Low-molecular weight inhibitors of the alternative complement pathway.

Dysregulation of the alternative complement pathway predisposes individuals to a number of diseases. It can either be evoked by genetic alterations in or by stabilizing antibodies to important pathway components and typically leads to severe diseases such as paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, C3 glomerulopathy, and age-related macular degeneration. In addition, the alternative pathway may also be involved in many other diseases where its amplifying function for all complement pathways might play a role. To identify specific alternative pathway inhibitors that qualify as therapeutics for these diseases, drug discovery efforts have focused on the two central proteases of the pathway, factor B and factor D. Although drug discovery has been challenging for a number of reasons, potent and selective low-molecular weight (LMW) oral inhibitors have now been discovered for both proteases and several molecules are in clinical development for multiple complement-mediated diseases. While the clinical development of these inhibitors initially focuses on diseases with systemic and/or peripheral tissue complement activation, the availability of LMW inhibitors may also open up the prospect of inhibiting complement in the central nervous system where its activation may also play an important role in several neurodegenerative diseases.

Complement C3-targeted therapy in C3 glomerulopathy, a prototype of complement-mediated kidney diseases.

C3 glomerulopathy (C3G) is a rare and complex kidney disease that primarily affects young adults. Renal outcomes remain poor in the absence of specific treatment. C3G is driven by uncontrolled overactivation of the alternative complement pathway, which is mainly of acquired origin. Functional characterization of complement abnormalities (i.e., autoantibodies targeting complement components and variants in complement genes) identified in patients and experimental models of the disease improved the understanding of the disease, making C3G a prototype of complement-mediated diseases. The contribution of C3 convertase, as well as C5 convertase, in disease occurrence, phenotype, and severity is now well established, offering various potential therapeutic interventions. However, the lack of sufficient efficiency in anti-C5 therapy highlights the extreme complexity of the disease and the need for new therapeutic approaches based on C3 and C3 convertase axis inhibition. Here, we provide an overview of the complement activation mechanism involved in C3G and discuss therapeutic options based on complement inhibitors, with a specific focus on C3 inhibition.

Association between circulatory complement activation and hypertensive renal damage: a case-control study.

OBJECTIVE: The aim of this study was to investigate the potential importance of complement system activation, with particular emphasis on the complement alternative pathway (AP), in the pathogenesis of hypertensive renal damage. METHODS: Serum complement C3, complement Factor H (CFH) and AP activation were assessed in 66 participants with established essential hypertension with renal damage (RD). Fifty-nine patients with age- and sex-matched essential hypertension without renal damage (NRD) and 58 healthy participants (normal) were selected. RESULTS: Our study revealed that C3 and AP50 continuously increased from normal to NRD to RD (p < 0.05, respectively), while CFH was significantly lower than that in NRD and healthy participants (p < 0.05, respectively). After multifactorial logistic regression analysis corrected for confounders, elevated serum C3 (p = 0.001) and decreased CFH (p < 0.001) were found to be independent risk factors for hypertension in healthy participants; elevated serum C3 (p = 0.034), elevated AP50 (p < 0.001), decreased CFH (p < 0.001), increased age (p = 0.011) and increased BMI (p = 0.013) were found to be independent risk factors for the progression of hypertension to hypertensive renal damage; elevated serum C3 (p = 0.017), elevated AP50 (p = 0.023), decreased CFH (p = 0.005) and increased age (p = 0.041) were found to be independent risk factors for the development of hypertensive renal damage in healthy participants. CONCLUSION: Abnormal activation of complement, particularly complement AP, may be a risk factor for the development and progression of hypertensive renal damage.

Thrombotic microangiopathy due to acquired complement factor I deficiency in a male receiving interferon-beta treatment for multiple sclerosis.

AIMS: Interferon-beta (IFNß), the most widely prescribed medication for multiple sclerosis, is generally considered safe. Nevertheless, rare serious and/or life-threatening side effects have been reported such as thrombotic microangiopathy. A few mechanisms have been proposed to explain how interferon causes thrombotic microangiopathy, but immunological studies have been unable to pin this phenomenon down to a single pathophysiologic pathway. The aim of this article was to report a new mechanism explaining Interferon beta related thrombotic microangiopathy. METHODS: We report thrombotic microangiopathy in a 28-year-old male receiving interferon-beta treatment for multiple sclerosis. RESULTS: After three years of starting interferon beta therapy, the patient presented with malignant hypertension causing seizures, rapidly progressive renal failure requiring haemodialysis and haemolytic anaemia. Corticosteroid and plasma exchange sessions permitted haemolysis control. Nonetheless, the patient remained hemodialysis-dependent. Exploration of the complement system found a complement factor I deficiency whose activity normalized at the control carried out after 2 years. CONCLUSION: IFNß treatment may cause complement factor I deficit, which can lead to thrombotic microangiopathy and severe renal failure.

Complement Activation and Thrombotic Microangiopathy Associated With Monoclonal Gammopathy: A National French Case Series.

RATIONALE & OBJECTIVE: Hemolytic uremic syndrome (HUS), a thrombotic microangiopathy (TMA) with kidney involvement, is a rare condition in patients with monoclonal gammopathy. In the absence of known causes of TMA, the role of complement activation in endothelial injury in patients with monoclonal gammopathy remains unknown and was the focus of this investigation. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: We studied the 24 patients in the French national registry of HUS between 2000 and 2020 who had monoclonal gammopathy without other causes of secondary TMA. We provide the clinical histories and complement studies of these patients. FINDINGS: Monoclonal gammopathy-associated TMA with kidney involvement is estimated to be 10 times less frequent than adult atypical HUS (aHUS) in the French national registry. It is characterized by severe clinical features, with 17 of 24 patients requiring dialysis at disease onset, and with median renal survival of only 20 months. TMA-mediated extrarenal manifestations, particularly cutaneous and neurological involvement, were common and associated with poor overall prognosis. Complement studies identified low C3, normal C4, and high soluble C5b-9 levels in 33%, 100%, and 77% of tested patients, respectively, indicating a contribution of the alternative and terminal complement pathways in the pathophysiology of the disease. Genetic abnormalities in complement genes known to be associated with aHUS were found in only 3 of 17 (17%) who were tested. LIMITATIONS: Retrospective study without comparison group; limited number of patients, limited available blood samples. CONCLUSIONS: Within the spectrum of TMA, TMA associated with monoclonal gammopathy represents a distinct subset. Our findings suggest that HUS associated with monoclonal immunoglobulin is a complement-mediated disease akin to aHUS.

Advances in Understanding of Pathogenesis and Treatment of Immune-Mediated Kidney Disease: A Review.

There continues to be rapid advancement in our understanding of the pathogenesis of immune-mediated kidney disease. This progress has culminated in the development of multiple therapeutic agents that have consistently improved renal and patient outcomes. The focus of this review is to discuss these recent advancements in immune-mediated kidney disease via the lens of direct and indirect immune-mediated mechanisms. In the direct immune-mediated disease, recently described antigens in anti-glomerular basement membrane (GBM) disease and membranous nephropathy are discussed, along with new therapeutic regimens in membranous nephropathy and focal segmental glomerulosclerosis. From an indirect immune-mediated disease standpoint, recent pivotal trials in antineutrophil cytoplasmic antibody vasculitis, lupus nephritis, and IgA nephropathy are examined from a real-world practice perspective. New molecular pathways in various disorders of alternate complement pathway are described, which in turn have led to development of various experimental therapies. In addition, pivotal and ongoing therapeutic trials in the aforementioned diseases are presented.

Anti-factor H antibody associated hemolytic uremic syndrome following SARS-CoV-2 infection.

BACKGROUND: The pathogenesis of autoantibody generation in anti-factor H (FH) antibody associated atypical hemolytic uremic syndrome (aHUS) is unknown and is perhaps triggered by an infectious or environmental agent. We observed an unusual increase of patients with anti-FH antibody associated aHUS coinciding with the second pandemic wave in New Delhi and suspected that SARS-CoV-2 infection might be a potential trigger. METHODS: We screened for SARS-CoV-2 infection using reverse transcriptase polymerase chain reaction (RT-PCR) and serology in 13 consecutive patients with anti-FH antibody associated aHUS during the past year in New Delhi. RESULTS: We report 5 patients, 4-13 years old, who presented with a febrile illness without respiratory symptoms during the second pandemic wave. Of these, 3 patients presented with a relapse 25-85 months following the initial episode of aHUS. SARS-CoV-2 was detected by RT-PCR in 1 patient and by serology in 4 patients (median titer 47.1 cut-off index). Patients had high titers of anti-FH antibodies (median 2,300 AU/ml). Genetic studies, done in 3 of the 5 patients, showed homozygous CFHR1 deletion without other significant genetic abnormalities. Specific management comprised plasma exchanges and oral prednisolone, combined with either cyclophosphamide or mycophenolate mofetil. At median follow-up of 3.3 months, the estimated glomerular filtration rate in 4 patients ranged from 62 to 110 ml/min/1.73 m2; one patient was dialysis-dependent. CONCLUSION: Increased vigilance is required during the pandemic, especially in patients with anti-FH associated aHUS, who might relapse despite quiescent disease for a prolonged period. A higher resolution version of the Graphical abstract is available as Supplementary information.

A novel complement inhibitor sMAP-FH targeting both the lectin and alternative complement pathways.

Inhibition of the complement activation has emerged as an option for treatment of a range of diseases. Activation of the lectin and alternative pathways (LP and AP, respectively) contribute to the deterioration of conditions in certain diseases such as ischemia-reperfusion injuries and age-related macular degeneration (AMD). In the current study, we generated dual complement inhibitors of the pathways MAp44-FH and sMAP-FH by fusing full-length MAp44 or small mannose-binding lectin-associated protein (sMAP), LP regulators, with the N-terminal five short consensus repeat (SCR) domains of complement factor H (SCR1/5-FH), an AP regulator. The murine forms of both fusion proteins formed a complex with endogenous mannose-binding lectin (MBL) or ficolin A in the circulation when administered in mice intraperitoneally. Multiple complement activation assays revealed that sMAP-FH had significantly higher inhibitory effects on activation of the LP and AP in vivo as well as in vitro compared to MAp44-FH. Human form of sMAP-FH also showed dual inhibitory effects on LP and AP activation in human sera. Our results indicate that the novel fusion protein sMAP-FH inhibits both the LP and AP activation in mice and in human sera, and could be an effective therapeutic agent for diseases in which both the LP and AP activation are significantly involved.

Deficiency of CFHR plasma proteins and autoantibody positive hemolytic uremic syndrome: treatment rationale, outcomes, and monitoring.

Deficiency of Complement Factor H Related (CFHR) plasma proteins and Autoantibody Positive Hemolytic Uremic Syndrome (DEAP-HUS) is a subtype of atypical hemolytic uremic syndrome, known to be associated with significant morbidity. Its pathogenesis is linked to the production of IgG autoantibodies against complement factor H, a regulator of the alternative complement pathway. The binding of the autoantibodies to the C terminal of complement factor H interferes with its regulatory function, leading to increased activation of the alternative complement pathway and consequent endothelial cellular damage. Early diagnosis and initiation of appropriate therapy is reported to lead to favorable outcomes. Institution of plasma exchange therapy within 24 h of diagnosis has been shown to rapidly lower antibody levels, leading to clinical improvement. Adjunctive immunosuppression therapy suppresses antibody production and helps in maintaining long-term clinical remission of the disease. Available data advocates a treatment regimen that combines plasma therapy (preferably plasma exchange) and immunosuppression to halt disease process and sustain long-term disease remission.

Activation of the alternative complement pathway predicts renal outcome in patients with lupus nephritis.

OBJECTIVES: The aims of this study were to clarify the activation of complement pathways in patients with lupus nephritis (LN), and to elucidate the association between these complement activation types and clinical outcomes. METHODS: We enrolled 115 patients with biopsy-proven LN from 2003 to 2016 from the lupus cohort at the Busan Paik Hospital and the Jeju National University Hospital in Korea. The patients were divided into two groups based on the patterns of glomerular complements deposits. The presence of C1q, C4 and/or C3 deposits in the glomerulus was considered evidence for the activation of the classical pathway with or without alternative pathway activation (group 1, N = 93), and glomerular C3 deposition without C1q and C4 deposits was considered as a marker for the alternative pathway limited activation (group 2, N = 22). The study end point was progression of kidney disease defined as a ≥50% reduction in estimated glomerular filtration rate from baseline values or advancement to end-stage renal disease. RESULTS: The mean estimated glomerular filtration rate and median urine protein-to-creatinine ratio of the patients were 85.7 ± 32.4 mL/min/1.73 m2 and 3.1 g/g, respectively, at the time of kidney biopsy. Forty-nine patients (43%) had nephrotic range of proteinuria. Compared to group 1 patients, those in group 2 were older, were more likely to be males and were more hypertensive. In addition, plasma C3 and C4 levels were significantly lower in group 1 patients compared to those in group 2. Moreover, anti-dsDNA concentration was significantly higher in group 1 patients compared to those in group 2. The mean follow-up time was 5.4 ± 3.4 years. The rates of response to one-year immunosuppressive treatment were poorer in group 2 patients compared to those in group 1. During the follow-up time, the progression of kidney disease was significantly higher in group 2 than in group 1 patients. CONCLUSION: This study showed that there was alternative complement pathway limited activation in the renal tissue in a small number of patients with LN, and these patients had worse renal outcomes compared to patients with glomerular classical complement pathway activation with or without alternative pathway activation.

The alternative complement pathway activation product Ba as a marker for transplant-associated thrombotic microangiopathy.

BACKGROUND: Transplant-associated thrombotic microangiopathy (TA-TMA) occurs after hematopoietic stem cell transplantation (HSCT) and is characterized by microvascular thrombosis and end-organ injury particularly of the kidneys. TA-TMA is challenging to diagnose and treat, which can lead to long-term complications and death in patients with severe disease. Studies have shown that genetic abnormalities of the alternative complement pathway (AP) are associated with TA-TMA. We hypothesized that patients with TA-TMA may generate elevated levels of the AP activation product, Ba, compared with HSCT patients without TA-TMA. PROCEDURE: We longitudinally measured plasma levels of complement activation products C3a, Ba, and C5a in 14 HSCT patients: 7 with TA-TMA and 7 without TA-TMA. We assessed renal function by calculating estimated glomerular filtration rate (eGFR) and correlated the extent of AP activation with renal dysfunction in both patient populations. RESULTS: The median days from HSCT to study enrollment were 154 (39-237) in the TA-TMA group and 84 (39-253) in the HSCT group without TA-TMA. Median Ba levels (ng/mL) at enrollment were 1096.9 (826.5-1562.0) in the TA-TMA group and 725.7 (494.7-818.9) in the HSCT group without TA-TMA (P = 0.007). Over the study duration, Ba levels inversely correlated with eGFR. There were no differences in C3a, C5a, or sC5b9 levels between the two populations at any measured interval. CONCLUSIONS: We conclude in this preliminary study that Ba protein may serve as a marker for TA-TMA, and furthermore, that components generated in the early phase of AP activation may be involved in the pathogenesis of renal endothelial injury in TA-TMA.

New insights into the pathogenesis of Streptococcus pneumoniae-associated hemolytic uremic syndrome.

The purpose of this review is to describe Streptococcus pneumoniae-associated hemolytic uremic syndrome (P-HUS) with emphasis on new insights into the pathophysiology and management over the past 10 years. Even though awareness of this clinico-pathological entity has increased, it likely remains under-recognized. Recent observations indicate that although neuraminidase activity and exposure of the T-antigen are necessary for development of P-HUS, they are not sufficient; activation of the alternate pathway of complement may also contribute. It is unclear, however, whether or not eculizumab and/or plasmapheresis are of value.

Molecular basis and outcomes of atypical haemolytic uraemic syndrome in Czech children.

Atypical haemolytic uraemic syndrome is an ultra-rare, life-threatening disease. Causative variants in genes that encode complement factors can be identified in 40-70% of cases. We performed genetic analysis of 21 Czech children with atypical haemolytic uraemic syndrome. Genetic or acquired predisposition to the disease was identified in the majority of our patients: CFHR1 and CFHR3 deletions in 14/21 (67%; 13 of them were positive for anti-complement factor H antibodies), variants in complement genes or DGKE in 13/21 (62%). Multiple genetic findings were identified in eight patients (38%). The incidence of atypical haemolytic uraemic syndrome in the Czech paediatric population was estimated to be 0.092 (CI 0.053-0.131) cases per million inhabitants and 0.92 (CI 0.53-1.32) cases per 100,000 births for the entire reporting period. Ten patients were initially treated with plasma exchange and eight with eculizumab or with a combination of eculizumab and plasma exchange. At the last follow-up, 20 patients were alive and one patient had end-stage renal disease.Conclusion: The incidence of atypical haemolytic uraemic syndrome in the Czech paediatric population corresponds to the reported incidence in Europe. We detected the unusually high rate of CFHR1/CFHR3 deletions associated with anti-complement factor H antibodies in Czech paediatric patients. Treatment by eculizumab led to superior outcomes and prevention of the disease relapses compared with plasma exchange therapy. Our results may help to understand the polygenic nature of atypical haemolytic uraemic syndrome as a disease that results from a combination of various risk factors. What is Known: • Atypical haemolytic uraemic syndrome (aHUS) is considered a polygenic and multifactorial disease. Genetic predisposition to aHUS is identified in 40-70% of children. • Anti-complement factor H antibodies are usually found in 6-25% of affected children. What is New: • Potentially causative genetic or acquired factors were confirmed in the majority of patients. The prevailing finding was the unusually high rate of CFHR1/CFHR3 deletions associated with anti-complement factor H antibodies (62% of patients). • The incidence of aHUS in Czech children is 0.092 (CI 0.053-0.131) cases per million inhabitants and 0.92 (CI 0.53-1.32) cases per 100,000 births for the entire reporting period.

Semi-solid phase assay for the alternative complement pathway activity assessment (AP100).

Since the introduction of the most expensive drug in the world (Eculizumab) in the therapeutic arsenal of many diseases involving the alternative complement pathway (ACP) in their pathophysiology, the unmet need to perform simple ACP assays affordable for all countries has become one of the major challenges of the contemporary medicine. The assay currently used is AH50, despite it still challenging for several laboratories. This educational chapter consists of a detail protocol of standardized hemolytic assay AP100 and aims to help clinical laboratories over the world and especially those of the developing and low income countries to perform it. The procedure is essentially the same as for the timed lysis assay and dilution methods (AP50) except the concentration of ACP buffer and the chicken erythrocyte density used to make the gels. In clinical field, AP100 has at least nine applications in disease diagnosis and follow-up. AP100 has many advantages over the AH50 as it is more reliable for the Eculizumab monitoring and more practical with a purpose to be stored and transported for several weeks. AP100 is a portable and easy to use device both at the bedside and in the companion medical care.

Brain microvascular endothelial cells exhibit lower activation of the alternative complement pathway than glomerular microvascular endothelial cells.

Atypical hemolytic uremic syndrome (aHUS) and bone marrow transplantation-associated thrombotic microangiopathy (TA-TMA) are associated with excessive activation of the alternative complement pathway (AP) and with severe renal, but rarely cerebral, microvascular damage. Here, we compared AP activation and regulation in human glomerular and brain microvascular endothelial cells (GMVECs and BMVECs, respectively) unstimulated or stimulated by the proinflammatory cytokine, tumor necrosis factor (TNF). Compared with GMVECs and under both experimental conditions, BMVECs had increased gene expression of the AP-related genes C3, CFB, and C5 and decreased expression of CFD This was associated with increased expression in BMVECs (relative to GMVECs) of the genes for surface and soluble regulatory molecules (CD46, THBD, CD55, CFI, and CFH) suppressing formation of the AP C3 and C5 convertases. Of note, unlike GMVECs, BMVECs generated extremely low levels of C3a and C5a and displayed decreased activation of the AP (as measured by a lower percentage of Ba generation than GMVECs). Moreover, BMVECs exhibited increased function of CD141, mediating activation of the natural anticoagulant protein C, compared with GMVECs. We also found that the C3a receptor (C3aR) is present on both cell types and that TNF greatly increases C3AR1 expression in GMVECs, but only slightly in BMVECs. Higher AP activation and C3a generation in GMVECs than in BMVECs, coupled with an increase in C3aR production in TNF-stimulated GMVECs, provides a possible explanation for the predominance of renal damage, and the absence of cerebral injury, in individuals with episodes of aHUS and TA-TMA.

C3aR and C5aR1 act as key regulators of human and mouse ß-cell function.

AIMS: Complement components 3 and 5 (C3 and C5) play essential roles in the complement system, generating C3a and C5a peptides that are best known as chemotactic and inflammatory factors. In this study we characterised islet expression of C3 and C5 complement components, and the impact of C3aR and C5aR1 activation on islet function and viability. MATERIALS AND METHODS: Human and mouse islet mRNAs encoding key elements of the complement system were quantified by qPCR and distribution of C3 and C5 proteins was determined by immunohistochemistry. Activation of C3aR and C5aR1 was determined using DiscoverX beta-arrestin assays. Insulin secretion from human and mouse islets was measured by radioimmunoassay, and intracellular calcium ([Ca2+]i), ATP generation and apoptosis were assessed by standard techniques. RESULTS: C3 and C5 proteins and C3aR and C5aR1 were expressed by human and mouse islets, and C3 and C5 were mainly localised to ß- and α-cells. Conditioned media from islets exposed for 1 h to 5.5 and 20 mM glucose stimulated C3aR and C5aR1-driven beta-arrestin recruitment. Activation of C3aR and C5aR1 potentiated glucose-induced insulin secretion from human and mouse islets, increased [Ca2+]i and ATP generation, and protected islets against apoptosis induced by a pro-apoptotic cytokine cocktail or palmitate. CONCLUSIONS: Our observations demonstrate a functional link between activation of components of the innate immune system and improved ß-cell function, suggesting that low-level chronic inflammation may improve glucose homeostasis through direct effects on ß-cells.

Complement and Complement Targeting Therapies in Glomerular Diseases.

The complement cascade is part of the innate immune system whose actions protect hosts from pathogens. Recent research shows complement involvement in a wide spectrum of renal disease pathogenesis including antibody-related glomerulopathies and non-antibody-mediated kidney diseases, such as C3 glomerular disease, atypical hemolytic uremic syndrome, and focal segmental glomerulosclerosis. A pivotal role in renal pathogenesis makes targeting complement activation an attractive therapeutic strategy. Over the last decade, a growing number of anti-complement agents have been developed; some are approved for clinical use and many others are in the pipeline. Herein, we review the pathways of complement activation and regulation, illustrate its role instigating or amplifying glomerular injury, and discuss the most promising novel complement-targeting therapies.

[Complement-mediated hemolytic uremic syndrome: a diagnostic approach].

Complement-mediated hemolytic uremic syndrome (a-HUS), an uncommon variant of thrombotic microangiopathy, is characterized by hemolytic anemia, thrombocytopenia and renal impairment. This disorder might be inherited or/and acquired and leads to dysregulation of the alternative complement pathway at the endothelial cell surface and formation of microvascular thrombi. The differential diagnosis includes other forms of hemolytic syndrome (eg. Shiga-toxin-producing E.coli or S. dysenteriae -associated HUS - STEC-HUS), thrombotic thrombocytopenic purpura (TTP) and congenital errors of vitamin B12 metabolism. The diagnostic approach is presented below.

Gingival Exudatome Dynamics Implicate Inhibition of the Alternative Complement Pathway in the Protective Action of the C3 Inhibitor Cp40 in Nonhuman Primate Periodontitis.

Periodontitis is a prevalent chronic inflammatory disease associated with dysbiosis. Although complement inhibition has been successfully used to treat periodontitis in animal models, studies globally analyzing inflamed tissue proteins to glean insight into possible mechanisms of action are missing. Using quantitative shotgun proteomics, we aimed to investigate differences in composition of inflammatory gingival tissue exudate ("gingival crevicular fluid"; GCF), before and after local administration of an inhibitor of the central complement component, C3, in nonhuman primates. The C3 inhibitor, Cp40 (also known as AMY-101) was administered locally in the maxillary gingival tissue of cynomolgus monkeys with established periodontitis, either once a week (1×-treatment; n = 5 animals) or three times per week (3×-treatment; n = 10 animals), for 6 weeks followed by another 6 weeks of observation in the absence of treatment. 45 GCF samples were processed for FASP digestion and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Data were processed using the ProgenesisQI software. The statistical significance of differences between the groups was determined by RM-ANOVA, and a protein expression change was considered as a true regulation at >2-fold and p < 0.05. The human orthologues were subjected to Gene Ontology analyses using PANTHER. Data are available via ProteomeXchange with identifier PXD009502. 573 proteins with >2 peptides were longitudinally quantified. Both 3× and 1× administration of Cp40 resulted in significant down-regulation of dozens of proteins during the 6-week course of treatment as compared to baseline. Following drug withdrawal at 6 weeks, more than 50% of the down-regulated proteins showed increased levels at week 12. The top scored pathway was "complement activation, alternative pathway", and several proteins involved in this pathway were down-regulated at 6 weeks. We mapped the proteomic fingerprint changes in local tissue exudate of cynomolgus monkey periodontitis in response to C3 inhibition and identified the alternative pathway of complement activation and leukocyte degranulation as main targets, which are thus likely to play significant roles in periodontal disease pathogenesis. Label-free quantitative proteomics strategies utilizing GCF are powerful tools for the identification of treatment targets and providing insights into disease mechanisms.

C3 glomerulonephritis and dense deposit disease share a similar disease course in a large United States cohort of patients with C3 glomerulopathy.

C3 glomerulonephritis (C3GN) and dense deposit disease comprise the two classes of C3 glomerulopathy. Studies from Europe and Asia have aided our understanding of this recently defined disorder, but whether these data apply to a diverse United States patient population remains unclear. We, therefore, reviewed clinical and histopathological data, including generation of a C3 Glomerulopathy Histologic Index to score biopsy activity and chronicity, to determine predictors of progression to end-stage renal disease (ESRD) and advanced chronic kidney disease (CKD) in 111 patients (approximately 35% non-white) with C3 glomerulopathy: 87 with C3GN and 24 with dense deposit disease. Complement-associated gene variants and autoantibodies were detected in 24% and 35% of screened patients, respectively. Our C3 Glomerulopathy Histologic Index denoted higher activity in patients with C3GN and higher chronicity in patients with dense deposit disease. Over an average of 72 months of follow-up, remission occurred in 38% of patients with C3GN and 25% of patients with dense deposit disease. Progression to late-stage CKD and ESRD was common, with no differences between C3GN (39%) and dense deposit disease (42%). In multivariable models, the strongest predictors for progression were estimated glomerular filtration rate at diagnosis (clinical variables model) and tubular atrophy/interstitial fibrosis (histopathology variables model). Using our C3 Glomerulopathy Histologic Index, both total activity and total chronicity scores emerged as the strongest predictors of progression. Thus, in a large, diverse American cohort of patients with C3 glomerulopathy, there is a high rate of progression to CKD and ESRD with no differences between C3GN and dense deposit disease.