C3 Consumption Research Articles

C3 glomerulopathy: a kidney disease mediated by alternative pathway deregulation.

C3 glomerulopathy (C3G) is an ultra-rare complement-mediated kidney disease caused by to the deregulation of the alternative pathway (AP) of proximal complement. Consequently, all effector loops of the complement are active and can lead to pathologies, such as C3a- and C5a-mediated inflammation, C3b opsonization, surface C3b-mediated AP C3 convertase assembly, C3 cleavage product deposition in the glomerulus, and lytic C5b-9/MAC cell damage. The most common pathologic mechanisms are defective chronic alternative pathway deregulation, mostly occurring in the plasma, often causing C3 consumption, and chronic complement-mediated glomerular damage. C3G develops over several years, and loss of renal function occurs in more than 50% of patients. C3G is triggered by both genetic and autoimmune alterations. Genetic causes include mutations in individual complement genes and chromosomal variations in the form of deletions and duplications affecting genes encoding complement modulators. Many genetic aberrations result in increased AP C3 convertase activity, either due to decreased activity of regulators, increased activity of modulators, or gain-of-function mutations in genes encoding components of the convertase. Autoimmune forms of C3G do also exist. Autoantibodies target individual complement components and regulators or bind to neoepitopes exposed in the central alternative pathway C3 convertase, thereby increasing enzyme activity. Overactive AP C3 convertase is common in C3G patients. Given that C3G is a complement disease mediated by defective alternative pathway action, complement blockade is an emerging concept for therapy. Here, we summarize both the causes of C3G and the rationale for complement inhibition and list the inhibitors that are being used in the most advanced clinical trials for C3G. With several inhibitors in phase II and III trials, it is expected that effectice treatment for C3G will become availabe in the near future.

5123 Remission of Antibodies Blocking the Insulin Receptor Reduces Atherogenicity of LDL Particles but Increases HDL Particle Atherogenicity

Abstract Disclosure: M. Hwang: None. R. Shamburek: None. M. Lightbourne: None. M. Sampson: None. A. Remaley: None. B. Abel: None. R.J. Brown: None. Background: Type B insulin resistance syndrome (TBIR) is a rare autoimmune disorder defined by the presence of autoantibodies against the insulin receptor, usually in the context of systemic autoimmune diseases such as lupus. In TBIR, insulin signaling is disrupted at the receptor-level, resulting in failure of insulin to both suppress hepatic glucose production and to stimulate de novo lipogenesis. This leads to a phenotype of extreme insulin resistance (IR) and hyperglycemia without dyslipidemia. IR and hyperglycemia resolve when remission of the autoantibody is induced by immunosuppression. Given the known association between IR and cardiovascular disease (CVD), we sought to compare biomarkers of CVD risk using lipoprotein particles measured by Nuclear Magnetic Resonance (NMR) in patients with TBIR during their active disease state vs remission. Methods: Patients with TBIR (N=14) had fasting labs including NMR lipoprotein profiles (analyzed using LP4 deconvolution algorithm) during active disease (positive antibodies to the insulin receptor and severe IR) and remission (defined by discontinuation of insulin or amelioration of hyperglycemia). Particle size (nm) and concentration of subclasses by size were measured for low-density lipoprotein (LDL) particles (nmol/L) and high-density lipoprotein (HDL) particles (umol/L). Results: Upon remission from TBIR, there were large decreases in hemoglobin A1c (from 10.9±3.0% to 6.1±1.1%, p<0.001) and insulin (from 1000.0 (715.9, 1000.0) mcU/mL to 16.8 (8.1, 39.2) mcU/mL, normal 2.6-24.9 mcU/mL, p<0.001), and increases in BMI (from 21.8±3.5 to 28.6±7.4 kg/m2, p<0.01), C3 (from 76±27 to 114±20 mg/dL, normal 82-185 mg/dL, p<0.01), and C4 (from 16±8 to 25±9 mg/dL, normal 15-53 mg/dL, p<0.01). After remission of TBIR, LDL profiles became less atherogenic: small LDL particle concentration decreased (from 523.4±170.2 to 362.8±119.7, normal 63.8-1719.6, p<0.01) and LDL particle size increased (from 20.6±0.5 to 21.2±0.3, normal 19.9 -21.6, p<0.01). By contrast, HDL profiles became more atherogenic after remission of TBIR: small HDL particle concentration increased (from 4.6±2.6 to 8.2±4.3, normal 6.6-19.3, p<0.01); the largest HDL particle concentration decreased (from 1.5±0.8 to 0.7±0.7, normal 0-1.2, p<0.01), and HDL particle size decreased (from 10.3±0.4 to 9.6±0.5, normal 8.4-9.9, p<0.001). Conclusions: Active TBIR is a pro-inflammatory state characterized by excess consumption of C3 and C4. Inflammation may contribute to an unfavorable LDL particle profile that improves after remission. However, lack of insulin signaling through the insulin receptor during active TBIR likely leads to an anti-atherogenic HDL profile that returns to normal levels when insulin signaling is restored after remission. Future studies will further investigate the role of insulin resistance and inflammation in CVD risk. Presentation: 6/3/2024

Functional Characterization of Anti-C3bBb Autoantibodies and C3 Glomerulopathy Phenotype.

C3 nephritic factors, i.e. autoantibodies that stabilize the C3 convertase of the alternative pathway are the most frequent acquired abnormality in C3 glomerulopathy and primary immunoglobulin-mediated membranoproliferative GN (Ig-MPGN). Our study included 27 patients with C3 glomerulopathy (n=21) or Ig-MPGN (n=6), of whom 78% were children at disease onset. At the time of sampling, 13/19 (68%) patients with low C3 levels and 8/8 (100%) patients with normal C3 levels were positive for C3 nephritic factors by haemolytic assay. Using novel Luminex assays, we performed a screening for IgG that recognize and affect the formation and/or the stabilization of the alternative pathway C3 convertase (C3bBb). Using Luminex assays, an increase in C3bBb formation and/or stabilization was observed in the presence of IgG from 18/27 patients, including 9 with a double-function, 6 only enhancing the C3bBb formation, and 3 that exclusively stabilized C3bBb. All patients presenting a formation and stabilization function had a low C3 level, versus 55% without this double-function. The level of C3bBb formation correlated to the plasmatic C3 but not sC5b-9 levels. The stabilization of C3bBb did not correlate with C3 or sC5b-9 levels. At the last follow-up, 5/27 patients (19%) reached kidney failure after a median delay of 87 [52,119] months. The patients positive for double-function anti-C3bBb antibodies had a 5-year kidney survival of 70% compared to 100% in those negative (P=0.02). Our findings highlight the association of the dual function of C3bBb formation and stabilization with severe C3 consumption and poor kidney survival in C3 glomerulopathy and Ig-MPGN.

Hypogammaglobulinemia in a child with atypical hemolytic-uremic syndrome

We present a unique clinical case of an atypical hemolytic-uremic syndrome in a child. The mutation in exon 6 of the CD46 gene (chr1:207940532G>C) leads to a homozygous or hemizygous missense substitution. An 8-year-old girl was urgently hospitalized with symptoms of hemorrhagic syndrome and acute kidney injury. The child from the second pregnancy with an aggravated obstetric anamnesis, the first operative labor at the 38th week, who has an aggravated genealogical anamnesis. Initially, the disease developed in the guise of gastroenterological pathology: the girl had dyspeptic disorders, most likely associated with pathology of carbohydrate metabolism, also frequent infectious diseases and a lag in physical development. From the age of 4 years, the girl suffered from persistent hypoalbuminemia, hypoproteinemia and hypogammaglobulinemia, requiring replacement therapy with intravenous immunoglobulins. She was repeatedly examined in gastroenterological departments in Yekaterinburg and Moscow in 2021-2023, but no data concerning protein-losing enteropathies or primary immunodeficiency was obtained. Also, the whole-exome sequencing with result validation hasn’t confirmed an inherited etiology of the presumed congenital immune error. However, a CD46 gene mutation, associated with the development of hemolytic-uremic syndrome in some publications, was identified in the study. The signs of thrombotic microangiopathy were preceded by fever of unspecified etiology: microangiopathic hemolysis, thrombocytopenia, hyperazotemia, C3 consumption, proteinuria, and macrohematuria; hypercholesterolemia, protein metabolism disorder, increased transaminases, ferritin were also noted. According to the ultrasound of the kidneys there were diffuse changes in the parenchyma, decreased velocity indices of blood flow in both renal arteries at all levels. Differential diagnosis was carried out with thrombotic thrombocytopenic purpura, autoimmune hemolytic anemia, antinuclear form of atypical hemolytic-uremic syndrome, viral and bacterial infections, systemic pathology, antiphospholipid syndrome, and hemoblastosis. The girl didn’t need a renal replacement therapy. When complement-blocking therapy with eculizumab was initiated on vital indications, the signs of the disease were gradually eliminated. The prolonged absence of nephropathy in the child may indicate the diversity of the CD46 gene’s functions and different phenotypic manifestation of its mutations. Analysis of literature sources and detection of CD46 “environment” genes (CYBA, LYST, ARPCIB) by full-exome sequencing suggest ambiguity and polymorphism of phenotypic manifestations of complement-mediated mutation.

Complement-Coagulation Cross-talk: Factor H-mediated regulation of the Complement Classical Pathway activation by fibrin clots.

The classical pathway of the complement system is activated by the binding of C1q in the C1 complex to the target activator, including immune complexes. Factor H is regarded as the key downregulatory protein of the complement alternative pathway. However, both C1q and factor H bind to target surfaces via charge distribution patterns. For a few targets, C1q and factor H compete for binding to common or overlapping sites. Factor H, therefore, can effectively regulate the classical pathway activation through such targets, in addition to its previously characterized role in the alternative pathway. Both C1q and factor H are known to recognize foreign or altered-self materials, e.g., bacteria, viruses, and apoptotic/necrotic cells. Clots, formed by the coagulation system, are an example of altered self. Factor H is present abundantly in platelets and is a well-known substrate for FXIIIa. Here, we investigated whether clots activate the complement classical pathway and whether this is regulated by factor H. We show here that both C1q and factor H bind to the fibrin formed in microtiter plates and the fibrin clots formed under in vitro physiological conditions. Both C1q and factor H become covalently bound to fibrin clots, and this is mediated via FXIIIa. We also show that fibrin clots activate the classical pathway of complement, as demonstrated by C4 consumption and membrane attack complex detection assays. Thus, factor H downregulates the activation of the classical pathway induced by fibrin clots. These results elucidate the intricate molecular mechanisms through which the complement and coagulation pathways intersect and have regulatory consequences.

#1940 Plasma complement activation profile in kidney transplant recipients with IgAN supports the importance of the complement alternative pathway in IgAN

Abstract Background and Aims The alternative complement and lectin pathways are key players in IgA nephropathy (IgAN). However, the precise dynamics of complement activation in IgAN remain poorly understood. Non-invasive complement biomarkers are urgently needed in view of the evolving landscape of complement-targeting therapies under evaluation in IgAN. Method We analyzed plasma complement activation biomarkers in a cohort of 87 kidney transplant recipients (KTR) with IgAN and 30 controls consisting of autosomal dominant polycystic kidney disease (ADPKD) KTR (NCT05234463, DC-2013-1990). Patients were excluded if 1) they had a biological inflammatory syndrome at the time of sampling or 2) they had experienced a cellular/humoral rejection in the year prior to or after sampling. We simultaneously measured a large panel of complement activation and regulation fragments (C3a, C5a, C4a, sC5b-9, Ba, Bb) and intact proteins (C3, C4, FI, FH, properdin) in plasma using multiplex ELISA (Quidel Ortho®, A900), nephelometry and in-house ELISA. Results There was no consumption of C3 and C4 proteins in IgAN patients. However, C3a and Bb concentrations were elevated in IgAN patients compared to ADPKD patients (161 [98-227] vs. 102 [66-172] ng/mL, p = 0.007; 3.0 [2.6-4.0] vs. 2.5 [2.0-2.8] µg/mL, p < 0.0001). Overall, 70/87 IgAN patients (80.5%) had elevated Bb levels. The plasma concentration of C5a was elevated in IgAN patients compared to ADPKD patients (6.3 [3.8-9.2] vs. 4.9 [2.8-6.3] ng/mL, p = 0.0274), with values within the reference range in 92.0% of IgAN patients. There was no difference in plasma levels of sC5b-9 between the two groups (p = 0.186). The combined analysis of C3a, C5a and sC5b-9 allowed us to distinguish 4 clusters of patients (Fig. 1). A total of 48 patients (55.2%) show evidence of C3 convertase activity in plasma (clusters 3 and 4), including 16 patients (18.4%) with the highest plasma concentrations of sC5b-9, C3a and Bb. In contrast, 15 patients (17.2%, cluster 1) have no (or very low) complement activation. The last group (n = 32, 36.8%, cluster 2) shows an isolated increase in sC5b-9 without evidence of plasma C3 convertase activity. Proteinuria was significantly increased in groups 3 and 4, which had the highest C3a concentrations, compared to groups 1 and 2 (p = 0.0051). Conclusion This study provides insights into the mechanisms of complement activation in IgAN, with a pivotal role for the activity and regulation of the alternative C3 pathway convertase. In addition, the combined analysis of complement biomarkers identified, for the first time, clusters of patients who may benefit from complement targeting therapies.

#1716 IgA nephropathy: our center's experience

Abstract Background and Aims IgA Nephropathy (IgAN) is the most common primary glomerulopathy worldwide. In the last years, significant advances have been made in understanding its pathophysiology and developing newer promising treatments. The accuracy of the International Risk-Prediction Tool in IgAN (IRP-IgAN) was already validated. Herein, we retrospectively analysed the relation of this risk score and the kidney outcomes. Method We performed a single center retrospective observational cross-sectional study of patients with histological diagnosis of IgAN between 2015 and 2023 in Centro Hospitalar de Setúbal, aiming to describe the demography, clinical presentation, histological characteristics, treatment and follow up of our cohort. The International Risk-Prediction Tool in IgAN was applied for patient stratification. Results Twenty-eight patients were diagnosed with IgAN in this eight-year period. Mean age was 46 years-old (SD ±12.2) and 71.4% were male. The majority were Caucasian (n = 26) with only two patients of Asian e African descent, respectively. The mean calculated Charlson Comorbidity Index was 1.43 (SD ±1.5). Eighteen patients (64.3%) had known arterial hypertension, diabetes was seen only in 2 patients, obesity in 4 patients, and hepatitis B in 2 patients. No cardiovascular disease or cancer was documented. On presentation, 71.4% (n = 20) had hypertension, 14.3% (n = 4) presented with rapidly progressive renal insufficiency, and 14.3% (n = 4) presented with nephrotic syndrome. Two patients (7.1%) required dialysis on presentation. Also, the mean glomerular filtration rate (GFR) was 55.3 ml/min (SD ±31.9) and mean proteinuria level (protein-to-creatinine ratio) was 2.42g/g (SD ±2.41). Most patients had hematuria (82.1%), C3 consumption was seen in only one patient while 10 patients had isolated higher levels of IgA. Mean time between the first symptoms or documented clinical features and dedicated Nephrology consultation was 2.9 years (SD ±3.78). Regarding the histological data and considering de MEST-C score, 71.4% had mesangial hypercellularity in more than 50% of the glomerulus (M1), 25% had endocapillary hypercellularity (E1), 17% had segmental glomerulosclerosis of at least one glomerulus (S1), 7% had interstitial fibrosis or cortical atrophy in 25-50% of the cortical area (T1) and 11% in more than 50% (T2), 17.9% had crescents in less than 25% of the glomerulus (C1) and 2.6% in more than 25% (C2). Fibrinoid necrosis was noticed in 7.1% of the patients. The presence of IgA in the mesangium on IF was universal and 18 patients (64.3%) had C3 co-stain. Approximately half of the patients (46.4%) were already on angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blockers (ARB) by the time of clinical presentation and nearly all (92.9%) by the time the diagnosis was established. SGTL-2 inhibitors were started in 42.9% of the patients. Eight patients (28.6%) started immunosuppression therapy, within a mean time from histological diagnosis of 0.7 years (SD ±1.03). Of those, all of them were on corticosteroids, one patient was additionally under oral cyclophosphamide and another one under mofetil mycophenolate. According to the IRP-IgAN, patients were stratified in low (35.7%), intermediate (10%) and high risk (8%) of kidney disease progression (GFR decline >50%) or ESKD. In a mean time of 0.53 (SD ±0.34) years of follow-up after diagnosis, 8 patients (28.6%) required renal replacement therapy, with 7 choosing hemodialysis and 1 peritoneal dialysis. Six patients lost follow-up. Three patients died a mean time of 1.2 years after diagnosis, one from immunosuppression-related adverse events. We also found an association between higher risk group and progression to ESKD (p < 0.001). Conclusion The IRP-IgAN tool is a useful tool for prediction of kidney disease progression and the need for renal replacement therapy. The supportive care in IgAN even with antiproteinuric approach could be insufficient for patients with high and intermediate risk. The risk progression to ESKD is indeed heterogeneous, and close follow-up of these patients should be guaranteed.

Gender-driven thyroid dysfunction in systemic lupus erythematosus patients: Clinical significance of an overlooked association and global stance

Aim of the workThis study aimed to determine the association of thyroid dysfunction in systemic lupus erythematosus (SLE) patients. Patients and methodsOut of a cohort including 312 adult SLE patients those with thyroid dysfunction (n = 53) were further evaluated. The medical history, clinical examination, laboratory investigations and medications received were recorded. The SLICC damage index (SLICC-DI) was assessed. ResultsThyroid dysfunction formed 17 % of the patients and their mean age was 39.5 ± 11.5 years and disease duration 5.6 ± 3.3 years were comparable to those without thyroid disorder, however female gender was predominantly higher (F:M 52:1 vs 6.2:1, p < 0.0001). The frequency of thyroid dysfunction was alike in Saudi (16 %) and non-Saudi (17.9 %) patients (p = 0.66). The majority of cases (96.2 %) had hypothyroidism, one with autoimmune thyroiditis, while only 2 (3.8 %) had hyperthyroidism. There was a significantly increased frequency of associated neuropsychiatric manifestations (64.2 % vs 45.2 %;p = 0.012), and hematological involvement (32.1 % vs 14.3 %; p = 0.011) and less complement (C4) consumption (15.1 % vs 23.6 %; p = 0.048) in those with thyroid dysfunction compared to those without. The frequency of anti-double stranded deoxyribonucleic acid (anti-dsDNA) positivity tended to be higher (71.7 % vs 66.8 %) and its titre significantly lower (316.3 ± 319.8 IU/ml vs 461.3 ± 459.1; p = 0.013). The SLICC-DI and mortality rate were comparable between groups. Only the presence of proteinuria inversely significantly correlated with the level of T4 (r = -0.31, p = 0.007). ConclusionThyroid dysfunction forms a notable percentage of SLE patients with a prominent female gender propensity. The significant relation of thyroid disorders to neuropsychiatric manifestations, hematological involvement, C4 consumption and anti-dsDNA deserves recognition.

Predictors of renal flares in systemic lupus erythematosus: a post-hoc analysis of four phase III clinical trials of belimumab.

To identify predictors of renal flares in patients with SLE treated for active extra-renal disease. Data from four clinical trials of belimumab in SLE (BLISS-52, NCT00424476; BLISS-76, NCT00410384; BLISS-NEA, NCT01345253; BLISS-SC, NCT01484496) were used. Patients were assigned to belimumab or placebo on top of standard therapy. We investigated the performance of predictors of renal flares through 52-76 weeks using proportional hazards regression analysis. Of 3225 participants, 192 developed at least one renal flare during follow-up, with the first occurring after a median time of 197 days. Current/former renal involvement (HR: 15.4; 95% CI: 8.3-28.2; p< 0.001), low serum albumin levels (HR 0.9; 95% CI: 0.8-0.9; p< 0.001), proteinuria (HR: 1.6; 95% CI: 1.5-1.7; p< 0.001), and low C3 levels (HR: 2.9; 95% CI: 2.1-4.1; p< 0.001) at baseline appeared robust determinants of renal flares. Anti-dsDNA positivity yielded an increased hazard for renal flares (HR: 2.1; 95% CI: 1.4-3.2; p< 0.001), which attenuated after adjustments. Anti-Sm positivity was associated with renal flares in the placebo (HR: 3.7; 95% CI: 2.0-6.9; p< 0.001) but not in the belimumab subgroup, whereas anti-ribosomal P positivity was associated with renal flares in the belimumab subgroup only (HR: 2.8; 95% CI: 1.5-5.0; p= 0.001). A history of renal involvement, high baseline proteinuria, hypoalbuminaemia, and C3 consumption were robust determinants of impending renal flares. Beyond anti-dsDNA, anti-Sm and anti-ribosomal P protein antibody positivity may have value in surveillance of renal SLE.

Complement components regulates ferroptosis in CVB3 viral myocarditis by interatction with TFRC

BackgroundDysregulated cell death machinery and an excessive inflammatory response in Coxsackievirus B3(CVB3)-infected myocarditis are hallmarks of an abnormal host response. Complement C4 and C3 are considered the central components of the classical activation pathway and often participate in the response process in the early stages of virus infection. MethodsIn our study, we constructed a mouse model of CVB3-related viral myocarditis via intraperitoneal injection of Fer-1 and detected myocarditis and ferroptosis markers in the mouse myocardium. Then, we performed co-IP and protein mass spectrometry analyses to explore which components interact with the ferroptosis gene transferrin receptor (TFRC). Finally, functional experiments were conducted to verify the role of complement components in regulating ferroptosis in CVB3 infection. ResultsIt showed that the ferroptosis inhibitor Fer-1 could alleviate the inflammation in viral myocarditis as well as ferroptosis. Mechanistically, during CVB3 infection, the key factor TFRC was activated and inhibited by Fer-1. Fer-1 effectively prevented the consumption of complement C3 and overload of the complement product C4b. Interestingly, we found that TFRC directly interacts with complement C4, leading to an increase in the product of C4b and a decrease in the downstream complement C3. Functional experiments have also confirmed that regulating the complement C4/C3 pathway can effectively rescue cell ferroptosis caused by CVB3 infection. ConclusionsIn this study, we found that ferroptosis occurs through crosstalk with complement C4 in viral myocarditis through interaction with TFRC and that regulating the complement C4/C3 pathway may rescue ferroptosis in CVB3-infected cardiomyocytes.

Renin and renin blockade have no role in complement activity

Renin, an aspartate protease, regulates the renin-angiotensin system by cleaving its only known substrate angiotensinogen to angiotensin. Recent studies have suggested that renin may also cleave complement component C3 to activate complement or contribute to its dysregulation. Typically, C3 is cleaved by C3 convertase, a serine protease that uses the hydroxyl group of a serine residue as a nucleophile. Here, we provide seven lines of evidence to show that renin does not cleave C3. First, there is no association between renin plasma levels and C3 levels in patients with C3 Glomerulopathies (C3G) and atypical Hemolytic Uremic Syndrome (aHUS), implying that serum C3 consumption is not increased in the presence of high renin. Second, in vitro tests of C3 conversion to C3b do not detect differences when sera from patients with high renin levels are compared to sera from patients with normal/low renin levels. Third, aliskiren, a renin inhibitor, does not block abnormal complement activity introduced by nephritic factors in the fluid phase. Fourth, aliskiren does not block dysregulated complement activity on cell surfaces. Fifth, recombinant renin from different sources does not cleave C3 even after 24 hours of incubation at 37 ⁰C. Sixth, direct spiking of recombinant renin into sera samples of patients with C3G and aHUS does not enhance complement activity in either the fluid phase or on cell surfaces. And seventh, molecular modeling and docking place C3 in the active site of renin in a position that is not consistent with a productive ground state complex for catalytic hydrolysis. Thus, our study does not support a role for renin in the activation of complement.

Design and research of MOOC teaching system based on TG-C4.5 algorithm

The emergence of Internet information technology has led to the development of MOOC-based online teaching methods. The study uses the traditional C4.5 algorithm for data mining to improve teaching quality and simplifies and quantifies it with the Taylor series and GINI index. The study also considers the uncertainty of data changes and the characteristics of MOOC teaching to design a parallel processing system of the HD-TG-C4.5 algorithm under the framework of the Hadoop platform. The experimental results show that the minimum data classification error of the algorithm is 2%, and the maximum recommendation accuracy of teaching resources is 92.6%. Moreover, the response time and resource search time of this algorithm system are significantly better than traditional algorithms in terms of system debugging. The average login response time is less than 0.87 s, and the success rate of system debugging reaches 90%. The probability value of students mastering teaching resource knowledge points is also above 0.7. The MOOC teaching system based on TG-C4.5 algorithm can effectively mine learner behavior data and reduce the complexity and consumption of C4.5 algorithm. The MOOC teaching system based on TG algorithm can provide technical support for the decision-making information of teaching participants and provide early warning information for predicting learning behavior.

E32 Intra cranial hypertension in juvenile neurolupus

Abstract Introduction Neurolupus is one of the two key prognostic parameters of lupus. Its manifestation can be central or peripheral, revealing the disease or occurring during the course of evolution. It’s important to not consider all neurological manifestations during SLE as related to lupus, ruling out Central nervous system (CNS) infection and anti-phospholipid syndrome (APS) is primordial. Objectives To share 3 rare observations of neurolupus with intracranial hypertension syndrome and discuss their therapeutic modalities. To highlight the lack of evidence in the treatment of such cases. Method A retrospective analysis of data from medical records. Results We report three observations of Intracranial hypertension syndrome involving three girls, ranging from 9 to 14 years. Clinical symptomatology was dominated by headache, vomiting and visual disturbances. Examination found papillary oedema stage 3 in all the three patients, convergent strabismus in two patients and elevated intracranial pressure measurement in all the three girls ranged from 95 mm to 57 mm of H2O. Brain MRI performed in all three-patients was normal. Data from laboratory tests showed, thrombocytopenia in one patient, pancytopenia in one patient, positive antinuclear antibodies in all patients, positive anti-DNA antibody in one patient, C3, C4 consumption in two patients, positive proteinuria in two patients and positive anti phospholipid antibodies in one patient. All patients had active SLE at the time of admission with a Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) at least at 17. Symptomatic treatment with carbonic anhydrase inhibitor was initiated, followed by methylprednisolone pulse therapy then oral corticosteroids and hydroxychloroquine in all the three patients. Immunosuppressive therapy with Rituximab 1 g at two-week intervals was administrated in two patients, the third one did not receive any suppressive treatment in addition to corticosteroids due to the favorable outcome. The course was favorable in all patients with regression of clinical symptoms of intracranial hypertension and papillary oedema immediately after cerebro spinal fluid (CSF) subtraction. Discussion and Conclusion Neurolupus presents with heterogeneous symptoms that make its diagnosis difficult. Intracranial hypertension syndrome is a rare manifestation resulting from a disorder of CSF resorption, its pathogenesis is poorly understood with an inflammatory hypothesis based on immune deposits. There are no therapeutic recommendations to date. This isolated syndrome without other neurological signs of severity responds very well to symptomatic treatment with carbonic anhydrase inhibitors and to CSF withdrawal, as was the case in our patients. The use of immunosuppressive therapy (rituximab in our patients) was indicated due to the severity of the clinical picture with severe renal involvement. In addition, other immunosuppressive drugs can be an alternative option therapy. Ethics The study was performed according to the principles of the Declaration of Helsinki.

North and South: Exploring isotopic analysis of bone carbonates and collagen to understand post-medieval diets in London and northern England.

We evaluate the potential of paired isotopic analysis of bone carbonate and collagen to examine the diet of post-medieval human and animal populations from England (17th-19th c.), including, for the first time, manufacturing towns in northern England. The potential for identifying C4 crop consumption is explored alongside regional and local patterning in diet by sex and socioeconomic status. Humans (n = 216) and animals (n = 168) were analyzed from sites in London and northern England for both carbon and nitrogen isotopes of bone collagen (𝛿13 Ccoll , 𝛿15 Ncoll ). Isotopic analysis of bone carbonates (𝛿13 Ccarb , 𝛿18 Ocarb ) was carried out on all humans and 27 animals, using Fourier transform infrared spectroscopy-attenuated total reflectance to assess diagenesis. Variations in diet were observed between and within different populations by geographical location and socioeconomic status. Three pigs and one cow consumed C4 resources, indicating the availability of C4 -fed animal protein. Londoners consumed more animal and marine protein and C4 resources. Middle- and upper-class populations from both London and northern populations also had greater access to these foods compared to those of lower status in the same regions. This substantial multi-isotope dataset deriving from bone carbonate and collagen combined from diverse post-medieval urban communities enabled, for the first time, the biomolecular identification of the dynamics of C4 consumption (cane sugar/maize) in England, providing insight into the dynamics of food globalization during this period. We also add substantially to the animal dataset for post-medieval England, providing further insight into animal management during a key moment of agricultural change.

Liver factor B silencing to cure C3 glomerulopathy: Evidence from a mouse model of complement dysregulation

Uncontrolled activation of the alternative pathway (AP) of complement, due to genetic and/or acquired defects, plays a primary pathogenetic role in C3 glomerulopathy (C3G), a rare and heterogeneous disease characterised by predominant C3 fragment deposition within the glomerulus, as well as glomerular damage. There are currently no approved disease-specific treatments for C3G, but new drugs that directly counteract AP dysregulation, targeting components of the pathway, have opened promising new perspectives for managing the disease.Complement factor B (FB), which is primarily synthesised by hepatocytes, is a key component of the AP, as it drives the central amplification loop of the complement system. In this study we used a GalNAc (N-Acetylgalactosamine)-conjugated siRNA to selectively target and suppress liver FB expression in two mouse models characterised by the complete (Cfh-/- mice) or partial (Cfh+/-) loss of function of complement factor H (FH). Homozygous deletion of FH induced a severe C3G phenotype, with strong dysregulation of the AP of complement, glomerular C3 deposition and almost complete C3 consumption. Mice with a heterozygous deletion of FH had intermediate C3 levels and exhibited slower disease progression, resembling human C3G more closely.Here we showed that FB siRNA treatment did not improve serum C3 levels, nor limit glomerular C3 deposition in Cfh-/- mice, while it did normalise circulating C3 levels, reduce glomerular C3 deposits, and limit mesangial electron-dense deposits in Cfh+/- mice. The present data provide important insights into the potential benefits and limitations of FB-targeted inhibition strategies and suggest RNA interference-mediated FB silencing in the liver as a possible therapeutic approach for treating C3G patients with FH haploinsufficiency.

What can hippopotamus isotopes tell us about past distributions of C4 grassy biomes on Madagascar?

Societal Impact StatementToday, expansive C4 grassy biomes exist across central, western, and northern Madagascar. Some researchers have argued that the island's now‐extinct pygmy hippopotamuses belonged to a megaherbivore grazing guild that maintained these grasslands prior to human arrival. However, the chemistry of hippo bones indicates that C4 grasses were only a minor part of hippo diet. This, in turn, suggests that C4 grasses were present but not widespread when hippos were alive and that grasses expanded only after Malagasy people shifted from hunting and foraging to agropastoralism approximately 1000 years ago. These results have important implications for environmental reconstructions and biodiversity management.Summary Extinct hippopotamuses (Hippopotamus spp.) were part of Madagascar's megaherbivore guild. Stable carbon (δ13C) and nitrogen (δ15N) isotopes in radiometrically dated bone collagen track spatial and temporal variation in diet and habitat. If hippos helped maintain C4 grassy biomes, then they should have regularly consumed C4 grasses, which have high δ13C values. However, if expansive C4 grassy biomes are anthropogenic, then forests would have been more extensive in the past, and hippos would have predominantly consumed C3 plants with low δ13C values. Nitrogen isotopes can clarify foraging habitat (moist or dry). We assessed δ13C and δ15N values for hippos from different ecoregions of Madagascar and compared these with data for extinct herbivorous lemurs from the same ecoregions. We further explored the effects of wet/dry transitions on isotopic trends for hippos from the central highlands and spiny thicket ecoregions. Carbon isotopes suggest (1) limited C4 consumption by hippos in the central highlands, dry deciduous forest, and succulent woodland ecoregions; and (2) moderate consumption of C4 resources in the spiny thicket. Nitrogen data indicate that hippos foraged in wetter habitats than sympatric lemurs in all regions. Malagasy hippos did not regularly graze C4 grasses in dry, open habitats, even in regions blanketed by C4 grassy biomes today. Malagasy grasses are adapted to grazing and fire, but these are likely ancient adaptations that accompanied grasses when they initially spread to Madagascar. C4 grassy biomes were spatially limited in extent in the past and only expanded after the Late Holocene introduction of domesticated ungulates.

Diet and mobility in Late Antique Sicily: Isotopic data from the catacombs of Santa Lucia, Siracusa (Italy)

The catacombs of Santa Lucia were built during the 3rd century CE in Siracusa, Sicily, Italy, as a burial site for members of the local Christian community until the early 8th century CE. This site is an important cemeterial context of the Late Roman and Byzantine periods. The tombs and artifacts found suggest that individuals of varying wealth were buried in the catacombs. Historical accounts also confirm the presence of a significant Christian community from Syria and the Levant in Siracusa during this period. The objective of this research is to investigate the life histories of the Late Antique community interred in the catacombs using stable isotope analysis. This technique aimed to clarify the dietary differences between individuals of different social status and geographical origins, in order to re-evaluate the data from historical documents. To achieve this, we conducted stable carbon, nitrogen, and oxygen isotope analyses on skeletal samples from 25 individuals recovered from the catacombs of Santa Lucia, using established methods. The results revealed significant dietary diversity among the individuals buried in the catacombs, with evidence of the consumption of both C3 and C4 plants, as well as fish from both freshwater and sea sources.The oxygen isotopes show a particularly broad range in both the small sample set of bones and the larger set of teeth, suggesting a significant degree of mobility for most of the individuals tested. The high variability found in the diet and the evidence of mobility for most of the individuals tested not only between early age and adulthood, but also throughout their lives. It raises new questions and calls for the consideration of the archaeological and historical implications of these novel discoveries.

#5076 MONOCLONAL GAMMOPATHY IN C3 GLOMERULOPATHY: DOES THE BUCKET STOP THERE?

Abstract Background and Aims C3 glomerulopathy (C3G) is a rare diagnosis, characterized by dysregulation of the alternative pathway of complement, classically presenting in children and young adults. Recently, it has been reported the association between the production of a monoclonal protein and the development of C3G, affecting a larger age span. Method We report the case of a 53-year-old male patient, that attended the emergency department due to persistent holocranial headache. He was an IV drug abuser with a history of treated Hepatitis C infection and free lambda light chain monoclonal protein, being studied by the Haematology Department. On admission, he was hypertensive (187/98 mmHg), and labs showed an acute on chronic kidney disease (serum creatinine 2.35 mg/dL from a basal of 1.5 mg/dL) with an active urinary sediment (38 erythrocytes/field, with dysmorphia), a urinary protein/creatinine ratio of 626 mg/g, and C3 consumption (0.52 g/L). The patient was admitted, and a kidney biopsy was performed. Results Further lab results confirmed a serum IgG Lambda monoclonal protein. Autoantibodies screening (ANCAs, ANAs, Anti-GBM), ASLO and Rheumatoid Factor were negative. Cryoglobulinemia was detected, and the cryoprecipitate's immunofixation revealed monoclonal proteins IgG Lambda and IgM Kappa. HCV viral load was negative. Bone marrow biopsy revealed a small population (&amp;lt; 3%) of plasma cells with Lambda light chain restriction. Kidney biopsy's light microscopy showed increased mesangial matrix and cells, endocapillary hypercellularity, and some glomeruli with lobulated appearance. Five out of 15 glomeruli presented fibrocellular crescents. Immunofluorescence showed C3 dominant staining on capillary walls and in the mesangium, with absent IgG and light chain deposits. A presumptive diagnosis of C3 glomerulopathy was made and the patient was empirically started on corticosteroids (3 pulses of intravenous methylprednisolone, followed by oral prednisolone 1mg/Kg/day), which was followed by paraprotein-directed chemotherapy with bortezomib, cyclophosphamide and dexamethasone (VCD). The patient is currently on the third VCD cycle, presenting both renal and haematological responses: recovery of serum creatinine to basal levels (1.54 mg/dL), resolution of haematuria and proteinuria, normalisation of C3 levels. Serum immunofixation is currently negative for monoclonal protein, with normal serum immunoglobulin levels. Electron microscopy revealed electron-dense deposits in the mesangium, and mesangium-capillary transition, supporting the diagnosis of C3 glomerulonephritis. Genetic testing of complement-related genes revealed a rare missense variation of unknown significance (c.4855A&amp;gt;C) on the C3 gene, that has been previously reported in association with C3 glomerulopathy and atypical Haemolytic-Uremic syndrome. Conclusion This case represents a monoclonal gammopathy associated-C3 glomerulonephritis with a favourable response to paraprotein-directed chemotherapy. Although the association between monoclonal gammopathy and C3G rests on epidemiologic findings, experimental evidence suggests that several monoclonal proteins have complement dysregulation features, which may enhance alternate complement pathway activation. Our patient's response is in line with observational data that have shown improved renal outcomes in patients who achieve a haematological response following clone-directed chemotherapy, which further supports the role of monoclonal gammopathy in C3G pathogenesis [1]. Interestingly, the genetic variation identified in our patient might have provided a favourable genetic background for the development of C3G, which is thought to rely upon a complex interaction of triggering events, such as a monoclonal gammopathy, and underlying complement abnormalities, such as genetic variants in complement genes.

Recurrent Membranoproliferative Glomerulonephritis After Kidney Transplantation: Risk Factors and Impact on Graft Survival.

BACKGROUND Membranoproliferative glomerulonephritis (MPGN) is an uncommon cause of end-stage renal disease (ESRD). Recurrence rates after transplantation range from 11.8% to 18.9% after 5 and 15 years, respectively. This study aimed to assess the risk factors of MPGN recurrence after kidney transplantation and its impact on graft survival. MATERIAL AND METHODS This was a single-center retrospective cohort, including renal transplant recipients older than 18 years, with a diagnosis of MPGN in native kidneys. Data were obtained from medical records during the first 5-year post-transplant follow-up. Primary endpoints were graft function and survival. Secondary endpoints were MPGN recurrence risk factors and these cases' clinical, laboratory, and histological features. RESULTS Twenty-eight patients were included; the majority male (60.7%), with a mean age of 24.0±9.4 years. At MPGN native diagnosis, all patients presented proteinuria, with C3 consumption in 42.9%. Histological analysis showed 13 (42.9%) MPGN type I and 5 (17.9%) type II, with no cases of type III. MPGN recurrence occurred in 7 (25.0%) patients; 85.7% were male, 57.1% were recipients from a living donor, all presenting nephrotic syndrome and hematuria, with C3 consumption in 71.4%. The graft function was similar between the groups. Two (28.6%) patients progressed to graft failure in the recurrence group, and 1 died with a functioning graft. CONCLUSIONS The MPGN recurrence rate was 25%, most of them recipients of kidneys from living donors. Nephrotic syndrome and C3 consumption were frequent at recurrence. The graft function was similar between the groups, and the 5-year graft survival rate in the recurrence group was higher than in other studies.

Plasticity in resource use explains the persistence of the largest living rodent in anthropized environments

AbstractHow organisms search for and obtain food is a determinant of their survival. It has been hypothesized that organisms facing food limitations might expand their dietary niche compared with optimal foraging conditions. Nonetheless, some organisms may reduce their dietary niche due to limiting resources. Here, we show the resource use plasticity of capybaras (Hydrochoerus hydrochaeris), the largest living rodent, in natural and anthropized environments of Brazil using stable carbon and nitrogen isotopes in hair. We assessed the resource use, size and overlap of isotopic niches, and the influence of body mass, age class, sex, and landscape composition on isotopic values among 13 capybara populations (210 individuals). We observed a wide variation in isotopic values of capybaras among and within populations in different environments. Surprisingly, diets varied from strictly C4‐based to strictly C3‐based, with most individuals feeding on C4 plants (65%). A substantial portion of individuals presented mixed diets (C3 and C4 plants), totaling 31% of the individuals, and few fed exclusively on C3 plants (4%). Isotopic niche size also varied among populations in both environments, with low overlap considering their core dietary niche. Capybara populations in natural environments had substantial incorporation of C3 resources, showing individuals with strictly C3 diets, and possibly relying on a high diversity of food items, while some populations in anthropized ones fed exclusively on C4 resources. Neither body mass, age class, sex, nor landscape composition significantly influenced isotopic values. Here, we provide evidence of the dietary plasticity of capybaras in different environments, transitioning from the consumption of C4 to C3 plants when needed, that is, from preferred to non‐preferred food items. Together with the species' behavioral plasticity, our results help explain its resilience in surviving, and even thriving, in both natural and human‐modified environments.