Therapeutic regulation of complement activation in extracorporeal circuits and intravascular treatments with special reference to the alternative pathway amplification loop

Preclinical safety and efficacy of the recombinant CR1 drug product CSL040 in rats and cynomolgus monkeys

CSL040 is a soluble, recombinant fragment of the complement receptor 1 (CR1) extracellular domain that acts as an inhibitor of all three pathways of the complement system. Systemic toxicity, toxicokinetics (TK), and pharmacodynamics (PD) of CSL040 were assessed in two-week intravenous (IV) bolus studies in Han Wistar rats and cynomolgus monkeys. Recovery from any effects was evaluated during a four-week recovery period. Daily repeat-dose administration for 2 weeks at doses of up to 500 mg/kg CSL040 IV was well tolerated in rats and cynomolgus monkeys, leading to a no observed adverse effect level (NOAEL) of 500 mg/kg for both species. Safety pharmacology parameters such as electrophysiology of the heart, blood pressure, heart rate, and respiratory rate measurements, and general toxicological readouts were considered unaffected by CSL040 treatment. Anti-drug antibodies (ADAs) were observed in all cynomolgus monkeys and in some rats at the highest dose of CSL040, but with no effect on pharmacokinetics (PK), supportive of adequate exposure levels as required for a safety assessment. All three complement pathways were inhibited dose-dependently by CSL040. Additionally, no effect on cytokine levels by CSL040 was detected in vitro using a cytokine release assay. These non-clinical studies with CSL040 demonstrated PD activity consistent with its mode of action, adequate PK properties, and a safety profile supporting a phase 1 clinical strategy. A small follow-up study comparing the PK/PD effects of CSL040 following IV and subcutaneous (SC) administration also suggested that the latter route of administration might be a viable alternative to IV administration.

Research progress on the pathogenesis of AKI complicated by ECMO

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) stands as a pivotal intervention for patients grappling with cardiopulmonary insufficiency. However, alongside its therapeutic benefits, ECMO carries the risk of complications, with acute kidney injury (AKI) emerging as a significant concern. The precise pathophysiological underpinnings of AKI in the context of ECMO remain incompletely elucidated.

METHODS

A comprehensive literature review was conducted to explore the epidemiology and pathophysiological mechanisms underlying the utilization of ECMO in the management of AKI.

RESULTS

ECMO initiates a multifaceted cascade of inflammatory reactions, encompassing complement activation, endothelial dysfunction, white blood cell activation, and cytokine release. Furthermore, factors such as renal hypoperfusion, ischemia-reperfusion injury, hemolysis, and fluid overload exacerbate AKI. Specifically, veno-arterial ECMO (VA-ECMO) may directly induce renal hypoperfusion, whereas veno-venous ECMO (VV-ECMO) predominantly impacts pulmonary function, indirectly influencing renal function.

CONCLUSION

While ECMO offers significant therapeutic advantages, AKI persists as a potentially fatal complication. A thorough comprehension of the pathogenesis underlying ECMO-associated AKI is imperative for effective prevention and management strategies. Moreover, additional research is warranted to delineate the incidence of AKI secondary to ECMO and to refine clinical approaches accordingly.

Moss-produced human complement factor H with modified glycans has an extended half-life and improved biological activity

Most drugs that target the complement system are designed to inhibit the complement pathway at either the proximal or terminal levels. The use of a natural complement regulator such as factor H (FH) could provide a superior treatment option by restoring the balance of an overactive complement system while preserving its normal physiological functions. Until now, the systemic treatment of complement-associated disorders with FH has been deemed unfeasible, primarily due to high production costs, risks related to FH purified from donors' blood, and the challenging expression of recombinant FH in different host systems. We recently demonstrated that a moss-based expression system can produce high yields of properly folded, fully functional, recombinant FH. However, the half-life of the initial variant (CPV-101) was relatively short. Here we show that the same polypeptide with modified glycosylation (CPV-104) achieves a pharmacokinetic profile comparable to that of native FH derived from human serum. The treatment of FH-deficient mice with CPV-104 significantly improved important efficacy parameters such as the normalization of serum C3 levels and the rapid degradation of C3 deposits in the kidney compared to treatment with CPV-101. Furthermore, CPV-104 showed comparable functionality to serum-derived FH in vitro, as well as similar performance in ex vivo assays involving samples from patients with atypical hemolytic uremic syndrome, C3 glomerulopathy and paroxysomal nocturnal hematuria. CPV-104 - the human FH analog expressed in moss - will therefore allow the treatment of complement-associated human diseases by rebalancing instead of inhibiting the complement cascade.

MUC5AC concentrations in lung lavage fluids are associated with acute lung injury after cardiac surgery

Heart surgery may be complicated by acute lung injury and adult respiratory distress syndrome. Expression and release of mucins MUC5AC and MUC5B in the lungs has been reported to be increased in acute lung injury. The aim of our study was to [1] investigate the perioperative changes of MUC5AC, MUC5B and other biomarkers in mini-bronchoalveolar lavage (minBAL), and [2] relate these to clinical outcomes after cardiac surgery. In this prospective cohort study in 49 adult cardiac surgery patients pre- and post-surgery non-fiberscopic miniBAL fluids were analysed for MUC5AC, MUC5B, IL-8, human neutrophil elastase, and neutrophils. All measured biomarkers increased after surgery. Perioperative MUC5AC-change showed a significant negative association with postoperative P/F ratio (p = 0.018), and a positive association with ICU stay (p = 0.027). In conclusion, development of lung injury after cardiac surgery and prolonged ICU stay are associated with an early increase of MUC5AC as detected in mini-BAL.

Prompt Thrombo-Inflammatory Response to Ischemia-Reperfusion Injury and Kidney Transplant Outcomes

Introduction

In kidney transplantation (KT), the role of the intravascular innate immune system (IIIS) in response to ischemia-reperfusion injury (IRI) is not well-understood. Here, we studied parallel changes in the generation of key activation products of the proteolytic cascade systems of the IIIS following living donor (LD) and deceased donor (DD) transplantation and evaluated potential associations with clinical outcomes.

Methods

In a cohort study, 63 patients undergoing LD (n = 26) and DD (n = 37) transplantation were prospectively included. Fifteen DD kidneys were preserved with hypothermic machine perfusion (HMP), and the remaining were cold stored. Activation products of the kallikrein-kinin, coagulation, and complement systems were measured in blood samples obtained systemically at baseline and locally from the transplant renal vein at 1, 10, and 30 minutes after reperfusion.

Results

DD kidneys exhibited a prompt and interlinked activation of all 3 cascade systems of IIIS postreperfusion, indicating a robust and local thrombo-inflammatory response to IRI. In this initial response, the complement activation product sC5b-9 exhibited a robust correlation with other IIIS activation markers and displayed a strong association with short-term and mid-term (24-month) graft dysfunction. In contrast, LD kidneys did not exhibit this thrombo-inflammatory response. The use of HMP was associated with reduced thromboinflammation and preserved mid-term kidney function.

Conclusion

Kidneys from DD are vulnerable to a prompt thrombo-inflammatory response to IRI, which adversely affects both short-term and long-term allograft function. Strategies aimed at minimizing graft immunogenicity prior to reperfusion are crucial to mitigate the intricate inflammatory response to IRI.

Clotting of the Extracorporeal Circuit in Hemodialysis: Beyond Contact-Activated Coagulation

Thrombotic complications in patients with end-stage kidney disease are frequent. While being a lifesaving treatment for these patients, hemodialysis introduces a thromboinflammatory environment. Additionally, the extracorporeal hemodialysis circuit itself is prone to clotting because of an interaction between different activation mechanisms of the coagulation system, platelets, and the immune system. Anticoagulation of the patient and the machine is frequently complicated by bleeding. We discuss the factors important in this balancing act and touch on potential strategies that are on the horizon to target thromboinflammation.

Complement factor I: Regulatory nexus, driver of immunopathology, and therapeutic

Complement factor I (FI) is the nexus for classical, lectin and alternative pathway complement regulation. FI is an 88 kDa plasma protein that circulates in an inactive configuration until it forms a trimolecular complex with its cofactor and substrate whereupon a structural reorganization allows the catalytic triad to cleave its substrates, C3b and C4b. In keeping with its role as the master complement regulatory enzyme, deficiency has been linked to immunopathology. In the setting of complete FI deficiency, a consumptive C3 deficiency results in recurrent infections with encapsulated microorganisms. Aseptic cerebral inflammation and vasculitic presentations are also less commonly observed. Heterozygous mutations in the factor I gene (CFI) have been demonstrated to be enriched in atypical haemolytic uraemic syndrome, albeit with a very low penetrance. Haploinsufficiency of CFI has also been associated with decreased retinal thickness and is a strong risk factor for the development of age-related macular degeneration. Supplementation of FI using plasma purified or recombinant protein has long been postulated, however, technical difficulties prevented progression into clinical trials. It is only using gene therapy that CFI supplementation has reached the clinic with GT005 in phase I/II clinical trials for geographic atrophy.

MyD88-dependent Toll-like receptor 2 signaling modulates macrophage activation on lysate-adsorbed Teflon™ AF surfaces in an in vitro biomaterial host response model

The adsorbed protein layer on an implanted biomaterial surface is known to mediate downstream cell-material interactions that drive the host response. While the adsorption of plasma-derived proteins has been studied extensively, the adsorption of damage-associated molecular patterns (DAMPs) derived from damaged cells and matrix surrounding the implant remains poorly understood. Previously, our group developed a DAMP-adsorption model in which 3T3 fibroblast lysates were used as a complex source of cell-derived DAMPs and we demonstrated that biomaterials with adsorbed lysate potently activated RAW-Blue macrophages via Toll-like receptor 2 (TLR2). In the present study, we characterized the response of mouse bone marrow derived macrophages (BMDM) from wildtype (WT), TLR2-/- and MyD88-/- mice on Teflon™ AF surfaces pre-adsorbed with 10% plasma or lysate-spiked plasma (10% w/w total protein from 3T3 fibroblast lysate) for 24 hours. WT BMDM cultured on adsorbates derived from 10% lysate in plasma had significantly higher gene and protein expression of IL-1β, IL-6, TNF-α, IL-10, RANTES/CCL5 and CXCL1/KC, compared to 10% plasma-adsorbed surfaces. Furthermore, the upregulation of pro-inflammatory cytokine and chemokine expression in the 10% lysate in plasma condition was attenuated in TLR2-/- and MyD88-/- BMDM. Proteomic analysis of the adsorbed protein layers showed that even this relatively small addition of lysate-derived proteins within plasma (10% w/w) caused a significant change to the adsorbed protein profile. The 10% plasma condition had fibrinogen, albumin, apolipoproteins, complement, and fibronectin among the top 25 most abundant proteins. While proteins layers generated from 10% lysate in plasma retained fibrinogen and fibronectin among the top 25 proteins, there was a disproportionate increase in intracellular proteins, including histones, tubulins, actins, and vimentin. Furthermore, we identified 7 DAMPs or DAMP-related proteins enriched in the 10% plasma condition (fibrinogen, apolipoproteins), compared to 39 DAMPs enriched in the 10% lysate in plasma condition, including high mobility group box 1 and histones. Together, these findings indicate that DAMPs and other intracellular proteins readily adsorb to biomaterial surfaces in competition with plasma proteins, and that adsorbed DAMPs induce an inflammatory response in adherent macrophages that is mediated by the MyD88-dependent TLR2 signaling pathway.

Magnetic blood purification-based soluble fms-like tyrosine kinase-1 removal in comparison with dextran sulfate apheresis and therapeutic plasma exchange

BACKGROUND

Preeclampsia remains one of the most serious complications of pregnancy. Effective therapies are yet to be developed. Recent research has identified an imbalance of angiogenic and antiangiogenic factors as a root cause of preeclampsia. In particular, soluble fms-like tyrosine kinase-1 (sFlt-1) has been shown to bind the angiogenic factors vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), reducing blood vessel growth. Increasing preclinical and clinical evidence suggests that removal of the sFlt-1 protein may benefit patients with early onset preeclampsia. sFlt-1 may be removed by conventional blood purification techniques, such as therapeutic plasma exchange (TPE) and dextran sulfate apheresis (DSA), or emerging technologies, including extracorporeal magnetic blood purification (MBP).

METHODS

We compare the performance and selectivity of TPE, DSA, and MBP for the therapeutic removal of sFlt-1. For MPB, we employ magnetic nanoparticles functionalized with either sFlt-1 antibodies or the sFlt-1-binding partner, vascular endothelial growth factor (VEGF).

RESULTS

We demonstrate that sFlt-1 removal by MBP is feasible and significantly more selective than TPE and DSA at comparable sFlt-1 removal efficiencies (MBP 96%, TPE 92%, DSA 78%). During both TPE and DSA, complement factors (incl. C3c and C4) are depleted to a considerable extent (-90% for TPE, -55% for DSA), while in MBP, complement factor concentrations remain unaltered. We further demonstrate that the removal efficacy of sFlt-1 in the MBP approach is strongly dependent on the nanoparticle type and dose and can be optimized to reach clinically feasible throughputs.

CONCLUSIONS

Taken together, the highly selective removal of sFlt-1 and potential other disease-causing factors by extracorporeal magnetic blood purification may offer new prospects for preeclamptic patients.