Recent advances in cytokines in cutaneous and systemic lupus erythematosus

Therapeutic potential of targeting IL-1 family cytokines in chronic inflammatory skin diseases

The interleukin-1 (IL-1) family of cytokines is a central regulator of a myriad of immunological responses. It comprises several cytokines, including those belonging to the IL-1, IL-36 and IL-18 subfamilies, as well as IL-33. The IL-1 family primarily plays a role in orchestrating innate immune responses but also in adaptive immunity. Increased interest in the IL-1 family occurred following the discovery that dysregulation of IL-1 signalling underlies the pathogenesis of several monogenic auto-inflammatory diseases, characterized by sterile inflammation involving the skin and other organs. This also provided increased understanding of the role of innate immunity and the IL-1 family in polygenic auto-inflammatory skin conditions, such as neutrophilic dermatoses, as well as in some of the most common chronic inflammatory skin diseases, such as psoriasis or hidradenitis suppurativa. Several therapeutic agents have been developed to inhibit the IL-1 family members and their signalling pathways. These have shown therapeutic efficacy in several chronic inflammatory skin disorders. The aim of this review is to thoroughly describe the consequences of pathological dysregulation of IL-1, IL-33, IL-36, IL-18 pathways in dermatological conditions and to provide a forward-looking update on therapeutic strategies targeting signalling by IL-1 family cytokines.

Lack of Association between Serum Interleukin-23 and Interleukin-27 Levels and Disease Activity in Patients with Active Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by the production of multiple autoantibodies, resulting in tissue and organ damage. Recent studies have revealed that interleukin-23 (IL-23) and interleukin-27 (IL-27) may be therapeutically relevant in selected SLE manifestations. This study aimed to identify associations between serum IL-27 and IL-23 levels and disease activity in Polish patients with different manifestations of SLE: neuropsychiatric lupus (NPSLE), and lupus nephritis (LN). Associations between interleukin levels and oligo-specific antibodies against double-stranded DNA (dsDNA), dose of glucocorticoids, and type of treatment were also analyzed. An enzyme-linked immunosorbent assay was used to assess anti-dsDNA antibodies and analyze the serum concentration of IL-27 and IL-23 from 72 patients aged 19-74 years with confirmed active SLE. Disease activity was measured using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI 2-K). No significant correlations between interleukin levels and SLEDAI score, anti-dsDNA, corticosteroid dose, or type of treatment were noted. Patients with NPSLE and LN presented the highest median scores of SLEDAI.

The role of interleukin-17 (IL-17) in the pathogenesis of discoid lupus erythematosus and lichen planopilaris: is immunohistochemistry for IL-17 a promising way to differentiate these entities?

BACKGROUND

Interleukin-17 (IL-17) is a pro-inflammatory mediator which its excess secretion by immune cells is found in many chronic autoimmune diseases. This survey is aimed to compare the amount and pattern of distribution of IL-17 positive cells in lichen planopilaris (LPP) and discoid lupus erythematosus (DLE) which are of the most frequent causes of primary cicatricial alopecia (CA).

METHODS

Biopsies of lesional scalp skin from adult LPP (n = 30), DLE patients (n = 19), and control scalp skin (n = 18) were analyzed by immunohistochemistry (IHC) method using rabbit polyclonal antibody against IL-17. Cells stained positive for IL-17 and their pattern of distribution were assessed and compared between these groups.

RESULTS

The mean of IL-17 positive cell counts per high power field (HPF) in both LPP and DLE groups was significantly higher in comparison with the control group (both p < .0001). The LPP group had higher values of IL-17 positive cell counts per HPF (47.56 ± 13.37) compared to the DLE group (22.21 ± 11.06) (p < .0001). More than 30 IL-17 positive cell counts in IHC have a sensitivity of 90% and a specificity of 78% for differentiating LPP from DLE.

CONCLUSIONS

Our findings suggest that IL-17 is effective in the pathogenesis of DLE and LPP and its role is more prominent in LPP. IL-17 positive cells in IHC can distinguish DLE from LPP with satisfactory sensitivity and specificity.

Immune Cell-Stromal Circuitry in Lupus Photosensitivity

Photosensitivity is a sensitivity to UV radiation (UVR) commonly found in systemic lupus erythematosus (SLE) patients who have cutaneous disease. Upon even ambient UVR exposure, patients can develop inflammatory skin lesions that can reduce the quality of life. Additionally, UVR-exposed skin lesions can be associated with systemic disease flares marked by rising autoantibody titers and worsening kidney disease. Why SLE patients are photosensitive and how skin sensitivity leads to systemic disease flares are not well understood, and treatment options are limited. In recent years, the importance of immune cell-stromal interactions in tissue function and maintenance is being increasingly recognized. In this review, we discuss SLE as an anatomic circuit and review recent findings in the pathogenesis of photosensitivity with a focus on immune cell-stromal circuitry in tissue health and disease.

The influence of interferon on healthy and diseased skin

Type I interferons (IFNs) are an immunomodulatory class of cytokines that serve to protect against viral and bacterial infection. In addition, mounting evidence suggests IFNs, particularly type I but also IFNγ, are important to the pathogenesis of autoimmune and inflammatory skin diseases, such as cutaneous lupus erythematosus (CLE). Understanding the role of IFNs is relevant to anti-viral responses in the skin, skin biology, and therapeutics for these IFN-related conditions. Type I IFNs (α and β) are produced by recruited inflammatory cells and by the epidermis itself (IFNκ) and have important roles in autoimmune and inflammatory skin disease. Here, we review the current literature utilizing a PubMed database search using terms [interferon/IFN/type I IFN AND lupus/ cutaneous lupus/CLE/dermatomyositis/Sjogrens/psoriasis/lichen planus/morphea/alopecia areata/vitiligo] with a focus on the role of IFNs in basic keratinocyte biology and their implications in the cutaneous autoimmune and inflammatory diseases: cutaneous lupus erythematosus, dermatomyositis, Sjogren's syndrome, psoriasis, lichen planus, alopecia areata and vitiligo. We provide information about genes and proteins induced by IFNs and how downstream mechanisms relate to clinical disease.

Molecular Profiling of Cutaneous Lupus Lesions Identifies Subgroups Distinct from Clinical Phenotypes

Cutaneous lupus erythematosus (CLE) is a common manifestation of systemic lupus erythematosus (SLE), and CLE can also develop without systemic involvement. CLE can be difficult to treat and negatively contributes to quality of life. Despite the importance of CLE, our knowledge of what differentiates cutaneous lupus subtypes is limited. Here, we utilized a large cohort of 90 CLE lesional biopsies to compare discoid lupus erythematosus (DLE) and subacute cutaneous lupus (SCLE) in patients with and without associated SLE in order to discern the drivers of disease activity and possibly uncover better treatment targets. Overall, we found that DLE and SCLE share many differentially expressed genes (DEG) reflecting type I interferon (IFN) signaling and repression of EGFR pathways. No differences between CLE only and SLE-associated CLE lesions were found. Of note, DLE uniquely expresses an IFN-γ node. Unbiased cluster analysis of the DEGs identified two groups separated by neutrophilic vs. monocytic signatures that did not sort the patients based on clinical phenotype or disease activity. This suggests that unbiased analysis of the pathobiology of CLE lesions may be important for personalized medicine and targeted therapeutic decision making.

Hypersensitive IFN Responses in Lupus Keratinocytes Reveal Key Mechanistic Determinants in Cutaneous Lupus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease in which 70% of patients experience disfiguring skin inflammation (grouped under the rubric of cutaneous lupus erythematosus [CLE]). There are limited treatment options for SLE and no Food and Drug Administration-approved therapies for CLE. Studies have revealed that IFNs are important mediators for SLE and CLE, but the mechanisms by which IFNs lead to disease are still poorly understood. We aimed to investigate how IFN responses in SLE keratinocytes contribute to development of CLE. A cohort of 72 RNA sequencing samples from 14 individuals (seven SLE and seven healthy controls) were analyzed to study the transcriptomic effects of type I and type II IFNs on SLE versus control keratinocytes. In-depth analysis of the IFN responses was conducted. Bioinformatics and functional assays were conducted to provide implications for the change of IFN response. A significant hypersensitive response to IFNs was identified in lupus keratinocytes, including genes (IFIH1, STAT1, and IRF7) encompassed in SLE susceptibility loci. Binding sites for the transcription factor PITX1 were enriched in genes that exhibit IFN-sensitive responses. PITX1 expression was increased in CLE lesions based on immunohistochemistry, and by using small interfering RNA knockdown, we illustrated that PITX1 was required for upregulation of IFN-regulated genes in vitro. SLE patients exhibit increased IFN signatures in their skin secondary to increased production and a robust, skewed IFN response that is regulated by PITX1. Targeting these exaggerated pathways may prove to be beneficial to prevent and treat hyperinflammatory responses in SLE skin.

Topical use and systemic action of green and roasted coffee oils and ground oils in a cutaneous incision model in rats (Rattus norvegicus albinus)

Introduction

Wounds are a common health problem. Coffee is widely consumed and its oil contains essential fatty acids. We evaluated the local (skin) and systemic effects associated with the topical use of coffee oils in rats.

Methods

Punch skin wounds (6 mm) incisions were generated on the backs of 75 rats. Saline (SS), mineral oil (MO), green coffee oil (GCO), roasted coffee oil (RCO), green coffee ground oil (GCGO) or roasted coffee ground oil (RCGO) were topically applied to the wounds. Healing was evaluated by visual and histological/morphometric optical microscopy examination; second harmonics generation (SHG) microscopy, wound tissue q-PCR (values in fold-change) and blood serum (ELISA, values in pg/mL).

Results

RCO treated animals presented faster wound healing (0.986 vs. 0.422), higher mRNA expression of IGF-1 (2.78 vs. 1.00, p = 0.01), IL-6 (10.72 vs. 1.00, p = 0.001) and IL-23 (4.10 vs. 1.2, p = 0.05) in early stages of wound healing; higher IL-12 (3.32 vs. 1.00, p = 0.05) in the later stages; and lower serum levels of IFN-γ (11.97 vs. 196.45, p = 0.01). GCO treatment led to higher mRNA expression of IL-6 (day 2: 7.94 vs. 1.00, p = 0.001 and day 4: 6.90 vs. 1.00, p = 0.01) and IL-23 (7.93 vs. 1.20, p = 0.001) in the early stages. The RCO treatment also produced higher serum IFN-α levels throughout the experiment (day 2: 52.53 vs. 21.20; day 4: 46.98 vs.21.56; day 10: 83.61 vs. 25.69, p = 0.05) and lower levels of IL-4 (day 4: 0.9 vs.13.36, p = 0.01), adiponectin (day 10: 8,367.47 vs. 16,526.38, p = 0.001) and IFN-γ (day 4: 43.03 vs.196.45, p = 0.05). The SHG analysis showed a higher collagen density in the RCO and GCO treatments (p = 0.05).

Conclusion

Topical treatment with coffee oils led to systemic actions and faster wound healing in rats. Further studies should be performed are necessary to assess the safety of topical vegetal oil use for skin lesions.

TWEAK/Fn14 Activation Participates in Skin Inflammation

Tumor necrosis factor- (TNF-) like weak inducer of apoptosis (TWEAK) participates in multiple biological activities via binding to its sole receptor-fibroblast growth factor-inducible 14 (Fn14). The TWEAK/Fn14 signaling pathway is activated in skin inflammation and modulates the inflammatory responses of keratinocytes by activating nuclear factor-κB signals and enhancing the production of several cytokines, including interleukins, monocyte chemotactic protein-1, RANTES (regulated on activation, normal T cell expressed and secreted), and interferon gamma-induced protein 10. Mild or transient TWEAK/Fn14 activation contributes to tissular repair and regeneration while excessive or persistent TWEAK/Fn14 signals may lead to severe inflammatory infiltration and tissue damage. TWEAK also regulates cell fate of keratinocytes, involving the function of Fn14-TNF receptor-associated factor-TNF receptor axis. By recruiting inflammatory cells, promoting cytokine production, and regulating cell fate, TWEAK/Fn14 activation plays a pivotal role in the pathogenesis of various skin disorders, such as psoriasis, atopic dermatitis, cutaneous vasculitis, human papillomavirus infection and related skin tumors, and cutaneous autoimmune diseases. Therefore, the TWEAK/Fn14 pathway may be a potential target for the development of novel therapeutics for skin inflammatory diseases.

Cutaneous lupus erythematosus: updates on pathogenesis and associations with systemic lupus

PURPOSE OF REVIEW

Cutaneous lupus erythematosus (CLE) is a common manifestation among systemic lupus patients. There are no U.S. Food and Drug Administration approved therapies for CLE, and these lesions are frequently disfiguring and refractory to treatment. The present review will cover the recent inroads made into understanding the mechanisms behind CLE lesions and discuss promising therapeutic developments.

RECENT FINDINGS

The definition of cutaneous lupus is being refined to facilitate diagnostic and research protocols. Research into the pathogenesis of CLE is accelerating, and discoveries are now identifying genetic and epigenetic changes which may predispose to particular disease manifestations. Furthermore, unique features of disease subtypes are being defined. Murine work supports a connection between cutaneous inflammation and systemic lupus disease activity. Importantly, human trials of type I interferon blockade hold promise for improving our treatment armamentarium for refractory CLE lesions.

SUMMARY

Continued research to understand the mechanisms driving CLE will provide new methods for prevention and treatment of cutaneous lesions. These improvements may also have important effects on systemic disease activity, and thus, efforts to understand this link should be supported.

Cytokines and Effector/Regulatory Cells Characterization in the Physiopathology of Cutaneous Lupus Erythematous: A Cross-Sectional Study

We compared the presence of diverse cytokines and regulatory T and B cells in skin biopsies of discoid lupus erythematosus (DLE) and subacute cutaneous lupus erythematosus (SCLE). We included 19 patients with DLE, 13 with SCLE, 8 healthy controls, and 5 patients with hypertrophic scars. We assessed the CLASI activity score. To determine IL-22-producing cells and the subpopulation of CD4(+)/IL-17A(+)-, CD4(+)/IL-4(+)-, and CD4(+)/IFN-γ (+)-expressing T cells, CD123(+)/IDO(+) pDCs, CD25(+)/Foxp3(+) Tregs, and CD20(+)/IL-10(+)-producing B cells, an immunostaining procedure was performed. Also intracellular IL-22, IL-17, IL-4, IFN-γ, and Foxp3 in CD4 T cells, IL-10 in B cells, and IDO in pDCs were analyzed by flow cytometry in peripheral blood. The main cellular participation in both lupus groups was IL-17- and IL-22-producing cell responses both at skin and at peripheral blood but prevailed in DLE. The CLASI activity scores negatively correlated with Th22 subpopulation and positively correlated with CD25(+)/Foxp3(+) Treg cells. In conclusion a proinflammatory and regulatory imbalance coexists in cutaneous lupus, both responses being more intense in DLE.

Lupus erythematosus revisited

Lupus erythematosus (LE) is a multifactorial autoimmune disease with clinical manifestations of differing severity. The exact pathomechanisms and interactions resulting in the inflammatory and immunological processes of this heterogeneous disease remain elusive. Approaches in the understanding of the pathomechanisms revealed that the clinical expression of LE is predisposed by susceptibility genes and that various environmental factors are responsible for an abnormal immune response. Several studies demonstrated that ultraviolet (UV) light is one of the major factors in the pathogenesis of the disease. Standardized photoprovocation in patients with LE has been shown to be a safe and efficient model for evaluating the underlying pathomechanisms which lead to the production of autoantibodies and immune complexes. In particular, interferons were defined as important players in the early activation of the immune system and were observed to play a specific role in the immunological interface between the innate and the adaptive immune system. Abnormalities or disturbances in the different processes of cell death, such as apoptosis or necrosis, have also been recognized as crucial in the pathogenesis of LE. Although each process is different and characterized by unique features, the processes are interrelated and result in a complex disease.

Genome-wide transcriptional profiling data from skin of chronic cutaneous lupus erythematosus (CCLE) patients

Cutaneous features manifest as a wide range of clinically significant, and in many cases disfiguring and debilitating components of lupus erythematosus (LE). While the definitive etiology is in question, multifactorial and polygenic causes are likely to be involved in the production of the characteristic anti-nuclear autoantibody titers and immune cell infiltrates observed in chronic cutaneous LE (CCLE) [1-3]. There is significant overlap of patients with systemic and cutaneous manifestations of LE, which suggests shared pathways and genetic background between the two. We have employed genome-wide microarray technology along with pathway-based analyses to investigate transcriptional differences between lesional and non-lesional skin from CCLE patients to address existing gaps in knowledge regarding disease mechanisms in lupus [4].

TWEAK/Fn14 Signaling Involvement in the Pathogenesis of Cutaneous Disease in the MRL/lpr Model of Spontaneous Lupus

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK, TNFSF12) and its sole receptor Fn14, belonging to the TNF ligand and receptor superfamilies respectively, are involved in cell survival and cytokine production. The role of TWEAK/Fn14 interactions in the pathogenesis of cutaneous lupus has not been explored. TWEAK treatment of murine PAM212 keratinocytes stimulated the secretion of RANTES via Fn14 and promoted apoptosis. Parthenolide, but not wortmanin or the MAPK inhibitor PD98059, significantly decreased production of RANTES, indicating that this effect of TWEAK is mediated via NF-κB signaling. UVB irradiation significantly upregulated the expression of Fn14 on keratinocytes in vitro and in vivo and increased RANTES production. MRL/lpr Fn14 knockout (KO) lupus mice were compared with MRL/lpr Fn14 wild-type (WT) mice to evaluate for any possible differences in the severity of cutaneous lesions and the presence of infiltrating immune cells. MRL/lpr Fn14 KO mice had markedly attenuated cutaneous disease as compared with their Fn14 WT littermates, as evidenced by the well-maintained architecture of the skin and significantly decreased skin infiltration of T cells and macrophages. Our data strongly implicate TWEAK/Fn14 signaling in the pathogenesis of the cutaneous manifestations in the MRL/lpr model of spontaneous lupus and suggest a possible target for therapeutic intervention.

Role of interleukin-10 and interleukin-10 receptor in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by excessive production of a variety of autoantibodies, accumulation of immune complexes, and multiple organ systems involvement. Interleukin-10 (IL-10) has an important role in the growth, survival, differentiation, and function of B cells. Abnormally increased IL-10 synthesis seems contributing to the spontaneous hyperactivity of the B cell compartment, so that it can directly result in autoantibody production by committed plasma cells, circulating immune complexes formation, and eventually in tissue and organ damage, suggesting it might associate with the development of SLE. A better understanding of the regulation of IL-10 and its receptors (IL-10R) can likely provide more valuable clues to the pathogenic mechanisms underlying specific forms of SLE, so as to pave the way toward more effective therapeutics.