Imlifidase: First Approval.

Imlifidase (IdefirixTM), a cysteine protease derived from the immunoglobulin G (IgG)­degrading enzyme of Streptococcus (S.) pyogenes is being developed by Hansa Biopharma AB for treatment of transplant rejection and rare IgG-mediated autoimmune conditions. In August 2020, intravenous imlifidase received its first global approval in the EU for desensitization treatment of highly sensitized adult kidney transplant patients with positive crossmatch against an available deceased donor. Imlifidase is currently undergoing clinical evaluation for the prevention of kidney transplant rejection in the USA, Australia, France and Austria, and clinical development is underway for anti-glomerular basement membrane disease, and for Guillain-Barre syndrome in France, the UK and the Netherlands. This article summarizes the milestones in the development of imlifidase leading to this first approval for desensitization treatment of highly sensitized adult kidney transplant patients with positive crossmatch against an available deceased donor.

Spleen tyrosine kinase inhibition attenuates autoantibody production and reverses experimental autoimmune GN.

Spleen tyrosine kinase (SYK) has an important role in immunoreceptor signaling, and SYK inhibition has accordingly attenuated immune-mediated injury in several in vivo models. However, the effect of SYK inhibition on autoantibody production remains unclear, and SYK inhibition has not been studied in an autoimmune model of renal disease. We, therefore, studied the effect of SYK inhibition in experimental autoimmune GN, a rodent model of antiglomerular basement membrane disease. We show glomerular SYK expression and activation by immunohistochemistry in both experimental and clinical disease, and we show that treatment with fostamatinib, a small molecule kinase inhibitor selective for SYK, completely prevents the induction of experimental autoimmune GN. In established experimental disease, introduction of fostamatinib treatment led to cessation of autoantibody production, reversal of renal injury, preservation of biochemical renal function, and complete protection from lung hemorrhage. B cell ELISpot and flow cytometric analysis suggest that short-term fostamatinib treatment inhibits the generation and activity of antigen-specific B cells without affecting overall B-cell survival. Additionally, fostamatinib inhibited proinflammatory cytokine production by nephritic glomeruli ex vivo and cultured bone marrow-derived macrophages in vitro, suggesting additional therapeutic effects independent of effects on autoantibody production that are likely related to inhibited Fc receptor signaling within macrophages in diseased glomeruli. Given these encouraging results in an in vivo model that is highly applicable to human disease, we believe clinical studies targeting SYK in GN are now warranted.

Low-level laser therapy improves crescentic glomerulonephritis in rats.

Low-level laser therapy (LLLT) can reduce inflammation in a variety of clinical conditions, including trauma, postherpetic neuralgia, and rheumatoid arthritis. However, the effect of LLLT on internal organs has not been elucidated. The goal of the present study was to investigate the anti-inflammatory effect of daily external LLLT in an animal model of crescentic glomerulonephritis. Crescentic glomerulonephritis was induced in male Wister Kyoto rats by intravenous injection of antibody for glomerular basement membrane (GBM). The rats were irradiated with a low-reactive level diode laser with an infrared wavelength of 830 nm from the shaved skin surface once a day for 14 days (irradiation spot size on the skin surface, 2.27 cm(2); power intensity, 880 mW/cm(2); irradiation mode, continuous mode; irradiation time, 250 s; energy, 500 J; energy density, 220 J/cm(2)). After laser irradiation for 14 days, animals were killed, and the extent of inflammation was evaluated. Expression of gene for inflammatory cytokines including interleukin (IL)-1ß and tumor necrosis factor alpha (TNF-α) was assessed by reverse transcription polymerase chain reaction. Crescent formation in glomeruli and infiltration of macrophages and lymphocytes were assessed by histochemical observation. Injection of anti-GBM antibody induced severe glomerulonephritis with crescent formation. Histological observations indicated that LLLT suppressed crescent formation and infiltration of ED1+ macrophages and CD8+ lymphocytes into the glomeruli. LLLT attenuated the levels of IL-1ß and TNF-α messenger RNA in the renal cortex. Externally directed LLLT suppresses the activity of rat anti-GBM crescentic glomerulonephritis in rats. LLLT has the potential to be used for direct treatment of glomerulonephritis.

The selective mineralocorticoid receptor antagonist eplerenone is protective in mild anti-GBM glomeru-lonephritis.

BACKGROUND: Growing evidence suggests that blockade of the aldosterone-receptor may preserve kidney function by anti-inflammatory effects independent of the blood pressure. We hypothesized that the selective aldosterone-receptor antagonist eplerenone has a profound anti-inflammatory effect in the autologous phase of anti-glomerular basement membrane (GBM) glomerulonephritis (GN). METHODS: Mice received ≈200mg/kg body wt/day eplerenone via supplemented chow diet or standard chow starting at the day of immunization with rabbit IgG. Three days later the anti-GBM antibody was injected and the experiments were stopped at day 7 and 14. RESULTS: Mice receiving eplerenone showed significantly decreased albuminuria and glomerular sclerosis at day 7 and 14 after induction of anti-GBM GN. Eplerenone treatment significantly inhibited the infiltration of CD4+, CD8+ T cells and macrophages into the kidneys. Circulating levels and glomerular deposition of autologous IgG were comparable in both groups. At day 7 the pro-inflammatory cytokines MCP-1 and IL-6 were found to be significantly decreased in regional draining lymph nodes of eplerenone-treated mice, whereas the anti-inflammatory cytokine IL-10 was significantly upregulated. In line, splenocytes from eplerenone-treated nephritic mice produced significantly increased IL-10. CONCLUSION: Aldosterone-receptor blockade by eplerenone effectively attenuated proteinuria, kidney damage and the inflammatory response in anti-GBM GN by significantly decreasing pro-inflammatory cytokines in the regional draining lymph nodes of the kidney. Our results suggest that this selective aldosterone receptor antagonist is a possible additional tool in the treatment of GN.

Pulmonary renal syndrome due to anti-GBM and IgM C-ANCA disease requiring the use of novel therapeutic agents.

There are several known causes for the clinical syndrome of pulmonary hemorrhage and acute renal failure. Here, we report a unique case of a 50-year-old man presenting in this manner. The initial diagnosis was one of antiglomerular basement membrane (anti-GBM) disease that responded well to steroids, cyclophosphamide, and plasma exchange (PE). The pulmonary hemorrhage resolved, but he remained dialysis dependent. However, despite falling anti-GBM titers, the symptoms relapsed and standard therapy was reinitiated with limited success. The anti-GBM antibody titer fell to zero despite clinical deterioration, prompting a search for an alternative diagnosis. He was found to be IgM anti-proteinase-3 antineutrophil cytoplasmic antibody (C-ANCA) positive. The pulmonary hemorrhage responded successfully to the use of intravenous immunoglobulin and the antilymphocyte monoclonal antibody CD52. To our knowledge, this is the first known case of IgM C-ANCA in association with anti-GBM disease. As such, it highlights the predominance of pulmonary hemorrhage in this condition, as well as the need to consider alternative therapies in refractory cases.

Development and fate of crescentic and granulomatous lesions in rat Masugi nephritis.

It has been observed that with Masugi nephritis in Wistar rats the initiation of endocapillary proliferative changes with macrophage accumulation is usually followed by glomerular sclerosis without extracapillary extension. In the present study, the provocation of an extracapillary lesion was attempted using accelerated Masugi nephritis in Wistar-Kyoto rats. In order to accelerate the accumulation of monocyte/macrophages, the administration of methylcellulose was added in an additional group. The development and fate of extracapillary lesions were analyzed histopathologically and immunohistochemically. As a result, the formation of extracapillary proliferation of granulomatous lesions could be initiated in this model. Granulomatous lesions were composed of CD4+ T cells and CD8+ T cells and monocyte/macrophages including multinucleated giant cells. These inflammatory cells had seemingly escaped from the capillary lumen through the injured glomerular basement membrane and formed cellular and granulomatous crescents. In addition, tenascin was strongly expressed in cellular crescents and was a unique extracellular matrix at this cellular stage. The cellular crescents then progressed to sclerosis with the formation of increased collagenous extracellular matrix. These results suggest that a delayed-type hypersensitivity plays a role in granulomatous crescent formation, even though the initial glomerular injury was evoked by a humoral antibody.

Molecular properties of the Goodpasture epitope.

Goodpasture disease fulfils all criteria for a classical autoimmune disease, where autoantibodies targeted against the non-collagenous domain of the alpha3-chain of collagen IV initiates an inflammatory destruction of the basement membrane in kidney glomeruli and lung alveoli. This leads to a rapidly progressive glomerulonephritis and severe pulmonary hemorrhage. Previous studies have indicated a limited epitope for the toxic antibodies in the N-terminal part of the non-collagenous domain. The epitope has been partially characterized by recreating the epitope in the non-reactive alpha1-chain by exchanging nine residues to the corresponding ones of alpha3. In this study we have investigated to what extent each of these amino acids contribute to the antibody binding in different patient sera. The results show that seven of the nine substitutions are enough to get an epitope that is recognized equally well as the native alpha3-chain by all sera from 20 clinically verified Goodpasture patients. Furthermore, the patient sera reactivity against the different recombinant chains used in the study are very similar, with some minor exceptions, strongly supporting a highly defined and restricted epitope. We are convinced that the restriction of the epitope is of significant importance for the understanding of the etiology of the disease. Thereby also making every step on the way to characterization of the epitope a crucial step on the way to specific therapy for the disease.

Síndrome pulmón-riñón / Lung-kidney syndrome

El síndrome pulmón riñón se caracteriza por hemorragia alveolar severa y glomerulonefritis. Obedece a variadas etiologías, siendo la vasculitis la causa más frecuente. Recientemente se ha establecido que aquellas vasculitis que comprometen a los capilares, alveolares y glomerulares, cursan con síndrome pulmón riñón. Histológicamente se expresan con una inflamación necrotizante de los capilares alveolares y con glomerulonefritis necrotizante y crescéntica en el riñón. El descubrimiento de los ANCA (Antineutrophil Cytoplasmic Antibodies) a permitido mejorar nuestra comprensión del síndrome pulmón riñón. En este artículo se revisa a la luz de los conocimientos actuales, el diagnóstico etiológico de este síndrome. Considerando que las alteraciones histológicas a nivel pulmón son inespecíficas, el diagnóstico etiológico debe realizarse en base a las manifestaciones clinicopatológicas del compromiso extrapulmonar y/o de las alteraciones serológicas características

Binding of anti-basement membrane antibody to alveolar basement membrane after intratracheal gasoline instillation in rabbits.

A possible causal relationship has been suggested between hydrocarbon (gasoline, solvents, etc.) exposure and development of anti-basement membrane antibody-associated Goodpasture's syndrome in man. The authors evaluated the effect of hydrocarbons on pulmonary capillary permeability and binding of heterologous anti-basement membrane antibodies in the lungs after intratracheal instillation of minute amounts of unleaded gasoline into rabbits. The anti-glomerular basement membrane (GBM) antibodies used reacted with the alveolar basement membrane (ABM) in vitro by indirect immunofluorescence. The gasoline treatment altered pulmonary capillary permeability, judging from the increased accumulation of systemically administered radioiodinated bovine serum albumin in the alveolar and extravascular spaces of lungs; it also induced focal macroscopic and microscopic pulmonary histologic lesions. The gasoline caused focal in vivo binding of the anti-GBM antibodies to the ABM detectable by immunofluorescence microscopy. No binding was observed in lungs from control rabbits given saline instillations when assayed by immunofluorescence. The paired label radioisotope technique confirmed the increased antibody binding to lungs injured with gasoline (1.08 +/- 0.03 micrograms) versus 0.37 +/- 0.07 microgram after saline (P less than 0.001). These results indicate that gasoline exposure damages a pulmonary barrier that normally prevents binding of anti-GBM/ABM antibody to ABM and suggest that hydrocarbon exposure may be one of perhaps several pneumotoxic events that contribute to the episodic pulmonary hemorrhage in Goodpasture's syndrome by temporarily allowing ABM binding of anti-basement membrane antibodies.