Serum IL-15 in patients with early systemic sclerosis: a potential novel marker of lung disease

Treatment with mycophenolate mofetil is associated with improved nailfold vasculature in systemic sclerosis

OBJECTIVE

To investigate the evolution of nailfold capillary density in patients with SSc in relation to immunosuppressive treatment and autoantibodies.

METHODS

This was a prospective study cohort. Consecutive newly diagnosed SSc patients were included into this study who, in a retrospective review, had at least two nailfold capillary microscopy measurements performed during the first 48 months of follow-up. Capillary density per 3 mm was measured with widefield nailfold capillary microscopy. Improvement of capillary density per finger and mean capillary density were analysed. Longitudinal measurements of mean capillary density were analysed by generalized estimating equation.

RESULTS

Eighty patients (68 women, 12 men) met the inclusion criteria. The median follow-up time was 27 months. Twenty-eight patients had an improved capillary density in per-finger analysis. MMF was associated with fewer numbers of fingers that had worsened in capillary density. Anti-topoisomerase antibodies were associated with low mean capillary density. Anti-RNA polymerase III antibodies were associated with improvement and anti-centromere antibodies with worsening of capillary density in per-finger analysis. MMF treatment was associated with less steep capillary density decline in a moderated generalized estimating equation model including presence of anti-topoisomerase antibodies and the interaction of MMF with follow-up time.

CONCLUSION

Nailfold capillary density improved over time in a substantial proportion of SSc patients. MMF treatment had a positive impact on the evolution of capillary density in these patients. SSc autoantibody phenotype may affect the capillary density development. The data support previous hypotheses that early immunosuppression may favourably affect vascular regeneration in SSc.

MCAM+CD161- Th17 Subset Expressing CD83 Enhances Tc17 Response in Psoriasis

Recent studies have highlighted the pathogenic roles of IL-17-producing CD8+ T cells (T-cytotoxic 17 [Tc17]) in psoriasis. However, the underlying mechanisms of Tc17 induction remain unclear. In this study, we focused on the pathogenic subsets of Th17 and their mechanism of promotion of Tc17 responses. We determined that the pathogenic Th17-enriched fraction expressed melanoma cell adhesion molecule (MCAM) and CCR6, but not CD161, because this subset produced IL-17A abundantly and the presence of these cells in the peripheral blood of patients has been correlated with the severity of psoriasis. Intriguingly, the serial analysis of gene expression revealed that CCR6+MCAM+CD161-CD4+ T cells displayed the gene profile for adaptive immune responses, including CD83, which is an activator for CD8+ T cells. Coculture assay with or without intercellular contact between CD4+ and CD8+ T cells showed that CCR6+MCAM+CD161-CD4+ T cells induced the proliferation of CD8+ T cells in a CD83-dependent manner. However, the production of IL-17A by CD8+ T cells required exogenous IL-17A, suggesting that intercellular contact via CD83 and the production of IL-17A from activated CD4+ T cells elicit Tc17 responses. Intriguingly, the CD83 expression was enhanced in the presence of IL-15, and CD83+ cells stimulated with IL-1β, IL-23, IL-15, and IL-15Rα did not express FOXP3. Furthermore, CCR6+MCAM+CD161-CD4+ T cells expressing CD83 were increased in the peripheral blood of patients, and the CD83+ Th17-type cells accumulated in the lesional skin of psoriasis. In conclusion, pathogenic MCAM+CD161- Th17 cells may be involved in the Tc17 responses via IL-17A and CD83 in psoriasis.

JAK inhibitors and autoimmune rheumatic diseases

The four Janus kinase (JAK) proteins and the seven Signal Transducers of Activated Transcription (STAT) mediate intracellular signal transduction downstream of cytokine receptors, which are involved in the pathology of allergic, autoimmune, and inflammatory diseases. The development of targeted small-molecule treatments with diverse selective inhibitory profiles, such as JAK inhibitors (JAKi), has supported an important change in the treatment of multiple disorders. Indeed, JAKi inhibit intracellular signalling controlled by numerous cytokines implicated in the disease process of rheumatoid arthritis and several other inflammatory and immune diseases. Therefore, JAKi have the capacity to target multiple pathways of those diseases. Other autoimmune diseases treated with JAKi include systemic sclerosis, systemic lupus erythematosus, dermatomyositis, primary Sjogren's syndrome, and vasculitis. In all of these cases, innate immunity stimulation activates adaptive immunity, resulting in the production of autoreactive T cells as well as the stimulation and differentiation of B cells. Mechanism-based treatments that target JAK-STAT pathways have the possibility of improving outcomes by reducing the consumption of glucocorticoids and/or non-specific immunosuppressive drugs in the management of systemic immune-mediated inflammatory diseases.

COVID-19 lung disease shares driver AT2 cytopathic features with Idiopathic pulmonary fibrosis

BACKGROUND

In the aftermath of Covid-19, some patients develop a fibrotic lung disease, i.e., post-COVID-19 lung disease (PCLD), for which we currently lack insights into pathogenesis, disease models, or treatment options.

METHODS

Using an AI-guided approach, we analyzed > 1000 human lung transcriptomic datasets associated with various lung conditions using two viral pandemic signatures (ViP and sViP) and one covid lung-derived signature. Upon identifying similarities between COVID-19 and idiopathic pulmonary fibrosis (IPF), we subsequently dissected the basis for such similarity from molecular, cytopathic, and immunologic perspectives using a panel of IPF-specific gene signatures, alongside signatures of alveolar type II (AT2) cytopathies and of prognostic monocyte-driven processes that are known drivers of IPF. Transcriptome-derived findings were used to construct protein-protein interaction (PPI) network to identify the major triggers of AT2 dysfunction. Key findings were validated in hamster and human adult lung organoid (ALO) pre-clinical models of COVID-19 using immunohistochemistry and qPCR.

FINDINGS

COVID-19 resembles IPF at a fundamental level; it recapitulates the gene expression patterns (ViP and IPF signatures), cytokine storm (IL15-centric), and the AT2 cytopathic changes, e.g., injury, DNA damage, arrest in a transient, damage-induced progenitor state, and senescence-associated secretory phenotype (SASP). These immunocytopathic features were induced in pre-clinical COVID models (ALO and hamster) and reversed with effective anti-CoV-2 therapeutics in hamsters. PPI-network analyses pinpointed ER stress as one of the shared early triggers of both diseases, and IHC studies validated the same in the lungs of deceased subjects with COVID-19 and SARS-CoV-2-challenged hamster lungs. Lungs from tg-mice, in which ER stress is induced specifically in the AT2 cells, faithfully recapitulate the host immune response and alveolar cytopathic changes that are induced by SARS-CoV-2.

INTERPRETATION

Like IPF, COVID-19 may be driven by injury-induced ER stress that culminates into progenitor state arrest and SASP in AT2 cells. The ViP signatures in monocytes may be key determinants of prognosis. The insights, signatures, disease models identified here are likely to spur the development of therapies for patients with IPF and other fibrotic interstitial lung diseases.

FUNDING

This work was supported by the National Institutes for Health grants R01- GM138385 and AI155696 and funding from the Tobacco-Related disease Research Program (R01RG3780).

COVID-19 lung disease shares driver AT2 cytopathic features with Idiopathic pulmonary fibrosis

Background

In the aftermath of Covid-19, some patients develop a fibrotic lung disease, i.e., p ost- C OVID-19 l ung d isease (PCLD), for which we currently lack insights into pathogenesis, disease models, or treatment options.

Method

Using an AI-guided approach, we analyzed > 1000 human lung transcriptomic datasets associated with various lung conditions using two viral pandemic signatures (ViP and sViP) and one covid lung-derived signature. Upon identifying similarities between COVID-19 and idiopathic pulmonary fibrosis (IPF), we subsequently dissected the basis for such similarity from molecular, cytopathic, and immunologic perspectives using a panel of IPF-specific gene signatures, alongside signatures of alveolar type II (AT2) cytopathies and of prognostic monocyte-driven processes that are known drivers of IPF. Transcriptome-derived findings were used to construct protein-protein interaction (PPI) network to identify the major triggers of AT2 dysfunction. Key findings were validated in hamster and human adult lung organoid (ALO) pre-clinical models of COVID-19 using immunohistochemistry and qPCR.

Findings

COVID-19 resembles IPF at a fundamental level; it recapitulates the gene expression patterns (ViP and IPF signatures), cytokine storm (IL15-centric), and the AT2 cytopathic changes, e.g., injury, DNA damage, arrest in a transient, damage-induced progenitor state, and senescence-associated secretory phenotype (SASP). These immunocytopathic features were induced in pre-clinical COVID models (ALO and hamster) and reversed with effective anti-CoV-2 therapeutics in hamsters. PPI-network analyses pinpointed ER stress as one of the shared early triggers of both diseases, and IHC studies validated the same in the lungs of deceased subjects with COVID-19 and SARS-CoV-2-challenged hamster lungs. Lungs from tg - mice, in which ER stress is induced specifically in the AT2 cells, faithfully recapitulate the host immune response and alveolar cytopathic changes that are induced by SARS-CoV-2.

Interpretation

Like IPF, COVID-19 may be driven by injury-induced ER stress that culminates into progenitor state arrest and SASP in AT2 cells. The ViP signatures in monocytes may be key determinants of prognosis. The insights, signatures, disease models identified here are likely to spur the development of therapies for patients with IPF and other fibrotic interstitial lung diseases.

Funding

This work was supported by the National Institutes for Health grants R01-GM138385 and AI155696 and funding from the Tobacco-Related disease Research Program (R01RG3780).

One Sentence Summary

Severe COVID-19 triggers cellular processes seen in fibrosing Interstitial Lung Disease.

RESEARCH IN CONTEXT

Evidence before this study: In its aftermath, the COVID-19 pandemic has left many survivors, almost a third of those who recovered, with a mysterious long-haul form of the disease which culminates in a fibrotic form of interstitial lung disease (post-COVID-19 ILD). Post-COVID-19 ILD remains a largely unknown entity. Currently, we lack insights into the core cytopathic features that drive this condition.Added value of this study: Using an AI-guided approach, which involves the use of sets of gene signatures, protein-protein network analysis, and a hamster model of COVID-19, we have revealed here that COVID-19 -lung fibrosis resembles IPF, the most common form of ILD, at a fundamental levelâ€"showing similar gene expression patterns in the lungs and blood, and dysfunctional AT2 processes (ER stress, telomere instability, progenitor cell arrest, and senescence). These findings are insightful because AT2 cells are known to contain an elegant quality control network to respond to intrinsic or extrinsic stress; a failure of such quality control results in diverse cellular phenotypes, of which ER stress appears to be a point of convergence, which appears to be sufficient to drive downstream fibrotic remodeling in the lung.Implications of all the available evidence: Because unbiased computational methods identified the shared fundamental aspects of gene expression and cellular processes between COVID-19 and IPF, the impact of our findings is likely to go beyond COVID-19 or any viral pandemic. The insights, tools (disease models, gene signatures, and biomarkers), and mechanisms identified here are likely to spur the development of therapies for patients with IPF and, other fibrotic interstitial lung diseases, all of whom have limited or no treatment options. To dissect the validated prognostic biomarkers to assess and track the risk of pulmonary fibrosis and develop therapeutics to halt fibrogenic progression.

Circulating Plasma microRNAs In Systemic Sclerosis-Associated Pulmonary Arterial Hypertension

Objectives

SSc-associated pulmonary arterial hypertension (SSc-APAH) is a late but devastating complication of SSc. Early identification of SSc-APAH may improve survival. We examined the role of circulating miRNAs in SSc-APAH.

Methods

Using quantitative RT-PCR the abundance of mature miRNAs in plasma was determined in 85 female patients with ACA-positive lcSSc. Twenty-two of the patients had SSc-APAH. Sixty-three SSc controls without PAH were matched for disease duration. Forty-six selected miRNA plasma levels were correlated with clinical data. Longitudinal samples were analysed from 14 SSc-APAH and 27 SSc patients.

Results

The disease duration was 12 years for the SSc-APAH patients and 12.7 years for the SSc controls. Plasma expression levels of 11 miRNAs were lower in patients with SSc-APAH. Four miRNAs displayed higher plasma levels in SSc-APAH patients compared with SSc controls. There was significant difference between groups for miR-20a-5p and miR-203a-3p when correcting for multiple comparisons (P = 0.002 for both). Receiver operating characteristics curve showed AUC = 0.69–0.83 for miR-21-5p and miR-20a-5p or their combination. miR-20a-5p and miR-203a-3p correlated inversely with NT-pro-Brain Natriuretic Protein levels (r = −0.42 and −0.47). Mixed effect model analysis could not identify any miRNAs as predictor of PAH development. However, miR-20a-5p plasma levels were lower in the longitudinal samples of SSc-APAH patients than in the SSc controls.

Conclusions

Our study links expression levels of the circulating plasma miRNAs, especially miR-20a-5p and miR-203a-3p, to the occurrence of SSc-APAH in female patients with ACA-positive lcSSc.

Longitudinal analysis of T-cell receptor repertoires reveals persistence of antigen-driven CD4+ and CD8+ T-cell clusters in systemic sclerosis

The T-cell receptor (TCR) is a highly polymorphic surface receptor that allows T-cells to recognize antigenic peptides presented on the major histocompatibility complex (MHC). Changes in the TCR repertoire have been observed in several autoimmune conditions, and these changes are suggested to predispose autoimmunity. Multiple lines of evidence have implied an important role for T-cells in the pathogenesis of Systemic Sclerosis (SSc), a complex autoimmune disease. One of the major questions regarding the roles of T-cells is whether expansion and activation of T-cells observed in the diseases pathogenesis is antigen driven. To investigate the temporal TCR repertoire dynamics in SSc, we performed high-throughput sequencing of CD4⁺ and CD8⁺ TCRβ chains on longitudinal samples obtained from four SSc patients collected over a minimum of two years. Repertoire overlap analysis revealed that samples taken from the same individual over time shared a high number of TCRβ sequences, indicating a clear temporal persistence of the TCRβ repertoire in CD4⁺ as well as CD8⁺ T-cells. Moreover, the TCRβs that were found with a high frequency at one time point were also found with a high frequency at the other time points (even after almost four years), showing that frequencies of dominant TCRβs are largely consistent over time. We also show that TCRβ generation probability and observed TCR frequency are not related in SSc samples, showing that clonal expansion and persistence of TCRβs is caused by antigenic selection rather than convergent recombination. Moreover, we demonstrate that TCRβ diversity is lower in CD4⁺ and CD8⁺ T-cells from SSc patients compared with memory T-cells from healthy individuals, as SSc TCRβ repertoires are largely dominated by clonally expanded persistent TCRβ sequences. Lastly, using "Grouping of Lymphocyte Interactions by Paratope Hotspots" (GLIPH2), we identify clusters of TCRβ sequences with homologous sequences that potentially recognize the same antigens and contain TCRβs that are persist in SSc patients. In conclusion, our results show that CD4⁺ and CD8⁺ T-cells are highly persistent in SSc patients over time, and this persistence is likely a result from antigenic selection. Moreover, persistent TCRs form high similarity clusters with other (non-)persistent sequences that potentially recognize the same epitopes. These data provide evidence for an antigen driven expansion of CD4⁺/CD8⁺ T-cells in SSc.

Type III, IV, and VI Collagens Turnover in Systemic Sclerosis - a Longitudinal Study

Tissue turnover, especially in the skin, is altered in systemic sclerosis (SSc), leading to tissue accumulation. The objective was to examine type III, IV, and VI collagens turnovers in SSc and investigate longitudinal alterations in relation to modified Rodnan Skin Score (mRSS). We included patients fulfilling the 2013 ACR/EULAR criteria for SSc (limited cutaneous [lcSSc, n = 20], diffuse cutaneous SSc [dcSSc, n = 23]) and healthy controls (HC, n = 10). Biomarkers of type III, IV, and VI collagens formation (PRO-C3, PRO-C4, PRO-C6) and degradation (C3M, C4M, C6M) were measured in serum. The fibrotic index of the individual collagens (FICol) were calculated. The fibrotic index of type III and VI collagens (FICol3 and FICol6) were increased in dcSSc compared to lcSSc (FICol3: 1.4 vs. 0.8, P = 0.0001; FICol6: 1.2 vs. 0.9, P = 0.03). The fibrotic index of type IV collagen (FICol4) was not different between the groups but was 1.5 times higher than HC (HC: 6.9, lcSSc 10.4, dcSSc: 10.5). Both FICol3 and FICol6 correlated with mRSS with rho's of 0.59 (P < 0.0001) and 0.35 (P = 0.04). Furthermore, FICol3 steadily decrease over the disease course. Examining collagen turnover and specific collagens could be beneficial in following patients' skin fibrosis and possibly identifying progressors.

[Altered serum cytokine expression profile in systemic sclerosis and its regulatory mechanisms]

OBJECTIVE

To analyze the expression profile of serum cytokines in patients with systemic sclerosis (SSc) and explore its possible regulatory mechanisms.

METHODS

Serum and DNA of peripheral blood mononuclear cells were collected from 30 SSc patients and 80 normal controls (NCs). According to the presence or absence of interstitial lung disease (ILD) in SSc, the patients were divided into SSc with ILD group and SSc without ILD group. According to the degree of skin involvement, the patients were divided into diffuse systemic scleroderma (dcSSc) group and limited systemic scleroderma (lcSSc) group. According to the presence of anti-topoisomerase-1 antibody (anti-Scl-70 antibody) in the serum of patients with SSc, they were divided into SSc Scl-70 (+) group and SSc Scl-70 (-) group. 27 cytokines in serum were detected by Luminex MAGPIX detection system and Bio-Plex Pro Human Cytokine 27-plex Assay kit: interleukin-1β (IL-1β), interleukin-1 receptor antagonist (IL-1ra), IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12P70, IL-13, IL-15, IL-17, basic fiber growth factor (BASIC FGF), eotaxin, granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage colony stimulating factor (GM-CSF), interferon-γ (IFN-γ), interferon-gamma induced protein 10(IP-10), monocyte chemotactic protein 1(MCP-1), macrophage inflammatory protein-1α (MIP-1α), macrophage inflammatory protein 1β(MIP-1β), platelet-derived growth factor BB (PDGF-BB), regulated on activation in normal T-cell expressed and secreted (RANTES), tumor necrosis factor-α (TNF-α), and vascular endothelial growth factor(VEGF). Methylation sites were detected by Illumina 450K methylation chip.

RESULTS

Compared with NCs group, the expression of 12 cytokines (BASIC FGF, eotaxin, G-CSF, GM-CSF, IFN-γ, IL-1β, IL-1ra, IL-6, IP-10, MCP-1, TNF-α and RANTES) in the SSc group significantly increased (P<0.05), IL-5 was decreased expression in the SSc group (P<0.05), there was no significant difference in the expressions of the other 14 cytokines. Compared with lcSSc group, 9 cytokines (eotaxin, IL-5, MCP-1, IL-2, RANTES, IL17A, IL-8, MIP-1β and PDGF-BB) increased in dcSSc group, but there was no significant difference. Compared with SSc without ILD group, IL-15 increased in SSC with ILD group [18.2 (172.97) ng/L vs. 2.03(0.05) ng/L, P<0.05]. Compared with SSc Scl-70 (-) group, the expression of IP-10 decreased in SSc Scl-70 (+) group [1 030 (2 196.6) ng/L vs. 1 878 (2 964) ng/L, P<0.05]. The correlation analysis of serum cytokines with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) showed that IL-6 was positively correlated with ESR (r =0.04, P= 0.017), MCP-1 (r=0.49, P=0.043) and MIP-1β (r=0.41, P=0.007) positively correlated with CRP. By analyzing the changes of methylation sites of cytokines, it was found that cg17744604 in IL-10 TSS1500 region, cg06111286 in IL-12P70 TSS200 region, cg07935264 in IL-1β TSS200 region, cg01467417 in IL-1ra TSS1500 region, cg03989987 in IL-1ra 5'UTR region and cg21099624 in VEGF TSS200 region were all hypomethylated.

CONCLUSION

There were different cytokines expression profiles in the serum of SSc patients, and the altered cytokines were correlected with the degree of skin damage and pulmonary fibrosis. Many cytokines were regulated by methylation.

Personalised medicine in interstitial lung diseases

Interstitial lung diseases in general, and idiopathic pulmonary fibrosis in particular, are complex disorders with multiple pathogenetic pathways, various disease behaviour profiles and different responses to treatment, all facets that make personalised medicine a highly attractive concept. Personalised medicine is aimed at describing distinct disease subsets taking into account individual lifestyle, environmental exposures, genetic profiles and molecular pathways. The cornerstone of personalised medicine is the identification of biomarkers that can be used to inform diagnosis, prognosis and treatment stratification. At present, no data exist validating a personalised approach in individual diseases. However, the importance of the goal amply justifies the characterisation of genotype and pathway signatures with a view to refining prognostic evaluation and trial design, with the ultimate aim of selecting treatments according to profiles in individual patients.

Current perspectives on the role of CD8+ T cells in systemic sclerosis

Despite long-standing recognition of the importance of T cells in systemic sclerosis (SSc; scleroderma), the role of CD8⁺ T cells in disease pathogenesis has not been well studied. Our work has shown that over-production of the pro-fibrotic cytokine IL-13 by peripheral blood effector/memory CD8⁺ T cells is critical for predisposing patients to more severe forms of cutaneous fibrosis. Moreover, IL-13-producing CD8⁺ T cells induce a pro-fibrotic phenotype in normal and SSc dermal fibroblasts, and exhibit a strong cytotoxic activity ex vivo. We also found that CD8⁺ T cells are predominantly abundant in the skin lesions of patients in the early stages of diffuse cutaneous (dc)SSc compare to late-stage disease patients. Isolation of CD8⁺ T cells from the lesional skin of early active dcSSc patients, established that they are skin-resident, express cytolytic molecules and co-express extremely high levels of IL-13 and IFNγ. Other recent studies corroborate these findings and together strongly suggest that CD8⁺ T cells contribute to SSc pathogenesis through the production of high levels of cytokines with pro-inflammatory and pro-fibrotic function as well as by exhibiting a cytotoxic activity.

Elevated levels of TL1A are associated with disease activity in patients with systemic sclerosis

TL1A is a member of the TNF superfamily. It performs significantly in the pathogenesis of rheumatic and autoimmune diseases partly through regulating the Th17 pathway. The clinical implication of circulating TL1A in patients with systemic sclerosis (SSc) remains unclear, and correlation between TL1A and Th17-related cytokines in the pathogenesis of SSc needs to be discussed. We measured serum levels of TL1A and Th17-related cytokines by ELISA in 47 patients with SSc, 56 patients with SLE, and 53 healthy subjects, and investigated association of these cytokines with clinical manifestations and laboratory variables. TL1A in relation to Th17-related cytokines were examined. In addition, the transcript level of TL1A in peripheral blood mononuclear cells (PBMCs) was determined by real-time reverse transcription polymerase chain reaction (real-time PCR). Serum TL1A levels were higher in patients with SSc than in healthy controls (P = 0.001), but were lower compared with SLE patients (P = 0.004). Diffuse cutaneous SSc or limited cutaneous SSc patients reported elevated expression of TL1A than those in healthy controls (P = 0.002, P = 0.007). Patients with active disease showed significantly higher expression of TL1A when compared with less active disease (P = 0.014). SSc patients with arthritis, elevated IgG titer, ESR >30 mm/h, and CRP >5 mg/l displayed elevated expression of TL1A, respectively. Serum levels of IL-17 and IL-21 were increased in SSc patients compared with healthy controls and positively related to TL1A levels (r _s = 0.373, P = 0.010; r _s = 0.370, P = 0.011, respectively). Moreover, TL1A mRNA expression in PBMCs was significantly higher in patients with SSc compared with healthy controls (P < 0.001). TL1A may play a role in the development of SSc.

Interleukin-15 receptor α on hepatic stellate cells regulates hepatic fibrogenesis in mice

BACKGROUND & AIMS

Interleukin-15 (IL-15) and its high affinity receptor interleukin-15 receptor alpha (IL-15Rα) are widely expressed in immune cells and hepatic resident cells. IL-15 signaling has important functions in homeostasis of natural killer (NK), natural killer T (NKT) and cytotoxic T (CD8(+) T) cells, and in liver regeneration. We hypothesized that IL-15 has a protective role in liver fibrosis progression by maintaining NK cell homeostasis.

METHODS

Fibrosis was induced using two mechanistically distinct models. Congenic bone marrow transplantation was used to evaluate the contribution of IL-15 signaling from various compartments to NK, CD8(+) T and NKT cell homeostasis and fibrogenesis. The gene expression profile of hepatic stellate cell (HSC) from IL-15Rα knockout (IL-15RαKO) mice and wild-type mice were captured using microarray analysis and validated in isolated HSC. Quantitative real-time PCR was used to assess repressors of collagen transcription.

RESULTS

IL-15RαKO mice exhibited more fibrosis in both models. IL-15 signaling from specific types of hepatic cells had divergent roles in maintaining liver NK, CD8(+) T and NKT cells, with a direct and protective role on radio-resistant non-parenchymal cells beyond the control of NK homeostasis. HSCs isolated from IL-15RαKO mice demonstrated upregulation of collagen production. Finally, IL-15RαKO HSC with or without transforming growth factor beta (TGF-β) stimulation exhibited increased expression of fibrosis markers and decreased collagen transcription repressors expression.

CONCLUSIONS

IL-15Rα signaling has a direct anti-fibrotic effect independent of preserving NK homeostasis. These findings establish a rationale to further explore the anti-fibrotic potential of enhancing IL-15 signaling in HSCs.

LAY SUMMARY

We investigated how a cellular protein, Interleukin-15 (IL-15), decreases the amount of scar tissue that is formed upon liver injury. We found that IL-15 and its receptor decrease the amount of scar tissue that is created by specialized liver cells (called stellate cells) and increase the number of a specific subgroup of immune cells (natural killer cells) that are known to eliminate stellate cells.

TRANSCRIPT PROFILING ACCESSION NUMBER

GSE45612, GSE 68001 and GSE 25097.

Metabolic Profiling of Systemic Lupus Erythematosus and Comparison with Primary Sjögren's Syndrome and Systemic Sclerosis

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease which can affect most organ systems including skin, joints and the kidney. Clinically, SLE is a heterogeneous disease and shares features of several other rheumatic diseases, in particular primary Sjögrens syndrome (pSS) and systemic sclerosis (SSc), why it is difficult to diagnose The pathogenesis of SLE is not completely understood, partly due to the heterogeneity of the disease. This study demonstrates that metabolomics can be used as a tool for improved diagnosis of SLE compared to other similar autoimmune diseases. We observed differences in metabolic profiles with a classification specificity above 67% in the comparison of SLE with pSS, SSc and a matched group of healthy individuals. Selected metabolites were also significantly different between studied diseases. Biochemical pathway analysis was conducted to gain understanding of underlying pathways involved in the SLE pathogenesis. We found an increased oxidative activity in SLE, supported by increased xanthine oxidase activity and an increased turnover in the urea cycle. The most discriminatory metabolite observed was tryptophan, with decreased levels in SLE patients compared to control groups. Changes of tryptophan levels were related to changes in the activity of the aromatic amino acid decarboxylase (AADC) and/or to activation of the kynurenine pathway.

Risk factors for severity and manifestations in systemic sclerosis and prediction of disease course

Systemic sclerosis (SSc, or scleroderma) is a rheumatic disease with distinct features that encompass autoimmunity, vascular lesions (vasculopathy) and tissue fibrosis. The disease has a high morbidity and mortality compared with other rheumatic diseases. This review discusses risk factors and markers that predict the disease course and the occurrence of disease manifestations, with an emphasis on major organ involvement. In addition, risk factors will be described that are associated with mortality in SSc patients. The review addresses the impact of recent developments on screening, diagnosis and risk stratification as well as the need for further research where data are lacking.

CD81 and CD48 show different expression on blood eosinophils in systemic sclerosis: new markers for disease and pulmonary inflammation?

OBJECTIVES

In systemic sclerosis (SSc)-related interstitial lung disease (ILD), elevated eosinophil counts in bronchoalveolar lavage are associated with a worse outcome. We hypothesized that eosinophils may be activated in the peripheral circulation, thereby increasing their recruitment to affected tissues and contributing to inflammation and fibrosis. The aim of this study was to characterize the blood eosinophils in SSc patients.

METHOD

Expression levels of surface markers CD11b, CD44, CD48, CD54, CD69, CD81, and HLA-DR on CD16(low)CD9(high)-expressing eosinophils were measured by flow cytometry in whole blood from SSc patients (n = 32) and controls (n = 11).

RESULTS

Expression levels of CD54, CD69, and HLA-DR were undetectable in all groups. CD44 and CD11b expression levels were similar between groups. CD81 expression was lower in patients compared to controls independent of disease duration (p = 0.001). CD48 expression was increased in patients with a short disease duration (< 2 years) compared to both controls (p = 0.042) and patients with longer disease duration (≥ 2 years; p = 0.027). In patients with short disease duration, increased CD48 expression was associated with alveolar inflammation as measured by an increased concentration of alveolar nitric oxide (r = 0.76, p = 0.003).

CONCLUSIONS

Blood eosinophils change phenotype during disease evolution in SSc, and CD48 expression may be used as a biomarker for pulmonary inflammation.

Specific autoantibody profiles and disease subgroups correlate with circulating micro-RNA in systemic sclerosis

OBJECTIVE

To evaluate the expression profiles of cell-free plasma miRNAs in SSc and to characterize their correlation with disease subgroups (lcSSc and dcSSc) and with autoantibody profiles.

METHODS

Using quantitative RT-PCR, the abundance of 45 mature miRNAs in plasma was determined in 95 patients (lcSSc = 63; dcSSc = 32), representing the following autoantibody subgroups: ACA, anti-DNA topoisomerase I, anti-RNA polymerase III and anti-U1-ribonucleoprotein. MiRNA data were correlated with clinical and paraclinical data. Multiple regression was used to model membership of the lcSSc, dcSSc and autoantibody subgroups, based on miRNA expression profiles.

RESULTS

Thirty-six miRNAs were measurable in all samples. Four (miRNA-223, -181b, -342-3p and -184) were differently expressed in lcSSc and dcSSc (false discovery rate < 0.05). Ten miRNAs exhibited statistically significantly different levels in one or more autoantibody groups, and five (miRNA-409, -184, -92a, -29a and -101) remained significant after correction for multiple comparisons. Multiple regression models accurately predicted ACA and anti-DNA topoisomerase I antibody-positive patients (area under the curve (AUC) = 0.97 and 0.93, respectively) as well as membership of the dcSSc and lcSSc groups (AUC = 0.88).

CONCLUSION

Circulating miRNA profiles differ between lcSSc and dcSSc patients and between patients with different autoantibodies. This is the first time autoantibody profiles, disease phenotypes and plasma miRNA profiles have been shown to correlate in an autoimmune disease. The data support a pathobiological role of miRNAs because specific miRNAs associate with autoantibody profiles of known diagnostic and prognostic value.

Truncated CXCL10 is associated with failure to achieve spontaneous clearance of acute hepatitis C infection

The pathogenesis of hepatitis C virus (HCV) infection is strongly influenced by the nature of the host's antiviral immunity. Counterintuitively, elevated serum concentrations of C-X-C chemokine 10 (CXCL10), a potent chemoattractant for antiviral T-cells and NK-cells, are associated with poor treatment outcomes in patients with chronic HCV. It has been reported that an N-terminal truncated form of CXCL10, generated by the protease dipeptidylpeptidase 4 (DPP4), can act as chemokine antagonist. We sought to investigate CXCL10 antagonism in the clinical outcome and evolution of acute HCV infection. We collected serial blood samples from 16 patients, at the clinical onset of acute HCV infection and at 12 standardized follow-up timepoints over the first year. Intact and truncated CXCL10 and DPP4 activity were quantified in all longitudinal samples. In addition, NK-cell frequency/phenotype, and HCV-specific T-cell responses were assessed. Subjects developing chronicity (n = 11) had higher concentrations of CXCL10 (P < 0.001), which was predominantly in a truncated form (P = 0.036) compared to patients who spontaneously resolved infection (n = 5). Truncated CXCL10 correlated with HCV-RNA (r = 0.40, P < 0.001) and DPP4 activity (r = 0.53, P < 0.001). Subjects who resolved infection had a higher frequency of HCV-specific interferon-gamma (IFNγ)-producing T-cells (P = 0.017) and predominance of cytotoxic NK-cells (P = 0.005) compared to patients who became chronic. Patients who became persistently infected had higher proportions of cytokine-producing NK-cells, which were correlated with concentrations of truncated CXCL10 (r = 0.92, P < 0.001).

CONCLUSION

This study provides the first evidence of chemokine antagonism during acute HCV infection. We suggest that the DPP4-CXCL10 axis inhibits antiviral innate and adaptive host immunity and favors establishment of viral persistence.

Circulating angiogenic modulatory factors predict survival and functional class in pulmonary arterial hypertension

The diagnosis of pulmonary arterial hypertension (PAH) is frequently delayed. We hypothesized that circulating angiogenic modulatory protein levels might correspond with vascular remodeling activity and serve as sensitive biomarkers of PAH. Levels of soluble endoglin (sEng), soluble vascular endothelial growth factor receptor-1 (sVEGFR1), N-terminal brain natriuretic peptide (NT-proBNP), C-reactive protein (CRP), and other biomarkers were measured in peripheral blood from 97 PAH patients, 16 first-degree relatives of idiopathic or heritable pulmonary arterial hypertension (HPAH) patients, and 56 controls, and correlated with disease, functional class, hemodynamic parameters, exercise capacity, and transplant-free survival. Endoglin expression was analyzed in lung tissues of six individuals with idiopathic or HPAH and four individuals without PAH. Levels of sEng, sVEGFR1, CRP, and NT-proBNP were elevated in Group I PAH of diverse etiologies, with sEng performing better than NT-proBNP in detecting PAH (receiver operator characteristic-area-under-the curve [ROC-AUC] of 0.82 ± 0.03 vs. 0.71 ± 0.05, P = 0.016). While sEng, sVEGFR1, and NT-proBNP correlated with New York Heart Association (NYHA) class, sEng levels were more sensitive than NT-proBNP in detecting NYHA Class I-II disease (ROC-AUC of 0.88 ± 0.05 vs. 0.67 ± 0.08, P = 0.028). sEng, sVEGFR1, CRP, and NT-proBNP predicted transplant-free survival by univariate Cox regression. After adjusting for NT-proBNP levels, each of the other three markers predicted transplant-free survival. In multivariate analysis, sEng and CRP were independent predictors of survival. Endoglin expression was markedly enhanced in the microvascular endothelium and endovascular lesions of PAH versus control lung tissues. Circulating angiogenic proteins sEng and sVEGFR1 are sensitive markers of prognosis and function in Group I PAH, including mildly symptomatic disease, and may provide unique noninvasive data reflecting underlying remodeling activity.

Increased serum type I interferon activity in early systemic sclerosis patients is associated with antibodies against Sjögren's syndrome antigens and nuclear ribonucleoprotein antigens

OBJECTIVE

To study serum type I interferon (IFN) activity in patients with early systemic sclerosis (SSc).

METHOD

Serum type I IFN activity was measured in 33 consecutive patients with SSc and a disease duration of < 2 years and in 13 healthy individuals by calculating a type I IFN score according to the induction of six IFN-α regulated genes in a reporter cell line.

RESULTS

Twenty-seven per cent of the SSc patients had an increased type I IFN score compared to none of the healthy individuals (p < 0.05). The clinical SSc phenotype associated with high serum type I IFN activity did not differ from patients with low serum type I IFN activity regarding the presence of skin or lung fibrosis, pulmonary hypertension, or digital complications. Patients with high serum type I IFN activity were younger (p < 0.01) and had a lower frequency of cardiac involvement (p = 0.053), lower leucocyte count (p < 0.001), higher immunoglobulin (Ig)G levels (p < 0.05), and a higher amount of antibodies against extractable nuclear antigens (p < 0.01) than patients with low serum type I IFN activity. The presence of antibodies against topoisomerase I, Sjögren's syndrome antigen, and nuclear ribonucleoprotein antigens was associated with higher type I IFN activity (p < 0.05 for all comparisons).

CONCLUSIONS

Our study indicates that increased serum type I IFN activity in early SSc patients is associated with an antibody and laboratory profile that may reflect a subclinical overlap of SSc with other type I IFN-driven connective tissue diseases (CTDs).

Brain interleukin-15 in neuroinflammation and behavior

Interleukin (IL)-15 is a ubiquitously expressed cytokine existing in both intracellular and secretory forms. Here we review the expression, regulation, and functions of IL15 and its receptors in the brain. IL15 receptors show robust upregulation after neuroinflammation, suggesting a major role of IL15 signaling in cerebral function. Involvement of the IL15 system in neuropsychiatric behavior is reflected by the effects of IL15, IL15Rα, and IL2Rγ deletions on neurobehavior and neurotransmitters, the effects of IL15 treatment on neuronal activity, and the potential role of IL15 in neuroplasticity/neurogenesis. The results show that IL15 modulates GABA and serotonin transmission. This may underlie deficits in mood (depressive-like behavior and decreased normal anxiety) and memory, as well as activity level, sleep, and thermoregulation. Although IL15 has only a low level of permeation across the blood-brain barrier, peripheral IL15 is able to activate multiple signaling pathways in neurons widely distributed in CNS regions. The effects of IL15 in "preventing" neuropsychiatric symptoms in normal mice implicate a potential therapeutic role of this polypeptide cytokine.

Circulating biomarkers of interstitial lung disease in systemic sclerosis

Interstitial lung disease (ILD) is a major cause of morbidity and mortality in patients with systemic sclerosis (SSc). Although a large proportion of SSc patients have only limited interstitial involvement with an indolent course, in a significant minority ILD is progressive, requiring prompt treatment and careful monitoring. One of the main challenges for the clinician treating this highly variable disease is the early identification of patients at risk of progressive ILD, while avoiding potentially toxic treatments in those whose disease is inherently stable. Easily available and repeatable biomarkers that allow estimation of the risk of ILD progression and early response to treatment are highly desirable. In this paper, we review the evidence for circulating biomarkers with potential roles in diagnosis, monitoring of disease activity, or determining prognosis. Peripheral blood biomarkers offer the advantages of being readily obtained, non-invasive, and serially monitored. Several possible candidates have emerged from studies performed so far, including SP-D, KL-6, and CCL18. Presently however, there are few prospective studies evaluating the predictive ability of prospective biomarkers after adjustment for disease severity. Future carefully designed, prospective studies of well characterised patients with ILD, with optimal definition of disease severity and outcome measures are needed.

Application of biomarkers to clinical trials in systemic sclerosis

Important clinical advances in the treatment of systemic sclerosis have been made, yet fibrotic disease remains largely untreatable. Optimal design of clinical trials to test new therapeutics for fibrotic disease features has suffered from dual difficulties in patient selection and patient evaluation. Patient selection for entry into trials for treatment of interstitial lung disease and/or skin fibrosis is challenged by the natural history of the disease, which stabilizes in some patients while relentlessly progressing in others, and our lack of good clinical markers to distinguish between these trajectories. Patient evaluation is made difficult, particularly in skin disease, by the inherent difficulty in quantifying the extent of disease. Biomarkers hold the potential to solve many of these problems as surrogate outcome measures and as markers for disease progression. Identified biomarkers may have the potential to graduate to surrogate outcome singly or, more likely, in combination. Predictive biomarkers are still largely unknown.

Systemic sclerosis with hemoptysis and a huge lung cavity

Systemic sclerosis or scleroderma is associated with distal vasculitis, Raynaud's phenomenon, and inflammation of internal organs and the skin. We present on a 58-year-old Thai woman with systemic sclerosis who came to the 10^th Zonal Tuberculosis and Chest Disease Center, Chiang Mai, Thailand in 2009 and presented with hemoptysis and a solitary huge-lung cavity as the predominant clinical manifestations which spontaneously resoluted 2 months later. This case demonstrates a solitary huge-lung cavity with hemoptysis and looked like from non-tuberculous Mycobacterial infections or malignancy with spontaneous resolution of hemoptysis and the lung cavity, which does not need invasive investigations.

Identification of a potent anti-IL-15 antibody with opposing mechanisms of action in vitro and in vivo

BACKGROUND AND PURPOSE

Interleukin-15 (IL-15) is important in the activation and proliferation of lymphocytic cell populations and is implicated in inflammatory disease. We report the characterization of a novel monoclonal antibody DISC0280 which is specific for human IL-15.

EXPERIMENTAL APPROACH

DISC0280 was characterized in a direct binding assay of IL-15 with IL-15 receptor α (IL-15Rα) and by its ability to alter IL-15 mediated proliferation of a range of cell lines (cytotoxic T lymphocyte line-2, M-07e, KIT225). A pharmacodynamic model injecting male C57/BL6 mice with IL-15 or IL-15/IL-15Rα, with or without DISC0280, and assessing changes in lymphocytic cell populations and serum cytokines was utilized.

KEY RESULTS

DISC0280 inhibited the binding of IL-15 to IL-15Rα and also potently inhibits IL-15 dependent proliferation of cells expressing IL-15Rα, shared interleukin 2/ interleukin 15 receptor β chain (IL-15Rβ) and common gamma chain (γ(c) ). DISC0280 also inhibited the IL-15 dependent proliferation of M-07e cells that only express IL-15Rβ/γ(c) subunits. Human IL-15 injected into mice caused an increase in NK1.1(+) and CD3(+) cells in the spleen and peripheral blood and these effects were unexpectedly potentiated by giving DISC0280 with human IL-15. This increase in cells caused by DISC0280/IL-15 co-administration was greater than that observed when IL-15 was administered complexed with soluble IL-15Rα.

CONCLUSIONS AND IMPLICATIONS

The ability of DISC0280 to bind to the IL-15Rα-binding site on IL-15 allows trans-presentation of IL-15 by DISC0280 in vivo, similar to the trans-presentation by soluble IL-15Rα. DISC0280 may be therefore suitable as a clinical substitute for IL-15.

Serum protein profiling of systemic lupus erythematosus and systemic sclerosis using recombinant antibody microarrays

Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are two severe autoimmune connective tissue diseases. The fundamental knowledge about their etiology is limited and the conditions display complex pathogenesis, multifaceted presentations, and unpredictable courses. Despite significant efforts, the lack of fully validated biomarkers enabling diagnosis, classification, and monitoring of disease activity represents significant unmet clinical needs. In this discovery study, we have for the first time used recombinant antibody microarrays for miniaturized, multiplexed serum protein profiling of SLE and SSc, targeting mainly immunoregulatory proteins. The data showed that several candidate SLE-associated multiplexed serum biomarker signatures were delineated, reflecting disease (diagnosis), disease severity (phenotypic subsets), and disease activity. Selected differentially expressed markers were validated using orthogonal assays and a second, independent patient cohort. Further, biomarker signatures differentiating SLE versus SSc were demonstrated, and the observed differences increased with severity of SLE. In contrast, the data showed that the serum profiles of SSc versus healthy controls were more similar. Hence, we have shown that affinity proteomics could be used to de-convolute crude, nonfractionated serum proteomes, extracting molecular portraits of SLE and SSc, further enhancing our fundamental understanding of these complex autoimmune conditions.

Increased cysteinyl-leukotrienes and 8-isoprostane in exhaled breath condensate from systemic sclerosis patients

OBJECTIVES

SSc is a systemic CTD characterized by fibrosis in skin and internal organs. Interstitial lung disease is a frequent complication with fibrosis in the lung parenchyma. The fibrotic process is believed to be influenced by leukotrienes (LTs) and also by oxidative stress. The aim of this study was to investigate the amount of LTs and 8-isoprostane, a marker of oxidative stress, in exhaled breath condensate (EBC) from SSc patients.

METHODS

Twenty-two SSc patients with median disease duration of 2.1 years were investigated. Fifteen patients had lcSSc, four patients had dcSSc and three patients only fulfilled criteria for limited SSc. Sixteen healthy controls were enrolled. Cysteinyl-LTs (CysLTs), LTB4 and 8-isoprostane were measured in EBC with EIA and related to the radiologic extent of pulmonary fibrosis.

RESULTS

Compared with controls, SSc patients displayed higher median (interquartile range) CysLT [6.1 (5.3-6.8) vs 4.9 (3.7-6.3) pg/ml; P=0.040], 8-isoprostane [0.23 (0.20-0.46) vs 0.19 (0.12-0.20) pg/ml; P=0.0020], but similar levels of LTB4 [0.70 (0.50-0.83) vs 0.60 (0.42-0.70) pg/ml]. CysLT correlated to LTB4, while 8-isoprostane did not correlate to any of the LTs. None of the biomarkers measured in EBC correlated to radiologic findings.

CONCLUSION

Increased levels of CysLT and 8-isoprostane in EBC from patients with SSc reflect the inflammatory pattern involving LTs as well as oxidative stress. These findings may indicate a possible non-invasive assessment of pulmonary involvement in SSc with a potential value for assessment of disease progress and therapy evaluation.

Biomarkers in systemic sclerosis

Systemic sclerosis is an autoimmune inflammatory disorder of unknown etiologycharacterized b y pronounced fibroproliferative alterations in the microvasculature, and frequent cellular and humoral immunity abnormalities, culminating in a severe and often progressive fibrotic process. Numerous biomarkers reflecting the three main pathogenetic mechanisms in systemic sclerosis have been described; however, aside from several disease-specific autoantibodies, other biomarkers have not been thoroughly validated and require further study. Thus, there is an unmet need for validated biomarkers for diagnosis, disease classification, and evaluation of organ involvement and therapeutic response in systemic sclerosis.