Activin A is a member of the TGF-β superfamily of growth factors which signals through two transmembrane serine/threonine kinase receptors

In bone metastasis, activin A produced by tumour cells acts as a stimulator of bone degradation, inhibiting osteoblast differentiation and stimulating osteoclast differentiation.

Anti-phosphatidylserine prothrombin antibodies (aPSPT) are reported to be highly associated with the lupus anticoagulant (LAC) in established antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE) cohorts.

Anti-phosphatidylserine prothrombin antibodies (aPSPT) are reported to be highly associated with the lupus anticoagulant (LAC) in established antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE) cohorts.

Complement component 1q (C1q) is a soluble protein complex acting as a key bridge between innate and adaptive immune responses. During infection and tissue damage, C1q binds to the fragment crystallizable (Fc) region of circulating IgG or IgM antibodies, apoptotic cells, bacterial surfaces, and ligand-bound C-reactive protein. This allows for the aggregation of antigen–antibody–C1q complexes to form. This process, known as opsonization, allows for increased phagocytic efficiency of cells such as macrophages via the classic complement cascade, which ends with the formation of a membrane attack complex that initiates target cell lysis.

Anti-histone antibodies (AHAs) make their appearance in a number of systemic autoimmune diseases including systemic lupus erythematosus (SLE) and drug-induced lupus erythematosus (DILE). Although being known for over 50 years, they are poorly studied and understood. There is emerging evidence for their use in predicting clinical features of SLE, diversifying their clinical use. AHAs, however, are probably less prevalent in DILE than once thought owing to a move away from older DILE drugs to modern biological agents which do not appear to elicit AHAs.

The apelin system is a broad regulator of physiology. It consists of the apelin receptor and its two endogenous ligands, apelin and elabela (also known as Toddler). The system is a particularly appealing target for cardiovascular disease as it promotes endothelium-dependent vasodilatation, inotropy, lowers blood pressure, and increases aqueous diuresis. Activating the apelin system also has metabolic and renal benefits.

Bone morphogenetic proteins (BMPs) are known to play important roles in a wide array of processes during formation and maintenance of various organs including bone, cartilage, muscle, kidney, and blood vessels. BMPs and the related “growth and differentiation factors” (GDFs) are members of the transforming growth factor β (TGF-β) family.

Bone morphogenetic protein-7 is (BMP-7) is a potent anti-inflammatory growth factor belonging to the Transforming Growth Factor Beta (TGF-β) superfamily. It plays an important role in various biological processes, including embryogenesis, hematopoiesis, neurogenesis and skeletal morphogenesis.

Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal survival and growth, serves as a neurotransmitter modulator, and participates in neuronal plasticity, which is essential for learning and memory. It is widely expressed in the CNS, gut and other tissues.

Cartilage oligomeric matrix protein (COMP) is an extracellular matrix (ECM) glycoprotein that is critical for collagen assembly and ECM stability. The bouquet-like structure of COMP allows it to act as a bridging molecule that regulates cellular phenotype and function. COMP is able to interact with many other ECM components and binds directly to a variety of cellular receptors and growth factors.