Unraveling IFN-I response dynamics and TNF crosstalk in the pathophysiology of systemic lupus erythematosus.

Introduction: The innate immune system serves the crucial first line of defense against a wide variety of potential threats, during which the production of pro-inflammatory cytokines IFN-I and TNFα are key. This astonishing power to fight invaders, however, comes at the cost of risking IFN-I-related pathologies, such as observed during autoimmune diseases, during which IFN-I and TNFα response dynamics are dysregulated. Therefore, these response dynamics must be tightly regulated, and precisely matched with the potential threat. This regulation is currently far from understood. Methods: Using droplet-based microfluidics and ODE modeling, we studied the fundamentals of single-cell decision-making upon TLR signaling in human primary immune cells (n = 23). Next, using biologicals used for treating autoimmune diseases [i.e., anti-TNFα, and JAK inhibitors], we unraveled the crosstalk between IFN-I and TNFα signaling dynamics. Finally, we studied primary immune cells isolated from SLE patients (n = 8) to provide insights into SLE pathophysiology. Results: single-cell IFN-I and TNFα response dynamics display remarkable differences, yet both being highly heterogeneous. Blocking TNFα signaling increases the percentage of IFN-I-producing cells, while blocking IFN-I signaling decreases the percentage of TNFα-producing cells. Single-cell decision-making in SLE patients is dysregulated, pointing towards a dysregulated crosstalk between IFN-I and TNFα response dynamics. Discussion: We provide a solid droplet-based microfluidic platform to study inherent immune secretory behaviors, substantiated by ODE modeling, which can challenge the conceptualization within and between different immune signaling systems. These insights will build towards an improved fundamental understanding on single-cell decision-making in health and disease.

The immunologic etiology of psychiatric manifestations in systemic lupus erythematosus: A narrative review on the role of the blood brain barrier, antibodies, cytokines and chemokines.

INTRODUCTION: The aim of this narrative review is to provide an overview of the literature on the possible immunologic pathophysiology of psychiatric manifestations of neuropsychiatric systemic lupus erythematosus (NPSLE). METHODS: A systematic search on PubMed was conducted. English studies with full text availability that investigated the correlation between blood-brain barrier (BBB) dysfunction, intrathecal synthesis of antibodies, antibodies, cytokines, chemokines, metalloproteinases, complement and psychiatric NPSLE manifestations in adults were included. RESULTS: Both transient BBB-dysfunction with consequent access of antibodies to the cerebrospinal fluid (CSF) and intrathecal synthesis of antibodies could occur in psychiatric NPSLE. Anti-phospholipid antibodies, anti-NMDA antibodies and anti-ribosomal protein p antibodies seem to mediate concentration dependent neuronal dysfunction. Interferon-α may induce microglial engulfment of neurons, direct neuronal damage and production of cytokines and chemokines in psychiatric NPSLE. Several cytokines, chemokines and matrix metalloproteinase-9 may contribute to the pathophysiology of psychiatric NPSLE by attracting and activating Th1-cells and B-cells. DISCUSSION: This potential pathophysiology may help understand NPSLE and may have implications for the diagnostic management and therapy of psychiatric NPSLE. However, the presented pathophysiological model is based on correlations between potential immunologic etiologies and psychiatric NPSLE that remain questionable. More research on this topic is necessary to further elucidate the pathophysiology of NPSLE.

Mycophenolate mofetil, azathioprine and tacrolimus: mechanisms in rheumatology.

The introduction of biologic DMARDs into rheumatology has resulted in a substantial reduction of the burden of many rheumatic diseases. In the slipstream of the success achieved with these biologic DMARDs, some conventional immunosuppressive drugs have also found use in new indications. Notably, mycophenolate mofetil, azathioprine and tacrolimus have made their way from solid organ transplantation drugs to become useful assets in rheumatology practice. Mycophenolate mofetil and azathioprine inhibit the purine pathway and subsequently diminish cell proliferation. Both drugs have a pivotal role in the treatment of various rheumatic diseases, including lupus nephritis. Tacrolimus inhibits lymphocyte activation by inhibiting the calcineurin pathway. Mycophenolate mofetil and tacrolimus are, among other indications, increasingly being recognized as useful drugs in the treatment of interstitial lung disease in systemic rheumatic diseases and skin fibrosis in systemic sclerosis. A broad array of trials with mycophenolate mofetil, azathioprine and/or tacrolimus are ongoing within the field of rheumatology that might provide further novel avenues for the use of these drugs. In this Review, we discuss the historical perspective, pharmacodynamics, clinical indications and novel avenues for mycophenolate mofetil, azathioprine and tacrolimus in rheumatology.

Quantification of Double Stranded DNA Breaks and Telomere Length as Proxies for Corneal Damage and Replicative Stress in Human Keratoconus Corneas.

PURPOSE: The pathogenesis of keratoconus (KC) is multifactorial, and associated with oxidative stress and subsequent DNA damage. We investigate differences in DNA damage and replicative stress in patients with KC, and in healthy and diseased controls. METHODS: We obtained 64 corneal buttons from 27 patients with KC after corneal transplant surgery, 21 with a decompensated graft (DG), and 16 healthy controls (HC). The amount of intact Alu elements per genome copy as measured by quantitative polymerase chain reaction (qPCR) was used to quantify intact DNA. Telomere length was measured as a proxy for replicative stress. In addition, telomerase reverse transcriptase (hTERT) gene expression level was assessed. RESULTS: Mean (± standard deviation [SD]) DNA damage was similar between the KC (5.56 ± 14.08), DG (3.16 ± 8.22), and HC (3.51 ± 6.66) groups (P = 0.807). No associations were found between DNA damage and patient age (P = 0.523), atopic constitution (P = 0.240), or contact lens wear (P = 0.393). Telomere length differed (P = 0.034), most notably in the KC group, and hTERT was not detected in any corneal sample. Three cross-linked (CXL) KC corneas did not contain significantly more DNA damage (×2.6, P = 0.750). CONCLUSIONS: Based on these findings, differences in actual corneal DNA damage in KC could not be identified, and the longer telomere length in KC did not support replicative stress as a major etiologic factor in the pathogenesis of KC. Future longitudinal investigations on KC etiology should assess progressively early cases to better comprehend the cellular and molecular processes preceding the archetypical morphologic changes. TRANSLATIONAL RELEVANCE: The standard treatment for progressive keratoconus promotes the crosslinking of collagen fibers through ultraviolet radiation and the subsequent formation of reactive oxygen species. Our study helps to underline the safety of this treatment approach.

B-cells and schizophrenia: A promising link or a finding lost in translation?

Recent genetic studies have suggested a potential role for B-cells in the pathogenesis of schizophrenia. Greater insight in the functioning of B-cells in patients with schizophrenia is therefore of importance. In this narrative review we aim to give an overview of the current literature on B-cells and schizophrenia. We found no evidence for altered numbers of these cells in blood. We did find support for increased levels of B-cell related cytokines and certain autoantibodies. Studies on B-cell development and function, or their numbers in cerebrospinal fluid or brain tissue are very limited. Based on the available data we appraise whether various B-cell mediated pathological mechanisms are likely to play a role in schizophrenia and provide directions for future research.

mTOR inhibition by metformin impacts monosodium urate crystal-induced inflammation and cell death in gout: a prelude to a new add-on therapy?

OBJECTIVE: Gout is the most common inflammatory arthritis worldwide, and patients experience a heavy burden of cardiovascular and metabolic diseases. The inflammation is caused by the deposition of monosodium urate (MSU) crystals in tissues, especially in the joints, triggering immune cells to mount an inflammatory reaction. Recently, it was shown that MSU crystals can induce mechanistic target of rapamycin (mTOR) signalling in monocytes encountering these crystals in vitro. The mTOR pathway is strongly implicated in cardiovascular and metabolic disease. We hypothesised that inhibiting this pathway in gout might be a novel avenue of treatment in these patients, targeting both inflammation and comorbidities. METHODS: We used a translational approach starting from ex vivo to in vitro and back to in vivo. RESULTS: We show that ex vivo immune cells from patients with gout exhibit higher expression of the mTOR pathway, which we can mimic in vitro by stimulating healthy immune cells (B lymphocytes, monocytes, T lymphocytes) with MSU crystals. Monocytes are the most prominent mTOR expressers. By using live imaging, we demonstrate that monocytes, on encountering MSU crystals, initiate cell death and release a wide array of proinflammatory cytokines. By inhibiting mTOR signalling with metformin or rapamycin, a reduction of cell death and release of inflammatory mediators was observed. Consistent with this, we show that patients with gout who are treated with the mTOR inhibitor metformin have a lower frequency of gout attacks. CONCLUSIONS: We propose mTOR inhibition as a novel therapeutic target of interest in gout treatment.

Metformin, A New Era for an Old Drug in the Treatment of Immune Mediated Disease?

BACKGROUND: Metformin, a widely prescribed blood glucose normalizing antidiabetic drug, is now beginning to receive increasing attention due to its anti-inflammatory properties. OBJECTIVE: To provide a critical and comprehensive review of the available literature describing the effects of metformin on the immune system and on auto-inflammatory diseases. RESULTS: Based on the available scientific literature, metformin suppresses immune responses mainly through its direct effect on the cellular functions of various immune cell types by induction of AMPK and subsequent inhibition of mTORC1, and by inhibition of mitochondrial ROS production. Among key immune events, this results in inhibited monocyte to macrophage differentiation and restrained inflammatory capacity of activated macrophages. In addition, metformin treatment increases differentiation of T cells into both regulatory and memory T cells, as well as decreasing the capacity of neutrophils to commence in NETosis. Due to its inhibitory effect on the proinflammatory phenotype of immune cells, metformin seems to reduce auto-immune disease burden not only in several animal models, but has also shown beneficial results in some human trials. CONCLUSIONS: Based on its immunomodulatory properties and high tolerability as a drug, metformin is an interesting add-on drug for future trials in treatment of immune mediated inflammatory diseases.

Telomere quantification in frontal and temporal brain tissue of patients with schizophrenia.

Recent imaging studies have suggested that accelerated aging occurs in schizophrenia. However, the exact cause of these findings is still unclear. In this study we measured telomere length, a marker for cell senescence, in gray and white matter brain tissue from the medial frontal gyrus (MFG) and superior temporal gyrus (STG) of 9 patients with schizophrenia and 11 controls. No alterations in telomere length were found in MFG gray and white matter and in STG gray matter. A significant reduction in telomere length was observed in STG white matter of patients with schizophrenia as compared to controls (fold change of -0.42, U = 5, P = 0.008). Our results support previous findings that telomere length in gray matter is not affected, whereas they suggest that increased cell senescence may affect white matter temporal brain tissue.

Aberrant leukocyte telomere length in Birdshot Uveitis.

PURPOSE: Birdshot Uveitis (BU) is an archetypical chronic inflammatory eye disease, with poor visual prognosis, that provides an excellent model for studying chronic inflammation. BU typically affects patients in the fifth decade of life. This suggests that it may represent an age-related chronic inflammatory disease, which has been linked to increased erosion of telomere length of leukocytes. METHODS: To study this in detail, we exploited a sensitive standardized quantitative real-time polymerase chain reaction to determine the peripheral blood leukocyte telomere length (LTL) in 91 genotyped Dutch BU patients and 150 unaffected Dutch controls. RESULTS: Although LTL erosion rates were very similar between BU patients and healthy controls, we observed that BU patients displayed longer LTL, with a median of log (LTL) = 4.87 (= 74131 base pair) compared to 4.31 (= 20417 base pair) in unaffected controls (P<0.0001). The cause underpinning the difference in LTL could not be explained by clinical parameters, immune cell-subtype distribution, nor genetic predisposition based upon the computed weighted genetic risk score of genotyped validated variants in TERC, TERT, NAF1, OBFC1 and RTEL1. CONCLUSIONS: These findings suggest that BU is accompanied by significantly longer LTL.

Association of MicroRNA-618 Expression With Altered Frequency and Activation of Plasmacytoid Dendritic Cells in Patients With Systemic Sclerosis.

OBJECTIVE: Plasmacytoid dendritic cells (PDCs) are a critical source of type I interferons (IFNs) that can contribute to the onset and maintenance of autoimmunity. Molecular mechanisms leading to PDC dysregulation and a persistent type I IFN signature are largely unexplored, especially in patients with systemic sclerosis (SSc), a disease in which PDCs infiltrate fibrotic skin lesions and produce higher levels of IFNα than those in healthy controls. This study was undertaken to investigate potential microRNA (miRNA)-mediated epigenetic mechanisms underlying PDC dysregulation and type I IFN production in SSc. METHODS: We performed miRNA expression profiling and validation in highly purified PDCs obtained from the peripheral blood of 3 independent cohorts of healthy controls and SSc patients. Possible functions of miRNA-618 (miR-618) on PDC biology were identified by overexpression in healthy PDCs. RESULTS: Expression of miR-618 was up-regulated in PDCs from SSc patients, including those with early disease who did not present with skin fibrosis. IFN regulatory factor 8, a crucial transcription factor for PDC development and activation, was identified as a target of miR-618. Overexpression of miR-618 reduced the development of PDCs from CD34+ cells in vitro and enhanced their ability to secrete IFNα, mimicking the PDC phenotype observed in SSc patients. CONCLUSION: Up-regulation of miR-618 suppresses the development of PDCs and increases their ability to secrete IFNα, potentially contributing to the type I IFN signature observed in SSc patients. Considering the importance of PDCs in the pathogenesis of SSc and other diseases characterized by a type I IFN signature, miR-618 potentially represents an important epigenetic target to regulate immune system homeostasis in these conditions.

Expression of ERAP2 and LST1 is increased before start of therapy in rheumatoid arthritis patients with good clinical response to glucocorticoids.

OBJECTIVES: Glucocorticoids (GC) remain a cornerstone of rheumatoid arthritis (RA) therapy, although a third of patients do not respond adequately. In order to find potential predictors for clinical response, the gene expression profile of CD4+T-cells as important players in the pathogenesis of RA was analysed before pulse therapy with 1000 mg methylprednisolone. METHODS: Patients were treated with 3x1000 mg methylprednisolone in 5 days; hereafter response was determined by the European League Against Rheumatism (EULAR) response criteria. Before start of treatment, CD4+T-cells (and CD14+monocytes) were separated by MACS sorting. Labelled cRNA from CD4+T-cells from 5 responders and 5 non-responders was hybridised to Agilent 4x44K microarray chips and differentially expressed genes were identified via mixed-model analysis of variance based on permutation-based false discovery rates. Selected genes were validated by quantitative real-time PCR (qPCR). RESULTS: Four genes were significantly increased in CD4+T-cells of GC-responders; expression of ERAP2 (endoplasmic reticulum aminopeptidase 2), LST1 (leucocyte-specific transcript 1) and FAM26F (Family With Sequence Similarity 26, Member F) was confirmed by quantitative PCR (qPCR); their expression was inversely correlated with DAS28 at day 5 (LST1 and FAM26F p<0.05; ERAP2: p=0.07). Elevated expression of ERAP2 was also detected by qPCR in CD14+monocytes and after 24 hours in both cell types (all p<0.02). CONCLUSIONS: The increased expression of ERAP2, LST1 and FAM26F in GC-responders before therapy warrants further investigation into their role as potential predictors for the response to GC, and in the inflammatory process of RA.

Gout Is a Chronic Inflammatory Disease in Which High Levels of Interleukin-8 (CXCL8), Myeloid-Related Protein 8/Myeloid-Related Protein 14 Complex, and an Altered Proteome Are Associated With Diabetes Mellitus and Cardiovascular Disease.

OBJECTIVE: The frequent association of gout with metabolic syndrome and cardiovascular disease (CVD) suggests that it has a systemic component. Our objective was to study whether circulating proinflammatory cytokines are associated with comorbidities in gout patients. METHODS: We studied 330 gout patients from 3 independent cohorts and compared them with 144 healthy individuals and 276 disease controls. We measured circulating levels of interleukin-8 (IL-8)/CXCL8, IL-1ß, IL-6, IL-10, IL-12, and tumor necrosis factor, after which we performed proteome-wide analysis in a selection of samples to identify proteins that were possibly prognostic for the development of comorbidities. Replication analysis was performed specifically for myeloid-related protein 8 (MRP-8)/MRP-14 complex. RESULTS: Compared to healthy controls and disease control patients, patients with gouty arthritis (n = 48) had significantly higher mean levels of CXCL8 (P < 0.001), while other cytokines were almost undetectable. Similarly, patients with intercritical gout showed high levels of CXCL8. CXCL8 was independently associated with diabetes mellitus in patients with intercritical gout (P < 0.0001). Proteome-wide analysis in gouty arthritis (n = 18) and intercritical gout (n = 39) revealed MRP-8 and MRP-14 as the proteins with the greatest differential expression between low and high levels of CXCL8 and also showed a positive correlation of MRP8/MRP14 complex with CXCL8 levels (R(2) = 0.49, P < 0.001). These findings were replicated in an independent cohort. The proteome of gout patients with high levels of CXCL8 was associated with diabetes mellitus (odds ratio 16.5 [95% confidence interval 2.8-96.6]) and CVD (odds ratio 3.9 [95% confidence interval 1.0-15.3]). CONCLUSION: Circulating levels of CXCL8 are increased during both the acute and intercritical phases of gout, and they coincide with a specific circulating proteome that is associated with risk of diabetes mellitus and CVD. Further research focused on the roles of CXCL8 and MRP8/MRP14 complex in patients with gout is warranted.

Inflamm-ageing and Senescence in Gout: The Tale of an Old King's Disease.

Gout is the most common auto-inflammatory arthritis that leads to severe comorbidities such as cardiovascular diseases, renal impairment and metabolic disorders at an early age. We hypothesize that chronic as well as frequent flares of intermittent inflammation, caused by uric acid contribute to an early onset of cardiovascular-, renal- and metabolic diseases. Persistent exposure of the cells to such inflammatory events elaborates DNA damage, excessive cell turnover inconsistent with age and telomere shortening which is representative for accelerated senescence. In this review we aim to untangle the intriguing effect of inflammation-induced cellular senescence on the high prevalence of age-related cardiovascular, renal and metabolic diseases in gout.

Longitudinal changes of telomere length and epigenetic age related to traumatic stress and post-traumatic stress disorder.

Several studies have reported an association between traumatic stress and telomere length suggesting that traumatic stress has an impact on ageing at the cellular level. A newly derived tool provides an additional means to investigate cellular ageing by estimating epigenetic age based on DNA methylation profiles. We therefore hypothesise that in a longitudinal study of traumatic stress both indicators of cellular ageing will show increased ageing. We expect that particularly in individuals that developed symptoms of post-traumatic stress disorder (PTSD) increases in these ageing parameters would stand out. From an existing longitudinal cohort study, ninety-six male soldiers were selected based on trauma exposure and the presence of symptoms of PTSD. All military personnel were deployed in a combat zone in Afghanistan and assessed before and 6 months after deployment. The Self-Rating Inventory for PTSD was used to measure the presence of PTSD symptoms, while exposure to combat trauma during deployment was measured with a 19-item deployment experiences checklist. These groups did not differ for age, gender, alcohol consumption, cigarette smoking, military rank, length, weight, or medication use. In DNA from whole blood telomere length was measured and DNA methylation levels were assessed using the Illumina 450K DNA methylation arrays. Epigenetic ageing was estimated using the DNAm age estimator procedure. The association of trauma with telomere length was in the expected direction but not significant (B=-10.2, p=0.52). However, contrary to our expectations, development of PTSD symptoms was associated with the reverse process, telomere lengthening (B=1.91, p=0.018). In concordance, trauma significantly accelerated epigenetic ageing (B=1.97, p=0.032) and similar to the findings in telomeres, development of PTSD symptoms was inversely associated with epigenetic ageing (B=-0.10, p=0.044). Blood cell count, medication and premorbid early life trauma exposure did not confound the results. Overall, in this longitudinal study of military personnel deployed to Afghanistan we show an acceleration of ageing by trauma. However, development of PTSD symptoms was associated with telomere lengthening and reversed epigenetic ageing. These findings warrant further study of a perhaps dysfunctional compensatory cellular ageing reversal in PTSD.

The role of genetics and epigenetics in the pathogenesis of systemic sclerosis.

Systemic sclerosis (SSc) is a complex autoimmune disease of unclear aetiology. A multitude of genetic studies, ranging from candidate-gene studies to genome-wide association studies, have identified a large number of genetic susceptibility factors for SSc and its clinical phenotypes, but the contribution of these factors to disease susceptibility is only modest. However, in an endeavour to explore how the environment might affect genetic susceptibility, epigenetic research into SSc is rapidly expanding. Orchestrated by environmental factors, epigenetic modifications can drive genetically predisposed individuals to develop autoimmunity, and are thought to represent the crossroads between the environment and genetics in SSc. Therefore, in addition to providing a comprehensive description of the current understanding of genetic susceptibility underlying SSc, this Review describes the involvement of epigenetic phenomena, including DNA methylation patterns, histone modifications and microRNAs, in SSc.

Overlapping gene expression profiles indicative of antigen processing and the interferon pathway characterize inflammatory fibrotic skin diseases.

Inflammatory fibrotic disorders have been of high interest both for dermatologists and rheumatologists. Although the phenotypic end stage of this group of diseases is ultimately the same, namely fibrosis, patients present with different clinical features and are often treated with distinct therapeutic modalities. This review addresses whether there is evidence for different underlying molecular pathways in the various inflammatory fibrotic diseases such as localized scleroderma, pediatric lichen sclerosus, adult lichen sclerosus, eosinophilic fasciitis and systemic sclerosis. To investigate this, a large number of gene expression microarray studies performed on skin or fibroblasts from patients with these aforementioned diseases were described, (re-)analysed, and compared. As suspected by the heterogeneous phenotype, most diseases showed unique gene expression features. Intriguingly, a clear overlap was observed between adult and pediatric lichen sclerosus and localized scleroderma, in antigen processing and the interferon pathway. Delineating the cause and consequence of these pathways may generate novel tools to better characterize and more effectively treat these patients.

Accelerated telomere shortening in rheumatic diseases: cause or consequence?

Accelerated aging of the immune system (immune aging), represented by telomere shortening, has been implicated in a variety of rheumatic diseases. Studies addressing telomere shortening in rheumatic diseases so far yielded controversial results. The current review aims to provide an overview on the role of immune aging in a plethora of immune-mediated conditions including systemic sclerosis, rheumatoid arthritis, systemic lupus erythematosus and osteoarthritis. The main question this review aims to answer is whether rheumatic diseases cause accelerated aging or that accelerated aging drives rheumatic diseases.