Amin, Shreyasee

ObjectiveType I interferon (IFN) is important to systemic lupus erythematosus (SLE) pathogenesis, but it is not clear how chronic elevations in IFN alter immune function. We compared cytokine responses after whole blood stimulation with Toll‐like receptor (TLR) agonists in high‐ and low‐IFN SLE patient subgroups.MethodsSLE patients and nonautoimmune controls were recruited, and SLE patients were categorized as either high or low IFN. Whole blood was dispensed into tubes coated with lipopolysaccharide (LPS), oligonucleotides with cytosine‐guanine repeats, Resiquimod, IFN‐α, and IFN‐α + LPS. Cytokine production in patient sera and after whole blood TLR stimulation was measured by multiplex assay, and type I IFN was assessed using a functional assay.ResultsCirculating plasmacytoid dendritic cell numbers were specifically reduced in high‐IFN SLE patients and not in low‐IFN SLE patients. In serum, we observed that the correlations between cytokines in serum differed to a much greater degree between the high‐ and low‐IFN groups (P < 0.0001) than the absolute cytokine levels differed between these same groups. In stimulated conditions, the high‐IFN patients had less cytokine production in response to TLR ligation than the low‐IFN SLE patients. LPS produced the most diverse response, and a number of interactions between type I IFN and LPS were observed.ConclusionWe find striking differences in resting and stimulated cytokine patterns in high‐ vs. low‐IFN SLE patients, which supports the biological importance of these patient subsets. These data could inform personalized treatment approaches and the pathogenesis of SLE flare following infection.

ObjectiveOur aim was to identify cytokines and chemokines in patients with adult dermatomyositis (DM) and juvenile dermatomyositis (JDM) that predict changes in disease activity.MethodsMultiplexed immunoassays (Meso Scale Discovery) enabled simultaneous measurement of interferon (IFN)‐regulated chemokines and other pro‐ and anti‐inflammatory cytokines specific to differentiation of specific T‐cell and innate pathways. Cytokine scores were computed for IFNCK (IP‐10, MCP‐1), Th1 (IFNɣ, TNFα, and IL2), Th2 (IL4, IL10, IL12, and IL 13), Th17 (IL6, IL17, IL1β), macrophage (MIP‐1α, MIP‐1β, IL8), and regulatory (IL10, TNFα) factors. Spearman correlation and mixed models were used to examine whether cytokines at a previous visit predict change in disease activity at the next visit.ResultsThe study included 36 patients (16 DM and 20 JDM) with at least two visits (87 patient intervals between two visits). Mean age (SD) at inclusion was 56.9 (18.4) years for DM and 10.8 (6.6) years in JDM, 67% of patients were female, 89% Caucasian. The mean (SD) physician global, muscle and extra‐muscular disease activity Visual Analog Scale scores at inclusion were 41 (26), 36 (30), and 34 (21) mm, respectively. The change in IFN score from one visit to the next was associated with the change in physician global (P = 0.010) and extramuscular (P < 0.001) disease activity scores. Preliminary results revealed significant correlations of previous IFNCK score and IL‐6 with subsequent disease activity measures, but after adjustment for multiple visits per patient, these associations did not reach statistical significance.ConclusionThere is a potential relationship between IFNCK and other cytokine scores seen in adult and juvenile DM with future disease states.

Objective To estimate the annual incidence and prevalence of and frequency of mortality associated with antiphospholipid syndrome ( APS ). Methods An inception cohort of patients with incident APS in 2000–2015 from a geographically well‐defined population was identified based on comprehensive individual medical records review. All cases met the 2006 Sydney criteria for APS (primary definition) or had a diagnosis of APS confirmed by physician consensus (secondary definition). Levels of lupus anticoagulant, IgM and IgG anticardiolipin antibodies, and anti–β2‐glycoprotein I antibodies were tested in a centralized laboratory. Incidence rates were age‐ and sex‐adjusted to the 2010 US white population. Prevalence estimates were obtained from the incidence rates, assuming that there was no increased mortality associated with APS and that migration in or out of the area was independent of disease status. Results Among this cohort in 2000–2015, 33 cases of incident APS , as defined by the Sydney criteria, were identified (mean age of patients 54.2 years; 55% female, 97% white). The annual incidence of APS in adults ages ≥18 years was 2.1 (95% confidence interval [95% CI ] 1.4–2.8) per 100,000 population. Incidence rates were similar in both sexes. The estimated prevalence of APS was 50 (95% CI 42–58) per 100,000 population, and was similar in both sexes. Six patients (18%) had a concurrent diagnosis of systemic lupus erythematosus. The most frequent clinical manifestation was deep vein thrombosis. The overall frequency of mortality among patients with APS was not significantly different from that in the general population (standardized mortality ratio 1.61, 95% CI 0.74–3.05). Conclusion APS occurred in ~2 persons per 100,000 population per year. The estimated prevalence was 50 per 100,000 population. Overall mortality was not notably different from that observed in the general population.

ObjectiveSystemic lupus erythematosus (SLE) is frequently characterized by activation of the type I interferon (IFN) pathway. We previously observed that a missense single‐nucleotide polymorphism (rs1049564) in the purine nucleoside phosphorylase (PNP) gene was associated with high levels of IFN in SLE. PNP is a key enzyme involved in purine metabolism. In this study, we performed functional follow‐up of this polymorphism in human cells.MethodsType I IFN was measured in patient sera, using a reporter cell assay. Structural modeling of the PNP variant was performed using PyMOL software. PNP messenger RNA (mRNA) and protein levels and type I IFN–induced gene expression were measured in lymphoblastoid cell lines with known PNP rs1049564 genotypes. The cell cycle was assayed using flow cytometry.ResultsStructural modeling indicated no major disruption in folding related to rs1049564. We observed that homozygous rs1049564 TT lymphoblastoid cells had decreased PNP mRNA expression and protein levels, and that cells with the TT genotype had reduced PNP enzymatic activity even when the amount of PNP was controlled. Cells with the TT genotype had a 2‐fold increase in S‐phase block as compared with cells with the homozygous CC phenotype. The S‐phase block could be pharmacologically reversed with hypoxanthine and adenosine, supporting the notion that relative PNP deficiency is the cause of the S‐phase block. Type I IFN–induced transcripts were increased in a dose‐response manner related to the rs1049564 T allele, at both baseline and after type I IFN stimulation.ConclusionThe PNP rs1049564 T allele is a loss‐of‐function variant that induces S‐phase block and IFN pathway activation in lymphocytes. The S‐phase block could be rescued in our in vitro experiments, suggesting the potential for personalized treatment.

Objectives Important findings can be masked in gene expression studies of mixed cell populations. We examined single-cell gene expression in SLE patient monocytes in the context of clinical and immunological features. Methods Monocytes were purified from patients with SLE and controls, and individually isolated for single-cell gene expression measurement. A panel of monocyte-related transcripts were measured in individual classical (CL) and non-classical (NCL) monocytes. Results Analyses of both CL and NCL monocytes demonstrated that many genes had a lower expression rate in SLE monocytes than in controls. Unsupervised hierarchical clustering of the CL and NCL data sets demonstrated independent clusters of cells from the patients with SLE that were related to disease activity, type I interferon (IFN) and medication use. Thus, each of these factors exerted a different impact on monocyte gene expression that could be identified separately, and a number of genes correlated uniquely with disease activity. We found within-cell correlations between genes directly induced by type I IFN-induced and other non–IFN-induced genes, suggesting the downstream biological effects of type I IFN in individual human SLE monocytes which differed between CLs and NCLs. Conclusions In summary, single-cell gene expression in monocytes was associated with a wide range of clinical and biological features in SLE, providing much greater detail and insight into the cellular biology underlying the disease than previous mixed-cell population studies.

In 2012, the Systemic Lupus International Collaborating Clinics (SLICC) group published a new set of classification criteria for systemic lupus erythematosus (SLE). Studies applying these criteria to real-life scenarios have found either equal or greater sensitivity and equal or lower specificity to the 1997 ACR classification criteria (ACR 97). Nonetheless, there are no studies that have used the SLICC 12 criteria to investigate the incidence of lupus. We used the resource of the Rochester Epidemiology Project to identify incident SLE patients in Olmsted County, Minnesota, from 1993 to 2005, who fulfilled the ACR 97 or SLICC 12 criteria. A total of 58 patients met criteria by SLICC 12 and 44 patients met criteria by ACR 97. The adjusted incidence of 4.9 per 100,000 person-years by SLICC 12 was higher than that by ACR 97 (3.7 per 100,000 person-years, p = 0.04). The median duration from the appearance of first criterion to fulfillment of the criteria was shorter for the SLICC 12 than for ACR 97 (3.9 months vs 8.1 months). The higher incidence by SLICC 12 criteria came primarily from the ability to classify patients with renal-limited disease, the expansion of the immunologic criteria and the expansion of neurologic criteria.

A bone loading estimation algorithm was previously developed that provides in vivo loading conditions required for in vivo bone remodelling simulations. The algorithm derives a bone's loading history from its microstructure as assessed by high-resolution (HR) computed tomography (CT). This reverse engineering approach showed accurate and realistic results based on micro-CT and HR-peripheral quantitative CT images. However, its voxel size dependency, reproducibility and sensitivity still need to be investigated, which is the purpose of this study. Voxel size dependency was tested on cadaveric distal radii with micro-CT images scanned at 25 µm and downscaled to 50, 61, 75, 82, 100, 125 and 150 µm. Reproducibility was calculated with repeated in vitro as well as in vivo HR-pQCT measurements at 82 µm. Sensitivity was defined using HR-pQCT images from women with fracture versus non-fracture, and low versus high bone volume fraction, expecting similar and different loading histories, respectively. Our results indicate that the algorithm is voxel size independent within an average (maximum) error of 8.2% (32.9%) at 61 µm, but that the dependency increases considerably at voxel sizes bigger than 82 µm. In vitro and in vivo reproducibility are up to 4.5% and 10.2%, respectively, which is comparable to other in vitro studies and slightly higher than in other in vivo studies. Subjects with different bone volume fraction were clearly distinguished but not subjects with and without fracture. This is in agreement with bone adapting to customary loading but not to fall loads. We conclude that the in vivo bone loading estimation algorithm provides reproducible, sensitive and fairly voxel size independent results at up to 82 µm, but that smaller voxel sizes would be advantageous.