Incomplete SLE (iSLE) is the designation of patients who display symptoms that are typical for SLE, but with insufficient criteria to fulfil the diagnosis. Unfortunately, predictive biomarkers for SLE development are lacking. Increased IFN-type I production is an important factor in the pathogenesis of SLE. Interferon-regulated chemokines therefore could possibly be useful as biomarkers for disease progression to SLE. Candidate biomarkers IFN-γ induced protein 10 (IP-10) and monocyte chemo attractant protein (MCP-1) have shown to be increased in SLE and to correlate with disease activity.
Objectives
To determine possible candidate biomarkers IFN-γ induced protein 10 (IP-10) and monocyte chemo attractant protein (MCP-1) in patients with iSLE.
Methods
Serum samples were collected of 30 iSLE patients, 29 SLE patients, and 17 ANA-negative patients with histologically proven cutaneous lupus erythematosus (ANCLE). Outcomes were compared with 25 age- and gender-matched controls (CTL) and 31 rheumatoid arthritis (RA) patients as disease control group. Levels of IP-10 and MCP-1 were measured using ELISA.
Results
IP-10 was significantly increased in SLE and RA patients compared with CTL and ANCLE. IP-10 levels were increased in 23% of iSLE patients. These patients had higher SLE disease activity index (SLEDAI) and more frequently decreased C3 level and joint involvement compared to those with normal IP-10 levels. Regarding MCP-1 levels, no significant differences were found between any of the groups and no correlations with clinical markers was found.
Conclusions
Levels of IP-10, but not MCP-1, might be useful as a predictive biomarker for progression to SLE in patients with iSLE, although future prospective longitudinal analyses are needed to confirm this hypothesis.
Incomplete SLE (iSLE) patients display symptoms typical for SLE but have insufficient criteria to fulfil the diagnosis. Biomarkers are needed to identify iSLE patients that will progress to SLE. IFN type I activation, B-cell-activating factor (BAFF) and B-cell subset distortions play an important role in the pathogenesis of SLE. The aim of this cross-sectional study was to investigate whether B-cell subsets are altered in iSLE patients, and whether these alterations correlate with IFN scores and BAFF levels.
Background: Systemic lupus erythematosus (SLE) is an autoimmune disease, which is characterized by skin lesions, amongst other symptoms. These lesions (chronic discoid lupus erythematosus (CDLE) and subacute cutaneous lupus erythematosus (SCLE)) feature lymphocytic infiltration close to basal layer of the epidermis (i.e. the location of the epidermal progenitor cells), namely the epidermal dermal junction (EDJ) area. Epidermal progenitor cells maintain the homeostasis of the skin through their proliferation and differentiation into keratinocytes. In fast turnover tissues, like the skin, a population of ‘transient amplifying cells’ (TA cells), additionally facilitates generation of enough daughter cells to maintain skin homeostasis. These cells are located in an upper layer (suprabasal layer) of the epidermis, next to the basal layer. Senescence is an irreversible and locally spreading phenomenon that induces permanent cell cycle arrest. Objectives: To evaluate expression of senescence markers p16 and p21 in the epidermal progenitor and TA niches in patients with SCLE and CDLE. This was compared to a panel of other dermatological conditions with and without infiltration close to EDJ, as disease controls, and to control skin tissue. Methods: Age-matched skin lesions from patients with SCLE (n=12), CDLE (n=8), other conditions with EDJ infiltration (e.g. lichen planus, n=22), and dermatoses without EDJ infiltration (e.g. eczema, n=27), and non-lesion control biopsies (n=3) from SLE patients were employed. p16 and p21 expression in the progenitor niche (basal layer) and TA cell niche (suprabasal layer), and the whole epidermis of skin lesions biopsies were examined by immunohistochemistry. Results: In healthy skin biopsies, 0 ± 0 SEM p16 + cells/mm2 in the progenitor niche and 5 ± 4 SEM p21 + cells/mm2 in TA niche were observed. In skin lesions from patients with CDLE and SCLE, significantly more p16 + cells in the progenitor cell niche (45 ± 14 SEM/mm2) and p21 + cells (182 ± 38 SEM/mm2) in TA niches were detected, compared to control biopsies (p < 0.05), and compared to those dermatoses without EDJ infiltration (p16 + 11 ± 3 SEM/mm2, p21 + 86 ± 28 SEM/mm2, p < 0.05, Figure 1). p16 and p21 expression in CDLE and SCLE lesions did not significantly differ from other dermatoses with EDJ infiltration (p>0.05). Across all dermatoses analyzed, the number of p16 + cells was significantly correlated with the number of p21 + cells, both in the progenitor niche (r=0.45, p<0.0001) and TA niche (r=0.47, p<0.0001). p16 + cells however were more frequently found in the progenitor cell niche, and p21 + cells conversely in the TA cell niche (p<0.0001). Figure 1. Increased p16 + and p21 + cells in the progenitor and TA niches in dermatoses with EDJ infiltration. A. Graphic illustration for the progenitor cell niche (the basal layer), the transient amplifying (TA, the supra-basal layer) cell niche, and the further differentiated area. B-D. Representative staining of p16 (blue) and epidermal growth factor receptor (EGFR, brown, an epithelial cell marker) in dermatoses with (CDLE) and without (PMLE) epidermal-dermal junction (EDJ) infiltration groups. Black arrowheads point to p16 + progenitor epidermal cells. E-G. Representative staining of p21 (blue) and EGFR (brown) in dermatoses with (CDLE) and without (PMLE) EDJ infiltration groups. Hollow arrowheads point to p21 + TA epidermal cells. The dashed line indicates the EDJ. CDLE: chronic discoid lupus erythematosus, PMLE: polymorphous light eruption. Conclusion: In CDLE and SCLE, cutaneous manifestations of SLE, more progenitor and TA cells expressing markers of senescence were detected. This was in common with other dermatological conditions where lymphocytic infiltration is in close proximity to the progenitor and TA cell niche, namely in the EDJ. Increased senescence might infer the collapse of homeostasis in target (local) epidermis, which may influence tissue repair in the lesion. Elimination of senescent cells may therefore represent a viable therapeutic option to encourage timely and complete wound healing, in skin lesions of CDLE and SCLE patients. Acknowledgements: This research was funded by a China Scholarship Council grant (201606220074), Dutch Arthritis Foundation Translational Research Grant (T015-052) and a Dutch Arthritis Foundation Long Term Project Grant (LLP-29). Disclosure of Interests: None declared.
Background To assess the prevalence of self-reported SLE-related symptoms associated with demographic and biochemical data and connective tissue disease (CTD)-related autoantibodies in a large population-based cohort. Methods Participants of the Dutch Lifelines population cohort filled out the Connective Tissue Disease Screening Questionnaire (CSQ), including 11 questions focusing on SLE-related symptoms (SLE-CSQ) based on the American College of Rheumatology classification criteria. CTD autoantibody screen was performed in 25% of participants. Results Of 85 295 participants with complete SLE-CSQ data, after excluding patients with SLE and other CTDs (n=126), 41 781 (49.1%) had no positively answered questions and 2210 (2.6% of total) had ≥4 positive answers. Participants with ≥4 answers on the SLE-CSQ were significantly younger, more frequently female, had lower body mass index (BMI) and were more often smokers than those with negative scores. Furthermore, counts of leucocytes, neutrophils and monocytes were significantly higher in these participants, while the levels of haemoglobin and creatinine were lower. CTD autoantibodies were present in 2.2% of participants with SLE-CSQ score of 0, compared with 3.5% with SLE-CSQ score ≥4 (p=0.001). Multivariate analysis showed, after adjusting for age, gender, BMI and smoking, that haemoglobin levels remained significantly lower in participants with SLE-CSQ score ≥4. Conclusions In this large population-based cohort, 2.6% of participants without diagnosed CTD reported ≥4 positive answers on the SLE-CSQ, indicating high suspicion for SLE. These individuals had demographic and haematological characteristics that differed from the remaining population. Potentially, this questionnaire, in combination with autoantibody determination, can be used as a starting point of a screening cascade in order to detect SLE at an early stage.
Background: A subgroup of lupus patients present with mild symptoms and immunologic features, while they do not meet classification criteria for SLE. This disease state can be referred to as “incomplete systemic lupus erythematosus” (iSLE). Up to 55% of iSLE patients progress to SLE. Furthermore, previous research has shown that iSLE might overlap with early primary Sjögren’s disease (pSS).(1) Unfortunately, there are no predictive markers available for progression to classifiable disease. Type-I interferon (IFN) plays an important role in disease initiation of both SLE and pSS.(2,3) Myxovirus-resistance protein A (MxA) is a GTP-ase that has previously be demonstrated to correlate strongly with IFN-type I expression. Furthermore, interferon-inducible chemokines IFN-γ induced protein 10 (IP-10), and B-cell activating factor (BAFF), that are both inducible by IFN, are of interest, because it is demonstrated that these proteins are increased prior to the diagnosis of SLE.(4) Objectives: To find predictive markers that identify patients with incomplete systemic lupus erythematosus (iSLE) who are at the highest risk to progress to classifiable systemic lupus erythematosus (SLE) or primary Sjögren’s syndrome (pSS). Methods: Patients with iSLE (ANA ≥ 1:80, ≥ 1 clinical SLICC criterion, but not fulfilling the criteria, and disease manifestation <5 years) were included in a longitudinal observational study. Every half year, clinical status was evaluated and regular immunological serologic assessment was performed. Annually, interferon (IFN)-gene expression was determined by RT-PCR in whole blood using 14 genes. These genes represented 3 IFN-related modules. Some genes were mainly inducible by IFN-type I, others by IFN-type II. Furthermore, IFN-related mediators Myxovirus resistance protein A (MxA), interferon-gamma-induced protein 10 (IP-10) and B-cell activating factor (BAFF) were measured. Results: Of 38 included iSLE patients, 6 had developed SLE and 1 develop pSS (18%) after median follow up of 36 months. The 7 patients who developed SLE/pSS were all women, and were younger at baseline than those who remained having iSLE (median 26 years, IQR 20-29 vs. median 42 years, IQR 30-56, p=0.0009). Over time, these patients had significantly lower complement 3 (p<0.0001) and complement 4 levels (p=0.005), higher IFN-gene expression (p=0.007), and lower neutrophil counts (p=0.033) (see Figure 1.). No difference was found between IFN-type I and IFN-type II inducible genes. Levels of MxA, IP-10 and BAFF did not differ between patients who remained iSLE and who progressed to SLE/pSS. Figure 1. Conclusion: Gender, age at diagnosis, persistent low complement levels, and high IFN-gene expression can help to identify iSLE patients at the highest risk of progressing to classifiable disease. References: [1]Md Yusof MY, et al. Prediction of autoimmune connective tissue disease in an at-risk cohort: Prognostic value of a novel two-score system for interferon status. Ann Rheum Dis. 2018;1–8. [2]Yao Y, et al. Type I interferons in Sjögren’s syndrome. Autoimmun Rev. 2013;12(5):558–66. [3]Crow MK. Type I Interferon in the Pathogenesis of Lupus. J Immunol [Internet]. 2014;192(12):5459–68. [4]Lu R, et al. Dysregulation of innate and adaptive serum mediators precedes systemic lupus erythematosus classification and improves prognostic accuracy of autoantibodies. J Autoimmun. 2016;74:182–93. Disclosure of Interests: None declared
Cutaneous lupus erythematosus (CLE) is an autoimmune disease that can occur as an isolated skin condition or as a skin manifestation secondary to systemic autoimmune diseases such as systemic lupus erythematosus and primary Sjögren's syndrome (Kuhn and Landmann, 2014Kuhn A. Landmann A. The classification and diagnosis of cutaneous lupus erythematosus.J Autoimmun. 2014; 48–49: 14-19Crossref PubMed Scopus (135) Google Scholar; Wenzel, 2019Wenzel J. Cutaneous lupus erythematosus: new insights into pathogenesis and therapeutic strategies.Nat Rev Rheumatol. 2019; 15: 519-532Crossref PubMed Scopus (69) Google Scholar). CLE is commonly associated with IFN-1– and IFN-3–driven inflammation, with chronic discoid lupus erythematosus (CDLE) and subacute CLE (SCLE) as frequent subtypes (Wenzel, 2019Wenzel J. Cutaneous lupus erythematosus: new insights into pathogenesis and therapeutic strategies.Nat Rev Rheumatol. 2019; 15: 519-532Crossref PubMed Scopus (69) Google Scholar). Both types of CLE lesions contain infiltrating lymphoid cells in the epithelium, in the dermis, and in particular, at the dermo‒epidermal junction (DEJ), albeit CDLE lesions comprise more infiltrating cells than SCLE lesions (Supplementary Figure S1a). In addition, scarring frequently occurs after CDLE lesion but not after SCLE lesion, causing aesthetic and psychosocial discomfort (McDaniel et al., 2021McDaniel B. Sukumaran S. Tanner L.S. Discoid lupus erythematosus.in: StatPearls [internet]. StatPearls Publishing, Treasure Island, FL2021Google Scholar). Skin homeostasis and wound healing are normally maintained by the epithelial progenitor cell self-renewal and differentiation, facilitated by transient amplifying (TA) cells (Krafts, 2010Krafts K.P. Tissue repair: the hidden drama.Organogenesis. 2010; 6: 225-233Crossref PubMed Scopus (145) Google Scholar). Senescence is an irreversible state of cell cycle arrest, where a lack of proliferation ability is accompanied by apoptosis resistance (Gorgoulis et al., 2019Gorgoulis V. Adams P.D. Alimonti A. Bennett D.C. Bischof O. Bishop C. et al.Cellular senescence: defining a path forward.Cell. 2019; 179: 813-827Abstract Full Text Full Text PDF PubMed Scopus (662) Google Scholar). Senescent cells secrete a panel of proinflammatory cytokines and chemokines, termed the senescence-associated secretory phenotype, factors mitigating the spread of senescence to adjacent cells and potentially augmenting general inflammation (Hernandez-Segura et al., 2018Hernandez-Segura A. Nehme J. Demaria M. Hallmarks of cellular senescence.Trends Cell Biol. 2018; 28: 436-453Abstract Full Text Full Text PDF PubMed Scopus (724) Google Scholar). p16 and p21 are commonly used as senescence markers (Bernardes de Jesus and Blasco, 2012Bernardes de Jesus B. Blasco M.A. Assessing cell and organ senescence biomarkers.Circ Res. 2012; 111: 97-109Crossref PubMed Scopus (116) Google Scholar). We recently showed increased p16+ cells in a progenitor cell niche in the salivary gland of patients with the autoimmune disease primary Sjögren's syndrome, the extent of which correlated with hyposalivation and increased salivary gland lymphocytic infiltration (Wang et al., 2020Wang X. Bootsma H. Terpstra J. Vissink A. van der Vegt B. Spijkervet F.K.L. et al.Progenitor cell niche senescence reflects pathology of the parotid salivary gland in primary Sjögren's syndrome.Rheumatology (Oxford). 2020; 59: 3003-3013Crossref PubMed Scopus (15) Google Scholar). We hypothesized that skin progenitor cells of patients with the autoimmune disease CLE may be senescent. Using immunohistochemistry, we first examined the expression of p16 and p21 in age-matched skin biopsies of patients with CLE lesions (n = 20, comprising 8 CDLE and 12 SCLE) compared with the expression in unaffected skin of patients with CLE as controls (n = 3) (Supplementary Figure S1b and c). Skin biopsies were taken during a routine biopsy for diagnosis and during the establishment of a local pathology database (METc201800245). According to national regulations in the Netherlands (Overheid.nl, 2018Overheid.nlMedical research involving humans act.https://wetten.overheid.nl/BWBR0009408/2018-08-01#Date: 2018Date accessed: June 24, 2021Google Scholar), this type of retrospective noninterventional study with leftover materials for diagnostic purposes does not require approval from the local medical ethical committee. For the analysis of p16+ and p21+ cells, the epidermis was divided into three areas: the basal layer (the progenitor cell niche), the suprabasal layer (the TA cell niche), and the further differentiated (FD) area (terminally differentiated keratinocytes) (Figure 1a). In unaffected skin, small numbers of scattered p16+ or p21+ cells were detected throughout the whole epidermis (Figure 1b, d, e, and g). In CLE lesions, significantly more p16+ cells per mm2 were detected in all the three layers, whereas for p21+ cells, this was only significant for the basal and suprabasal layer and as a trend for the FD area (Figure 1b‒g). Within CLE subtypes, there was a trend for more p16+ cells per mm2 in CDLE than in SCLE lesions in all the three layers of epidermis examined; however, this trend was seen for p21+ cells per mm2 only in the basal and suprabasal layers (Supplementary Figure S1d‒i). Next, to explore the possible influence of inflammation on skin stem cell senescence, we compared (i) CLE with 16 other dermatoses, with varying amounts and distribution of infiltrating cells in the skin. These dermatoses were split into four groups categorized into (ii) other dermatoses with DEJ infiltrates (non-CLE lichenoid dermatoses, n = 22) and dermatoses without DEJ infiltrates, including (iii) non-CLE sunlight induced, n = 7; (iv) spongiotic and psoriasiform, n = 6; and (v) superficial and deep, n = 14. The 18 individual dermatoses comprising a total of five pathological groups are listed in Supplementary Table S1. Skin lesions of non-CLE lichenoid dermatoses contained similar numbers of p16+ and p21+ cells per mm2 as the CLE group in all epidermal layers (Figure 2i and j). The p16+ and p21+ cells per mm2 were higher in CLE and non-CLE lichenoid groups than in all other dermatoses in the basal and suprabasal layers (Figure 2a‒j). In the FD area, CLE and non-CLE lichenoid groups also contain higher numbers of p16+ cells per mm2 than other groups, whereas the spongiotic and psoriasiform group contained the most p21+ cells per mm2 than all other groups (Figure 2i and j). When dermatoses were grouped according to the presence or absence of DEJ infiltration (see Supplementary Table S1), significantly more p16+ and p21+ cells per mm2 in the basal and suprabasal layers were found in dermatoses with DEJ infiltration than in those without DEJ infiltration and in the unaffected skin (Figure 2k and l). In the FD area, more p16+ cells per mm2 were observed in dermatoses with DEJ infiltration than in those without DEJ infiltration and in unaffected skin (Figure 2k and l). p21+ cells per mm2 in the FD area were similar with and without DEJ infiltration, both were higher than in unaffected skin (Figure 2k and l). p16+ and p21+ cells per mm2 in different epidermal layers in individual dermatosis are shown in Supplementary Figure S1d‒i. Across all dermatoses, p16+ and p21+ cells per mm2 were significantly positively correlated in both basal (R = 0.45, P < 0.0001) and suprabasal (R = 0.47, P < 0.0001) layers (Figure 2m). This was not the case in the FD area (R = 0.04, P = 0.76; Supplementary Figure S1j) and in total epidermis (R = 0.21, P = 0.07; Supplementary Figure S1k). Further probing revealed that p16+ cells were more likely in basal layer than in suprabasal layer (P < 0.0001), whereas p21 was conversely enriched in the suprabasal layer compared with that in the basal layer (P < 0.0001) (Figure 2n and o). Interestingly, the amount of basal p16+ cells per mm2 and suprabasal p21+ cells per mm2 were also significantly correlated (R = 0.46, P < 0.0001; Supplementary Figure S1l). Our findings reveal that dermatoses, including the autoimmune disease CLE, with infiltration spatially close to progenitor/TA niches (the DEJ) contain higher numbers of p16+ and p21+ progenitor/TA cells than dermatoses without these infiltrates. In line with this difference, within the CLE group, CDLE lesions, containing denser DEJ infiltration than SCLE lesions, contain more p16+ and p21+ cells. These findings suggest that inflammation and senescence (and senescence-associated secretory phenotype) are at least associated with each other, as has also been shown for other epithelial organs (e.g., salivary gland and intestine) (Coppé et al., 2010Coppé J.P. Desprez P.Y. Krtolica A. Campisi J. The senescence-associated secretory phenotype: the dark side of tumor suppression.Annu Rev Pathol. 2010; 5: 99-118Crossref PubMed Scopus (2385) Google Scholar; Freund et al., 2010Freund A. Orjalo A.V. Desprez P.Y. Campisi J. Inflammatory networks during cellular senescence: causes and consequences.Trends Mol Med. 2010; 16: 238-246Abstract Full Text Full Text PDF PubMed Scopus (832) Google Scholar; Parrinello et al., 2005Parrinello S. Coppe J.P. Krtolica A. Campisi J. Stromal-epithelial interactions in aging and cancer: senescent fibroblasts alter epithelial cell differentiation.J Cell Sci. 2005; 118: 485-496Crossref PubMed Scopus (437) Google Scholar; Pringle et al., 2018Pringle S. Wang X. Verstappen G.M.P.J. Terpstra J.H. Zhang C.K. He A. et al.Salivary gland stem cells age prematurely in primary Sjögren's syndrome.Arthritis Rheumatol. 2018; 71: 133-142Crossref Scopus (28) Google Scholar; Wang et al., 2020Wang X. Bootsma H. Terpstra J. Vissink A. van der Vegt B. Spijkervet F.K.L. et al.Progenitor cell niche senescence reflects pathology of the parotid salivary gland in primary Sjögren's syndrome.Rheumatology (Oxford). 2020; 59: 3003-3013Crossref PubMed Scopus (15) Google Scholar). Considering the proinflammatory nature of the components of the senescence-associated secretory phenotype, it is also possible that inflammation and senescence may augment each other's presence, also an interesting phenomenon to be explored in future studies. The nature of the infiltration in different dermatoses, in terms of immune cell types and their respective secretomes, may also play a significant role in the sum effect of the inflammation on progenitor and TA compartments. Inflammation has also been associated with impaired clearance of apoptotic epithelial cells in CLE and likely contributes significantly to CLE disease development (Kuhn and Bijl, 2008Kuhn A. Bijl M. Pathogenesis of cutaneous lupus erythematosus.Lupus. 2008; 17: 389-393Crossref PubMed Scopus (41) Google Scholar). Furthermore, the extent of inflammatory infiltration is also associated with the likelihood of scarring (Marshall et al., 2018Marshall C.D. Hu M.S. Leavitt T. Barnes L.A. Lorenz H.P. Longaker M.T. Cutaneous scarring: basic science, current treatments, and future directions.Adv Wound Care (New Rochelle). 2018; 7: 29-45Crossref PubMed Scopus (99) Google Scholar; Wilgus, 2020Wilgus T.A. Inflammation as an orchestrator of cutaneous scar formation: a review of the literature.Plast Aesthet Res. 2020; 7: 54PubMed Google Scholar). Whether DEJ infiltration, progenitor cell senescence, or epithelial cell apoptosis contributes equally or not to scar formation in CDLE lesions remains to be established and may dictate the most appropriate treatment regime. In particular, timely removal of senescent cells using senolytics, paired with blockade of chronic inflammation, may promote optimal CDLE lesion resolution. The preferable expression of p16 in the progenitor niche and p21 in the TA niche were also observed in another fast-turnover organ in an autoimmune disease context, namely intestines, from patients with Crohn disease (Wang et al., 2019Wang X. Bootsma H. Kroese F. Dijkstra G. Pringle S. Senescent stem and transient amplifying cells in Crohn's disease intestine.Inflamm Bowel Dis. 2019; 26: e8-e9Crossref Scopus (3) Google Scholar). In our study of the salivary gland (a slow turnover organ) in primary Sjögren's syndrome, only p16 was observed (Wang et al., 2020Wang X. Bootsma H. Terpstra J. Vissink A. van der Vegt B. Spijkervet F.K.L. et al.Progenitor cell niche senescence reflects pathology of the parotid salivary gland in primary Sjögren's syndrome.Rheumatology (Oxford). 2020; 59: 3003-3013Crossref PubMed Scopus (15) Google Scholar). We hypothesize that p21-induced senescence is more likely to occur in epithelial organs containing TA cells, usually fast-turnover tissues, whereas p16 drives a more general epithelial senescence. The different p16/p21 expression profiles in the FD area (this study) among dermatoses may also underpin the differences in p16- or p21-mediated senescence pathway activation, of which the mechanisms remain to be investigated. In conclusion, we propose that dysfunctional epidermal progenitor and TA cells in CLE and other dermatoses with DEJ infiltration may be senescent as a result of close proximity to inflammatory infiltrate and may be hindered in their ability to repair epidermal damage. No datasets were generated or analyzed during this study. Xiaoyan Wang: http://orcid.org/0000-0002-6778-727X Gilles Diercks: http://orcid.org/0000-0001-8053-216X Wietske M. Lambers: http://orcid.org/0000-0002-2026-5191 Johanna Westra: http://orcid.org/0000-0002-6581-6508 Hendrika Bootsma: http://orcid.org/0000-0001-7126-9785 Frans G.M. Kroese: http://orcid.org/0000-0003-3660-0617 Karina de Leeuw http://orcid.org/0000-0003-0218-9364 Sarah Pringle: http://orcid.org/0000-0002-0779-1680 The authors state no conflict of interest. The authors gratefully acknowledge the patients who took part in this research and agreed to provide their skin biopsies for this study. This research was funded by a China Scholarship Council grant (201606220074), a Dutch Arthritis Foundation Translational Research Grant (T015-052), and a Dutch Arthritis Foundation Long Term Project Grant (LLP-29). Conceptualization: SP, XW, GD, KDL; Data Curation: XW; Formal analysis: XW, SP, GD, KDL, FGMK; Methodology: SP, XW, GD, KDL; Writing - Original Draft Preparation: XW, GD, WML, JW, HB, FGMK, KDL, SP; Writing - Review and Editing: XW, GD, WML, JW, HB, FGMK, KDL, SP Supplementary Table S1Grouping of DermatosesDermatosesGroupsMain Infiltration in the DEJ AreaCDLECLEYesSCLEBenign lichenoid keratosisNon-CLE lichenoidEEMLichen planusLichenoid drug eruptionGVHDFixed drug reactionPLEVARosaceaNon-CLE sunlight inducedNoPorphyriaPMLESuperficial and deepUrticariaInsect bitePerniosisEACEczemaSpongiotic and psoriasiformPsoriasisAbbreviations: CDLE, chronic discoid lupus erythematosus; CLE, cutaneous lupus erythematosus; DEJ, dermo‒epidermal junction; EAC, erythema annulare centrifugum; EEM, erythema multiforme; GVHD, graft-versus-host disease; PLEVA, pityriasis lichenoides et varioliformis acuta; PMLE, polymorphous light eruption; SCLE, subacute cutaneous lupus erythematosus. Open table in a new tab Abbreviations: CDLE, chronic discoid lupus erythematosus; CLE, cutaneous lupus erythematosus; DEJ, dermo‒epidermal junction; EAC, erythema annulare centrifugum; EEM, erythema multiforme; GVHD, graft-versus-host disease; PLEVA, pityriasis lichenoides et varioliformis acuta; PMLE, polymorphous light eruption; SCLE, subacute cutaneous lupus erythematosus.
Systemic lupus erythematosus (SLE) is a complex and heterogeneous autoimmune disease. A main challenge faced by clinicians is early identification of SLE, frequently resulting in diagnostic delay. Timely treatment, however, is important to limit disease progression, and prevent organ damage and mortality. Often, patients present with clinical symptoms and immunologic abnormalities suggestive of SLE, while not meeting classification criteria yet. This is referred to as incomplete SLE (iSLE). However, not all these patients will develop SLE. Therefore, there is need for predictive biomarkers that can distinguish patients at high risk of developing SLE, in order to allow early treatment. This article reviews the current literature on immunological changes in patients with stages preceding SLE, focusing on autoantibodies, type-I and -II interferons, and the complement system. We also provide an overview of possible predictive markers for progression to SLE that are applicable in daily clinical practice.
Incomplete systemic lupus erythematosus (iSLE) patients display symptoms typical for SLE but have insufficient criteria to fulfil the diagnosis. Biomarkers are needed to identify iSLE patients that will progress to SLE. Interferon (IFN) type I activation, B-cell activating factor (BAFF) and B-cell subset distortions play an important role in the pathogenesis of SLE. The aim of this cross-sectional study was to investigate whether B-cell subsets are altered in iSLE patients, and whether these alterations correlate with IFN scores and BAFF levels. Methods iSLE patients (n =34), SLE patients (n =41) with quiescent disease (SLEDAI ≤ 4) and healthy controls (HCs; n =22) were included. Proportions of B-cell subsets were measured with flow cytometry, IFN scores with RT-PCR and BAFF levels with ELISA.
Results
Proportions of age-associated B-cells were elevated in iSLE patients compared to HCs and correlated with IgG levels. In iSLE patients, IFN scores and BAFF levels were significantly increased compared to HCs. Also, IFN scores correlated with proportions of switched memory B-cells, plasma cells, IgG levels and correlated negatively with complement levels in iSLE patients.
Conclusions
In this cross-sectional study, distortions in B-cell subsets were observed in iSLE patients and were correlated with IFN scores and IgG levels. Since these factors play an important role in the pathogenesis of SLE, iSLE patients with these distortions, high IFN scores, and high levels of IgG and BAFF may be at risk for progression to SLE.
Incomplete systemic lupus erythematosus (iSLE) marks a group of patients with typical features of SLE, who do not meet classification criteria. Up to 55% progress to SLE, but there are no predictive markers available. Interferon (IFN) type-I is an important early mediator in SLE. The majority of SLE patients show upregulation of interferon-inducible genes. Levels of IFN-related soluble markers, which are more easily applicable, are also increased in SLE.
Objectives
To measure IFN signature and IFN-related soluble markers in iSLE patients to determine if these can serve as predictors of SLE.
Methods
Thirty iSLE patients (ANA titer ≥1:80, disease duration <5 years,≥1 ACR clinical feature), 39 SLE patients with quiescent disease (fulfilling ACR or SLICC criteria, SLEDAI ≤4) and 11 healthy controls (HC) were included. Clinical and serological data were retrieved from medical charts. RNA was isolated from whole blood using PAXgene tubes, reversely transcribed to cDNA and quantitatively analysed by Real time PCR. IFN score was calculated based on cumulative expression of 12 IFN-related transcripts (IP-10, IFI44L, IFIT3, LY6E, MX1, SERPING1, IFITM1, IRF7, STAT1, C1QA, IFI16 and IRF9). A positive IFN-score was defined as >2 SD of the mean of the control group. Levels of IFN-related mediators, including IFN-γ induced protein 10 (IP-10) and Myxovirus-resistance protein A (MxA) were measured using ELISA. Statistical significance between groups was tested with Mann-Whitney U tests. Correlations of continuous data were calculated using Spearman's r test.
Results
Baseline characteristics are shown in table 1. An increased IFN score was present in 55% of iSLE patients (p=0.05) and 46% of SLE patients (p=0.07) (figure 1a).In iSLE, IFN score correlated positively with ESR (r=0.52, p=0.004), SSA titer (r=0.64, p=0.02) and cumulative number of ENA (r=0.57, p=0.001), and negatively with leukocyte count (r=-0.38, p=0.04), Hb (r=-0.39, p=0.04), and C4 (r=-0.47, p=0.01). SLEDAI, clinical symptoms, nor use of hydroxychloroquine were correlated with IFN score. Levels of MxA correlated strongly with IFN score in both iSLE (r=0.78, p<0.0001) (figure 1b) and SLE (r=0.6, p<0.0001). IP-10 levels correlated with IFN score in iSLE (r=0.45, p=0.02), but not in SLE.
Conclusions
IFN-signature is present in 55% of patients with iSLE and correlates with ESR, autoantibody number, leukopenia, anaemia and hypocomplementemia. Interestingly, MxA levels correlated strongly with IFN-gene upregulation and thus might be a suitable and easily applicable surrogate marker for IFN type-I activity. iSLE patients with IFN upregulation might be those at most risk for disease progression; longitudinal data however should be awaited.
