Cfh, or Complement factor H, is a key complement inhibitor present as a soluble protein and attached to cell surfaces. It plays a crucial role in complement homeostasis, particularly in inhibiting excessive activation of the complement cascade, especially the alternative pathway. Its significance is underscored by the diverse phenotypes associated with its gene variants [4].

In a mouse model of atherosclerosis, Cfh deficiency limited plaque necrosis in a C3-dependent manner. Deletion of Cfh in monocyte-derived inflammatory macrophages led to uncontrolled cell-autonomous C3 consumption without downstream C5 activation and increased efferocytotic capacity. This shows that Cfh controls intracellular C3 levels of macrophages in a cell-autonomous way, highlighting its importance in the pathogenesis of inflammatory diseases [5]. In early-onset macular degeneration (EOMD), a novel Cfh variant led to loss of Cfh and factor H-like protein 1 (FHL-1) expression, increased local complement activity, and higher MAC deposition, indicating Cfh haploinsufficiency's role in EOMD pathogenesis [1]. In atypical hemolytic uremic syndrome (aHUS), uncommon Cfh-CFHR genomic rearrangements, such as Cfh-CFHR1 hybrid genes, were found in some patients, and those involving Cfh were associated with a poor prognosis but responsiveness to anti-complement therapy [2,3].

In conclusion, Cfh is essential for regulating the complement system. Studies using gene knockout or related models in mice and human patients have revealed its role in diseases like atherosclerosis, EOMD, and aHUS. Understanding Cfh's function through these models helps in elucidating disease mechanisms and potentially developing new treatment strategies for these conditions.

References:

1. Lim, Rayne R, Shirali, Sharlene, Rowlan, Jessica, Neitz, Maureen, Chao, Jennifer R. . CFH Haploinsufficiency and Complement Alterations in Early-Onset Macular Degeneration. In Investigative ophthalmology & visual science, 65, 43. doi:10.1167/iovs.65.4.43. https://pubmed.ncbi.nlm.nih.gov/38683564/

2. Piras, Rossella, Valoti, Elisabetta, Alberti, Marta, Remuzzi, Giuseppe, Noris, Marina. 2023. CFH and CFHR structural variants in atypical Hemolytic Uremic Syndrome: Prevalence, genomic characterization and impact on outcome. In Frontiers in immunology, 13, 1011580. doi:10.3389/fimmu.2022.1011580. https://pubmed.ncbi.nlm.nih.gov/36793547/

3. Sugawara, Yuka, Kato, Hideki, Nagasaki, Masao, Yamamoto, Masayuki, Nangaku, Masaomi. 2023. CFH-CFHR1 hybrid genes in two cases of atypical hemolytic uremic syndrome. In Journal of human genetics, 68, 427-430. doi:10.1038/s10038-023-01129-1. https://pubmed.ncbi.nlm.nih.gov/36755127/

4. Boon, Camiel J F, van de Kar, Nicole C, Klevering, B Jeroen, Daha, Mohamed R, den Hollander, Anneke I. 2009. The spectrum of phenotypes caused by variants in the CFH gene. In Molecular immunology, 46, 1573-94. doi:10.1016/j.molimm.2009.02.013. https://pubmed.ncbi.nlm.nih.gov/19297022/

5. Kiss, Máté G, Papac-Miličević, Nikolina, Porsch, Florentina, Mallat, Ziad, Binder, Christoph J. 2023. Cell-autonomous regulation of complement C3 by factor H limits macrophage efferocytosis and exacerbates atherosclerosis. In Immunity, 56, 1809-1824.e10. doi:10.1016/j.immuni.2023.06.026. https://pubmed.ncbi.nlm.nih.gov/37499656/