Krista Kuuliala

Cord blood monocytes, neutrophils and lymphocytes from preterm and full-term neonates show multiple aberrations in signalling profiles measured using phospho-specific whole-blood flow cytometry.

Immaturity of the immune system renders newborns susceptible to infections. We searched for aberrations in leucocyte signalling profiles, using phospho‐specific whole‐blood flow cytometry, in cord blood of nine preterm (two born before 32nd gestational week) and nine full‐term infants, born by caesarean section. Thirteen adults served as reference subjects. Monocyte NF‐κB phosphorylation following tumour necrosis factor (TNF) or bacterial stimulation was higher in preterm neonates than in full‐term neonates or adults, p38 phosphorylation following bacterial stimulation was higher in both preterm and full‐term neonates than in adults, while STAT1 phosphorylation by IFN‐γ or IL‐6, STAT3 phosphorylation by IL‐6 and STAT5 phosphorylation by GM‐CSF were lower in both full‐term and preterm neonates than in adults. Neutrophil STAT1 and STAT3 phosphorylation following IFN‐γ stimulation and STAT5 phosphorylation following GM‐CSF stimulation were lower in newborn neonates than in adults. In both CD3+CD4+ and CD3+CD8+ lymphocytes, NF‐κB phosphorylation by TNF was higher and STAT5 phosphorylation by IL‐2 was lower in preterm and full‐term newborns than in adults. STAT6 phosphorylation by IL‐4 was comparable in monocytes and lymphocytes of newborns and adults. The results suggest that innate immune signalling pathways responding to inflammatory stimuli are strongly functional in leucocytes of preterm neonates, which may render these neonates susceptible to inappropriate tissue injury. In leucocytes of both preterm and full‐term newborns, responses needed against intracellular pathogens, and regulatory functions show immaturities, possibly contributing to worse control of infections.

Constitutive STAT3 Phosphorylation in Circulating CD4(+) T Lymphocytes Associates with Disease Activity and Treatment Response in Recent-Onset Rheumatoid Arthritis

The aim of the present study was to examine constitutive signal transducer and activator of transcription 3 (STAT3) phosphorylation in circulating leukocytes as a candidate biomarker in rheumatoid arthritis (RA). 25 patients with recent-onset, untreated RA provided samples for whole blood flow cytometric determination of intracellular STAT3 phosphorylation, expressed as relative fluorescence units. The occurrence of constitutive STAT3 phosphorylation was evaluated by determining proportion of STAT3-phosphorylated cells among different leukocyte subtypes. Plasma levels of interleukin (IL)-6, IL-17 and IL-21 were measured by immunoassay, radiographs of hands and feet were examined and disease activity score (DAS28) was determined. Biomarkers were restudied and treatment response (according to European League Against Rheumatism) was determined after 12 months of treatment with disease-modifying antirheumatic drugs. At baseline, constitutive phosphorylation of STAT3 occurred in CD4+ T cells of 14 (56%) patients, CD8+ T cells of 13 (52%) patients, in CD19+ B cells of 7 (28%) patients, and in CD14+ monocytes of 12 (48%) patients. STAT3 phosphorylation levels of CD4+ T cells associated with DAS28, and those of all leukocyte subtypes studied associated with erosive disease. The presence of constitutive STAT3 phosphorylation in CD4+ T lymphocytes, pSTAT3 fluorescence intensity of CD4+ and CD8+ T cells and C-reactive protein (CRP) levels at baseline associated with good treatment response. In conclusion, constitutive STAT3 phosphorylation in circulating CD4+ T cells is common in recent-onset untreated RA and associates with good treatment response in patients characterized by high disease activity and the presence of systemic inflammation.

Somatic mutations in clonally expanded cytotoxic T lymphocytes in patients with newly diagnosed rheumatoid arthritis

Somatic mutations contribute to tumorigenesis. Although these mutations occur in all proliferating cells, their accumulation under non-malignant conditions, such as in autoimmune disorders, has not been investigated. Here, we show that patients with newly diagnosed rheumatoid arthritis have expanded CD8+ T-cell clones; in 20% (5/25) of patients CD8+ T cells, but not CD4+ T cells, harbour somatic mutations. In healthy controls (n=20), only one mutation is identified in the CD8+ T-cell pool. Mutations exist exclusively in the expanded CD8+ effector-memory subset, persist during follow-up, and are predicted to change protein functions. Some of the mutated genes (SLAMF6, IRF1) have previously been associated with autoimmunity. RNA sequencing of mutation-harbouring cells shows signatures corresponding to cell proliferation. Our data provide evidence of accumulation of somatic mutations in expanded CD8+ T cells, which may have pathogenic significance for RA and other autoimmune diseases.

Signalling profiles of circulating leucocytes in patients recovered from reactive arthritis

Objectives: Reactive arthritis (ReA) is a sterile joint inflammation triggered by a remote infection and associated with human leucocyte antigen (HLA)-B27. Its pathogenesis is unknown, but abnormal response to microbial structures or endogenous inflammatory mediators may be involved. We studied responses in leucocyte signalling profiles in patients with previous ReA after a full recovery. Method: The study comprised 10 HLA-B27-positive healthy subjects with a history of Yersinia enterocolitica-triggered ReA (B27+ReA+) and 20 healthy reference subjects, of whom 10 carried HLA-B27 (B27+ReA–) and 10 did not (B27–ReA–). Phosphospecific fluorescent monoclonal antibodies and flow cytometry were used to determine activation of nuclear factor kappa B (NF-κB), signal transducers and activators of transcription (STATs) 1, 3, 5, and 6, and two mitogen-activated protein (MAP) kinases, p38 and extracellular signal-regulated kinase (ERK)1/2, in monocytes, lymphocytes, lymphocyte subsets, and neutrophils. B27+ReA+ and B27–ReA– whole-blood samples were incubated with Yersinia with or without infliximab to study the role of tumour necrosis factor (TNF) in lymphocyte subset activation. Samples of the three subject groups were studied using soluble bacterial or endogenous stimuli. Fluorescence levels were determined as relative fluorescence units (RFU) and the proportion of positively fluorescing cells. Results: The intracellular activation of circulating leucocytes in response to soluble stimuli was consistently comparable in B27+ReA+, B27+ReA–, and B27–ReA– subjects. Infliximab inhibited Yersinia-induced lymphocyte NF-κB phosphorylation similarly in B27+ReA+ and B27–ReA– groups. Conclusions: ReA susceptibility is not reflected in leucocyte signalling profiles elicited by phlogistic stimuli. However, the possibility remains that aberrations occur in response to combinations of stimuli, such as those associated with leucocyte adhesion.

Detection of muramyl dipeptide-sensing pathway defects in monocytes of patients with Crohn's disease using phospho-specific whole blood flow cytometry.

Abstract Peripheral blood mononuclear cells of Crohns disease (CD) patients with the common 1007fs mutation of the caspase recruitment domain-containing 15/nucleotide-binding oligomerization domain-containing 2 (CARD15/NOD2) gene show impaired nuclear factor kappa B (NF-κB) activation in response to muramyl dipeptide (MDP), as determined by Western blotting. We applied phospho-specific flow cytometry to examine NF-κB and p38 activation in whole blood monocytes of 16 CD patients with or without the 1007fs and previously described rare mutations of the CARD15 gene, and healthy reference subjects. Aliquots of whole blood were supplemented with MDP (0–1000 ng/mL), incubated for 10–40 min and processed for flow cytometry. Bacterial lipopolysaccharide (LPS) was used as a positive control agonist. We found that NF-κB and p38 phosphorylation induced by MDP was not detectable in monocytes of patients homozygous for the CARD15 1007fs mutation, while those induced by LPS were normal. We also determined MDP-induced NF-κB phosphorylation levels in nuclear extracts of mononuclear cells separated from blood using enzyme-linked immunosorbent assay (ELISA), and observed that the levels decreased in a 1007fs mutation-dose dependent manner. We conclude that phospho-specific whole blood flow cytometry provides a means to study phosphorylation of NF-κB and p38 in clinical samples and can be applied to screening of CD patients homozygous for the CARD15 1007fs mutation.

Association of Matrix Metalloproteinases-7,-8 and-9 and TIMP-1 with Disease Severity in Acute Pancreatitis. A Cohort Study

Objectives Several biomarkers for early detection of severe acute pancreatitis (SAP) have been presented. Matrix metalloproteinases (MMP) and their tissue inhibitors (TIMP) are released early in inflammation. We aimed to assess levels of MMP-7, -8, -9 and TIMP-1 in acute pancreatitis (AP) and explore their ability to detect disease severity. Our second aim was to find an association between MMPs, TIMP and creatinine. Methods We collected plasma samples for MMP-7, -8, -9 and TIMP-1 analyses from 176 patients presenting within 96 h from onset of acute pancreatitis (AP) symptoms. We used samples from 32 control subjects as comparison. The revised Atlanta Classification was utilised to assess severity of disease. Receiver operating characteristic curve analysis and Spearman´s Rho-test were utilised for statistical calculations. Results Compared with controls, patients showed higher levels of all studied markers. MMP-8 was higher in moderately severe AP than in mild AP (p = 0.005) and MMP-8, -9 and TIMP-1 were higher in severe than in mild AP (p<0.001, p = 0.005 and p = 0.019). MMP-8 detected SAP with an AUC of 0.939 [95% CI 0.894–0.984], LR+ 9.03 [5.30–15.39]. MMP-8, -9 and TIMP-1 failed to discern moderately severe AP from SAP. MMP-7 was not different between patient groups. MMP-7 and TIMP-1 correlated weakly with creatinine (Rho = 0.221 and 0.243). MMP-8 might be a useful biomarker in early detection of SAP.

Impaired Akt Phosphorylation in Monocytes of Patients with Rheumatoid Arthritis

It has been proposed that the Akt kinase pathway provides a regulatory mechanism to limit the inflammatory response. We examined the activation of Akt upon lipopolysaccharide (LPS) challenge in monocytes of patients with rheumatoid arthritis (RA) and correlated it with disease activity. Twelve subjects with recent‐onset, DMARD‐naïve RA, thirteen patients with chronic, DMARD therapy–non‐responding RA and 27 healthy volunteers provided whole blood samples for phosphospecific flow cytometric measurement of unstimulated and LPS‐stimulated Akt phosphorylation at serine 473 in monocytes, determined in relative fluorescence units (RFU). Activation capability, that is responsiveness of monocytes, was determined as the difference between stimulated and unstimulated samples and compared between groups using Mann–Whitney test. CRP and ESR, swollen and tender joint counts, patients’ global assessment of disease activity, DAS28 score and plasma IL‐6 determined by ELISA were correlated with Akt activation using Spearman method. Median (interquartile range) Akt activation capability was significantly lower in DMARD‐naïve (379 RFU [285, 432], P = 0.016) and even lower in DMARD‐non‐responding RA (258 RFU [213, 338], P < 0.001), compared to healthy controls (505 RFU[408, 639]) and showed a negative correlation with swollen joint count (r = −0.48, CI −0.78 to −0.05, P = 0.014), CRP (r = −0.42, CI −0.80 to −0.02, P = 0.039) and plasma IL‐6 levels (r = −0.44, CI −0.65 to −0.17, P = 0.001). In conclusion, Akt activation capability of monocytes is low in early untreated RA and even lower in chronic, DMARD‐non‐responding RA, suggesting a role for Akt pathway in the pathogenesis of RA.

STAT6 and STAT1 Pathway Activation in Circulating Lymphocytes and Monocytes as Predictor of Treatment Response in Rheumatoid Arthritis.

Objective To find novel predictors of treatment response to disease-modifying antirheumatic drugs (DMARDs), we studied activation of STAT (signal transducers and activators of transcription) 6 and 1 in circulating leukocytes of patients with rheumatoid arthritis (RA). Methods 19 patients with untreated recent-onset RA, 16 patients with chronic RA irresponsive to synthetic DMARDs and 37 healthy volunteers provided blood samples for whole blood flow cytometric determination of intracellular STAT6 and STAT1 phosphorylation, expressed as relative fluorescence units, in response to IL-4 and IFN-γ, respectively. Phosphorylation was restudied and treatment response (according to European League Against Rheumatism) determined after 1-year treatment with synthetic DMARDs in recent-onset RA and with biological DMARD in synthetic DMARD-irresponsive RA. Estimation-based exact logistic regression was used to investigate relation of baseline variables to treatment response. 95% confidence intervals of means were estimated by bias-corrected bootstrapping and the significance between baseline and follow-up values was calculated by permutation test. Results At baseline, levels of phosphorylated STAT6 (pSTAT6) induced by IL-4 in monocytes were higher in those who achieved good treatment response to synthetic DMARDs than in those who did not among patients with untreated RA (OR 2.74, 95% CI 1.05 to 9.47), and IFN-γ -stimulated lymphocyte pSTAT1 levels were higher in those who achieved good treatment response to a biological drug than in those who did not among patients with chronic RA (OR 3.91, 95% CI 1.12 to 20.68). During follow-up, in recent-onset RA patients with good treatment response to synthetic DMARDS, the lymphocyte pSTAT6 levels decreased (p = 0.011), and, consequently, the ratio of pSTAT1/pSTAT6 in lymphocytes increased (p = 0.042). Conclusion Cytokine-stimulated STAT6 and STAT1 phosphorylation in circulating leukocytes was associated with treatment response to DMARDs in this pilot study. The result, if confirmed in larger studies, may aid in developing personalized medicine in RA.

Signalling Profiles of Blood Leucocytes in Sepsis and in Acute Pancreatitis in Relation to Disease Severity

Intracellular signalling in blood leucocytes shows multiple aberrations in acute pancreatitis (AP) complicated by organ dysfunction (OD). We studied whether the aberrations associate with severity of AP and occur in sepsis complicated by OD. The study comprises 14 sepsis patients (11 with shock), 18 AP patients (nine mild; six moderately severe; three severe) and 28 healthy volunteers. Within 48 h after admission to hospital, phosphorylation of nuclear factor‐ĸB (NF‐ĸB), signal transducers and activators of transcription (STATs) 1,3, and extracellular signal‐regulated kinases 1/2 were measured from stimulated or non‐stimulated leucocytes using phosphospecific whole blood flow cytometry. In sepsis, as compared with healthy subjects, phosphorylated NF‐ĸB levels of monocytes promoted by bacterial lipopolysaccharides, tumour necrosis factor or Escherichia coli cells were lower (P < 0.001 for all), pSTAT1 levels of monocytes promoted by IL‐6 were lower (P < 0.05 for all), and STAT3 was constitutively phosphorylated in monocytes, neutrophils and lymphocytes (P < 0.001 for all). In AP, severity was associated with proportions of pSTAT1‐positive monocytes and lymphocytes promoted by IL‐6 (P < 0.01 for both), constitutive STAT3 phosphorylation in neutrophils (P < 0.05), but not with any of the pNF‐ĸB levels. Monocyte pSTAT3 fluorescence intensity, promoted by IL‐6, was lower in sepsis and AP patients with OD than in AP patients without OD (P < 0.001). Collectively, signalling aberrations in sepsis with OD mimic those described previously in AP with OD. Possibility that aberrations in STAT1 and STAT3 pathways provide novel markers predicting evolution of OD warrants studies including patients presenting without OD but developing it during follow‐up.

Interleukin 8 and hepatocyte growth factor in predicting development of severe acute pancreatitis

Abstract Objectives: We aimed to study if interleukin (IL) 8 and hepatocyte growth factor (HGF) predict development of severe acute pancreatitis (SAP) among patients without organ dysfunction (OD) at presentation, and if they discriminate transient OD from persistent OD among patients presenting with OD. Methods: From prospectively collected cohort of 176 AP patients and 32 healthy controls, plasma levels of IL-8 and HGF were determined within 5 days after symptom onset using an enzyme-linked immunosorbent assay. Results: AP was severe in 23 patients, of whom 10 did not have clinical signs of OD at presentation. IL-8 and HGF levels increased along with the severity of AP (P < 0.001). In patients without OD at study entry, IL-8 and HGF values predicted the development of SAP with the AUCs of 0.73 (95% CI, 0.56–0.91) and 0.79 (95% CI, 0.66–0.93), respectively. Of all patients, 22 presented with OD, and among them IL-8 predicted persistence of OD with the AUC of 0.88 (95% CI 0.69–1.0). Combining IL-8 and HGF did not improve the models. Conclusions: In AP patients without OD at presentation, circulating levels of IL-8, or HGF, may predict the development of SAP. In patients presenting with OD, IL-8 level may discriminate the patients with transient OD from those with persistent OD.