Complement-associated disorders are caused by the dysregulation and disbalance of the complement system, especially excessive activation. 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 balance to an overactive complement system. We recently reported the moss-based production of an analog of human FH with an optimized glycan profile (CPV-104), which showed in vitro and in vivo characteristics comparable to its human counterpart. Here, we follow up our previous work, focusing in more detail on the time course and long-term efficacy of CPV-104 treatment in FH-deficient (FH–/–) mice. The analysis of long-term treatment effects following multiple injections of human FH into mice was previously hindered by the immune response, so we developed a protocol for the sustained depletion of CD20+ B-cells and CD4+ T-cells, preventing antibody formation without influencing the C3G phenotype. Using this dual-depletion method, we were able to complete dosing interval experiments in FH–/– mice, administering up to three injections of CPV-104 at different intervals. Repeated CPV-104 administration was able to lastingly resolve C3 deposits, offering additional rationale for the clinical testing of CPV-104 in human C3G patients. Moreover, our novel dual-depletion method has the potential for adaptation to different mouse models, allowing the testing of multiple doses of other therapeutic proteins.

AMD is a multifactorial progressive disease of the central retina that leads to severe vision loss among the elderly. Genome-wide association studies in AMD patients and preclinical data have identified a dysregulated complement system and aberrant microglia responses in the pathogenesis of AMD. Specifically, a genetic variant in the complement factor H (CFH) gene, an important inhibitor of the alternative complement pathway, confers the strongest risk for AMD. Here, we investigated whether moss-derived recombinant human CFH proteins, termed CPV-101 and CPV-104, can modulate microglia reactivity and limit retinal degeneration in a murine light damage paradigm mimicking important features of AMD. Two glycosylated human recombinant CFH proteins CPV101, and CPV-104 were produced in moss suspension cultures. In addition, glycans of the CPV-104 variant are sialylated, an optimization that makes CPV-104 an analog of human CFH. BALB/cJ mice received intravitreal injections of 5 µg CPV-101 and CPV-104 or vehicle, starting 1 day prior to exposure to 10,000 lx white light for 30 min. The effects of CPV-101 and CPV-104 treatment on mononuclear phagocyte and Müller cell reactivity were analyzed by immunostainings of retinal sections and flat mounts. Gene expression of microglia markers was analyzed using quantitative real-time PCR (qRT-PCR). Optical coherence tomography (OCT); Blue Peak Autofluorescence (BAF); terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and morphometric analyses were used to quantify the extent of retinal degeneration and photoreceptor apoptosis. Light-exposed mice treated with moss-derived recombinant human full-length CFH showed reduced complement activation and MAC deposition in the retina. Concomitantly, mononuclear phagocyte and Müller cell reactivity in light-exposed retinas were also ameliorated upon CFH substitution. Moreover, attenuated light-induced retinal degeneration was detected in mice that received moss-derived CFH. Modulating the alternative complement pathway using moss-derived recombinant human full-length CFH variant CPV-101 and CPV-104 counter-regulate gliosis and attenuates light-induced retinal degeneration, highlighting a promising concept for the treatment of AMD patients.

Background: Complement-associated disorders are caused by the dysregulation of the complement system, especially its excessive activation. 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 rebalancing an overactive complement system. Utilizing Eleva‘s moss-based expression system allowed the generation of clinically relevant amounts of recombinant FH (CPV-104), which in vitro and in vivo characteristic was found comparable to that of its human counterpart[1]. We have investigated the therapeutic potential of CPV-104 focusing on C3 glomerulopathy (C3G) and age-related macular degeneration (AMD). Methods: CPV-104 was produced in moss suspension cultures cultivated in illuminated 500-L single-use stirred-tank reactors. In vivo long-term efficacy of CPV-104 was tested by repeated intravenous (IV) or subcutaneous (SC) administration of CPV-104 in FH deficient mice. To overcome the detrimental immune response in animals and enable the repeated treatment regime, we applied a protocol for depletion of CD20+ B-cells and CD4+ T-cells, preventing antibody formation without influencing the C3G phenotype. CPV-104 efficacy was also tested following intravitreal injection into wild-type mice undergoing light-induced acute retinal degeneration (AMD model). Results: The repeated intravenous CPV-104 administration showed the ability to lastingly resolve C3 deposits in FH-deficient mice[2]. Multiple SC injections also lead to prolonged FH availability in mouse sera, resulting in sustained elevation of serum C3 levels and reduced kidney C3 deposits. Further experiments in cynomolgus monkeys validated these findings, suggesting SC injections as another viable road of administration for CPV-104. Light-exposed wild type mice (AMD model) treated with CPV-104 showed strongly decreased microglia and Müller cell reactivity concomitantly with reduced pro-inflammatory cytokines compared to vehicle controls. Furthermore, light-induced retinal degeneration was attenuated in mice that received CPV-104. Conclusion: CPV-104 – the human FH analogue – has the potential to enable treatment of complement-associated human diseases by rebalancing rather than inhibiting the complement cascade. References: [1] Tschongov et al. Front. Immunol., doi: 10.3389/fimmu.2024.1383123 [2] Tschongov et al. Front. Immunol., doi: 10.3389/fimmu.2025.1535547.

The moss Physcomitrium patens is an advantageous host for the production of biopharmaceutical proteins, particularly due to the ease of glyco-engineering. However, the ability to produce proteins with paucimannosidic (MM) glycans in this species currently depends solely on the nature of the product. MM glycans offer benefits for some therapeutic proteins by facilitating their import into target cells via a presumed mannose receptor. Here, we describe the use of Spodoptera frugiperda enzymes expressed in moss to produce recombinant human lysosomal acid α-glucosidase with mainly MM glycans. We tested the expression of mannosidase type III and a hexosaminidase by varying the promoter strength and protein localization. The parental line produced recombinant α-glucosidase with no detectable MM glycans at all, whereas the weak expression of mannosidase type III targeted to the medial Golgi produced 4% MM glycans. The strong expression of a hexosaminidase targeted to the extracellular space increased the MM glycan content to 43.5%. Unlike previous attempts to express proteins with MM glycans in plants, neither of our introduced modifications interfered with growth or recombinant protein production. Our data confirm that the finely tuned expression and cellular localization of the glycosylation machinery can improve the efficiency of glyco-engineering. We also exploit the assembly of DNA fragments in vivo, which overcomes the limitations of traditional knock-in methods and facilitates the screening of different genetic elements. Our combined methods therefore represent the first straightforward approach allowing the production of recombinant proteins with abundant MM glycans.

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.

Fabry disease (FD, OMIM 301500) is a rare X-linked inherited lysosomal storage disorder associated with reduced activities of α-galactosidase A (aGal, EC 3.2.1.22). The current standard of care for FD is based on enzyme replacement therapy (ERT), in which a recombinantly produced version of αGal is intravenously (iv) applied to Fabry patients in biweekly intervals. Though the iv application is clinically efficacious, periodical infusions are inconvenient, time- and resource-consuming and they negatively impact the patients' quality of life. Subcutaneous (sc) injection, in contrast, is an established route of administration for treatment of chronic conditions. It opens the beneficial option of self-administration, thereby improving patients' quality of life and at the same time reducing treatment costs. We have previously shown that Moss-α-Galactosidase (moss-aGal), recombinantly produced in the moss Physcomitrium patens, is efficient in degrading accumulated Gb3 in target organs of murine model of FD and in the phase I clinical study, we obtained first efficacy evidence in human patients following single iv infusion. Here, we tested the efficacy of subcutaneous administration of moss-aGal and compared it with the results observed following iv infusion in Fabry mice. The obtained findings demonstrate that subcutaneously applied moss-aGal is correctly transported to target organs and efficacious in degrading Gb3 deposits there and thus suggest the possibility of using this route of administration for therapy of Fabry disease.

Abstract Pompe disease, an autosomal recessive lysosomal storage disorder, is caused by deficiency of lysosomal acid alpha‐glucosidase (GAA). On cellular level, there is lysosomal‐bound and free accumulation of glycogen and subsequent damage of organelles and organs. The most severe affected tissues are skeletal muscles and heart. The only available treatment to date is an enzyme replacement therapy (ERT) with alglucosidase alfa, a recombinant human GAA (rhGAA) modified with mannose‐6‐phosphate (M6P), which is internalized via M6P‐mediated endocytosis. There is an unmet need to improve this type of therapy, especially in regard to skeletal muscle. Using different tissue culture models, we recently provided evidence that a moss‐derived nonphosphorylated rhGAA (moss‐GAA), carrying a glycosylation with terminal N‐acetylglucosamine residues (GnGn), might have the potential to improve targeting of skeletal muscle. Now, we present a pilot treatment of Gaa−/− mice with moss‐GAA. We investigated general effects as well as the uptake into different organs following short‐term treatment. Our results do confirm that moss‐GAA reaches the target disease organs and thus might have the potential to be an alternative or complementary ERT to the existing one.

Pompe disease is an autosomal recessive lysosomal storage disorder (LSD) caused by deficiency of lysosomal acid alpha-glucosidase (GAA). The result of the GAA deficiency is a ubiquitous lysosomal and non-lysosomal accumulation of glycogen. The most affected tissues are heart, skeletal muscle, liver, and the nervous system. Replacement therapy with the currently approved enzyme relies on M6P-mediated endocytosis. However, therapeutic outcomes still leave room for improvement, especially with regard to skeletal muscles. We tested the uptake, activity, and effect on glucose metabolism of a non-phosphorylated recombinant human GAA produced in moss (moss-GAA). Three variants of moss-GAA differing in glycosylation pattern have been analyzed: two with terminal mannose residues in a paucimannosidic (Man3) or high-mannose (Man 5) configuration and one with terminal N-acetylglucosamine residues (GnGn). Compared to alglucosidase alfa the moss-GAA GnGn variant showed increased uptake in differentiated myotubes. Moreover, incubation of immortalized muscle cells of Gaa−/− mice with moss-GAA GnGn led to similarly efficient clearance of accumulated glycogen as with alglucosidase alfa. These initial data suggest that M6P-residues might not always be necessary for the cellular uptake in enzyme replacement therapy (ERT) and indicate the potential of moss-GAA GnGn as novel alternative drug for targeting skeletal muscle in Pompe patients.

Host cell proteins are inevitable contaminants of biopharmaceuticals. Here, we performed detailed analyses of the host cell proteome of moss ( Physcomitrella patens) bioreactor supernatants using mass spectrometry and subsequent bioinformatics analysis. Distinguishing between the apparent secretome and intracellular contaminants, a complex extracellular proteolytic network including subtilisin-like proteases, metallo-proteases, and aspartic proteases was identified. Knockout of a subtilisin-like protease affected the overall extracellular proteolytic activity. Besides proteases, also secreted protease-inhibiting proteins such as serpins were identified. Further, we confirmed predicted cleavage sites of 40 endogenous signal peptides employing an N-terminomics approach. The present data provide novel aspects to optimize both product stability of recombinant biopharmaceuticals as well as their maturation along the secretory pathway. Data are available via ProteomeXchange with identifier PXD009517.

Moss-aGalactosidase A (moss-aGal) is a moss-derived version of human -galactosidase developed for enzyme replacement therapy in patients with Fabry disease. It exhibits a homogenous N-glycosylation profile with >90% mannose-terminated glycans. In contrast to mammalian cell produced -galactosidase, moss-aGal does not rely on mannose-6-phosphate receptor mediated endocytosis but targets the mannose receptor for tissue uptake. We conducted a phase 1 clinical trial with moss-aGal in six patients with confirmed diagnosis of Fabry disease during a 28-day schedule. All patients received a single dose of 0.2 mg/kg moss-aGal by i.v.-infusion. Primary endpoints of the trial were safety and pharmacokinetics; secondary endpoints were pharmacodynamics by analyzing urine and plasma Gb3 and lyso-Gb3 concentrations. In all patients, the administered single dose was well tolerated. No safety issues were observed. Pharmacokinetic data revealed a stable nonlinear profile with a short plasma half-life of moss-aGal of 14minutes. After one single dose of moss-aGal, urinary Gb3 concentrations decreased up to 23% 7 days and up to 60% 28days post-dose. Plasma concentrations of lyso-Gb3 decreased by 3.8% and of Gb3 by 11% 28days post-dose. These data reveal that a single dose of moss-aGal was safe, well tolerated, and led to a prolonged reduction of Gb3 excretion. As previously shown, moss-aGal is taken up via the mannose receptor, which is expressed on macrophages but also on endothelial and kidney cells. Thus, these data indicate that moss-aGal may target kidney cells. After these promising results, phase 2/3 clinical trials are in preparation.

Human Leukocyte Antigen-G (HLA-G) is known as an immune suppressive molecule; it interacts with several immune cells and inhibits their functions. HLA-G molecule is highly represented in pathological conditions including malignant transformation. To the best of our knowledge this is the first study that focuses on the expression of soluble HLA-G (sHLA-G) in endometrial cancer (EC). We aimed at exploring sHLA-G plasma levels and its prognostic value in EC.We examined total sHLA-G expression as well as the sHLA-G1 and HLA-G5 isoforms expression in plasma samples from 40 patients with EC and 45 healthy controls by a specific sandwich ELISA. Immunoprecipitation and Coomassie blue staining were performed to explore the presence of plasmatic sHLA-G monomers and dimers.sHLA-G plasma level was significantly enhanced in patients with EC compared to healthy controls (p = 0.028). Additionally, HLA-G5 molecules were highly represented than sHLA-G1 molecules in EC, at the borderline of significance (p = 0.061). Interestingly, sHLA-G has been shown to be increased in early stages (Stages I and II) as well as in high grade EC (Grade 3) that is associated with rapid spread of the disease (p = 0.057). sHLA-G positive EC plasma were majorly in monomeric form (75%). Clinically, all the HLA-G dimers were detected in early stages and in high grade of EC.Our data strengthen the implication of HLA-G molecules in EC etiology and especially in progression.

Genetic defects in complement regulatory proteins can lead to severe renal diseases, including atypical hemolytic uremic syndrome and C3 glomerulopathies, and age-related macular degeneration. The majority of the mutations found in patients with these diseases affect the glycoprotein complement factor H, the main regulator of the alternative pathway of complement activation. Therapeutic options are limited, and novel treatments, specifically those targeting alternative pathway activation, are highly desirable. Substitution with biologically active factor H could potentially treat a variety of diseases that involve increased alternative pathway activation, but no therapeutic factor H is commercially available. We recently reported the expression of full-length recombinant factor H in moss (Physcomitrella patens). Here, we present the production of an improved moss-derived recombinant human factor H devoid of potentially immunogenic plant-specific sugar residues on protein N-glycans, yielding approximately 1 mg purified moss-derived human factor H per liter of initial P. patens culture after a multistep purification process. This glycosylation-optimized factor H showed full in vitro complement regulatory activity similar to that of plasma-derived factor H and efficiently blocked LPS-induced alternative pathway activation and hemolysis induced by sera from patients with atypical hemolytic uremic syndrome. Furthermore, injection of moss-derived factor H reduced C3 deposition and increased serum C3 levels in a murine model of C3 glomerulopathy. Thus, we consider moss-produced recombinant human factor H a promising pharmaceutical product for therapeutic intervention in patients suffering from complement dysregulation.

Aberrant type 2 responses underlie the pathologies in allergic diseases like asthma, yet, our understanding of the mechanisms that drive them remains limited. Recent evidence suggests that dysregulated innate immune factors can perpetuate asthma pathogenesis. In susceptible individuals, allergen exposure triggers the activation of complement, a major arm of innate immunity, leading to the aberrant generation of the C3a anaphylatoxin. C3 and C3a have been shown to be important for the development of Th2 responses, yet remarkably, the mechanisms by which C3a regulates type 2 immunity are relatively unknown. We demonstrate a central role for C3a in driving type 2 innate lymphoid cells (ILC2)-mediated inflammation in response to allergen and IL-33. Our data suggests that ILC2 recruitment is C3a-dependent. Further, we show that ILC2s directly respond to C3a, promoting type 2 responses by specifically: (1) inducing IL-13 and granulocyte-macrophage colony-stimulating factor, whereas inhibiting IL-10 production from ILC2; and (2) enhancing their antigen-presenting capability during ILC-T-cell cross-talk. In summary, we identify a novel mechanism by which C3a can mediate aberrant type 2 responses to aeroallergen exposure, which involves a yet unrecognized cross-talk between two major innate immune components—complement and group 2 innate lymphoid cells.

Plant-based expression systems, such as Physcomitrella patens (Moss), have only recently emerged as an alternative to established recombinant protein production platforms (e.g. bacterial cell lines, yeast cell lines or mammalian cell lines). Generally, generic Host Cell Protein ELISAs (HCP ELISAs) are used for the detection of potential impurities during downstream process development of drug products and in early clinical phases (phase I and II). However, no generic HCP ELISAs for plant-based expression systems are available. To meet the requirements for release of drug product to be used in phase 1 clinical trial in Germany it was necessary to develop an ELISA specific for P.patens HCP.