Gastrointestinal and Extra-Intestinal Manifestations of IgG4-Related Disease.

IgG4-related disease (IgG4-RD) is a chronic relapsing multi-organ fibro-inflammatory syndrome of presumed autoimmune etiology. It is characterized by increased serum levels of IgG4 and tissue infiltration by IgG4+ cells. Increased titers of autoantibodies against a spectrum of self-antigens and response to steroids have led to its characterization as an autoimmune disease. However, the pathognomonic antigens probably differ among manifestations, and different antigens or autoantibodies produce similar immune reactions in different organs. Little is known about the pathogenic effects, if any, of serum IgG4 or IgG4+ plasma cells in tissues. Despite several animal models of the disease, none truly recapitulates human IgG4-RD. Histologic analyses of tissues from patients with IgG4-RD reveal a dense lymphoplasmacytic infiltrate rich in IgG4+ plasma cells, storiform fibrosis, and obliterative phlebitis, although these features vary among organs. Typical presentation and imaging findings include mass-forming synchronous or metachronous lesions in almost any organ, but most commonly in the pancreas, bile duct, retroperitoneum, kidneys, lungs, salivary and lacrimal glands, orbit, and lymph nodes. In all organs, inflammation can be reduced by corticosteroids and drugs that deplete B cells, such as rituximab. Patients with IgG4-RD have relapses that respond to primary therapy. Intense fibrosis accompanies the inflammatory response, leading to permanent organ damage and insufficiency. Death from IgG4-RD is rare. IgG4-RD is a multi-organ disease with predominant pancreatico-biliary involvement. Despite its relapsing-remitting course, patients have an excellent prognosis.

Concomitant Disruption of CD4 and CD8 Genes Facilitates the Development of Double Negative αß TCR+ Peripheral T Cells That Respond Robustly to Staphylococcal Superantigen.

Mature peripheral double negative T (DNT) cells expressing αß TCR but lacking CD4/CD8 coreceptors play protective as well as pathogenic roles. To better understand their development and functioning in vivo, we concomitantly inactivated CD4 and CD8 genes in mice with intact MHC class I and class II molecules with the hypothesis that this would enable the development of DNT cells. We also envisaged that these DNT cells could be activated by bacterial superantigens in vivo as activation of T cells by superantigens does not require CD4 and CD8 coreceptors. Because HLA class II molecules present superantigens more efficiently than murine MHC class II molecules, CD4 CD8 double knockout (DKO) mice transgenically expressing HLA-DR3 or HLA-DQ8 molecules were generated. Although thymic cellularity was comparable between wild type (WT) and DKO mice, CD3+ αß TCR+ thymocytes were significantly reduced in DKO mice, implying defects in thymic-positive selection. Splenic CD3+ αß TCR+ cells and Foxp3+ T regulatory cells were present in DKO mice but significantly reduced. However, the in vivo inflammatory responses and immunopathology elicited by acute challenge with the staphylococcal superantigen enterotoxin B were comparable between WT and DKO mice. Choric exposure to staphylococcal enterotoxin B precipitated a lupus-like inflammatory disease with characteristic lympho-monocytic infiltration in lungs, livers, and kidneys, along with production of anti-nuclear Abs in DKO mice as in WT mice. Overall, our results suggest that DNT cells can develop efficiently in vivo and chronic exposure to bacterial superantigens may precipitate a lupus-like autoimmune disease through activation of DNT cells.

A Central Role for HLA-DR3 in Anti-Smith Antibody Responses and Glomerulonephritis in a Transgenic Mouse Model of Spontaneous Lupus.

MHC, especially HLA-DR3 and HLA-DR2, is one of the most important genetic susceptibility regions for systemic lupus erythematosus. Human studies to understand the role of specific HLA alleles in disease pathogenesis have been hampered by the presence of strong linkage disequilibrium in this region. To overcome this, we produced transgenic mice expressing HLA-DR3 (DRß1*0301) and devoid of endogenous class II (both I-A and I-E genes, AE(0)) on a lupus-prone NZM2328 background (NZM2328.DR3(+)AE(0)). Both NZM2328 and NZM2328.DR3(+)AE(0) mice developed anti-dsDNA and glomerulonephritis, but anti-dsDNA titers were higher in the latter. Although kidney histological scores were similar in NZM2328 and NZM2328.DR3(+)AE(0) mice (7.2 ± 4.3 and 8.6 ± 5.7, respectively, p = 0.48), the onset of severe proteinuria occurred earlier in NZM2328.DR3(+)AE(0) mice compared with NZM2328 mice (median, 5 and 9 mo respectively, p < 0.001). Periarterial lymphoid aggregates, classic wire loop lesions, and occasional crescents were seen only in kidneys from NZM2328.DR3(+)AE(0) mice. Interestingly, NZM2328.DR3(+)AE(0) mice, but not NZM2328 mice, spontaneously developed anti-Smith (Sm) Abs. The anti-Sm Abs were seen in NZM2328.DR3(+)AE(0) mice that were completely devoid of endogenous class II (AE(-/) (-)) but not in mice homozygous (AE(+/+)) or heterozygous (AE(+/-)) for endogenous MHC class II. It appears that only HLA-DR3 molecules can preferentially select SmD-reactive CD4(+) T cells for generation of the spontaneous anti-Sm immune response. Thus, our mouse model unravels a critical role for HLA-DR3 in generating an autoimmune response to SmD and lupus nephritis in the NZM2328 background.

Cancer risk in cutaneous lupus erythematosus: a population-based cohort study.

OBJECTIVE: Immune dysregulation associated with chronic autoimmune diseases, such as SLE, has been associated with increased cancer risk. It is unclear whether isolated cutaneous lupus erythematosus (CLE) modifies cancer risk. We estimated the cumulative incidence of cancer in a population-based CLE cohort and compared the risk with a matched non-CLE cohort. METHODS: All incident cases of CLE in Olmsted County, MN, USA between 1965 and 2005 were identified and followed to December 2013. Estimates for the cumulative incidence of any cancer and skin cancer in patients with CLE were derived and compared with an age-, sex- and calendar-year-matched non-CLE cohort using Cox models. RESULTS: There were a total of 155 patients with CLE [age at diagnosis, 48 (sd 16) years; 65% females; BMI, 26.3 (sd 7.1) kg/m2; 40% smokers, 9% with diabetes]. During a median follow-up of 14.6 years, we observed 35 cases of incident cancer (including 10 cases of skin cancer). The cumulative 1-, 5- and 10-year incidence of any cancer after diagnosis of CLE was 1.4, 7.5 and 11.6%, respectively. Compared with matched non-CLE controls, the overall risk of malignancies was not increased in patients with CLE (smoking-adjusted hazard ratio = 1.29; 95% CI: 0.78, 2.13; P = 0.31). There was also no significant increase in risk of any skin cancer in patients with CLE (hazard ratio = 2.51; 95% CI: 0.91, 6.96; P = 0.16). CONCLUSION: CLE is not associated with an increased risk of any cancers, including skin cancers, compared with the general population. However, the number of events was small, limiting the power of the study.

Systemic inflammatory response elicited by superantigen destabilizes T regulatory cells, rendering them ineffective during toxic shock syndrome.

Life-threatening infections caused by Staphylococcus aureus, particularly the community-acquired methicillin-resistant strains of S. aureus, continue to pose serious problems. Greater virulence and increased pathogenicity of certain S. aureus strains are attributed to higher prevalence of exotoxins. Of these exotoxins, the superantigens (SAg) are likely most pathogenic because of their ability to rapidly and robustly activate the T cells even in extremely small quantities. Therefore, countering SAg-mediated T cell activation using T regulatory cells (Tregs) might be beneficial in diseases such as toxic shock syndrome (TSS). As the normal numbers of endogenous Tregs in a typical host are insufficient, we hypothesized that increasing the Treg numbers by administration of IL-2/anti-IL-2 Ab immune complexes (IL2C) or by adoptive transfer of ex vivo expanded Tregs might be more effective in countering SAg-mediated immune activation. HLA-DR3 transgenic mice that closely recapitulate human TSS were treated with IL2C to increase endogenous Tregs or received ex vivo expanded Tregs. Subsequently, they were challenged with SAg to induce TSS. Analyses of various parameters reflective of TSS (serum cytokine/chemokine levels, multiple organ pathology, and SAg-induced peripheral T cell expansion) indicated that increasing the Tregs failed to mitigate TSS. On the contrary, serum IFN-γ levels were increased in IL2C-treated mice. Exploration into the reasons behind the lack of protective effect of Tregs revealed IL-17 and IFN-γ-dependent loss of Tregs during TSS. In addition, significant upregulation of glucocorticoid-induced TNFR family-related receptor on conventional T cells during TSS could render them resistant to Treg-mediated suppression, contributing to failure of Treg-mediated immune regulation.

Chronic exposure to staphylococcal superantigen elicits a systemic inflammatory disease mimicking lupus.

Chronic nasal and skin colonization with superantigen (SAg)-producing Staphylococcus aureus is well documented in humans. Given that trans-mucosal and trans-cutaneous absorption of SAgs can occur, we determined whether chronic exposure to small amounts of SAg per se could activate autoreactive CD4(+) and CD8(+) T cells and precipitate any autoimmune disease without further external autoantigenic stimulation. Because HLA class II molecules present SAg more efficiently than do mouse MHC class II molecules, HLA-DQ8 transgenic mice were implanted s.c. with mini-osmotic pumps capable of continuously delivering the SAg, staphylococcal enterotoxin B (total of 10 µg/mouse), or PBS over 4 wk. Chronic exposure to staphylococcal enterotoxin B resulted in a multisystem autoimmune inflammatory disease with features similar to systemic lupus erythematosus. The disease was characterized by mononuclear cell infiltration of lungs, liver, and kidneys, accompanied by the production of anti-nuclear Abs and deposition of immune complexes in the renal glomeruli. The inflammatory infiltrates in various organs predominantly consisted of CD4(+) T cells bearing TCR Vß8. The extent of immunopathology was markedly reduced in mice lacking CD4(+) T cells and CD28, indicating that the disease is CD4(+) T cell mediated and CD28 dependent. The absence of disease in STAT4-deficient, as well as IFN-γ-deficient, HLA-DQ8 mice suggested the pathogenic role of Th1-type cytokines, IL-12 and IFN-γ. In conclusion, our study suggests that chronic exposure to extremely small amounts of bacterial SAg could be an etiological factor for systemic lupus erythematosus.

Is yearly interferon gamma release assay latent tuberculosis infection screening warranted among patients with rheumatological diseases on disease-modifying drugs in non-endemic settings?

OBJECTIVE: Patients living with rheumatologic diseases on disease-modifying antirheumatic drugs (DMARD) are at an increased risk of developing tuberculosis (TB). Current guidelines recommend screening for latent tuberculosis infection (LTBI) before initiating DMARD. However, data is lacking on the value of yearly screening for LTBI. METHODS: A retrospective chart review was conducted on adult patients (≥ 18 years) with rheumatologic disease on DMARD followed longitudinally in the outpatient rheumatology clinics between 2017-2021. Collected data included patient demographics, rheumatologic diagnosis, medications, TB-related risk factors, interferon gamma release assay (IGRA) results, LTBI diagnosis and treatment. Descriptive statistics were performed. RESULTS: Among 339 patients, 81 (23.9%) were male, 259 (76.4%) were white, and 93 (27.5%) were Latinx. Inflammatory arthritis (84.1%) was the most common rheumatic diagnosis. Common DMARD were JAK inhibitors (19.2%), TNF-alpha inhibitors (18.9%), and IL-17 A inhibitors (18.0%). Only 2 patients at baseline had positive IGRA, and both had a history of treated LTBI. Positive IGRA tests were recorded in 1 (0.7%), 3 (1.8%), 3 (1.3%), and 3 (1.1%) in the years 2018, 2019, 2020, and 2021, respectively. Four patients converted from negative to positive during serial yearly IGRA testing. After reviewing the IGRA test and TB risk factors, only one patient was considered newly diagnosed with LTBI, requiring 4 months of rifampin. CONCLUSION: In a non-endemic area, serial IGRA testing of low-risk patients on DMARD yielded very low rate of newly diagnosed LTBI. A targeted LTBI screening based on TB-related risk factors should be performed prior to IGRA testing rather than universal yearly screening in a non-endemic setting.

Regional european genetic ancestry predicts type I interferon level and risk of severe viral infection.

BACKGROUND: Viral infection outcomes vary widely between individuals, ranging from mild symptoms to severe organ failure and death, and it is clear that host genetic factors play a role in this variability. Type I interferon (IFN) is a critical anti-viral cytokine, and we have previously noted differences in type I IFN levels between world populations. METHODS: In this study, we investigate the interrelationship between regional European genetic ancestry, type I IFN levels, and severe viral infection outcomes. RESULTS: In cohorts of European ancestry lupus patients living in Europe, we noted higher IFN in the Northwestern populations as compared to Southeastern populations. In an independent cohort of European ancestry lupus patients from the United States with varying proportional regional European genetic admixture, we observed the same Northwest vs. Southeast European ancestry IFN gradient. We developed a model to predict type I IFN level based on regional European ancestry (AUC = 0.73, p = 6.1e-6). Examining large databases containing serious viral outcomes data, we found that lower predicted IFN in the corresponding European country was significantly correlated with increased viral infection fatality rate, including COVID-19, viral hepatitis, and HIV [Correlation coefficients: -0.79 (p = 4e-2), -0.94 (p = 6e-3), and -0.96 (p = 8e-2) respectively]. CONCLUSIONS: This association between predicted type I IFN level and viral outcome severity suggests a potential causal relationship, as greater intrinsic type I IFN is beneficial in host defense against viruses. Genetic testing could provide insight into individual and population level risk of fatality due to viruses prior to infection, across a wide range of viral pathogens.

2023 American College of Rheumatology (ACR)/American College of Chest Physicians (CHEST) Guideline for the Screening and Monitoring of Interstitial Lung Disease in People with Systemic Autoimmune Rheumatic Diseases.

OBJECTIVE: We provide evidence-based recommendations regarding screening for interstitial lung disease (ILD) and the monitoring for ILD progression in people with systemic autoimmune rheumatic diseases (SARDs), specifically rheumatoid arthritis, systemic sclerosis, idiopathic inflammatory myopathies, mixed connective tissue disease, and Sjögren disease. METHODS: We developed clinically relevant population, intervention, comparator, and outcomes questions related to screening and monitoring for ILD in patients with SARDs. A systematic literature review was performed, and the available evidence was rated using the Grading of Recommendations, Assessment, Development, and Evaluation methodology. A Voting Panel of interdisciplinary clinician experts and patients achieved consensus on the direction and strength of each recommendation. RESULTS: Fifteen recommendations were developed. For screening people with these SARDs at risk for ILD, we conditionally recommend pulmonary function tests (PFTs) and high-resolution computed tomography of the chest (HRCT chest); conditionally recommend against screening with 6-minute walk test distance (6MWD), chest radiography, ambulatory desaturation testing, or bronchoscopy; and strongly recommend against screening with surgical lung biopsy. We conditionally recommend monitoring ILD with PFTs, HRCT chest, and ambulatory desaturation testing and conditionally recommend against monitoring with 6MWD, chest radiography, or bronchoscopy. We provide guidance on ILD risk factors and suggestions on frequency of testing to evaluate for the development of ILD in people with SARDs. CONCLUSION: This clinical practice guideline presents the first recommendations endorsed by the American College of Rheumatology and American College of Chest Physicians for the screening and monitoring of ILD in people with SARDs.

2023 American College of Rheumatology (ACR)/American College of Chest Physicians (CHEST) Guideline for the Screening and Monitoring of Interstitial Lung Disease in People with Systemic Autoimmune Rheumatic Diseases.

OBJECTIVE: We provide evidence-based recommendations regarding screening for interstitial lung disease (ILD) and the monitoring for ILD progression in people with systemic autoimmune rheumatic diseases (SARDs), specifically rheumatoid arthritis, systemic sclerosis, idiopathic inflammatory myopathies, mixed connective tissue disease, and Sjögren disease. METHODS: We developed clinically relevant population, intervention, comparator, and outcomes questions related to screening and monitoring for ILD in patients with SARDs. A systematic literature review was performed, and the available evidence was rated using the Grading of Recommendations, Assessment, Development, and Evaluation methodology. A Voting Panel of interdisciplinary clinician experts and patients achieved consensus on the direction and strength of each recommendation. RESULTS: Fifteen recommendations were developed. For screening people with these SARDs at risk for ILD, we conditionally recommend pulmonary function tests (PFTs) and high-resolution computed tomography of the chest (HRCT chest); conditionally recommend against screening with 6-minute walk test distance (6MWD), chest radiography, ambulatory desaturation testing, or bronchoscopy; and strongly recommend against screening with surgical lung biopsy. We conditionally recommend monitoring ILD with PFTs, HRCT chest, and ambulatory desaturation testing and conditionally recommend against monitoring with 6MWD, chest radiography, or bronchoscopy. We provide guidance on ILD risk factors and suggestions on frequency of testing to evaluate for the development of ILD in people with SARDs. CONCLUSION: This clinical practice guideline presents the first recommendations endorsed by the American College of Rheumatology and American College of Chest Physicians for the screening and monitoring of ILD in people with SARDs.

2023 American College of Rheumatology (ACR)/American College of Chest Physicians (CHEST) Guideline for the Treatment of Interstitial Lung Disease in People with Systemic Autoimmune Rheumatic Diseases.

OBJECTIVE: We provide evidence-based recommendations regarding the treatment of interstitial lung disease (ILD) in adults with systemic autoimmune rheumatic diseases (SARDs). METHODS: We developed clinically relevant population, intervention, comparator, and outcomes questions. A systematic literature review was then performed, and the available evidence was rated using the Grading of Recommendations, Assessment, Development, and Evaluation methodology. A panel of clinicians and patients reached consensus on the direction and strength of the recommendations. RESULTS: Thirty-five recommendations were generated (including two strong recommendations) for first-line SARD-ILD treatment, treatment of SARD-ILD progression despite first-line ILD therapy, and treatment of rapidly progressive ILD. The strong recommendations were against using glucocorticoids in systemic sclerosis-ILD as a first-line ILD therapy and after ILD progression. Otherwise, glucocorticoids are conditionally recommended for first-line ILD treatment in all other SARDs. CONCLUSION: This clinical practice guideline presents the first recommendations endorsed by the American College of Rheumatology and American College of Chest Physicians for the treatment of ILD in people with SARDs.

Implementation of a Best Practice Advisory to Improve Infection Screening Prior to New Prescriptions of Biologics and Targeted Synthetic Drugs.

OBJECTIVE: Use of biologic and targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) in patients with preexisting tuberculosis (TB), hepatitis B virus (HBV), or hepatitis C virus (HCV) infection can have serious consequences. Although various society guidelines recommend routine screening for these infections before initiating certain b/tsDMARDs, adherence to these recommendations varies widely. This quality improvement initiative evaluated local compliance with screening and assessed whether an automated computerized decision support system in the form of a best practice advisory (BPA) in the electronic health record could improve patient screening. METHODS: Established patients with autoimmune rheumatic disease (ARD) aged 18 years or older with at least one visit to our rheumatology practice between October 1, 2017, and March 3, 2022, were included. When prescribing a new b/tsDMARD, clinicians were alerted via a BPA that showed the most recent results for TB, HBV, and HCV. Screening proportions for TB, HBV, and HCV before BPA initiation were compared with those of eligible patients after the BPA implementation. RESULTS: A total of 711 patients pre-BPA and 257 patients post-BPA implementation were included in the study. The BPA implementation was associated with statistically significant improvement in screening for TB from 66% to 82% (P ≤ 0.001), HCV from 60% to 79% (P ≤ 0.001), hepatitis B core antibody 32% to 51% (P ≤ 0.001), and hepatitis B surface antigen from 51% to 70% (P ≤ 0.001). CONCLUSION: Implementation of a BPA can improve infectious disease screening for patients with ARD who are started on b/tsDMARDs and has potential to improve patient safety.

High Systemic Type I Interferon Activity Is Associated With Active Class III/IV Lupus Nephritis.

OBJECTIVE: Previous studies suggest a link between high serum type I interferon (IFN) and lupus nephritis (LN). We determined whether serum IFN activity is associated with subtypes of LN and studied renal tissues and cells to understand the effect of IFN in LN. METHODS: Two hundred and twenty-one patients with systemic lupus erythematosus were studied. Serum IFN activity was measured by WISH bioassay. mRNA in situ hybridization was used in renal tissue to measure expression of the representative IFN-induced gene, IFN-induced protein with tetratricopeptide repeats-1 (IFIT1), and the plasmacytoid dendritic cell (pDC) marker gene C-type lectin domain family-4 member C (CLEC4C). Podocyte cell line gene expression was measured by real-time PCR. RESULTS: Class III/IV LN prevalence was significantly increased in patients with high serum IFN compared with those with low IFN (odds ratio 5.40, P = 0.009). In multivariate regression models, type I IFN was a stronger predictor of class III/IV LN than complement C3 or anti-dsDNA antibody, and could account for the association of these variables with LN. IFIT1 expression was increased in all classes of LN, but most in the glomerular areas of active class III/IV LN kidneys. IFIT1 expression was not closely colocalized with pDCs. IFN directly activated podocyte cell lines to induce chemokines and proapoptotic molecules. CONCLUSION: Systemic high IFN is involved in the pathogenesis of severe LN. We did not find colocalization of pDCs with IFN signature in renal tissue, and instead observed the greatest intensity of the IFN signature in glomerular areas, which could suggest a blood source of IFN.

Coronavirus Disease 2019 in a Patient With a Systemic Autoinflammatory Syndrome due to an NLRC4 Inflammasomopathy.

The effect of autoinflammatory diseases on severe acute respiratory syndrome coronavirus 2 infection remains unknown. We report a case of coronavirus disease 2019 (COVID-19) in a patient with autoinflammation with infantile enterocolitis with inflammatory flares due to a mutation in the inflammasome component NLRC4. This case highlights the role of immunosuppression in patients with autoinflammation with COVID-19.

Single-cell expression quantitative trait loci (eQTL) analysis of SLE-risk loci in lupus patient monocytes.

BACKGROUND: We performed expression quantitative trait locus (eQTL) analysis in single classical (CL) and non-classical (NCL) monocytes from patients with systemic lupus erythematosus (SLE) to quantify the impact of well-established genetic risk alleles on transcription at single-cell resolution. METHODS: Single-cell gene expression was quantified using qPCR in purified monocyte subpopulations (CD14++CD16- CL and CD14dimCD16+ NCL) from SLE patients. Novel analysis methods were used to control for the within-person correlations observed, and eQTLs were compared between cell types and risk alleles. RESULTS: The SLE-risk alleles demonstrated significantly more eQTLs in NCLs as compared to CLs (p = 0.0004). There were 18 eQTLs exclusive to NCL cells, 5 eQTLs exclusive to CL cells, and only one shared eQTL, supporting large differences in the impact of the risk alleles between these monocyte subsets. The SPP1 and TNFAIP3 loci were associated with the greatest number of transcripts. Patterns of shared influence in which different SNPs impacted the same transcript also differed between monocyte subsets, with greater evidence for synergy in NCL cells. IRF1 expression demonstrated an on/off pattern, in which expression was zero in all of the monocytes studied from some individuals, and this pattern was associated with a number of SLE risk alleles. We observed corroborating evidence of this IRF1 expression pattern in public data sets. CONCLUSIONS: We document multiple SLE-risk allele eQTLs in single monocytes which differ greatly between CL and NCL subsets. These data support the importance of the SPP1 and TNFAIP3 risk variants and the IRF1 transcript in SLE patient monocyte function.

Baseline characteristics and long-term outcomes of eosinophilic fasciitis in 89 patients seen at a single center over 20 years.

AIM: Eosinophilic fasciitis (EF) is a rare, fibrosing disorder of skin and subcutaneous tissue. This study was undertaken to describe its clinical and laboratory features and identify prognostic factors associated with outcome. METHODS: We conducted a retrospective review of all EF patients evaluated at our institution from 1 January1997 to 30 December 2016. Kaplan-Meier methods were used to determine treatment response rates over time. Potential associations between baseline characteristics and complete response were examined using Cox models adjusted for age and sex. Time-dependent covariates were used to examine treatment effects. RESULTS: We identified 89 EF patients, with a female-to-male ratio of 1:1. Clinical features included groove sign in 26 (29%), peau d'orange/dimpling in 22 (25%), inflammatory arthritis in 9 (10%) and muscle weakness in 9 (10%). Aldolase was elevated in 11/36 (31%). Complete response rate was 60% (95% confidence interval [CI]: 35-75) at 3 years. Diagnostic delay was inversely associated with treatment response (hazards ratio: 0.84 per 1 month increase; 95% CI: 0.73-0.98). No baseline characteristics correlated with treatment response, but a trend toward positive association of elevated aldolase, hypergammaglobulinemia and presence of hematologic disorders was noted. Methotrexate was the most commonly used immunosuppressant in 79%, hydroxychloroquine in 45%, mycophenolate mofetil in 18% and azathioprine in 8%. No single immunosuppressant agent was associated with a superior response during treatment. CONCLUSIONS: EF is characterized by relatively high response rates. Consensus diagnostic criteria, standardized management algorithms, and large prospective multi-center cohorts are needed to develop an evidence-directed approach to this challenging condition.

Type I Interferon Predicts an Alternate Immune System Phenotype in Systemic Lupus Erythematosus.

OBJECTIVE: Type 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. METHODS: SLE 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. RESULTS: Circulating 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. CONCLUSION: We 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.

Broad Concepts in Management of Systemic Lupus Erythematosus.

Systemic lupus erythematosus is a multisystem autoimmune disease with protean manifestation. Although commonly seen in young women, it can affect men as well as elderly patients. Approach to treatment is multidisciplinary, involves defining the extent of organ involvement, and distinguishing between active manifestations and damage. The mainstay of therapy is judicious use of immunosuppressive medications. Long-term follow-up to address morbidity arising from treatment complications, disease damage, and increased cardiovascular risk is essential.

Lupus-Associated Functional Polymorphism in PNP Causes Cell Cycle Abnormalities and Interferon Pathway Activation in Human Immune Cells.

OBJECTIVE: Systemic 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. METHODS: Type 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. RESULTS: Structural 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. CONCLUSION: The 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.

Single-cell gene expression patterns in lupus monocytes independently indicate disease activity, interferon and therapy.

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.