SUMMARYHuman b-defensins are broad-spectrum antimicrobial peptides known to be produced by epithelial cells. It was recently shown that b-defensins also display chemotactic activity for dendritic cells (DC) and T cells, and thus may serve to link innate and adaptive immunity. The aim of the present study was to explore expression of mRNA for these peptides in mononuclear phagocytes and DC. The results revealed that monocytes, monocyte-derivedmacrophages (MDM), and monocyte-derived-dendritic cells (DC) all express humanb-defensin-1 (hBD-1) mRNA. hBD-1 mRNA expression by monocytes and MDM was increased after activation with interferon-c (IFN-c) and/or lipopolysaccharide (LPS) in a dose-and time-dependent fashion. Alveolar macrophages showed an intense hBD-1 expression, which could not be further increased. Expression of hBD-1 mRNA by immature DC was low, and increased considerably after maturation. Monocytes, MDM, alveolar macrophages and DC showed a limited expression of human b-defensin-2 (hBD-2) mRNA, which could only be increased in monocytes and alveolar macrophages by IFN-c and/or LPS in a dose-and time-dependent fashion. Immunocytochemical stainings demonstrated the expression of hBD-2 peptide by freshly isolated blood monocytes and alveolar macrophages in cytospin preparations.

The limited capacity of current bioreactors has led the biopharmaceutical industry to investigate alternative protein expression systems. The milk of transgenic cattle may provide an attractive vehicle for large-scale production of biopharmaceuticals, but there have been no reports on the characteristics of such recombinant proteins. Here we describe the production of recombinant human lactoferrin (rhLF), an iron-binding glycoprotein involved in innate host defense, at gram per liter concentrations in bovine milk. Natural hLF from human milk and rhLF had identical iron-binding and -release properties. Although natural hLF and rhLF underwent differential N-linked glycosylation, they were equally effective in three different in vivo infection models employing immunocompetent and leukocytopenic mice, and showed similar localization at sites of infection. Taken together, the results illustrate the potential of transgenic cattle in the large-scale production of biopharmaceuticals.

The human cathelicidin LL-37 has broad-spectrum antimicrobial activity. It also participates at the interface of innate and adaptive immunity by chemoattracting immune effector cells, modulating the production of a variety of inflammatory mediators by different cell types, and regulating the differentiation of monocytes into dendritic cells. In this study, we investigated the effects of LL-37 on the differentiation of human monocytes into anti-inflammatory macrophages (MΦ-2; driven by M-CSF) versus proinflammatory macrophages (MΦ-1; driven by GM-CSF) as well as on fully differentiated MΦ-1 and MΦ-2. Results revealed that monocytes cultured with M-CSF in the presence of LL-37 resulted in macrophages displaying a proinflammatory signature, namely, low expression of CD163 and little IL-10 and profound IL-12p40 production on LPS stimulation. The effects of LL-37 on M-CSF-driven macrophage differentiation were dose- and time-dependent with maximal effects observed at 10 μg/ml when the peptide was present from the start of the cultures. The peptide enhanced the GM-CSF–driven macrophage differentiation. Exposure of fully differentiated MΦ-2 to LL-37 for 6 d resulted in macrophages that produced less IL-10 and more IL-12p40 on LPS stimulation than control MΦ-2. In contrast, LL-37 had no effect on fully differentiated MΦ-1. Peptide mapping using a set of 16 overlapping 22-mer peptides covering the complete LL-37 sequence revealed that the C-terminal portion of LL-37 is responsible for directing macrophage differentiation. Our results furthermore indicate that the effects of LL-37 on macrophage differentiation required internalization of the peptide. Together, we conclude that LL-37 directs macrophage differentiation toward macrophages with a proinflammatory signature.

Psoriasis vulgaris, a type-1 cytokine-mediated chronic skin disease, can be treated successfully with fumaric acid esters (FAE). Beneficial effects of this medication coincided with decreased production of IFN-+ . Since dendritic cells (DC) regulate the differentiation of T helper (Th) cells, this study focussed on effects of monomethylfumarate (MMF, bioactive metabolite of FAE) on polarization of monocyte-derived DC. MMF-incubated, lipopolysaccharide-stimulated DC (MMF-DC) produced dramatically (p X 0.05) reduced levels of IL-12p70 and IL-10 (8±4% and 20±4%, respectively) compared to control DC. MMF-DC were mature. MMF affected polarization of DC irrespective of polarization factor(s) and ligands for the various Toll-like receptors used. Coculture of MMF-DC with naive and primed allogenous Th cells resulted in lymphocytes producing less IFN-+ , i.e. 59% and 54% of that by the respective Th cells cocultured with control DC. IL-4 production by primed, but not naive Th cells cocultured with MMF-DC was decreased as compared to cocultures with control DC. IL-10 production by naive and primed Th cells cocultured with MMF-DC and control DC did not differ. In addition, MMF inhibited LPS-induced NF-‹ B activation in DC. Together, beneficial effects of FAE in psoriasis involve modulation of DC polarization by MMF such that these cells down-regulate IFN-+ production by Th cells.

The human lactoferrin-derived peptide hLF1-11 displays antimicrobial activities in vitro and is effective against infections with antibiotic-resistant bacteria and fluconazole-resistant Candida albicans in animals. However, the mechanisms underlying these activities remain largely unclear. Since hLF1-11 is ineffective in vitro at physiological salt concentrations, we suggested modulation of the immune system as an additional mechanism of action of the peptide. We investigated whether hLF1-11 affects human monocyte-macrophage differentiation and determined the antimicrobial activities of the resulting macrophages. Monocytes were cultured for 7 days with GM-CSF in the presence of hLF1-11, control peptide, or saline for various intervals. At day 6, the cells were stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), or heat-killed C. albicans for 24 h. Thereafter, the levels of cytokines in the culture supernatants, the expression of pathogen recognition receptors, and the antimicrobial activities of these macrophages were determined. The results showed that a short exposure of monocytes to hLF1-11 during GM-CSF-driven differentiation is sufficient to direct differentiation of monocytes toward a macrophage subset characterized by both pro-and anti-inflammatory cytokine production and increased responsiveness to microbial structures. Moreover, these macrophages are highly effective against C. albicans and Staphylococcus aureus. In conclusion, hLF1-11 directs GM-CSF-driven differentiation of monocytes toward macrophages with enhanced effector functions.

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We previously found the LL-37-derived peptide P60.4Ac to be effective against methicillin-resistant Staphylococcus aureus (MRSA) on human epidermal models (EMs). The goal of this study was to identify the preferred carrier for this peptide for topical application on skin and mucosal surfaces. We prepared P60.4Ac in three formulations, i.e., a water-in-oil cream with lanolin (Softisan 649), an oil-in-water cream with polyethylene glycol hexadecyl ether (Cetomacrogol), and a hydroxypropyl methylcellulose (hypromellose) 4000 gel. We tested the antimicrobial efficacy of the peptide in these formulations against mupirocin-resistant and -sensitive MRSA strains on EMs and bronchial epithelial models (BEMs). The cytotoxic effects of formulated P60.4Ac on these models were determined using histology and WST-1 and lactate dehydrogenase assays. Moreover, we assessed the stability of the peptide in these formulations with storage for up to 3 months. Killing of MRSA by P60.4Ac in the two creams was less effective than that by P60.4Ac in the hypromellose gel. In agreement with those findings, P60.4Ac in the hypromellose gel was highly effective in eradicating the two MRSA strains from EMs. We found that even 0.1% (wt/wt) P60.4Ac in the hypromellose gel killed >99% of the viable planktonic bacteria and >85% of the biofilm-associated bacteria on EMs. Hypromellose gels containing 0.1% and 0.5% (wt/wt) P60.4Ac effectively reduced the numbers of viable MRSA cells from BEMs by >90%. No cytotoxic effects of P60.4Ac in the hypromellose gel with up to 2% (wt/wt) P60.4Ac on keratinocytes in EMs and in the hypromellose gel with up to 0.5% (wt/wt) P60.4Ac on epithelial cells in BEMs were observed. High-performance liquid chromatography analysis showed that P60.4Ac was stable in the Softisan cream and the hypromellose gel but not in the Cetomacrogol cream. We conclude that P60.4Ac formulated in hypromellose gel is both stable and highly effective in eradicating MRSA from colonized EMs and BEMs.A bout 10 to 35% of humans are persistent carriers of Staphylococcus aureus, while 20 to 75% are intermediate carriers (1-3). The primary sites for colonization of humans are the nasal cavity, pharynx, perineum, and skin (3). Colonization of healthy individuals with this opportunistic bacterium causes no serious health problems; however, the risk of developing an S. aureus infection is increased in hospitalized patients or those undergoing surgery (4-6). Common infection problems include surgical site infections (7), wound and burn wound infections (5), bloodstream infections (8), catheter-related bacteremia (9, 10), and catheter (intubation)-related infections, such as pneumonia (11). Moreover, the symptoms of atopic eczema patients are often aggravated by the actions of S. aureus and S. epidermidis on their lesion sites (12, 13).Strategies currently used to eradicate methicillin-resistant S. aureus (MRSA) from carriers involve treatment with antibiotics, such as vancomycin, mupirocin, bacitracin, rifampin, and retapamulin (14-18). It has been show...

MMF inhibited the monocyte-derived DC differentiation resulting in cells that cannot be appropriately matured to DCs. Consequently, these MMF-DCs are less effective than control DCs in stimulating type 1 cytokine, but not type 2 cytokine production, in Th lymphocytes. This general immunomodulatory effect may in part explain the beneficial effects of FAE therapy in psoriasis.