Eosinophil cationic protein (ECP) also known as ribonuclease 3 is a basic protein located in the eosinophil primary matrix.[4] In humans, the eosinophil cationic protein is encoded by the RNASE3gene.[5]
ECP is released during degranulation of eosinophils. This protein is related to inflammation and asthma because in these cases, there are increased levels of ECP in the body.
There are three glycosylated forms of ECP and consequently ECP has a range of molecular weights from 18-22 kDa.[6]
The ribonuclease activity of ECP is not essential for cytotoxicity.[8]
When the two known ribonuclease active-site residues are modified to non-functional counterparts (Lysine at position 38 to Arginine and Histidine at position 128 to Aspartate)[9] and compared to the wild-type ECP, the mutated ECP retains its cytotoxicity but no longer has its ribonuclease activity. The experiment confirmed that converting the two amino acids to non-functional counterparts did inhibit ECP’s ribonuclease activity. However, ECP retained its anti-parasitic activity. Also, it did not change the production and transportation of ECP in bacteria.
ECP is a potent cytotoxic protein capable of killing cells of guinea pig tracheal epithelium,[10] mammalian leukemia,[11] epidermis carcinoma,[10] and breast carcinoma,[12] as well as non-mammalian cells such as parasites, bacteria, and viruses.[13]
Studies show that ECP, along with other RNases including EDN, had been reported to induce apoptosis in cells. A latest study indicated that ECP caused cytotoxicity in HL-60 and HeLa cells via caspase-3 like activity.[16] Accordingly, cytotoxic RNases play an important role in cell death. However, the mechanism of ECP-induced apoptosis is still not fully verified. Recent studies have shown that eosinophils can induce epithelial cell death via apoptosis and necrosis.[17]
ECP triggers apoptosis by caspase-8 activation through mitochondria-independent pathway.[15] Increases in chromatin condensation, sub-G1 population, PARP cleavage, and DNA fragmentation indicate that ECP induces apoptosis in human bronchial epithelial (BEAS-2B) cells.[15]
Clinical significance
Eosinophil granulocytes appear in large numbers in inflammation sites and in response to certain parasitic infections. These cytoplasmic granules contain positively charged proteins that characterize the cells. ECP is one of the four highly basic proteins that enter the surrounding tissues when activated eosinophils degranulate. Although circulating ECP levels can vary widely among patients, some studies show that serum ECP measurements are useful in monitoring many active inflammatory diseases.[18] ECP concentrations in plasma and other body fluids increase during inflammatory reactions marked by activated eosinophils.[19]
Serum ECP levels are also a useful, objective measurement for asthma severity. Increased ECP levels correspond to symptom onset. In seasonal asthmatic patients, ECP measurement reflected changes in disease activity throughout the year.[20]
There are several mechanisms that can be combined to generate an asthma attack, including specific IgE antibodies, activated inflammatory cells, neurogenic mechanisms, hyperresponsiveness and individual hormonal imbalances. Allergic reactions in the lung typically have two phases. The late phase typically occurs several hours after exposure, upon which eosinophils accumulate in the bronchus and release granule proteins that cause bronchial irritability. ECP is also toxic to neurons, some epithelial cell lines, and isolated myocardial cells.[21] This could be a reason for itching disorders of the skin.
Serum ECP measurement for assessing asthma severity, monitoring therapy, and indicating severity of certain inflammatory skin conditions present an advantage over subjective clinical measures that are prone to inconsistencies due to broad variability of individual investigator and patient assessments, especially in young children.
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Boix E, Carreras E, Nikolovski Z, Cuchillo CM, Nogués MV (June 2001). "Identification and characterization of human eosinophil cationic protein by an epitope-specific antibody". J. Leukoc. Biol. 69 (6): 1027–35. doi:10.1189/jlb.69.6.1027. PMID11404391. S2CID11326107.
^Mastrianni DM, Eddy RL, Rosenberg HF, Corrette SE, Shows TB, Tenen DG, Ackerman SJ (May 1992). "Localization of the human eosinophil Charcot-Leyden crystal protein (lysophospholipase) gene (CLC) to chromosome 19 and the human ribonuclease 2 (eosinophil-derived neurotoxin) and ribonuclease 3 (eosinophil cationic protein) genes (RNS2 and RNS3) to chromosome 14". Genomics. 13 (1): 240–2. doi:10.1016/0888-7543(92)90237-M. PMID1577491.
^Hamann KJ, Ten RM, Loegering DA, Jenkins RB, Heise MT, Schad CR, Pease LR, Gleich GJ, Barker RL (August 1990). "Structure and chromosome localization of the human eosinophil-derived neurotoxin and eosinophil cationic protein genes: evidence for intronless coding sequences in the ribonuclease gene superfamily". Genomics. 7 (4): 535–46. doi:10.1016/0888-7543(90)90197-3. PMID2387583.
^ abMotojima S, Frigas E, Loegering DA, Gleich GJ (March 1989). "Toxicity of eosinophil cationic proteins for guinea pig tracheal epithelium in vitro". Am. Rev. Respir. Dis. 139 (3): 801–5. doi:10.1164/ajrccm/139.3.801. PMID2923379.
^Carreras E, Boix E, Navarro S, Rosenberg HF, Cuchillo CM, Nogués MV (April 2005). "Surface-exposed amino acids of eosinophil cationic protein play a critical role in the inhibition of mammalian cell proliferation". Mol. Cell. Biochem. 272 (1–2): 1–7. doi:10.1007/s11010-005-4777-2. PMID16010966. S2CID41675640.
^D'Amato G, Liccardi G, Russo M, Saggese M, D'Amato M (April 1996). "Measurement of serum levels of eosinophil cationic protein to monitor patients with seasonal respiratory allergy induced by Parietaria pollen (treated and untreated with specific immunotherapy)". Allergy. 51 (4): 245–50. doi:10.1111/j.1398-9995.1996.tb00075.x. PMID8792921.
^ abCzech W, Krutmann J, Schöpf E, Kapp A (April 1992). "Serum eosinophil cationic protein (ECP) is a sensitive measure for disease activity in atopic dermatitis". Br. J. Dermatol. 126 (4): 351–5. doi:10.1111/j.1365-2133.1992.tb00677.x. PMID1571256. S2CID23425301.
^Reference range list from Uppsala University Hospital ("Laborationslista"). Artnr 40284 Sj74a. Issued on April 22, 2008
Behnecke A, Mayr S, Schick B, et al. (2008). "Evaluation of ECP release from intact tissue biopsies from patients with nasal polyps". Inflamm. Res. 57 (Suppl 1): S65–6. doi:10.1007/s00011-007-0632-0. PMID18345486. S2CID28257312.
Eberlein B, Gulyas A, Schultz K, et al. (2009). "Benefits of alpine mountain climate of Bavaria in patients with allergic diseases and chronic obstructive pulmonary disease: results from the AURA* study". J Investig Allergol Clin Immunol. 19 (2): 159–61. PMID19476022.
Torrent M, Navarro S, Moussaoui M, et al. (2008). "Eosinophil cationic protein high-affinity binding to bacteria-wall lipopolysaccharides and peptidoglycans". Biochemistry. 47 (11): 3544–55. doi:10.1021/bi702065b. PMID18293932.
Fukuda T, Iwata M, Kitazoe M, et al. (2009). "Human eosinophil cationic protein enhances stress fiber formation in Balb/c 3T3 fibroblasts and differentiation of rat neonatal cardiomyocytes". Growth Factors. 27 (4): 228–36. doi:10.1080/08977190902987149. PMID19521893. S2CID13245523.
Kang I, An XH, Oh YK, et al. (2010). "Identification of polymorphisms in the RNase3 gene and the association with allergic rhinitis". Eur Arch Otorhinolaryngol. 267 (3): 391–5. doi:10.1007/s00405-009-1103-8. PMID19760211. S2CID8311866.
Yuksel H, Yilmaz O, Sogut A, et al. (2009). "Correlation of quality of life with clinical parameters and eosinophilic cation protein levels in children with allergic rhinoconjunctivitis". Int. Arch. Allergy Immunol. 148 (1): 18–22. doi:10.1159/000151501. PMID18716399. S2CID24634035.
Laurents DV, Bruix M, Jiménez MA, et al. (2009). "The (1)H, (13)C, (15)N resonance assignment, solution structure, and residue level stability of eosinophil cationic protein/RNase 3 determined by NMR spectroscopy". Biopolymers. 91 (12): 1018–28. doi:10.1002/bip.21152. PMID19189375. S2CID205493978.
Peona V, De Amici M, Quaglini S, et al. (2010). "Serum eosinophilic cationic protein: is there a role in respiratory disorders?". J Asthma. 47 (2): 131–4. doi:10.3109/02770900903497170. PMID20170318. S2CID28187167.
1dyt: X-RAY CRYSTAL STRUCTURE OF ECP (RNASE 3) AT 1.75 A
1h1h: CRYSTAL STRUCTURE OF EOSINOPHIL CATIONIC PROTEIN IN COMPLEX WITH 2',5'-ADP AT 2.0 A RESOLUTION REVEALS THE DETAILS OF THE RIBONUCLEOLYTIC ACTIVE SITE
1qmt: RECOMBINANT HUMAN EOSINOPHIL CATIONIC PROTEIN