Use of laser microdissection in the analysis of renal-infiltrating T cells in MRL/lpr mice

BAFF Induces Tertiary Lymphoid Structures and Positions T Cells within the Glomeruli during Lupus Nephritis

Tissue-specific immune responses play an important role in the pathology of autoimmune diseases. In systemic lupus erythematosus, deposits of IgG-immune complexes and the activation of complement in the kidney have long been thought to promote inflammation and lupus nephritis. However, the events that localize cells in non-lymphoid tertiary organs and sustain tissue-specific immune responses remain undefined. In this manuscript, we show that BAFF promotes events leading to lupus nephritis. Using an inducible model of systemic lupus erythematosus, we found that passive transfer of antinucleosome IgG into AID^-/-MRL/lpr mice elevated autoantibody levels and promoted lupus nephritis by inducing BAFF production in the kidneys, and the formation of renal tertiary lymphoid structures (TLSs). Reducing BAFF in vivo prevented the formation of TLSs and lupus nephritis; however, it did not reduce immune cell infiltrates, or the deposits of IgG and complement in the kidney. Mechanistically, lowering BAFF levels also diminished the number of T cells positioned inside the glomeruli and reduced inflammation. Thus, BAFF plays a previously unappreciated role in lupus nephritis by inducing renal TLSs and regulating the position of T cells within the glomeruli.

Lupus pathobiology based on genomics

Systemic lupus erythematosus (SLE) is an autoimmune disorder with complex genetic underpinnings. This review attempts to assemble the myriad of genomic findings to build a clearer picture of the pathobiology of SLE to serve as a guide for therapeutics. Over 100 genes are now known for SLE, and several more penetrant ones have led to the emergence of more defined lupus phenotypes. Also discussed here are the targeted therapies that have come up on the horizon and the specific biologic mechanisms of more traditional therapies which have only recently been explored. The diagnostic toolbox has been enhanced by the addition of new antibodies, gene expression signatures, and mutation panels. This provides an opportunity to piece together the lupus puzzle and even revisit the clinical classification of SLE.

FLI1 Levels Impact CXCR3 Expression and Renal Infiltration of T Cells and Renal Glycosphingolipid Metabolism in the MRL/lpr Lupus Mouse Strain

The ETS factor Friend leukemia virus integration 1 (FLI1) is a key modulator of lupus disease expression. Overexpressing FLI1 in healthy mice results in the development of an autoimmune kidney disease similar to that observed in lupus. Lowering the global levels of FLI1 in two lupus strains (Fli1(+/-)) significantly improved kidney disease and prolonged survival. T cells from MRL/lpr Fli1(+/-) lupus mice have reduced activation and IL-4 production, neuraminidase 1 expression, and the levels of the glycosphingolipid lactosylceramide. In this study, we demonstrate that MRL/lpr Fli1(+/-) mice have significantly decreased renal neuraminidase 1 and lactosylceramide levels. This corresponds with a significant decrease in the number of total CD3(+) cells, as well as CD4(+) and CD44(+)CD62L(-) T cell subsets in the kidney of MRL/lpr Fli1(+/-) mice compared with the Fli1(+/+) nephritic mice. We further demonstrate that the percentage of CXCR3(+) T cells and Cxcr3 message levels in T cells are significantly decreased and correspond with a decrease in renal CXCR3(+) cells and in Cxcl9 and Cxcl10 expression in the MRL/lpr Fli1(+/-) compared with the Fli1(+/+) nephritic mice. Our results suggest that reducing the levels of FLI1 in MRL/lpr mice may be protective against development of nephritis in part through downregulation of CXCR3, reducing renal T cell infiltration and glycosphingolipid levels.

Glomerular cytokine expression in murine lupus nephritis

BACKGROUND

Aberrant expression of T helper cell (Th) cytokines is believed to play a central role in the pathogenesis of systemic lupus erythematosus (SLE). While the glomerulus is one of the major targets of lupus inflammation, little is known about the cytokine expression in glomeruli. The current study aimed to explore the profiles of Th cytokine gene expressions in isolated glomeruli of lupus-prone mice.

METHODS

Glomeruli were purified from lupus-prone MRL/lpr mice using the magnetic microbead method. Expressions of cytokine genes representing the Th subset and FoxP3 were examined using real-time polymerase chain reaction. Serum levels of these cytokines were also measured by enzyme-linked immunosorbent assay. MRL/n mice were used as controls. Histologic glomerular damages were scored semiquantitatively. To examine the role of TNF-α in glomerular damage, we administered etanercept, a TNF-α antagonist, into the subjects.

RESULTS

Glomerular gene expressions of TNF-α in lpr mice increased with week postpartum and reached statistically significant levels at 16 weeks compared with those of the glomeruli from control mice. Expressions of IFN-γ, IL-4 and FoxP3 also increased, but the difference was not significant. There was a significant increase in serum levels of TNF-α, IFN-γ, and IL-17 and decrease in those of IL-4. Among the genes examined, TNF-α significantly correlated with glomerular damage score. Administration of etanercept did not affect glomerular cytokine expressions or proteinuria and failed to ameliorate histologic glomerular damages.

CONCLUSION

Our data suggest that Th1 cytokines, especially TNF-α, are dominantly expressed in the glomeruli of lupus-prone mice, but its pathophysiological role remains unclear.

IL-17 and IL-23 in lupus nephritis - association to histopathology and response to treatment

Background

Recent studies indicate a central role for the IL-23/IL-17 axis in the pathogenesis of lupus nephritis (LN) but the importance in the context of treatment outcome is unknown. We studied various cytokines, including the IL-23/IL-17 axis, in association to histopathology and response to therapy.

Methods

Fifty-two patients with active LN were included. Renal biopsies were performed at baseline and after immunosuppressive treatment. Serum levels of TNF-α, IFN-γ, IL-6, IL-10, IL-17, IL-23 and TGF-β were analysed at both biopsy occasions and in 13 healthy controls. IL-17 expression in renal tissue was assessed by immunohistochemistry. Biopsies were evaluated regarding WHO-classification and renal disease activity was estimated using the BILAG-index. Improvement of 2 grades in renal BILAG was regarded complete response, and 1 grade partial response.

Results

At baseline, all patients had high disease activity (BILAG A/B). Baseline levels of IL-6, IL-10, IL-17, IL-23 (p < 0.001) and IFN-γ (p = 0.03) were increased in patients vs. controls. In contrast, TGF-β was lower in patients compared to controls (p < 0.001).

Baseline levels of IL-17 were higher in patients with persisting active nephritis (WHO III, IV, V) after treatment, i.e. a poor histological response, vs. WHO I-II (p < 0.03). At follow-up, IL-23 were higher in BILAG-non-responders vs. responders (p < 0.05). Immunostaining of renal tissue revealed IL-17 expression in inflammatory infiltrates.

Conclusions

High baseline IL-17 predicted an unfavourable histopathological response, and BILAG-non-responders had high IL-23, indicating that that a subset of LN-patients has a Th-17 phenotype that may influence response to treatment and could be evaluated as a biomarker for poor therapeutic response.

Use of laser microdissection in the analysis of renal-infiltrating T cells in murine lupus

Objective

To clarify the role of T cells in kidney pathology of three widely used murine lupus models.

Material and methods

Cells infiltrating the glomeruli and perivascular areas in MRL/lpr (n = 10 female), NZB× NZW F1 (B/W F1) (n = 9 female), and BXSB (n = 10 male) mice were captured by laser microdissection (LMD). Samples were subjected to nested reverse transcription polymerase chain reaction (RT-PCR) with primers specific to β-actin, T-cell receptor β chain (TCR-Cβ), interleukin (IL)-10, IL-13, IL-17, and interferon-g (IFN-γ). Frozen sections of lesions were also stained immunohistochemically for tissue and cellular characterization.

Results

T cells infiltrating the glomeruli and perivascular areas predominantly produced IFN-γ, IL-13, and IL-17 in MRL/lpr, B/W F1, and BXSB mice, with IL-17 expression in glomeruli of BXSB mice being significantly lower than that of MRL/lpr and B/W F1 mice. IL-10 was detected only in the perivascular areas of MRL/lpr and B/W F1 mice and not in glomeruli isolates. Immunohistochemical staining revealed positive for the expression of Thy-1, CD4, CD8, and B220 in glomeruli and perivascular areas from all three strains of mice.

Conclusions

Cytokine balance in murine SLE is complex and cannot be attributed simply to the balance between Th1 and Th2 cells. Th17 cells may play a critical role in disease pathology, possibly with greater contribution toward disease progression in MRL/lpr and B/W F1 mice than in BXSB mice. Furthermore, these findings lend support to the concept that different molecular mechanisms underlie glomerulonephritis as compared to vasculitis.

Enhanced expression of the soluble form of E-selectin attenuates progression of lupus nephritis and vasculitis in MRL/lpr mice

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that causes inflammatory tissue damage, including lupus nephritis and vasculitis. Local generation of adhesion molecules and expression of their ligands on inflammatory cells appears to contribute to the progression of SLE. We found significantly increased E-selectin expression in the glomeruli and renal interstitial microvasculature of MRL/MpJ-lpr/lpr (MRL/lpr) lupus model mice. This was accompanied with infiltration of inflammatory cells, especially macrophages and CD8(+) T cells. Similarly, in 21 patients with proliferative lupus nephritis, there was a significant correlation between renal E-selectin levels and macrophage and CD8(+) T cell infiltration in the affected kidneys. By contrast, in transgenic MRL/lpr mice exhibiting elevated levels of circulating soluble E-selectin (sE-selectin) protein, which competitively inhibits E- and P-selectin-mediated extravasation of inflammatory cells, the progression of lupus nephritis and vasculitis was significantly suppressed and survival was significantly prolonged. This improvement was accompanied by significant reductions in renal infiltration by macrophages and CD8(+) T cells. These results suggest that E-selectin plays a crucial role in lupus nephritis and vasculitis by mediating renal infiltration of inflammatory cells, and that because it inhibits this process, sE-selectin could potentially serve as an effective treatment for lupus nephritis and vasculitis.

IL-17: a new actor in IFN-driven systemic autoimmune diseases

Systemic autoimmune diseases such as systemic lupus erythematosus are type I IFN-driven diseases with exaggerated B-cell responses and autoantibody production. Th17 cells, a T-helper-cell subset with high inflammatory capacity, was initially discovered and characterized in the context of experimental autoimmune encephalomyelitis - an animal model of multiple sclerosis. There is now emerging evidence that Th17 cells, and more generally IL-17 and IL-17-producing cells, may play a role in the pathogenesis of type I IFN-driven systemic autoimmune diseases such as lupus. Here, we review the different studies suggesting a role for IL-17 and IL-17-producing cells in systemic autoimmune diseases, both in humans and in animal models, and we consider the possible mechanisms by which these cells may contribute to disease. We also discuss the hypothesis that type I IFN and IL-17 act in concert to sustain and amplify autoimmune and inflammatory responses, making them a dangerous combination involved in the pathogenesis of systemic autoimmune diseases.

Mechanisms of tissue injury in lupus nephritis

Systemic lupus erythematosus is a prototypic autoimmune disease characterized by autoantibody production and immune complex formation/deposition in target organs such as the kidney. Resultant local inflammation then leads to organ damage. Nephritis, a major cause of morbidity and mortality in patients with lupus, occurs in approximately 50% of lupus patients. In the present review, we provide an overview of the current research and knowledge concerning mechanisms of renal injury in both lupus-prone mouse models and human lupus patients.

Regulatory T-cell-associated cytokines in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production, complement activation, and immune complex deposition, resulting in tissue and organ damage. An understanding of the mechanisms responsible for homeostatic control of inflammation, which involve both innate and adoptive immune responses, will enable the development of novel therapies for SLE. Regulatory T cells (Treg) play critical roles in the induction of peripheral tolerance to self- and foreign antigens. Naturally occurring CD4⁺CD25⁺ Treg, which characteristically express the transcription factor forkhead box protein P3 (Foxp3), have been intensively studied because their deficiency abrogates self-tolerance and causes autoimmune disease. Moreover, regulatory cytokines such as interleukin-10 (IL-10) also play a central role in controlling inflammatory processes. This paper focuses on Tregs and Treg-associated cytokines which might regulate the pathogenesis of SLE and, hence, have clinical applications.

Recovery of the immune balance between Th17 and regulatory T cells as a treatment for systemic lupus erythematosus

The Th17 lineage, a lineage of effector CD4(+) T cells, is characterized by the production of IL-17. Expansion of Th17 cells has been implicated in a growing list of autoimmune disorders. Our studies, as well as others, have shown that Th17 cells play a key role in the pathogenesis of SLE. Therefore, some investigators advocate that Th17 cells are a promising therapeutic target for SLE. However, neutralization of IL-17 in vivo actually aggravated inflammation by inducing infiltration of other effector cells. Thus, the therapeutic effects of antagonizing Th17 cells for the treatment of SLE in the clinic are worth discussing. Moreover, in patients with SLE, the expansion of effector T cells is always closely related to the depletion and dysfunction of Treg cells. Therefore, we hypothesize that for the treatment of SLE, we should focus on therapeutic agents that can regulate the immune balance between Th17 and Treg cells rather than on those that exclusively regulate Th17 cells.

Identification of Baicalin as an immunoregulatory compound by controlling T(H)17 cell differentiation

T_H17 cells have been implicated in a growing list of inflammatory disorders. Antagonism of T_H17 cells can be used for the treatment of inflammatory injury. Currently, very little is known about the natural compound controlling the differentiation of T_H17 cells. Here, we showed that Baicalin, a compound isolated from a Chinese herb, inhibited T_H17 cell differentiation both in vitro and in vivo. Baicalin might inhibit newly generated T_H17 cells via reducing RORγt expression, and together with up-regulating Foxp3 expression to suppress RORγt-mediated IL-17 expression in established T_H17 cells. In vivo treatment with Baicalin could inhibit T_H17 cell differentiation, restrain T_H17 cells infiltration into kidney, and protect MRL/lpr mice against nephritis. Our findings not only demonstrate that Baicalin could control T_H17 cell differentiation but also suggest that Baicalin might be a promising therapeutic agent for the treatment of T_H17 cells-mediated inflammatory diseases.

Cytokine overproduction, T-cell activation, and defective T-regulatory functions promote nephritis in systemic lupus erythematosus

Lupus nephritis (LN) occurs in more than one-third of patients with systemic lupus erythematosus. Its pathogenesis is mostly attributable to the glomerular deposition of immune complexes and overproduction of T helper- (Th-) 1 cytokines. In this context, the high glomerular expression of IL-12 and IL-18 exerts a major pathogenetic role. These cytokines are locally produced by both macrophages and dendritic cells (DCs) which attract other inflammatory cells leading to maintenance of the kidney inflammation. However, other populations including T-cells and B-cells are integral for the development and worsening of renal damage. T-cells include many pathogenetic subsets, and the activation of Th-17 in keeping with defective T-regulatory (Treg) cell function regards as further event contributing to the glomerular damage. These populations also activate B-cells to produce nephritogenic auto-antibodies. Thus, LN includes a complex pathogenetic mechanism that involves different players and the evaluation of their activity may provide an effective tool for monitoring the onset of the disease.

IL-17 in systemic lupus erythematosus

IL-17 is a cytokine with powerful proinflammatory activity. Production of IL-17 is abnormally increased in patients with systemic lupus erythematosus (SLE), a multiorgan chronic autoimmune disease. In patients with SLE, CD3⁺CD4⁻CD8⁻ (double negative) T cells are an important source of IL-17. IL-17 produced by double negative and CD4 T cells participates in the pathogenesis of the disease. IL-17-producing T cells are present in the kidneys of patients with lupus nephritis. IL-17 increased production in patients with SLE can amplify the immune response by increasing target organ inflammation and damage and by augmenting the production of antibodies by B cells.

Pathogenesis of kidney disease in systemic lupus erythematosus

PURPOSE OF REVIEW

A combination of systemic autoimmunity and tissue response to immune injury underlie renal involvement in lupus erythematosus. In this review, we discuss recent literature investigating pathogenetic mechanisms of lupus glomerulonephritis.

RECENT FINDINGS

In lupus glomerulonephritis, glomerular immune complexes were believed to be the primary mediators of renal disease. Recent studies make it apparent that autoantibodies of multiple specificities participate in the formation of immune complexes, deposited in the kidneys. Renal infiltration by T cells, macrophages, and dendritic cells have a dominant role in the progression of lupus glomerulonephritis leading to renal failure. Activation of Toll-like receptors modulates autoantibody production and systemic interferon responses. However, glomerular cell responses to immune injury influence disease outcome. In addition, new insights on the genetics of susceptibility to end-organ damage in lupus glomerulonephritis have been discovered. Differential glomerular responses reflected in gene expression profiles during disease progression provide potential markers for diagnosis of lupus glomerulonephritis progression and flares. In addition, studies of end-organ responses provide new targets for therapeutic interventions.

SUMMARY

Lupus glomerulonephritis is a prototype of immune complex disease mediated by autoantibodies of multiple specificities, one of which is anti-DNA. Murine models of spontaneous systemic lupus erythematosus have been critical for understanding the underlying disease. Recent studies demonstrate that in addition to systemic autoimmunity, end-organ responses, and end-organ resistance to damage are also critical in determining disease outcome. This understanding should influence design of novel therapeutic approaches in systemic lupus erythematosus.

Laser microdissection-based analysis of cytokine balance in the kidneys of patients with lupus nephritis

To determine the cytokine balance in patients with lupus nephritis (LN), we analysed kidney-infiltrating T cells. Renal biopsy samples from 15 systemic lupus erythematosus (SLE) patients were used. In accordance with the classification of International Society of Nephrology/Renal Pathology Society, they were categorized into Class III, Class III+V (Class III-predominant group, n = 4), Class IV, Class IV+V (Class IV-predominant group, n = 7) and Class V (n = 4) groups. The single-cell samples of both the glomelular and interstitial infiltrating cells were captured by laser-microdissection. The glomerular and interstitial infiltrating T cells produced interleukin (IL)-2, IL-4, IL-10, IL-13 and IL-17 cytokines in the Class III-predominant, Class IV-predominant and Class V groups. Interferon-gamma was detected only in the glomeruli of the Class III-predominant and Class V group samples. The expression level of IL-17 was correlated closely with clinical parameters such as haematuria, blood urea nitrogen level, SLE Disease Activity Index scores in both glomeruli and interstitium, urine protein level in glomeruli and serum creatinine and creatinine clearance levels in interstitium. This suggests that the glomerular infiltrating T cells might act as T helper type 1 (Th1), Th2 and Th17 cells while the interstitial infiltrating T cells, act as Th2 and Th17 cells in the Class III-predominant and Class V groups. In contrast, both the glomerular and interstitial infiltrating T cells might act as Th2 and Th17 cells in the Class IV-predominant group. The cytokine balances may be dependent upon the classification of renal pathology, and IL-17 might play a critical role in SLE development.

Interleukin-17 and systemic lupus erythematosus: current concepts

The emerging role of interleukin (IL)-17 as a hallmark proinflammatory cytokine of the adaptive immune system, produced primarily by a new T helper cell subset termed 'Th17', has received considerable attention. Differentiation of Th17 cells is driven by the simultaneous presence of transforming growth factor-beta and certain inflammatory cytokines (e.g. IL-6, IL-21), and recent studies have shown that inflammation instigated by IL-17-producing cells is central to the development and pathogenesis of several human autoimmune diseases and animal models of autoimmunity. In this review, we focus on the information regarding IL-17 and systemic lupus erythematosus (SLE), a chronic autoimmune disease. The work that has explored the development and behaviour of IL-17-producing cells in SLE is discussed, and different mechanisms by which IL-17 could potentially augment inflammation and autoantibody production in the context of SLE are proposed.