The Overlapping Roles of Antimicrobial Peptides and Complement in Recruitment and Activation of Tumor-Associated Inflammatory Cells

Abstract

Antimicrobial peptides (AMPs) represent a group of small (6–100 amino acids), biologically active molecules, which are produced by plants, mammals, and microorganisms (1). An important element of the innate immune response, AMP, possesses potent antibiotic, antifungal, and antiviral activities. Furthermore, AMP may be involved in a number of other processes such as angiogenesis and modulation of the immune response such as stimulation of chemokines and chemotaxis of leukocytes. AMPs have been proposed as alternative therapies for infectious diseases. AMP may also exert cytotoxic activity against tumor cells. Further understanding of the biological function of these peptides during tumor development and progression may aid in the development of novel anti-tumor therapies with refined application of innate molecules. AMP and complement have distinct roles to play in shaping the microenvironment (Table 1). Components of the complement system are integral contributors in responding to infection and sterile inflammation. Moreover, complement plays a role in the trafficking of cells in the tumor microenvironment, and thereby possibly in the immune response to cancer. This article will try to outline characteristics of AMP and complement in mobilization and recruitment of cells in tumor microenvironment.

Immunomodulatory activity of pidotimod administered with standard antibiotic therapy in children hospitalized for community-acquired pneumonia

“…In particular, TLR2 plays a major role in promoting protective immunity against respiratory pathogens [ 30 ], and its upregulation could reduce susceptibility to further respiratory infections. In contrast in PDT-treated children, the increased expression of antimicrobial peptides (e.g., CAMP, LCN2, LTF and MPO) and genes involved in cell chemotaxis, the upregulation of the inflammatory response and increased apoptosis [ 31 – 33 ], (e.g., CCL3, CXCL1, CXCL2, IL-18, IL-1b, IL-6, IL-8, NFkB1, and NLRP3) suggest that PDT administration might significantly increase the activity of the immune system for a long period of time, thus reducing the risk of early recurrences during CAP in children.…”

A New Era of Antibiotics: The Clinical Potential of Antimicrobial Peptides

“…Defensins are produced by multiple cell types, such as neutrophils, macrophages, cardiomyocytes, lymphocytes, keratinocytes, and intestinal epithelial cells [ 37 ]. In addition to their role as chemoattractants, defensins are also involved in the activation of classical complement pathways [ 40 ].…”

Multifunctional Activity of the β-Defensin-2 during Respiratory Infections

“…It has been described that HBD2 binds to C1q (first component of the complement system) and inhibits the classical complement pathway. HBD2 have a dual protective role not only as an antimicrobial agent but also to provide protection against uncontrolled activation of complement system [73,75,76].…”