Complement-mediated Inflammation Research Articles

The complement system in neurodegenerative diseases.

Complement is an important component of innate immune defence against pathogens and crucial for efficient immune complex disposal. These core protective activities are dependent in large part on properly regulated complement-mediated inflammation. Dysregulated complement activation, often driven by persistence of activating triggers, is a cause of pathological inflammation in numerous diseases, including neurological diseases. Increasingly, this has become apparent not only in well-recognized neuroinflammatory diseases like multiple sclerosis but also in neurodegenerative and neuropsychiatric diseases where inflammation was previously either ignored or dismissed as a secondary event. There is now a large and rapidly growing body of evidence implicating complement in neurological diseases that cannot be comprehensively addressed in a brief review. Here, we will focus on neurodegenerative diseases, including not only the 'classical' neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, but also two other neurological diseases where neurodegeneration is a neglected feature and complement is implicated, namely, schizophrenia, a neurodevelopmental disorder with many mechanistic features of neurodegeneration, and multiple sclerosis, a demyelinating disorder where neurodegeneration is a major cause of progressive decline. We will discuss the evidence implicating complement as a driver of pathology in these diverse diseases and address briefly the potential and pitfalls of anti-complement drug therapy for neurodegenerative diseases.

Immune Checkpoint Inhibitor-Induced Inflammatory Arthritis: Overview of Therapies and a Personalized Approach to Optimized Combined Therapy.

Immune checkpoint inhibitors (ICIs), including anti-cytotoxic T lymphocyte antigen 4, anti-programmed cell death 1, and anti-programmed cell death ligand 1 (PD-L1) antibodies, are currently widely used in oncology clinical practice, achieving considerable success in improving disease outcomes. New checkpoint targets are being discovered and investigated through basic science research and clinical trials. ICI remove negative regulatory immune signals on T cells, leading to immune activation and induction of antitumor immunity. Patients who receive ICI, however, are at risk for developing immune-related adverse events (irAEs), which are attributed to increased T cell activity against antigens in both tumors and in healthy tissues, to increased inflammatory cytokine levels, to increased levels of preexisting autoantibodies, and to enhanced complement-mediated inflammation. Arthritis is one of the most common irAEs. ICI-induced rheumatic irAEs are categorized by levels of severity which guide the choice of treatment options. Management of ICI-induced rheumatic irAEs includes the use of glucocorticoids, disease-modifying antirheumatic drugs (mainly methotrexate), and biological agents (e.g., tumor necrosis factor, interleukin-6 receptor, and CD20 inhibitors). This review aims to summarize the current ICI subtypes, their role in rheumatic irAEs development, and therapies currently used in clinical practice to manage irAEs. In addition, we propose to use an ex vivo personalized diagnostic assay for the selection of the most effective ICI with antirheumatic drugs combinations that will inhibit the advancement of ICI-induced adverse events.

Rational design of antibody-like peptides for targeting the human complement fragment protein C5a.

Human complement fragment 5a (C5a) is one of the most potent glycoproteins generated downstream of C3a and C4a during late-stage activation of the complement signaling cascade. C5a recruits receptors like C5aR1 and C5aR2 and is established to play a critical role in complement-mediated inflammation. Thus, excessive C5a in the plasma due to aberrant activation of the complement contributes to the pathophysiology of several chronic inflammatory diseases. Therefore, restricting the excessive interaction of C5a with its receptors by neutralizing C5a has been one of the most effective therapeutic strategies for the management of inflammatory diseases. Indeed, antibodies targeting C5 (Eculizumab), the precursor of C5a, and C5a (Vilobelimab) have already been approved by the FDA. Still, small designer peptides that work like antibodies and can target and stop C5a from interacting with its receptors seem to be a possible therapeutic alternative to antibodies because they are smaller, cheaper to make, more specific to their target, and can get through membrane barriers. As a proof-of-principle, the current study describes the computational design and evaluation of a pair of peptides that are able to form stable high-affinity complexes with the epitope regions of C5a that are important for the recruitment of C5aR1 and C5aR2. The computational data further supports the potential of designer peptides for mimicking the function of antibodies targeting C5a. However, further experimental studies will be required to establish the structure-function relationship of the designer peptides and also to establish the hypothesis of antibody-like peptides targeting C5a.

Complement-mediated inflammation and mitochondrial energy metabolism in the proteomic profile of myopic human corneas

Myopia is one of the most common causes of visual impairment worldwide. To identify proteins related to myopiagenesis, data-independent acquisition proteomic analysis was performed using corneal lenticules of myopic patients who underwent small incision lenticule extraction surgery. A total of 19 lenticules from 19 age and sex-matched patients were analyzed, 10 in high refractive error (HR, spherical equivalent over −6.00 D) group and 9 in low refractive error (LR, spherical equivalent between −3.00 and − 1.00 D) group. Differentially expressed proteins (DEPs) were identified by comparing the corneal proteome between the two groups. Functional analyses were performed to explore the biological pathways and interactions of the DEPs. 107 DEPs (67 upregulated and 40 downregulated in HR group, compared to LR) were identified from 2138 quantified proteins. Functional analyses indicated that upregulated proteins were primarily involved in the complement pathways and extracellular matrix (ECM) remodeling, while downregulated proteins were involved in mitochondrial energy metabolism. Western blot analysis confirmed increased complement C3a and apolipoprotein E in HR samples, further supporting the proteomics data. In conclusion, this proteomic study reveals that proteins associated with the complement system, ECM remodeling, and mitochondrial energy metabolism might be key effectors in myopiagenesis. SignificanceMyopia has become one of the most prevalent causes of visual impairment, especially in Asia. The underlying mechanism of myopia development is still up for debate. This study compares the proteomic profiles of high and low myopic corneas, identifying differentially expressed proteins associated with the complement system, ECM remodeling, and mitochondrial energy metabolism. The findings of this study could provide novel insights into the pathogenesis of myopia. The complement system and mitochondrial energy metabolism may provide potential therapeutic targets in the treatment and prevention of myopia.

Multifocal motor neuropathy is not associated with altered innate immune responses to endotoxin

ObjectiveAntibody- and complement-mediated peripheral nerve inflammation are central in the pathogenesis of MMN. Here, we studied innate immune responses to endotoxin in patients with MMN and controls to further our understanding of MMN risk factors and disease modifiers. MethodsWe stimulated whole blood of 52 patients with MMN and 24 controls with endotoxin and collected plasma. With a multiplex assay, we determined levels of the immunoregulating proteins IL-1RA, IL-1β, IL-6, IL-10, IL-21, TNF-α, IL-8 and CD40L in unstimulated and LPS-stimulated plasma. We compared baseline and stimulated protein levels between patients and controls and correlated concentrations to clinical parameters. ResultsProtein level changes after stimulation were comparable between groups (p > 0.05). IL-1RA, IL-1β, IL-6 and IL-21 baseline concentrations showed a positive correlation with monthly IVIg dosage (all corrected p-values < 0.016). Patients with anti-GM1 IgM antibodies showed a more pronounced IL-21 increase after stimulation (p 0.048). ConclusionsAltered endotoxin-induced innate immune responses are unlikely to be a susceptibility factor for MMN.

Therapeutic Potential of Targeting Complement C5a Receptors in Diabetic Kidney Disease.

Diabetic kidney disease (DKD) affects 30-40% of patients with diabetes and is currently the leading cause of end-stage renal disease (ESRD). The activation of the complement cascade, a highly conserved element of the innate immune system, has been implicated in the pathogenesis of diabetes and its complications. The potent anaphylatoxin C5a is a critical effector of complement-mediated inflammation. Excessive activation of the C5a-signalling axis promotes a potent inflammatory environment and is associated with mitochondrial dysfunction, inflammasome activation, and the production of reactive oxygen species. Conventional renoprotective agents used in the treatment of diabetes do not target the complement system. Mounting preclinical evidence indicates that inhibition of the complement system may prove protective in DKD by reducing inflammation and fibrosis. Targeting the C5a-receptor signaling axis is of particular interest, as inhibition at this level attenuates inflammation while preserving the critical immunological defense functions of the complement system. In this review, the important role of the C5a/C5a-receptor axis in the pathogenesis of diabetes and kidney injuries will be discussed, and an overview of the status and mechanisms of action of current complement therapeutics in development will be provided.

CONTINUOUS FORMS OF INTRA-OPERATIVE ULTRAFILTRATION ENHANCE RECOVERY AFTER ADULT CARDIAC SURGERY WITH CARDIOPULMONARY BYPASS: A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS

CONTINUOUS FORMS OF INTRA-OPERATIVE ULTRAFILTRATION ENHANCE RECOVERY AFTER ADULT CARDIAC SURGERY WITH CARDIOPULMONARY BYPASS: A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS

Exploring the risk factors for ischemic cerebrovascular disease in systemic lupus erythematosus: A single-center case-control study.

ObjectivesIschemic cerebrovascular disease (ICVD) is one of the most common and severe complications in systemic lupus erythematosus (SLE). We aim to explore the risk factors for ICVD in SLE and to assess their associated clinical characteristics.MethodsIn this study, 44 lupus patients with ICVD (ICVD-SLE) and 80 age- and sex-matched lupus patients without ICVD (non-ICVD-SLE) who were hospitalized in our center between 2014 and 2021 were enrolled. A comprehensive set of clinical and socio-demographic data was recorded. In the ICVD-SLE group, the modified Rankin score (mRS) at 90 days after the occurrence of ICVD, the brain MRI, and arterial ultrasonography findings were collected. Group comparisons were made with continuous variables using an independent t-test or the Mann–Whitney test, and with categorical variables using the chi-square test or Fisher exact test. Multivariate logistic regression analysis was performed to identify the risk factors for ICVD in SLE. Patients with ICVD-SLE were divided into three subgroups according to the gradations of intracranial arterial stenosis (ICAS). The subgroup comparisons were performed by one-way ANOVA test or Kruskal–Wallis test.ResultsOf the 44 patients with ICVD, 45% had a large-vessel ischemic stroke, 50% had a symptomatic lacunar stroke, and 9% had a transient ischemic attack. 2 (4.5%) had both large-vessel ischemic stroke and symptomatic lacunar stroke. Multivariate logistic regression analysis showed that cutaneous vasculitis (OR=7.36, 95% CI=2.11–25.65), anticardiolipin antibody (aCL) (OR=4.38, 95% CI=1.435–13.350), and lupus anticoagulant (LA) (OR=7.543,95% CI=1.789–31.808) were the risk factors, and hydroxychloroquine (HCQ) therapy (OR=0.198, 95% CI=0.078–0.502) was the protective factor, after controlling for confounders. During the analysis of the subgroups, no significant difference was observed between the patients in the group without internal carotid arterial occlusion (ICAS) and those with severe ICAS except for diagnostic delay. However, patients in the moderate ICAS group were older when SLE occurred (P<0.01), had a longer diagnostic delay (P<0.01), a lower percentage of hypocomplementemia (P=0.05) and steroids and HCQ therapy (P=0.01, P=0.05, respectively), a trend toward lower mRS score, but a higher incidence of carotid atherosclerotic plaque (P<0.01), when compared with the other two subgroups.ConclusionCutaneous vasculitis and antiphospholipid antibodies (aPLs) are associated with an increased risk of ICVD, while HCQ therapy may provide protection against ICVD in SLE. The ICVD in younger lupus patients is associated with complement-mediated inflammation and poorer outcome, and require immunosuppressive therapy, whereas the ICVD in elderly patients are characterized by moderate ICAS and carotid atherosclerotic plaques.

Cervicovaginal Complement Activation and Microbiota During Pregnancy and in Parturition.

BackgroundVaginal microbiome and the local innate immune defense, including the complement system, contribute to anti- and proinflammatory homeostasis during pregnancy and parturition. The relationship between commensal vaginal bacteria and complement activation during pregnancy and delivery is not known.ObjectiveTo study the association of the cervicovaginal microbiota composition to activation and regulation of the complement system during pregnancy and labor.Study designWe recruited women during late pregnancy (weeks 41 + 5 to 42 + 0, n=48) and women in active labor (weeks 38 + 4 to 42 + 2, n=25). Mucosal swabs were taken from the external cervix and lateral fornix of the vagina. From the same sampling site, microbiota was analyzed with 16S RNA gene amplicon sequencing. A Western blot technique was used to detect complement C3, C4 and factor B activation and presence of complement inhibitors. For semiquantitative analysis, the bands of the electrophoresed proteins in gels were digitized on a flatbed photo scanner and staining intensities were analyzed using ImageJ/Fiji win-64 software. Patient data was collected from medical records and questionnaires.ResultsThe vaginal microbiota was Lactobacillus-dominant in most of the samples (n=60), L. iners and L. crispatus being the dominant species. L. gasseri and L. jensenii were found to be more abundant during pregnancy than active labor. L. jensenii abundance correlated with C4 activation during pregnancy but not in labor. Gardnerella vaginalis was associated with C4 activation both during pregnancy and labor. The amount of L. gasseri correlated with factor B activation during pregnancy but not during labor. Atopobium vaginae was more abundant during pregnancy than labor and correlated with C4 activation during labor and with factor B activation during pregnancy. Activation of the alternative pathway factor B was significantly stronger during pregnancy compared to labor. During labor complement activation may be inhibited by the abundant presence of factor H and FHL1.ConclusionsThese results indicate that bacterial composition of the vaginal microbiota could have a role in the local activation and regulation of complement-mediated inflammation during pregnancy. At the time of parturition complement activation appears to be more strictly regulated than during pregnancy.

New Treatment Strategies for IgA Nephropathy: Targeting Plasma Cells as the Main Source of Pathogenic Antibodies.

Immunoglobulin A nephropathy (IgAN) is a rare autoimmune disorder and the leading cause of biopsy-reported glomerulonephritis (GN) worldwide. Disease progression is driven by the formation and deposition of immune complexes composed of galactose-deficient IgA1 (Gd-IgA1) and Gd-IgA1 autoantibodies (anti-Gd-IgA1 antibodies) in the glomeruli, where they trigger complement-mediated inflammation that can result in loss of kidney function and end-stage kidney disease (ESKD). With the risk of progression and limited treatment options, there is an unmet need for therapies that address the formation of pathogenic Gd-IgA1 antibody and anti-Gd-IgA1 antibody-containing immune complexes. New therapeutic approaches target immunological aspects of IgAN, including complement-mediated inflammation and pathogenic antibody production by inhibiting activation or promoting depletion of B cells and CD38-positive plasma cells. This article will review therapies, both approved and in development, that support the depletion of Gd-IgA1-producing cells in IgAN and have the potential to modify the course of this disease. Ultimately, we propose here a novel therapeutic approach by depleting CD38-positive plasma cells, as the source of the autoimmunity, to treat patients with IgAN.

Inhibition of CL-11 reduces pulmonary inflammation in a mouse model of Klebsiella pneumoniae lung infection

Infection caused by K. pneumoniae is associated with severe inflammation due to stimulation of the innate immune components including the complement system, which is the main player of the innate immune response. Excessive complement-mediated inflammation may cause severe lung injury. Here we clearly show that K. pneumoniae binds to different lectin pathway carbohydrate recognition molecules and activates the complement cascade via the LP. Administration of anti-CL-11 antibodies 6 h before the infection impairs LP functional activity but it shows no effect on the survival time of mice infected with K. pneumoniae. Similarly, no significant difference in bacterial load in blood and lung tissues was observed between mice that received anti-CL-11 and control group treated with an isotype antibody. Interestingly, treatment of mice with anti-CL-11 prior to infection significantly improved histopathological changes and lung injury score induced by K. pneumoniae. Moreover, administration of anti-CL-11 reduced leukocytes infiltration into lung tissues and decreased the levels of the inflammatory mediators TNF-α, IL-6, and IL-1β in the infected mice. These findings indicate that inhibition of the LP could secure a significant level of protection against lung injury during the infection caused by K. pneumoniae.

MERS-CoV infection causes brain damage in human DPP4-transgenic mice through complement-mediated inflammation.

The highly pathogenic Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a severe respiratory virus. Recent reports indicate additional central nervous system (CNS) involvement. In this study, human DPP4 transgenic mice were infected with MERS-CoV, and viral antigens were first detected in the midbrain-hindbrain 4 days post-infection, suggesting the virus may enter the brainstem via peripheral nerves. Neurons and astrocytes throughout the brain were infected, followed by damage of the blood brain barrier (BBB), as well as microglial activation and inflammatory cell infiltration, which may be caused by complement activation based on the observation of deposition of complement activation product C3 and high expression of C3a receptor (C3aR) and C5a receptor (C5aR1) in neurons and glial cells. It may be concluded that these effects were mediated by complement activation in the brain, because of their reduction resulted from the treatment with mouse C5aR1-specific mAb. Such mAb significantly reduced nucleoprotein expression, suppressed microglial activation and decreased activation of caspase-3 in neurons and p38 phosphorylation in the brain. Collectively, these results suggest that MERS-CoV infection of CNS triggers complement activation, leading to inflammation-mediated damage of brain tissue, and regulating of complement activation could be a promising intervention and adjunctive treatment for CNS injury by MERS-CoV and other coronaviruses.

Formation and Cellular Impact of Cholesterol Crystals in Health and Disease.

Cholesterol crystals (CCs) were first discovered in atherosclerotic plaque tissue in the early 1900 and have since been observed and implicated in many diseases and conditions, including myocardial infarction, abdominal aortic aneurism, kidney disease, ocular diseases, and even central nervous system anomalies. Despite the widespread involvement of CCs in many pathologies, the mechanisms involved in their formation and their role in various diseases are still not fully understood. Current knowledge concerning the formation of CCs, as well as the molecular pathways activated upon cellular exposure to CCs, will be explored in this review. As CC formation is tightly associated with lipid metabolism, the role of cellular lipid homeostasis in the formation of CCs is highlighted, including the role of lysosomes. In addition, cellular pathways and processes known to be affected by CCs are described. In particular, CC-induced activation of the inflammasome and production of reactive oxygen species, along with the role of CCs in complement-mediated inflammation is discussed. Moreover, the clinical manifestation of embolized CCs is described with a focus on renal and skin diseases associated with CC embolism. Lastly, potential therapeutic measures that target either the formation of CCs or their impact on different cell types and tissues are highlighted.

Hippocampal alpha-synuclein mediates depressive-like behaviors

Alpha-synuclein (α-syn) which encoded by SNCA plays a critical role in the neurotransmission, vesicle dynamics, and neuroplasticity. Alteration to SNCA expression is associated with major depressive disorder. However, the pathogenic mechanism of SNCA in depression remains unknown. Herein, we reported that SNCA was up-regulated in the peripheral blood of major depressive disorder (MDD) patients and the depressive mice. Chronic restraint stress (CRS) also up-regulated the SNCA expression in the hippocampus. Moreover, over-expression of SNCA in the hippocampus triggered spontaneous depressive-like behaviors under the non-stressed conditions in mice, and knockout of SNCA could reverse CRS-induced depressive-like behaviors. SNCA led to synapse loss and neuronal cell death in the hippocampus possibly via complement-mediated microglial engulfment and inflammation, and thus contributed to the pathogenesis of depressive disorder. Overall, hippocampal SNCA and complement system are involved in the pathogenesis of depressive disorder and it provides a new perspective for the occurrence of depressive disorder.

Factor H Autoantibodies and Complement-Mediated Diseases.

Factor H (FH), a member of the regulators-of-complement-activation (RCA) family of proteins, circulates in human plasma at concentrations of 180–420 mg/L where it controls the alternative pathway (AP) of complement in the fluid phase and on cell surfaces. When the regulatory function of FH is impaired, complement-mediated tissue injury and inflammation occur, leading to diseases such as atypical hemolytic uremic syndrome (a thrombotic microangiopathy or TMA), C3 glomerulopathy (C3G) and monoclonal gammopathy of renal significance (MGRS). A pathophysiological cause of compromised FH function is the development of autoantibodies to various domains of the FH protein. FH autoantibodies (FHAAs) are identified in 10.9% of patients with aHUS, 3.2% of patients with C3G, and rarely in patients with MGRS. The phenotypic variability of FHAA-mediated disease reflects both the complexity of FH and the epitope specificity of FHAA for select regions of the native protein. In this paper, we have characterized FHAA epitopes in a large cohort of patients diagnosed with TMA, C3G or MGRS. We explore the epitopes recognized by FHAAs in these diseases and the association of FHAAs with the genetic deletion of both copies of the CFHR1 gene to show how these disease phenotypes are associated with this diverse spectrum of autoantibodies.

Mechanisms and biomarkers of inflammatory endotypes in chronic rhinosinusitis without nasal polyps

Chronic rhinosinusitis (CRS) without nasal polyps (CRSsNP) is a common disease that is characterized by multiple inflammatory endotypes. However, the molecular mechanisms in CRSsNP are poorly understood compared with those of polypoid CRS. Our aim was to identify mechanisms and biomarkers associated with inflammatory endotypes underpinning CRSsNP. Ethmoid tissues and nasal lavage fluids (NLFs) were obtained from control patients and patients with CRS. The gene expression profiles were determined by microarray analysis and quantitative RT-PCR, and expression of proteins was measured by ELISA and Luminex analysis. Microarray found that compared with their levels of expression in control tissue, the levels of expression of 126, 241, and 545 genes were more than 3-fold and significantly elevated in CRSsNP with type 1 (T1) endotype, type 2 (T2) endotype, and type 3 (T3) endotype, respectively. Selected identified genes were confirmed by RT-PCR. Gene set enrichment analysis suggested that T1 CRSsNP was associated with IFN-γ signaling and antiviral immunity controlled by T cells (TH1 and CD8+), natural killer cells, and antigen-presenting cells; T2 CRSsNP was associated with STAT6 signaling and IgE-mediated activation controlled by eosinophils, mast cells, TH2 cells, group 2 innate lymphoid cells, and antigen-presenting cells; and T3 CRSsNP was associated with IL-17 signaling, acute inflammatory response, complement-mediated inflammation, and infection controlled by neutrophils, TH17 cells, B cells, and antigen-presenting cells. The results suggest that T1 (CXCL9 and CXCL10), T2 (eosinophilic proteins and CCL26), and T3 (CSF3) endotypic biomarkers in NLF may be able to distinguish tissue endotypes in CRSsNP. Inflammatory endotypes in CRSsNP were controlled by different molecular mechanisms. NLF biomarker assays may allow for more precise and personalized medicaltreatments in CRS.

Function and Dysfunction of Complement Factor H During Formation of Lipid-Rich Deposits.

Complement-mediated inflammation or dysregulation in lipid metabolism are associated with the pathogenesis of several diseases. These include age-related macular degeneration (AMD), C3 glomerulonephritis (C3GN), dense deposit disease (DDD), atherosclerosis, and Alzheimer’s disease (AD). In all these diseases, formation of characteristic lipid-rich deposits is evident. Here, we will discuss molecular mechanisms whereby dysfunction of complement, and especially of its key regulator factor H, could be involved in lipid accumulation and related inflammation. The genetic associations to factor H polymorphisms, the role of factor H in the resolution of inflammation in lipid-rich deposits, modification of macrophage functions, and complement-mediated clearance of apoptotic and damaged cells indicate that the function of factor H is crucial in limiting inflammation in these diseases.

Complement peptide C3a receptor 1 promotes optic nerve degeneration in DBA/2J mice

BackgroundThe risk of glaucoma increases significantly with age and exposure to elevated intraocular pressure, two factors linked with neuroinflammation. The complement cascade is a complex immune process with many bioactive end-products, including mediators of inflammation. Complement cascade activation has been shown in glaucoma patients and models of glaucoma. However, the function of complement-mediated inflammation in glaucoma is largely untested. Here, the complement peptide C3a receptor 1 was genetically disrupted in DBA/2J mice, an ocular hypertensive model of glaucoma, to test its contribution to neurodegeneration.MethodsA null allele of C3ar1 was backcrossed into DBA/2J mice. Development of iris disease, ocular hypertension, optic nerve degeneration, retinal ganglion cell activity, loss of RGCs, and myeloid cell infiltration in C3ar1-deficient and sufficient DBA/2J mice were compared across multiple ages. RNA sequencing was performed on microglia from primary culture to determine global effects of C3ar1 on microglia gene expression.ResultsDeficiency in C3ar1 lowered the risk of degeneration in ocular hypertensive mice without affecting intraocular pressure elevation at 10.5 months of age. Differences were found in the percentage of mice affected, but not in individual characteristics of disease progression. The protective effect of C3ar1 deficiency was then overcome by additional aging and ocular hypertensive injury. Microglia and other myeloid-derived cells were the primary cells identified that express C3ar1. In the absence of C3ar1, microglial expression of genes associated with neuroinflammation and other immune functions were differentially expressed compared to WT. A network analysis of these data suggested that the IL10 signaling pathway is a major interaction partner of C3AR1 signaling in microglia.ConclusionsC3AR1 was identified as a damaging neuroinflammatory factor. These data help suggest complement activation causes glaucomatous neurodegeneration through multiple mechanisms, including inflammation. Microglia and infiltrating myeloid cells expressed high levels of C3ar1 and are the primary candidates to mediate its effects. C3AR1 appeared to be a major regulator of microglia reactivity and neuroinflammatory function due to its interaction with IL10 signaling and other immune related pathways. Targeting myeloid-derived cells and C3AR1 signaling with therapies is expected to add to or improve neuroprotective therapeutic strategies.

Inflammation and Fatigue in Patients with Cold Agglutinin Disease (CAD): Analysis from the Phase 3 Cardinal Study

Introduction CAD is a rare, chronic type of autoimmune hemolytic anemia, where hemolysis is driven by classical complement pathway (CP) activation. Complement activation assures rapid initiation of the complement cascade as part of an early immune response and inflammation. A proinflammatory state secondary to complement activation has been demonstrated in other hemolytic disease such as paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome (Weitz et al. Thromb Res. 2012; Cofiell et al. Blood. 2015). Complement activation stimulates cytokine production (tumor necrosis factor, interleukin 6 [IL-6], IL-8, IL-17) via anaphylatoxins C3a and C5a and increases vascular inflammatory markers, consistent with complement-mediated inflammation (Landsem et al. Clin Exp Immunol. 2017; Cofiell et al. Blood. 2015). In patients with chronic fatigue syndrome, complement activation is associated with higher levels of fatigue (Sorensen et al. J Allergy Clin Immunol. 2003) and inflammatory cytokine activity correlates with the severity of fatigue symptoms (Montoya et al. PNAS. 2017). In addition, IL-6 plays a more dominant role in immune stimulation, particularly during chronic inflammation stress such as rheumatoid arthritis (Choy et al. Rheumatology. 2018). In CAD, CP activation and chronic inflammation may contribute to patient fatigue, apart from anemia. CP activation resulting in a proinflammatory state has not been formally studied in CAD. The interplay between complement-mediated inflammation and fatigue also has not been previously explored in patients with CAD. In the Cardinal study (NCT03347396), efficacy and safety of the humanized monoclonal anti-C1s antibody, sutimlimab (formerly BIVV009), was evaluated in patients with CAD and recent history of blood transfusion. Here we summarize the results of inflammatory cytokine expression for IL-6 and IL-10 and their relation to fatigue over the Part A 26-week treatment period of Cardinal. Methods In Cardinal Part A, patients with CAD received intravenous doses of sutimlimab on Days 0 and 7, and biweekly infusions thereafter. Patients weighing &amp;lt;75 kg and ≥75 kg received a 6.5 g and 7.5 g dose, respectively. Cytokine levels for IL-6 and IL-10 were assessed in patients with available serum samples. Cytokine profiles and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scores were evaluated from baseline to follow-up time points at Weeks 1, 3, 5, and 25, as represented by the treatment assessment time point (TAT) after initiating sutimlimab treatment. Summary statistics describing IL-6, IL-10, and FACIT-F changes at each week were reported. Results Mean IL-6 level (mean pg/mL [standard error of the mean (SEM)]) steadily decreased from baseline (3.21 [0.958]; normal values IL-6 &amp;lt;3.2 pg/mL) to follow up at all time points after initiating sutimlimab treatment (Figure 1), showing rapid onset and durable pattern of decline as early as Week 1 (2.70 [0.839]). Mean IL-6 level was reduced by more than half by Week 3 (1.56 [0.297]), slightly rose at Week 5 (1.88 [0.383]), and was lowest at TAT (1.31 [0.201]). Mean IL-10 level (pg/mL [SEM]) also decreased in a time-dependent manner from baseline (1.36 [0.310]) initially at Week 1 (0.99 [0.250]). Mean IL-10 slightly increased at Week 3 (1.07 [0.306]), but dropped at Week 5 (0.83 [0.142]) and was lowest by TAT (0.82 [0.129]) with sutimlimab treatment (Figure 2). At baseline, mean (SEM) FACIT-F score was 32.5 (2.266) (Figures 1-2). Patient FACIT-F scores showed early and late improvements with mean score increases at Week 1 (39.67 [1.741]), Week 3 (40.70 [1.543]), Week 5 (43.75 [1.192]), and at TAT (41.86 [1.958]). Decreased inflammation, as demonstrated by IL-6 and IL-10 activity, occurred concurrently with FACIT-F score improvements over time. Conclusions In Cardinal Part A, decrease from baseline to TAT in mean proinflammatory cytokine IL-6 and regulatory cytokine IL-10 levels were observed during sutimlimab treatment, highlighting the influence of complement inhibition on inflammation in CAD. Improved FACIT-F scores are concurrent with sutimlimab treatment and inhibition of the CP. Concurrent inverse changes were noted between select inflammatory cytokines and improvements in patients' fatigue, suggesting complement-mediated inflammation may additionally contribute to manifestation of fatigue in patients with CAD. Disclosures Weitz: Apellis: Consultancy, Honoraria; Alexion: Consultancy, Honoraria, Speakers Bureau. Ueda:Novartis: Honoraria; Alexion Pharmaceuticals: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria. Shafer:Sanofi: Current Employment. Su:Sanofi: Current Employment. Foster:Sanofi Genzyme: Current Employment. Storek:Sanofi: Current Employment. Patel:Sanofi: Current Employment.

IMMUNE CHECK POINT INHIBITOR-INDUCED ORGANIZING PNEUMONIA IN A LUNG TRANSPLANT PATIENT

SESSION TITLE: Medical Student/Resident Diffuse Lung Disease SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Immune check point inhibitors (ICI) are an effective therapy in treatment of multiple malignancies. Ipilimumab, a CTLA-4 antibody was the first ICI to be approved for advanced melanoma, followed by pembrolizumab, a PD1 inhibitor(1)(2). A myriad of immune related adverse effects have been observed with use of checkpoint inhibitors, due to T cell activation. ICI up regulate immune response to cancer but also leads to rejection of transplanted organs. Here we present a case of ICI pneumonitis after treatment with pembrolizumab in a lung transplant patient. CASE PRESENTATION: An 80-year-old Caucasian male received bilateral lung allografts in 2003 for idiopathic pulmonary fibrosis. In 2014, he was diagnosed with malignant melanoma and squamous cell carcinoma of scalp and neck, and underwent wide local excision with radiation therapy. He received two cycles of pembrolizumab for recurrence of melanoma (BRAF wildtype) after which he developed acute hypoxemic respiratory failure requiring mechanical ventilation. The patient received broad spectrum antibiotics and pulse dose methyl prednisolone for suspected transplant rejection. Bronchoalveolar lavage showed bilateral alveolar hemorrhage and trans-bronchial biopsies of the left lower lobe and lingula showed acute organizing pneumonia. With the concern for ICI pneumonitis versus ICI induced rejection of lung allograft the patient was treated with pulse dose steroids and then a prolonged steroid taper. DISCUSSION: Multiple adverse events have been reported with ICI including pulmonary toxicity. In a meta-analysis of 6360 patients, the incidence of pneumonitis from anti-PD-1 immunotherapy was 2.92% (3). Increased T-cell activity, inflammatory cytokines, and enhanced complement-mediated inflammation is suggested as the mechanism. ICI pneumonitis may manifest as cryptogenic organizing pneumonia, interstitial pneumonia, hypersensitivity pneumonitis, or acute respiratory distress syndrome patterns (4). Lung toxicities are graded dependent on severity of symptoms and extent of radiological involvement and American Society of Clinical Oncology provides expert consensus on treatment recommendations. Current guidelines indicated the discontinuation of ICI and initiation of corticosteroids in our patient with grade 3 toxicity. In refractory cases, anti-TNF-a agent infliximab, has been used. Allograft rejection must also be considered in lung transplant patients who undergo ICI therapy. Infectious pneumonia must also be excluded as this can be fatal if left untreated (5). CONCLUSIONS: Our patient presented with ICI related organizing pneumonia in transplanted lungs, which has been reported in few case reports with favorable response to high dose steroids. Awareness of potential complications of ICI especially in transplant population facilitates early recognition and prompt treatment with improved outcomes. Reference #1: 1) Alexander W. The Checkpoint Immunotherapy Revolution: What Started as a Trickle Has Become a Flood, Despite Some Daunting Adverse Effects; New Drugs, Indications, and Combinations Continue to Emerge. P T. 2016;41(3):185–191. Reference #2: 2) Robert, C., Schachter, J., Long, G. V., Arance, A., Grob, J. J., Mortier, L., … Ribas, A. (2015). Pembrolizumab versus Ipilimumab in Advanced Melanoma. New England Journal of Medicine, 372(26), 2521–2532. doi: 10.1056/nejmoa1503093 Reference #3: 3) Nishino M, Giobbie-Hurder A, Hatabu H, Ramaiya NH, Hodi FS. Incidence of Programmed Cell Death 1 Inhibitor–Related Pneumonitis in Patients With Advanced Cancer: A Systematic Review and Meta-analysis. JAMA Oncol. 2016;2(12):1607–1616. doi:10.1001/jamaoncol.2016.2453 4) Nishino, M., Giobbie-Hurder, A., Hatabu, H., Ramaiya, N. H., & Hodi, F. S. (2016). Incidence of Programmed Cell Death 1 Inhibitor–Related Pneumonitis in Patients With Advanced Cancer. JAMA Oncology, 2(12), 1607. doi: 10.1001/jamaoncol.2016.2453 5) Jun, J., Lee, S. R., Lee, J. Y., Choi, M. J., Noh, J. Y., Cheong, H. J., … Song, J. Y. (2019). Pneumonitis and concomitant bacterial pneumonia in patients receiving pembrolizumab treatment: Three case reports and literature review. Medicine, 98(25), e16158. doi:10.1097/MD.000000000001615 DISCLOSURES: no disclosure on file for Deepa Gotur; No relevant relationships by Uchenne Mbaraonye, source=Web Response no disclosure on file for Cindy Nguyen; no disclosure on file for Lily Romero Karam; Speaker/Speaker's Bureau relationship with Astellas Pharma US, Inc. Please note: $1001 - $5000 Added 03/10/2020 by Simon Yau, source=Web Response, value=Salary