Antibacterial properties of eosinophil major basic protein and eosinophil cationic protein.

Abstract

We examined the bactericidal activity of two proteins that are abundant in the cytoplasmic granules of human eosinophils, major basic protein (MBP) and eosinophil cationic protein (ECP). Unlike the human neutrophil's peptide defensins, both MBP and ECP killed stationary phase Staphylococcus aureus 502A in a simple nutrient-free buffer solution. Although MBP also killed Escherichia coli ML-35 with considerable efficacy under these experimental conditions, the in vitro activity of ECP against E. coli was considerably enhanced if mid-logarithmic phase bacteria replaced stationary phase organisms or if the assay medium was enriched with trypticase soy broth. The antibacterial activity of both eosinophil proteins was modulated by incubation time, protein concentration, temperature and pH. A pBR322-transformed derivative of E. coli ML-35 was used to examine the effects of ECP and MBP on integrity of the bacterial inner membrane (IM) and outer membrane. Although both MBP and ECP caused outer and inner membrane permeabilization when nutrients were present, only MBP was effective under nutrient-free conditions. Two proton ionophores (DNP and carbonyl cyanide m-chlorophenyl hydrazone) protected E. coli from the bactericidal effects of ECP but not from MBP. These findings establish that MBP and ECP have bactericidal properties and suggest that these proteins kill E. coli by similar but nonidentical mechanisms marked by an attack on the target cell's membranes. In view of evidence that high concentrations of ECP and MBP exist in cytoplasmic granules whose contents are translocated to phagocytic vacuoles, we suggest that MBP and ECP contribute to the eosinophil's ability to kill ingested bacteria.

Eosinophilic Esophagitis and Microbiota: State of the Art

“…The EoE activity did not seem to directly affect a load of bacteria in EoE. However, eosinophils possess extracellular DNA traps and numerous anti-microbial properties with the release of defensins (63)(64)(65). The microbiota of untreated EoE subjects showed a shift from a mostly Gram (+) population to an increase in Gram (−) bacteria similar to what has been described in GERD (49).…”

Proposed refined diagnostic criteria and classification of eosinophil disorders and related syndromes

“…Eosinophils produce and store many biologically active molecules in their granules, including eosinophil peroxidase (EPX), eosinophil cationic protein (ECP), eosinophil major basic protein 1 (eMBP1), major basic protein 2, and numerous cytokines, including TGF‐ß (Table S2 ). 12 , 13 , 14 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 In the setting of massive and persistent eosinophil activation, eosinophil‐derived (toxic) substances can cause substantial changes in the local microenvironment, resulting in organ damage, often in association with local inflammation, cytotoxicity, thromboembolic complications, and/or fibrosis. 1 , 2 , 3 , 12 , 13 , 14 , 42 , 43 , 44 In patients with tissue HE and persistent eosinophil activation, marked deposition of eosinophil granule proteins, including eMBP1 and EPX, is usually found although staining for these eosinophil‐derived proteins is not standardized or available in most centers.…”

In silico characterization of differentially expressed short-read nucleotide sequences identified in dieback stress-induced transcriptomic analysis reveals their role as antimicrobial peptides

“…The results revealed that Ds-DbRCaG-07-Rga1p, Ds-DbRCaG-09-Rga9p, Ds-DbRCaG-10-Rga13p, and Ds-DbRCaG-11-Rga15p are basic proteins. Eosinophil protein (MBP) has antibacterial activity against microbes ( Lehrer et al., 1989 ). Arginine has an essential role in immune mechanisms and in combating pathogen attacks.…”