Human and Murine Toll-like Receptor-Driven Disease in Systemic Lupus Erythematosus.

The pathogenesis of systemic lupus erythematosus (SLE) is linked to the differential roles of toll-like receptors (TLRs), particularly TLR7, TLR8, and TLR9. TLR7 overexpression or gene duplication, as seen with the Y-linked autoimmune accelerator (Yaa) locus or TLR7 agonist imiquimod, correlates with increased SLE severity, and specific TLR7 polymorphisms and gain-of-function variants are associated with enhanced SLE susceptibility and severity. In addition, the X-chromosome location of TLR7 and its escape from X-chromosome inactivation provide a genetic basis for female predominance in SLE. The absence of TLR8 and TLR9 have been shown to exacerbate the detrimental effects of TLR7, leading to upregulated TLR7 activity and increased disease severity in mouse models of SLE. The regulatory functions of TLR8 and TLR9 have been proposed to involve competition for the endosomal trafficking chaperone UNC93B1. However, recent evidence implies more direct, regulatory functions of TLR9 on TLR7 activity. The association between age-associated B cells (ABCs) and autoantibody production positions these cells as potential targets for treatment in SLE, but the lack of specific markers necessitates further research for precise therapeutic intervention. Therapeutically, targeting TLRs is a promising strategy for SLE treatment, with drugs like hydroxychloroquine already in clinical use.

Advanced methods and novel biomarkers in autoimmune diseases ­ a review of the recent years progress in systemic lupus erythematosus.

There are several autoimmune and rheumatic diseases affecting different organs of the human body. Multiple sclerosis (MS) mainly affects brain, rheumatoid arthritis (RA) mainly affects joints, Type 1 diabetes (T1D) mainly affects pancreas, Sjogren's syndrome (SS) mainly affects salivary glands, while systemic lupus erythematosus (SLE) affects almost every organ of the body. Autoimmune diseases are characterized by production of autoantibodies, activation of immune cells, increased expression of pro-inflammatory cytokines, and activation of type I interferons. Despite improvements in treatments and diagnostic tools, the time it takes for the patients to be diagnosed is too long, and the main treatment for these diseases is still non-specific anti-inflammatory drugs. Thus, there is an urgent need for better biomarkers, as well as tailored, personalized treatment. This review focus on SLE and the organs affected in this disease. We have used the results from various rheumatic and autoimmune diseases and the organs involved with an aim to identify advanced methods and possible biomarkers to be utilized in the diagnosis of SLE, disease monitoring, and response to treatment.

Chip-based multimodal super-resolution microscopy for histological investigations of cryopreserved tissue sections.

Histology involves the observation of structural features in tissues using a microscope. While diffraction-limited optical microscopes are commonly used in histological investigations, their resolving capabilities are insufficient to visualize details at subcellular level. Although a novel set of super-resolution optical microscopy techniques can fulfill the resolution demands in such cases, the system complexity, high operating cost, lack of multi-modality, and low-throughput imaging of these methods limit their wide adoption for histological analysis. In this study, we introduce the photonic chip as a feasible high-throughput microscopy platform for super-resolution imaging of histological samples. Using cryopreserved ultrathin tissue sections of human placenta, mouse kidney, pig heart, and zebrafish eye retina prepared by the Tokuyasu method, we demonstrate diverse imaging capabilities of the photonic chip including total internal reflection fluorescence microscopy, intensity fluctuation-based optical nanoscopy, single-molecule localization microscopy, and correlative light-electron microscopy. Our results validate the photonic chip as a feasible imaging platform for tissue sections and pave the way for the adoption of super-resolution high-throughput multimodal analysis of cryopreserved tissue samples both in research and clinical settings.

Interplay of immune and kidney resident cells in the formation of tertiary lymphoid structures in lupus nephritis.

Kidney involvement confers significant morbidity and mortality in patients with systemic lupus erythematosus (SLE). The pathogenesis of lupus nephritis (LN) involves diverse mechanisms instigated by elements of the autoimmune response which alter the biology of kidney resident cells. Processes in the glomeruli and in the interstitium may proceed independently albeit crosstalk between the two is inevitable. Podocytes, mesangial cells, tubular epithelial cells, kidney resident macrophages and stromal cells with input from cytokines and autoantibodies present in the circulation alter the expression of enzymes, produce cytokines and chemokines which lead to their injury and damage of the kidney. Several of these molecules can be targeted independently to prevent and reverse kidney failure. Tertiary lymphoid structures with true germinal centers are present in the kidneys of patients with lupus nephritis and have been increasingly recognized to associate with poorer renal outcomes. Stromal cells, tubular epithelial cells, high endothelial vessel and lymphatic venule cells produce chemokines which enable the formation of structures composed of a T-cell-rich zone with mature dendritic cells next to a B-cell follicle with the characteristics of a germinal center surrounded by plasma cells. Following an overview on the interaction of the immune cells with kidney resident cells, we discuss the cellular and molecular events which lead to the formation of tertiary lymphoid structures in the interstitium of the kidneys of mice and patients with lupus nephritis. In parallel, molecules and processes that can be targeted therapeutically are presented.

Kidney Tertiary Lymphoid Structures in Lupus Nephritis Develop into Large Interconnected Networks and Resemble Lymph Nodes in Gene Signature.

Immune aggregates organized as tertiary lymphoid structures (TLS) are observed within the kidneys of patients with systemic lupus erythematosus and lupus nephritis (LN). Renal TLS was characterized in lupus-prone New Zealand black × New Zealand white F1 mice analyzing cell composition and vessel formation. RNA sequencing was performed on transcriptomes isolated from lymph nodes, macrodissected TLS from kidneys, and total kidneys of mice at different disease stages by using a personal genome machine and RNA sequencing. Formation of TLS was found in anti-double-stranded DNA antibody-positive mice, and the structures were organized as interconnected large networks with distinct T/B cell zones with adjacent dendritic cells, macrophages, plasma cells, high endothelial venules, supporting follicular dendritic cells network, and functional germinal centers. Comparison of gene profiles of whole kidney, renal TLS, and lymph nodes revealed a similar gene signature of TLS and lymph nodes. The up-regulated genes within the kidneys of lupus-prone mice during LN development reflected TLS formation, whereas the down-regulated genes were involved in metabolic processes of the kidney cells. A comparison with human LN gene expression revealed similar up-regulated genes as observed during the development of murine LN and TLS. In conclusion, kidney TLS have a similar cell composition, structure, and gene signature as lymph nodes and therefore may function as a kidney-specific type of lymph node.

LMW heparin prevents increased kidney expression of proinflammatory mediators in (NZBxNZW)F1 mice.

We have previously demonstrated that continuous infusion of low molecular weight (LMW) heparin delays autoantibody production and development of lupus nephritis in (NZBxNZW)F1 (B/W) mice. In this study we investigated the effect of LMW heparin on renal cytokine and chemokine expression and on nucleosome-mediated activation of nucleosome-specific splenocytes. Total mRNA extracted from kidneys of heparin-treated or -untreated B/W mice was analysed by qPCR for the expression of several cytokines, chemokines, and Toll-like receptors. Splenocytes taken from B/W mice were stimulated with nucleosomes with or without the presence of heparin. Splenocyte cell proliferation as thymidine incorporation and the expression of costimulatory molecules and cell activation markers were measured. Heparin treatment of B/W mice reduced the in vivo expression of CCR2, IL1 ß , and TLR7 compared to untreated B/W mice. Nucleosome-induced cell proliferation of splenocytes was not influenced by heparin. The expression of CD80, CD86, CD69, CD25, CTLA-4, and TLR 2, 7, 8, and 9 was upregulated upon stimulation by nucleosomes, irrespective of whether heparin was added to the cell culture or not. In conclusion, treatment with heparin lowers the kidney expression of proinflammatory mediators in B/W mice but does not affect nucleosomal activation of splenocytes.

Pure anti-dsDNA mAbs need chromatin structures to promote glomerular mesangial deposits in BALB/c mice.

The glomerular targets for nephritogenic antibodies have been identified as membrane-associated chromatin fragments. The processes responsible for their deposition are poorly understood. To determine early events in antibody-mediated nephritis, we injected highly pure anti-dsDNA mAbs into BALB/c mice. Mice receiving one dose of anti-dsDNA mAbs were sacrificed 6 or 24 h later. No direct binding of mAbs to glomerular membranes or to the mesangial matrix was observed by immune electron microscopy. In contrast, repeated injections of the same antibodies over 4 weeks resulted in deposition of electron dense structures predominantly in the mesangial matrix. These structures contained mAbs and chromatin fragments as determined by co-localization immune electron microscopy. Biotinylated anti-dsDNA mAbs, injected into nephritic (NZB x NZW)F1 or MRL(lpr/lpr) mice were detected in newly formed electron dense structures within glomerular capillary membranes. There were no correlation between mAb affinity for DNA, as determined by surface plasmon resonance analyses, and ability to bind chromatin fragments in vivo. No direct binding of mAbs to inherent membrane antigens was observed. Quantification of DNA in sera before and after one single injection of antibodies revealed increased DNA levels at 6 h after injection of anti-dsDNA mAb, and lower levels after 24 h. Repeated injections of anti-dsDNA caused an increase in circulating DNA. These results indicate that availability of chromatin fragments, presumable in circulation, is important for glomerular mesangial matrix deposition of anti-dsDNA antibody-containing immune complexes in context of lupus nephritis.

Renal expression of polyomavirus large T antigen is associated with nephritis in human systemic lupus erythematosus.

We have demonstrated that glomerular expression of polyomavirus large T antigen (T-ag) in a binary tetracycline-regulated T-ag transgenic mouse model (i) terminated tolerance for nucleosomes, (ii) released complexes of nucleosomes and T-ag to the microenvironment from dead cells, and (iii) that these complexes bound induced anti-nucleosome antibodies and finally (iv) that they associated with glomerular membranes as immune complexes. This process may be relevant for human lupus nephritis, since productive polyomavirus infection is associated with this organ manifestation. Here, we compare nephritis in the T-ag transgenic mouse with nephritis in human SLE. Glomerular sections were analysed by transmission electron microscopy, immune electron microscopy (IEM) and by co-localization IEM and TUNEL IEM assays to compare morphological changes, composition of immune complexes and formation of nucleosome-T-ag complexes. Affinity of nucleosome-T-ag complexes for glomerular collagen IV and laminin was determined by surface plasmon resonance (SPR). Analyses revealed electron dense structures in both human and murine kidney samples. These EDS were shown to contain T-ag, DNA and histones, indicating that extra-cellular chromatin may originate from polyomavirus infected cells in human kidneys. SPR analyses demonstrated high affinity of nucleosomes and nucleosome-T-ag complexes for collagen IV and laminin. Complexes of nucleosomes, T-ag and anti-T-ag and anti-dsDNA antibodies bind glomerular membranes and contribute to the evolution of lupus nephritis in human SLE.