Worse cardiovascular and renal outcome in male SLE patients.

Systemic lupus erythematosus (SLE) in males is rare and poorly understood. Thus, still little is known about sex differences in SLE. We set out to identify sex differences regarding clinical manifestations as well as renal and cardiovascular outcomes of SLE. We analyzed patient data from the Swiss SLE Cohort Study. Cumulative clinical manifestations according to the updated American College of Rheumatology criteria were recorded at inclusion. Cardiovascular events were recorded within Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC-SDI). Renal failure was defined as eGFR < 15 ml/min/1.73 m2, initiation of renal replacement therapy or doubling of serum creatinine which were all assessed yearly or documented as end stage renal disease in SLICC-SDI. Risk differences were calculated using logistic regression and cox regression models. We analyzed 93 men and 529 women with a median follow up time of 2 years. Males were significantly older at diagnosis (44.4 versus 33.1 years, p < 0.001) and had less often arthritis (57% versus 74%, p = 0.001) and dermatological disorders (61% versus 76%, p < 0.01). In multivariate analysis female sex remained a significantly associated with arthritis and dermatological disorders. In multivariate analysis men had a significantly higher hazard ratio of 2.3 for renal failure (95% confidence interval (95%-CI) 1.1-5.2, p < 0.04). Total SLICC-SDI Score was comparable. Men had significantly more coronary artery disease (CAD) (17% versus 4%, p < 0.001) and myocardial infarction (10% versus 2%, p < 0.01). In multivariate analysis, male sex remained a significant risk factor for CAD (odds ratio (OR) 5.6, 95%-CI 2.3-13.7, p < 0.001) and myocardial infarction (OR 8.3, 95%-CI 2.1-32.6, p = 0.002). This first sex study in a western European population demonstrates significant sex differences in SLE. Male sex is a risk factor for cardiovascular events and renal failure in SLE. Potential etiological pathomechanisms such as hormonal or X-chromosomal factors remain to be further investigated.

Current Concepts on the Pathogenesis of Systemic Sclerosis.

From the clinical standpoint, systemic sclerosis (SSc) is characterized by skin and internal organ fibrosis, diffuse fibroproliferative vascular modifications, and autoimmunity. Clinical presentation and course are highly heterogenous and life expectancy variably affected mostly dependent on lung and heart involvement. SSc touches more women than men with differences in disease severity and environmental exposure. Pathogenetic events originate from altered homeostasis favored by genetic predisposition, environmental cues and a variety of endogenous and exogenous triggers. Epigenetic modifications modulate SSc pathogenesis which strikingly associate profound immune-inflammatory dysregulation, abnormal endothelial cell behavior, and cell trans-differentiation into myofibroblasts. SSc myofibroblasts show enhanced survival and enhanced extracellular matrix deposition presenting altered structure and altered physicochemical properties. Additional cell types of likely pathogenic importance are pericytes, platelets, and keratinocytes in conjunction with their relationship with vessel wall cells and fibroblasts. In SSc, the profibrotic milieu is favored by cell signaling initiated in the one hand by transforming growth factor-beta and related cytokines and in the other hand by innate and adaptive type 2 immune responses. Radical oxygen species and invariant receptors sensing danger participate to altered cell behavior. Conventional and SSc-specific T cell subsets modulate both fibroblasts as well as endothelial cell dysfunction. Beside autoantibodies directed against ubiquitous antigens important for enhanced clinical classification, antigen-specific agonistic autoantibodies may have a pathogenic role. Recent studies based on single-cell RNAseq and multi-omics approaches are revealing unforeseen heterogeneity in SSc cell differentiation and functional states. Advances in system biology applied to the wealth of data generated by unbiased screening are allowing to subgroup patients based on distinct pathogenic mechanisms. Deciphering heterogeneity in pathogenic mechanisms will pave the way to highly needed personalized therapeutic approaches.

Cutaneous vasculitis occurring in the setting of systemic lupus erythematosus: a multicentre cohort study.

OBJECTIVES: To describe the clinical and pathological features of biopsy-proven cutaneous vasculitis (CV) associated with SLE, focusing on diagnosis classification and impact on overall SLE activity. METHODS: Retrospective multicentric cohort study including SLE patients with biopsy-proven CV identified by (i) data from pathology departments of three university hospitals and (ii) a national call for cases. SLE was defined according to 1997 revised ACR and/or 2019 ACR/EULAR criteria. CV diagnosis was confirmed histologically and classified by using the dermatological addendum of the Chapel Hill classification. SLE activity and flare severity at the time of CV diagnosis were assessed independently of vasculitis items with the SELENA-SLEDAI and SELENA-SLEDAI Flare Index. RESULTS: Overall, 39 patients were included; 35 (90%) were female. Cutaneous manifestations included mostly palpable purpura (n = 21; 54%) and urticarial lesions (n = 18; 46%); lower limbs were the most common location (n = 33; 85%). Eleven (28%) patients exhibited extracutaneous vasculitis. A higher prevalence of Sjögren's syndrome (51%) was found compared with SLE patients without CV from the French referral centre group (12%, P < 0.0001) and the Swiss SLE Cohort (11%, P < 0.0001). CV was mostly classified as urticarial vasculitis (n = 14, 36%) and cryoglobulinaemia (n = 13, 33%). Only 2 (5%) patients had no other cause than SLE to explain the CV. Sixty-one percent of patients had inactive SLE. CONCLUSION: SLE-related vasculitis seems very rare and other causes of vasculitis should be ruled out before considering this diagnosis. Moreover, in more than half of patients, CV was not associated with another sign of active SLE.

Urinary incontinence in systemic sclerosis: a prospective multicentre cohort study.

Investigate the natural history of urinary incontinence (UI) in systemic sclerosis (SSc) and assess its impact on quality of life (QoL). A longitudinal, international observational study followed 189 patients with SSc for a median duration of 5 years (IQR: 4.8-5.3). Presence, subtype and severity of UI, hospital admission and QoL were assessed using serial self-administered questionnaires. Mortality data came from national death registries. Multilevel mixed-effect logistic regressions explored factors associated with UI. Cox models adjusted the effects of UI on hospitalization and death for age, sex and subtype of SSc. Mean annual rates of new-onset UI and remission were 16.3% (95%CI 8.3%-24.2%) and 20.8% (95%CI 12.6-29.1), respectively. Among UI patients, 57.9% (95%CI 51.8-64.0) changed from one UI subtype to another. Between annual questionnaires, the severity of UI was the same in 51.1% (95%CI 40.8-61.4), milder or resolved in 35.2% (95%CI 25.3-44.9), and worse in 13.8% (95%CI 6.7-20.9). Anti-centromere antibodies, digestive symptoms, sex, age, neurological or urological comorbidities, diuretics and puffy fingers were all associated with UI. The two strongest predictors of UI and UI subtypes were a recent UI episode and the subtype of previous leakage episodes. UI at inclusion was not associated with hospital admission (adjusted HR: 1.86; 95%CI 0.88-3.93), time to death (aHR: 0.84; 95%CI 0.41-1.73) or change in QoL over time. Self-reported UI among SSc patients is highly dynamic: it waxes and wanes, changing from one subtype to another over time.

Contribution of keratinocytes to dermal fibrosis.

PURPOSE OF REVIEW: The cellular pathogenesis of fibrotic disorders including systemic sclerosis (SSc) remains largely speculative. Currently, the altered function of endothelial cells and fibroblasts under the influence of an inappropriate immune response are considered central pathogenic events in SSc. Adding to this complexity, novel evidence here reviewed suggests that keratinocytes may concur in the development of skin fibrosis. RECENT FINDINGS: Epidermal equivalents (EE) generated from primary SSc keratinocytes display a distinct gene expression program when compared to healthy donor (HD) EE. SSc-EE, among others, exhibited enhanced oxidative and metabolic response pathways. Immunohistochemical studies demonstrated similarities between SSc-EE and SSc epidermis including altered keratinocyte differentiation, enhanced expression of activation markers, and reduced rate of basal keratinocytes proliferation. SSc-EE supernatants more than HD-EE modified the inflammatory and extracellular matrix deposition/resorption program of dermal fibroblasts. Further evidence indicated that the relative lack rather than the excess of interleukin-25 in keratinocytes may contribute to enhanced dermal fibrotic changes. Overall, these data support keratinocyte-intrinsic SSc-related modifications. SUMMARY: Improved methods for engineering epidermal and skin equivalents are helping to address the question whether keratinocyte alterations in SSc are primary and capable to dysregulate dermal homeostasis or secondary following dermal fibrotic changes.

IL-25 participates in keratinocyte-driven dermal matrix turnover and is reduced in systemic sclerosis epidermis.

OBJECTIVES: Evidence shows that dysfunctional SSc keratinocytes contribute to fibrosis by altering dermal homeostasis. Whether IL-25, an IL-17 family member regulating many epidermal functions, takes part in skin fibrosis is unknown. Here we address the role of IL-25 in skin fibrosis. METHODS: The expression of IL-25 was evaluated by immunofluorescence and in situ hybridization in 10 SSc and seven healthy donor (HD) skin biopsies. Epidermal equivalents (EE) reconstituted by primary HD keratinocytes were used as a model to study transcriptomic changes induced by IL-25 in the epidermis. RNA expression profile in EEs was characterized by RNAseq. The conditioned medium (CM) from primary SSc and HD keratinocytes primed with IL-25 was used to stimulate fibroblasts. IL-6, IL-8, MMP-1, type-I collagen (Col-I), and fibronectin production by fibroblasts was assessed by ELISA. RESULTS: SSc epidermis expressed lower levels of IL-25 compared with HDs. In EEs, IL-25 regulated several molecular pathways related to wound healing and extracellular matrix remodelling. Compared with control CM, the CM from IL-25-primed keratinocytes enhanced the fibroblast production of MMP-1, IL-6 and IL-8, but not of Col-I nor fibronectin. However, IL-25 significantly reduced the production of Col-I when applied directly to fibroblasts. The activation of keratinocytes by IL-25 was receptor-dependent and evident after a very short incubation time (10 min), largely mediated by IL-1, suggesting enhanced and specific release of preformed mediators. CONCLUSIONS: These results show that IL-25 participates in skin homeostasis, and its decreased expression in SSc may contribute to skin fibrosis by favouring extracellular matrix deposition over degradation.

Interleukin-1ß-Activated Microvascular Endothelial Cells Promote DC-SIGN-Positive Alternatively Activated Macrophages as a Mechanism of Skin Fibrosis in Systemic Sclerosis.

OBJECTIVE: To characterize the role of interleukin-1ß (IL-1ß) and microvascular endothelial cells (MVECs) in the generation of alternatively activated macrophages in the skin, and to explore their role in the development of skin fibrosis in patients with systemic sclerosis (SSc; scleroderma). METHODS: Conditioned medium prepared with MVECs purified from the skin of healthy donors and the skin of SSc patients was used to generate monocyte-derived macrophages. Flow cytometry, multiplex protein assessment, real-time quantitative polymerase chain reaction, and tissue immunofluorescence were used to characterize MVEC-induced polarization of alternatively activated macrophages. Coculture experiments were conducted to assess the role of MVEC-induced alternatively activated macrophages in fibroblast activation. Alternatively activated macrophages were characterized in the skin of healthy donors and SSc patients using multiparametric immunofluorescence and multiplex immunostaining for gene expression. Based on our in vitro data, we defined a supervised macrophage gene signature score to assess correlation between the macrophage score and clinical features in patients with SSc, using the Spearman's test. RESULTS: IL-1ß-activated MVECs from SSc patients induced monocytes to differentiate into DC-SIGN+ alternatively activated macrophages producing high levels of CCL18, CCL2, and CXCL8 but low levels of IL-10. DC-SIGN+ alternatively activated macrophages showed significant enhancing effects in promoting the production of proinflammatory fibroblasts and were found to be enriched in perivascular regions of the skin of SSc patients who had a high fibrosis severity score. A novel skin transcriptomic macrophage signature, defined from our in vitro findings, correlated with the extent of skin fibrosis (Spearman's r = 0.6, P = 0.0018) and was associated with early disease manifestations and lung involvement in patients with SSc. CONCLUSION: Our findings shed new light on the vicious circle implicating unabated IL-1ß secretion, MVEC activation, and the generation of DC-SIGN+ alternatively activated macrophages in the development of skin fibrosis in patients with SSc.

Variants Affecting the C-Terminal Tail of UNC93B1 Are Not a Common Risk Factor for Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a heterogeneous multifactorial disease. Upregulated TLR7 signaling is a known risk factor for SLE. Recently, it was shown that specific genetic variants in UNC93B1 affect the physiological regulation of TLR7 signaling and cause characteristic autoimmune phenotypes with monogenic autosomal recessive inheritance in mutant mice and dogs. We therefore hypothesized that homologous variants in the human UNC93B1 gene might be responsible for a fraction of human SLE patients. We analyzed 536 patients of the Swiss SLE Cohort Study for the presence of genetic variants affecting the C-terminal tail of UNC93B1. None of the investigated patients carried bi-allelic UNC93B1 variants that were likely to explain their SLE phenotypes. We conclude that genetic variants affecting the C-terminal tail of UNC93B1 are not a common risk factor for SLE. It cannot be excluded that such variants might contribute to other heritable autoimmune diseases.

TGFß promotes low IL10-producing ILC2 with profibrotic ability involved in skin fibrosis in systemic sclerosis.

OBJECTIVE: Innate lymphoid cells-2 (ILC2) were shown to be involved in the development of lung or hepatic fibrosis. We sought to explore the functional and phenotypic heterogeneity of ILC2 in skin fibrosis within systemic sclerosis (SSc). METHODS: Blood samples and skin biopsies from healthy donor or patients with SSc were analysed by immunostaining techniques. The fibrotic role of sorted ILC2 was studied in vitro on dermal fibroblast and further explored by transcriptomic approach. Finally, the efficacy of a new treatment against fibrosis was assessed with a mouse model of SSc. RESULTS: We found that ILC2 numbers were increased in the skin of patients with SSc and correlated with the extent of skin fibrosis. In SSc skin, KLRG1- ILC2 (natural ILC2) were dominating over KLRG1+ ILC2 (inflammatory ILC2). The cytokine transforming growth factor-ß (TGFß), whose activity is increased in SSc, favoured the expansion of KLRG1- ILC2 simultaneously decreasing their production of interleukin 10 (IL10), which regulates negatively collagen production by dermal fibroblasts. TGFß-stimulated ILC2 also increased myofibroblast differentiation. Thus, human KLRG1- ILC2 had an enhanced profibrotic activity. In a mouse model of SSc, therapeutic intervention-combining pirfenidone with the administration of IL10 was required to reduce the numbers of skin infiltrating ILC2, enhancing their expression of KLRG1 and strongly alleviating skin fibrosis. CONCLUSION: Our results demonstrate a novel role for natural ILC2 and highlight their inter-relationships with TGFß and IL10 in the development of skin fibrosis, thereby opening up new therapeutic approaches in SSc.

A new molecular classification to drive precision treatment strategies in primary Sjögren's syndrome.

There is currently no approved treatment for primary Sjögren's syndrome, a disease that primarily affects adult women. The difficulty in developing effective therapies is -in part- because of the heterogeneity in the clinical manifestation and pathophysiology of the disease. Finding common molecular signatures among patient subgroups could improve our understanding of disease etiology, and facilitate the development of targeted therapeutics. Here, we report, in a cross-sectional cohort, a molecular classification scheme for Sjögren's syndrome patients based on the multi-omic profiling of whole blood samples from a European cohort of over 300 patients, and a similar number of age and gender-matched healthy volunteers. Using transcriptomic, genomic, epigenetic, cytokine expression and flow cytometry data, combined with clinical parameters, we identify four groups of patients with distinct patterns of immune dysregulation. The biomarkers we identify can be used by machine learning classifiers to sort future patients into subgroups, allowing the re-evaluation of response to treatments in clinical trials.

Type I Interferons in Systemic Autoimmune Diseases: Distinguishing Between Afferent and Efferent Functions for Precision Medicine and Individualized Treatment.

A sustained increase in type I interferon (IFN-I) may accompany clinical manifestations and disease activity in systemic autoimmune diseases (SADs). Despite the very frequent presence of IFN-I in SADs, clinical manifestations are extremely varied between and within SADs. The present short review will address the following key questions associated with high IFN-I in SADs in the perspective of precision medicine. 1) What are the mechanisms leading to high IFN-I? 2) What are the predisposing conditions favoring high IFN-I production? 3) What is the role of IFN-I in the development of distinct clinical manifestations within SADs? 4) Would therapeutic strategies targeting IFN-I be helpful in controlling or even preventing SADs? In answering these questions, we will underlie areas of incertitude and the intertwined role of autoantibodies, immune complexes, and neutrophils.

Dysfunctional Keratinocytes Increase Dermal Inflammation in Systemic Sclerosis: Results From Studies Using Tissue-Engineered Scleroderma Epidermis.

OBJECTIVE: Evidence suggests that keratinocyte-fibroblast interactions are abnormal in systemic sclerosis (SSc). The present study was undertaken to investigate potential epidermal dysfunction in SSc and its effects on dermal homeostasis. METHODS: Epidermal equivalents (EEs) were generated using keratinocytes from 6 healthy donors and 4 individuals with SSc. Skin and EE expression of markers of proliferation, differentiation, and activation was evaluated by immunohistochemistry. The transcriptomic profile of SSc EEs and healthy donor EEs was identified by RNA sequencing. EE conditioned medium (CM) was used to stimulate fibroblasts, and their production of interleukin-6 (IL-6), IL-8, matrix metalloproteinase 1 (MMP-1), type I collagen, and fibronectin was assessed by enzyme-linked immunosorbent assay. RESULTS: Compared to healthy donor EEs, SSc EEs exhibited aberrant differentiation, enhanced expression of activation markers, and a lower rate of basal keratinocyte mitosis, reproducing most of the abnormalities observed in SSc epidermis. RNA sequencing analysis revealed that, compared to healthy donor EEs, SSc EEs were characterized by lower expression of homeobox gene family members and by enhanced metabolic and oxidative stress molecular pathways. EE CM enhanced fibroblast production of IL-6, IL-8, MMP-1, type I collagen, and fibronectin (P < 0.05). Except for type I collagen and fibronectin, this effect was 2-fold higher in the presence of CM generated form SSc EEs. IL-1 was responsible, at least in part, for keratinocyte-dependent fibroblast activation. CONCLUSION: SSc EEs recapitulate the in vivo characteristics of SSc epidermis, demonstrating that SSc keratinocytes have an intrinsically altered differentiation program, possibly due to the dysregulation of genes from the homeobox family. The increased metabolic and oxidative stress associated with SSc epidermis may contribute to chronic inflammation and fibrosis of the dermis.

Epitope-Specific Anti-C1q Autoantibodies in Systemic Lupus Erythematosus.

Objective: In patients with systemic lupus erythematosus (SLE) complement C1q is frequently targeted by autoantibodies (anti-C1q), that correlate best with active renal disease. Anti-C1q bind to largely unknown epitopes on the collagen-like region (CLR) of this highly functional molecule. Here we aimed at exploring the role of epitope-specific anti-C1q in SLE patients. Methods: First, 22 sera of SLE patients, healthy controls and anti-C1q positive patients without SLE were screened for anti-C1q epitopes by a PEPperMAP® microarray, expressing CLR of C1q derived peptides with one amino acid (AA) shift in different lengths and conformations. Afterwards, samples of 378 SLE patients and 100 healthy blood donors were analyzed for antibodies against the identified epitopes by peptide-based ELISA. Relationships between peptide-specific autoantibodies and SLE disease manifestations were explored by logistic regression models. Results: The epitope mapping showed increased IgG binding to three peptides of the C1q A- and three of the C1q B-chain. In subsequent peptide-based ELISAs, SLE sera showed significantly higher binding to two N-terminally located C1q A-chain peptides than controls (p < 0.0001), but not to the other peptides. While anti-C1q were associated with a broad spectrum of disease manifestations, some of the peptide-antibodies were associated with selected disease manifestations, and antibodies against the N-terminal C1q A-chain showed a stronger discrimination between SLE and controls than conventional anti-C1q. Conclusion: In this large explorative study anti-C1q correlate with SLE overall disease activity. In contrast, peptide-antibodies are associated with specific aspects of the disease suggesting epitope-specific effects of anti-C1q in patients with SLE.

Anti-CXCL4 Antibody Reactivity Is Present in Systemic Sclerosis (SSc) and Correlates with the SSc Type I Interferon Signature.

Systemic sclerosis (SSc) is characterized by skin/internal organ fibrosis, vasculopathy and autoimmunity. Chemokine (C-X-C motif) ligand 4 (CXCL4) is an SSc biomarker, predicting unfavorable prognosis and lung fibrosis. CXCL4 binds DNA/RNA and favors interferon (IFN)-α production by plasmacytoid dendritic cells (pDCs), contributing to the type I IFN (IFN-I) signature in SSc patients. However, whether CXCL4 is an autoantigen in SSc is unknown. Here, we show that at least half of SSc patients show consistent antibody reactivity to CXCL4. T-cell proliferation to CXCL4, tested in a limited number of patients, correlates with anti-CXCL4 antibody reactivity. Antibodies to CXCL4 mostly correlate with circulating IFN-α levels and are significantly higher in patients with lung fibrosis in two independent SSc cohorts. Antibodies to CXCL4 implement the CXCL4-DNA complex's effect on IFN-α production by pDCs; CXCL4-DNA/RNA complexes stimulate purified human B-cells to become antibody-secreting plasma cells in vitro. These data indicate that CXCL4 is indeed an autoantigen in SSc and suggest that CXCL4, and CXCL4-specific autoantibodies, can fuel a harmful loop: CXCL4-DNA/RNA complexes induce IFN-α in pDCs and direct B-cell stimulation, including the secretion of anti-CXCL4 antibodies. Anti-CXCL4 antibodies may further increase pDC stimulation and IFN-α release in vivo, creating a vicious cycle which sustains the SSc IFN-I signature and general inflammation.

Genome-wide whole blood transcriptome profiling in a large European cohort of systemic sclerosis patients.

OBJECTIVES: The analysis of annotated transcripts from genome-wide expression studies may help to understand the pathogenesis of complex diseases, such as systemic sclerosis (SSc). We performed a whole blood (WB) transcriptome analysis on RNA collected in the context of the European PRECISESADS project, aiming at characterising the pathways that differentiate SSc from controls and that are reproducible in geographically diverse populations. METHODS: Samples from 162 patients and 252 controls were collected in RNA stabilisers. Cases and controls were divided into a discovery (n=79+163; Southern Europe) and validation cohort (n=83+89; Central-Western Europe). RNA sequencing was performed by an Illumina assay. Functional annotations of Reactome pathways were performed with the Functional Analysis of Individual Microarray Expression (FAIME) algorithm. In parallel, immunophenotyping of 28 circulating cell populations was performed. We tested the presence of differentially expressed genes/pathways and the correlation between absolute cell counts and RNA transcripts/FAIME scores in regression models. Results significant in both populations were considered as replicated. RESULTS: Overall, 15 224 genes and 1277 functional pathways were available; of these, 99 and 225 were significant in both sets. Among replicated pathways, we found a deregulation in type-I interferon, Toll-like receptor cascade, tumour suppressor p53 protein function, platelet degranulation and activation. RNA transcripts or FAIME scores were jointly correlated with cell subtypes with strong geographical differences; neutrophils were the major determinant of gene expression in SSc-WB samples. CONCLUSIONS: We discovered a set of differentially expressed genes/pathways validated in two independent sets of patients with SSc, highlighting a number of deregulated processes that have relevance for the pathogenesis of autoimmunity and SSc.

Interplay Between Keratinocytes and Fibroblasts: A Systematic Review Providing a New Angle for Understanding Skin Fibrotic Disorders.

Background/Objective: Skin fibrosis is the result of aberrant processes leading to abnormal deposition of extracellular matrix (ECM) in the dermis. In healthy skin, keratinocytes participate to maintain skin homeostasis by actively crosstalking with fibroblasts. Within the wide spectrum of fibrotic skin disorders, relatively little attention has been devoted to the role of keratinocytes for their capacity to participate to skin fibrosis. This systematic review aims at summarizing the available knowledge on the reciprocal interplay of keratinocytes with fibroblasts and their soluble mediators in physiological states, mostly wound healing, and conditions associated with skin fibrosis. Methods: We performed a systematic literature search on PubMed to identify in vitro and ex vivo human studies investigating the keratinocyte characteristics and their interplay with fibroblasts in physiological conditions and within fibrotic skin disorders including hypertrophic scars, keloids, and systemic sclerosis. Studies were selected according to pre-specified eligibility criteria. Data on study methods, models, stimuli and outcomes were retrieved and summarized according to pre-specified criteria. Results: Among the 6,271 abstracts retrieved, 73 articles were included, of which 14 were specifically dealing with fibrotic skin pathologies. Fifty-six studies investigated how keratinocyte may affect fibroblast responses in terms of ECM-related genes or protein production, phenotype modification, and cytokine production. Most studies in both physiological conditions and fibrosis demonstrated that keratinocytes stimulate fibroblasts through the production of interleukin 1, inducing keratinocyte growth factor (KGF) and metalloproteinases in the fibroblasts. When the potential of keratinocytes to modulate collagen synthesis by healthy fibroblasts was explored, the results were controversial. Nevertheless, studies investigating keratinocytes from fibrotic skin, including keloids, hypertrophic scar, and scleroderma, suggested their potential involvement in enhancing ECM deposition. Twenty-three papers investigated keratinocyte proliferation differentiation and production of soluble mediators in response to interactions with fibroblasts. Most studies showed that fibroblasts modulate keratinocyte viability, proliferation, and differentiation. The production of KGF by fibroblast was identified as key for these functions. Conclusions: This review condenses evidence for the active interaction between keratinocytes and fibroblasts in maintaining skin homeostasis and the altered homeostatic interplay between keratinocytes and dermal fibroblasts in scleroderma and scleroderma-like disorders.

Generation of Monoclonal Antibodies Specific for Native LL37 and Citrullinated LL37 That Discriminate the Two LL37 Forms in the Skin and Circulation of Cutaneous/Systemic Lupus Erythematosus and Rheumatoid Arthritis Patients.

Human cathelicidin LL37 is a cationic antimicrobial peptide active against bacteria and viruses and exerting immune modulatory functions. LL37 can be also a target of autoreactive B- and T-lymphocytes in autoimmune settings. Irreversible post-translational modifications, such as citrullination and carbamylation, mainly occurring at the level of cationic amino acids arginine and lysine, can affect the inflammatory properties and reduce antibacterial effects. Moreover, these modifications could be implicated in the rupture of immune tolerance to LL37 in chronic conditions such as psoriatic disease and cutaneous lupus (LE)/systemic lupus erythematosus (SLE). Here, we describe the generation and fine specificity of six recombinant antibodies (MRB137-MRB142), produced as a monovalent mouse antibody with the antigen-binding scFv portion fused to a mouse IgG2a Fc, and their ability to recognize either native or citrullinated LL37 (cit-LL37) and not cross-react to carbamylated LL37. By using these antibodies, we detected native LL37 or cit-LL37 in SLE and rheumatoid arthritis (RA) sera, and in LE skin, by ELISA and immunohistochemistry, respectively. Such antibodies represent previously unavailable and useful tools to address relationships between the presence of post-translational modified LL37 and the immune system status (in terms of innate/adaptive responses activation) and the clinical characteristics of patients affected by chronic immune-mediated diseases or infectious diseases.

Identification of highly active systemic lupus erythematosus by combined type I interferon and neutrophil gene scores vs classical serologic markers.

OBJECTIVES: In SLE, heterogeneous clinical expression and activity may reflect diverse pathogenic and/or effector mechanisms. We investigated SLE heterogeneity by assessing the expression of three gene sets representative of type I IFN (IFN-I), polymorphonuclear neutrophil (PMN) and plasmablast (PB) signatures in a well-characterized, multidisciplinary cohort of SLE patients. We further assessed whether individual gene products could be representative of these three signatures. METHODS: Whole blood, serum and clinical data were obtained from 140 SLE individuals. Gene expression was assessed by NanoString technology, using a panel of 37 probes to compute six IFN-I, one PMN and one PB scores. Protein levels were measured by ELISA. RESULTS: Depending on the score, 45-50% of SLE individuals showed high IFN-I gene expression. All six IFN-I scores were significantly associated with active skin involvement, and two of six were associated with arthritis. IFN-induced Mx1 protein (MX1) level was correlated with IFN-I score (P < 0.0001) and associated with a similar clinical phenotype. In all, 25% of SLE individuals showed high PMN gene expression, associated with SLE fever, serositis, leukopoenia and glucocorticoid use. PB gene expression was highly affected by immunosuppressant agents, with no association with SLE features. Combined IFN-I and PMN gene scores were significantly associated with high disease activity and outperformed anti-dsDNA and anti-C1q autoantibody and complement levels for predicting SLE activity. CONCLUSION: IFN-I and PMN gene scores segregate with distinct SLE clinical features, and their combination may identify high disease activity. MX1 protein level performed similar to IFN-I gene expression.