Biology subjects

Garred, P.

Publications and source records attributed to Garred, P..

5 recordsLinked to original sources

bioRxiv2025

Collectin-11 regulates osteoclastogenesis and bone maintenance via a complement-dependent mechanism.

The human developmental disorder 3MC syndrome is characterized by skeletal deformities associated with a deficiency of the pattern recognition molecule collectin-11 (CL-11), yet the underlying molecular and cellular mechanisms remain unclear. Here, we demonstrate that CL-11 deletion alone does not cause bone abnormalities in mice; however, combined deficiencies involving CL-11 and complement components MASP-2 (lectin pathway), CFB, or C3 (alternative amplification pathway) lead to significant vertebral bone loss and spinal curvature by 12 weeks of age. Ex vivo osteoclast (OCL) differentiation from bone marrow-derived cells of these double-knockout (DKO) mice was markedly impaired, but differentiation capacity was substantially restored by supplementation with CL-11. Furthermore, CL-11 and membrane attack complex (C5b-9) deposition were co-localized to OCLs and their precursors in normal bone tissues from embryonic stages to adulthood. These findings identify CL-11 as a critical osteoclastogenesis and bone maintenance regulator in conjunction with complement system-mediated signalling pathways and highlight CL-11 as a potential therapeutic target in diseases involving dysregulated osteoclast function and bone remodelling. Significance statementOur research in mice provides new insights into how mutations in the immune surveillance molecule collectin-11 contribute to skeletal abnormalities in humans. Evidence from our study suggests that normal osteoclasts interact with collectin-11 and complement, and that the disruption of this cooperation results in impaired bone maintenance in adulthood. These findings not only advance our understanding of osteoclast function but also highlight the therapeutic potential of targeting collectin-11 in conditions associated with osteoclast dysfunction.

immunology↗

bioRxiv2024

C1q in non-immune human serum has a non-redundant complement function towards clinical Mycobacterium tuberculosis complex strains

The Mycobacterium tuberculosis complex (MTBC) includes three human-adapted species: Mycobacterium tuberculosis, Mycobacterium africanum, and Mycobacterium canettii. With their genetic diversity and inherent virulence, these bacteria interact with host factors to influence tuberculosis (TB) transmission and pathogenesis. A critical yet poorly understood aspect of the immune response in TB involves the role of the complement system. Our study aimed to assess the general interaction between the complement system and key clinical MTBC strains representing the principal lineages known to vary in virulence. We found that not only mannose binding lectin (MBL) from the lectin pathway, but also C1q from the classical pathway directly recognize mycobacteria. While MBL generally showed a higher level of binding than C1q, the binding interactions varied across different MTBC strains. We further observed that complement activation products C4b, C3b and the terminal complement complex (TCC) were deposited on the surface of MTBC strains. Inhibition of MBL alone did not substantially alter complement activation, whereas C1q inhibition ceased activation for most strains investigated. Exposure to human serum did not impact the viability or growth of the MTBC strains. In conclusion, both the classical and lectin pathways of complement via C1q and MBL are activated by a broad range of lineages of the MTBC. The classical pathway is the main complement activator in non-immune serum across diverse MTBC lineages, with C1q playing a potentially novel role in the immune response in TB.

immunology↗

bioRxiv2024

C1q/MASP complexes - hybrid complexes of classical and lectin pathway proteins are found in the circulation

Complement pathways, traditionally regarded as separate entities in vitro, are increasingly noted for cross-communication and bypass mechanisms. Among these, the MBL/Ficolin/CL associated serine protease-3 (MASP-3) -- a component of lectin pathway pattern recognition receptors (PRMs) -- has shown the ability to process critical substrates like pro-factor D and insulin growth factor binding protein-5 (IGFBP-5). Given shared features between lectin pathway PRMs and C1q from the classical pathway, we hypothesized that C1q might be a viable in vivo binding partner for the MASPs. We used microscale thermophoresis, ELISA and immunoprecipitation assays to detect C1q/MASP complexes and functionally assessed the complexes through enzymatic cleavage assays. C1q/MASP-3 complexes were detected in human serum and correlated well with MASP-3 serum levels in healthy individuals. The binding affinity between MASP-3 and C1q in vitro was in the nanomolar range, and the interaction was calcium-dependent, as demonstrated by their dissociation in the presence of EDTA. Furthermore, most of the circulating C1q-bound MASP-3 was activated. Based on immunoprecipitatin, also C1q/MASP-2 complexes appereared to be present in serum. Finally, C1q/MASP-2 and C1q/MASP-3 in vitro complexes were able to cleave C4 and pro-factor D, respectively. Our study reveals the existence of C1q/MASP complexes in the circulation of healthy individuals and both C1q/MASP-2 and C1q/MASP-3 complexes display proteolytic activity. Hence, this study uncovers a crosstalk route between complement pathways not previously described.

immunology↗

bioRxiv2021

The SARS-CoV-2 Y453F mink variant displays a striking increase in ACE-2 affinity but does not challenge antibody neutralization

SARS-CoV-2 transmission from humans to animals has been reported for many domesticated species, including cats, dogs and minks. Identification of novel spike gene mutations appearing in minks has raised major concerns about potential immune evasion and challenges for the global vaccine strategy. The genetic variant, known as "cluster-five", arose among farmed minks in Denmark and resulted in a complete shutdown of the worlds largest mink production. However, the functional properties of this new variant are not established. Here we present functional data on the Y453F cluster-five receptor-binding domain (RBD) and show that it does not decrease established humoral immunity or affect the neutralizing response in a vaccine model based on wild-type RBD or spike. However, it binds the human ACE-2 receptor with a four-fold higher affinity suggesting an enhanced transmission capacity and a possible challenge for viral control.

immunology↗

bioRxiv2018

Proteomics-based comparative mapping of the human brown and white adipocyte secretome reveals EPDR1 as a novel batokine

Secreted proteins from adipose tissue play a role in metabolic cross-talk and homeostasis. We performed high sensitivity mass spectrometry-based proteomics on the cell media of in vitro differentiated, non-immortalized brown adipocytes derived from supraclavicular adipose of adult humans and white adipocytes derived from subcutaneous adipose of adult humans. We identified 471 potentially secreted proteins covering interesting protein categories such as hormones, growth factors, growth factor binding proteins, cytokines, extracellular matrix proteins, and proteins of the complement system, which were differentially regulated in brown and white adipocytes. A total of 101 proteins were exclusively quantified in brown adipocytes, among these ependymin-related protein 1 (EPDR1). Ablation of EPDR1 impaired the induction of thermogenic transcripts in response to norepinephrine in brown adipocytes, while EPDR1-treated mice increased their energy consumption, suggesting a role in brown fat commitment and activation. Our work reveals substantial differences between the secretomes of brown and white human adipocytes and identifies novel candidate batokines.

physiology↗