression levels of ASNS in mesenchymal stromal cells in childhood acute lymphoblastic leukemia

Increased levels of asparagine synthetase (ASNS), an enzyme producing intracellular asparagine, have been implicated in the development of asparaginase resistance. The aim of this study was to assess ASNS mRNA and protein expression in bone marrow cell populations of children with acute lymphoblastic leukemia (ALL). Bone marrow mononuclear cells at diagnosis, day 33 of treatment, and after completion of chemotherapy were isolated and studied. ASNS mRNA expression was assessed by real-time PCR, and protein levels by Western blot. Our results indicate that MSC ASNS mRNA expression is upregulated in ALL samples compared to controls. ASNS expression of mesenchymal stromal cells (MSC) was found to be 2.3 times higher than that of blasts at diagnosis of ALL. We also observed that the values of the ASNS mRNA of MSC seem to reach a peak at diagnosis, and tend to decline with treatment. No correlation was found between the ASNS mRNA and protein levels. Chemotherapy does not exert any effect on the protein expression. Variability of asparaginase-induced effect may be attributable to factors involved in the interaction of hematopoietic cells with their microenvironment.

Dysregulated production of interleukin-1β upon activation of the NLRP3 inflammasome in patients with familial Mediterranean fever.

Familial Mediterranean fever (FMF) is caused by mutations in pyrin, a protein expressed in innate immune cells that interacts with caspase-1 and other inflammasome components to regulate interleukin (IL)-1β maturation. Since NLRP3 inflammasome represents major source of IL-1β, we studied its protein expression and function in FMF. We isolated peripheral white blood cells (WBCs) from 20 symptoms-free FMF patients and 21 healthy individuals. Intracellular protein expression of NLRP3, caspase-1, IL-1β at baseline and after LPS/ATP sequential treatment for NLRP3 activation was assessed by immunoblotting. Secreted IL-1β was quantified by ELISA. THP-1 cells were transfected with wild-type or mutant pyrin and IL-1β secretion was measured. FMF WBCs exhibited lower NLRP3 and active caspase-1 protein expression compared to healthy individuals, and LPS/ATP treatment resulted in significantly lower intracellular IL-1β levels in FMF patients. Likewise, LPS/ATP induced caspase-1-dependent IL-1β release at significantly lower amounts in the FMF group (1182±192 versus 2134±245pg/mL in controls, p=0.004). Consistently, THP-1 cells transfected with FMF-associated M694V mutant pyrin displayed lower LPS/ATP-induced IL-1β compared with wild-type pyrin-transfected cells. FMF WBCs demonstrate reduced NLRP3-mediated IL-1β production. Additional studies are needed to define whether this finding represents a compensatory mechanism to control inflammation or is directly linked to disease pathogenesis.

Genetic association and functional consequences of a common SNP in the CD40 region with systemic lupus erythematosus and rheumatoid arthritis in a homogeneous Greek population

Background There is increasing evidence that different autoimmune diseases may share some common pathogenetic pathways. The CD40 locus has recently been identified by a genome-wide study as a genetic risk factor for rheumatoid arthritis (RA). CD40 is a member of the tumour necrosis factor receptor superfamily which is constitutively or inducible expressed on the surface of a variety of immune and non-immune cell types, indicating that this locus might be involved in several autoimmune diseases. Aim To investigate whether the rs4810485 single-nucleotide polymorphism (SNP) of CD40 gene is associated with the development of RA and systemic lupus erythematosus (SLE) in the genetic homogeneous population of the island of Crete. The functional significance of this gene polymorphism will also be analysed. Materials and methods The SLE and RA sample sets consisted of 351 and 272 patients, respectively, while the control group consisted of 670 samples. Genotyping of the rs4810485 SNP was performed by PCR-restriction fragment length polymorphism or using the Sequenom MassArray technology. Genotyping of rs4810485 was performed by PCR-restriction fragment length polymorphism and by the Sequenom MassArray technology. The expression of CD40 in SLE patients with different genotypes was assessed in peripheral blood mononuclear cells (PBMCs) by flow cytometry. Quantification of CD40 mRNA was performed by quantitative real time PCR in freshly isolated PBMCs from patients with different genotype. Results The risk allele G of the CD40 rs4810485 SNP was more frequent in individuals with SLE and RA than in healthy controls (p<0.0001, OR 1.5, 95% CI 1.3 to 1.9 and p<0.0001, OR 1.6, 95% CI 1.3 to 1.9 respectively). SLE patients with the rs4810485 G/G genotype had significantly higher CD40 mRNA and protein expression in freshly isolated peripheral blood B cells and monocytes, compared to patients with the G/T or T/T genotype. Conclusions The CD40 rs4810485 SNP is associated with increased susceptibility to both SLE and RA in a homogeneous Greek population. Identification of shared genetic susceptibility loci may provide insight to their understanding of the pathophysiology of autoimmune diseases. The risk allele G seems to confer susceptibility to clinically distinct disorders through similar or differential effects on disease-specific cell types. Quantitative analysis of the allelic expression of CD40 in SLE patients demonstrated that the risk allele was accompanied by higher expression of CD40 both at mRNA and protein level especially in B lymphocytes and CD14 monocytes.