Antimicrobial efficacy of granulysin-derived synthetic peptides in acne vulgaris

A Polylysine dendrigraft is able to differentially impact Cutibacterium acnes strains preventing acneic skin

With a view to reducing the impact of Cutibacterium acnes on acne vulgaris, it now appears interesting to modify the balance between acneic and non-acneic strains of C. acnes using moderate approach. In the present study, we identified that a G2 dendrigraft of lysine dendrimer (G2 dendrimer) was able to modify membrane fluidity and biofilm formation of a C. acnes acneic strain (RT5), whereas it appeared no or less active on a C. acnes non-acneic strain (RT6). Moreover, skin ex vivo data indicated that the G2 is able to decrease inflammation (IL1α and TLR2) and improve skin desquamation after of C. acnes acneic strains colonization. Then, in vivo data confirmed, after C. acnes quantification by metagenomic analysis, that the G2 cream after 28 days of treatment was able to increase the diversity of C. acnes strains versus placebo cream. Data showed also a modification of the balance expression between C. acnes phylotype IA1 and phylotype II abundances. Taken together, the results confirm the interest of using soft compounds in cosmetic product for modifying phylotype abundances as well as diversity of C. acnes strains could be a new strategy for prevent acne vulgaris outbreak.

Gran1: A Granulysin-Derived Peptide with Potent Activity against Intracellular Mycobacterium tuberculosis

Granulysin is an antimicrobial peptide (AMP) expressed by human T-lymphocytes and natural killer cells. Despite a remarkably broad antimicrobial spectrum, its implementation into clinical practice has been hampered by its large size and off-target effects. To circumvent these limitations, we synthesized a 29 amino acid fragment within the putative cytolytic site of Granulysin (termed “Gran1”). We evaluated the antimicrobial activity of Gran1 against the major human pathogen Mycobacterium tuberculosis (Mtb) and a panel of clinically relevant non-tuberculous mycobacteria which are notoriously difficult to treat. Gran1 efficiently inhibited the mycobacterial proliferation in the low micro molar range. Super-resolution fluorescence microscopy and scanning electron microscopy indicated that Gran1 interacts with the surface of Mtb, causing lethal distortions of the cell wall. Importantly, Gran1 showed no off-target effects (cytokine release, chemotaxis, cell death) in primary human cells or zebrafish embryos (cytotoxicity, developmental toxicity, neurotoxicity, cardiotoxicity). Gran1 was selectively internalized by macrophages, the major host cell of Mtb, and restricted the proliferation of the pathogen. Our results demonstrate that the hypothesis-driven design of AMPs is a powerful approach for the identification of small bioactive compounds with specific antimicrobial activity. Gran1 is a promising component for the design of AMP-containing nanoparticles with selective activity and favorable pharmacokinetics to be pushed forward into experimental in vivo models of infectious diseases, most notably tuberculosis.

Topical antimicrobial peptides in combined treatment of acne patients

BACKGROUND

Acne vulgaris (AV) is a chronic inflammatory disorder of the pilosebaceous unit that affects over 80% of adolescents and young adults. This study aimed to compare the therapeutic efficacy and tolerability of an isotretinoin treatment course with GDP-20 (granulysin-derived peptides) versus the conventional isotretinoin monotherapy prescribed to patients with mild-to-moderate acne.

METHODS

Our study included 60 Russian subjects affected with AV of mild-to-moderate severity divided into two therapeutic groups. Half of the patients were female; mean age was 19.5 ± 5.6 years. Group 1 was treated with topical GDP-20 twice daily to the affected skin of the face combined with systemic isotretinoin in a fixed low dose of 0.3 mg/kg/day. Group 2 was treated with systemic isotretinoin as a monotherapy.

RESULTS

The assessment of the changes of AV lesion count on the 12th week of the treatment showed that in Group 1, the mean value of open comedo number reduced from 21.4 ± 6.1 at day 0 to 4.4 ± 2.5 (p < 0.05), the mean number of closed comedo reduced from 7.6 ± 3.5 to 2.4 ± 1.05 (p < 0.05), and those of papules-pustules reduced from 6.1 ± 1.03 to 1.4 ± 0.2 (p < 0.05).

CONCLUSIONS

Topical antimicrobial peptides (GDP-20) combined with low doses of systemic isotretinoin mild-to-moderate resulted in considerable improvement of clinical manifestations of mild-to-moderate AV and threefold reduction in the disease severity with IGA score 0-1 after 12 weeks. Topical application of GDP-20 antimicrobial peptides can improve the efficacy of low-dose systemic isotretinoin in combined treatment of mild-to-moderate AV.

Roles of Plant-Specific Inserts in Plant Defense

Ubiquitously expressed in plants, the plant-specific insert (PSI) of typical plant aspartic proteases (tpAPs) has been associated with plant development, stress response, and defense processes against invading pathogens. Despite sharing high sequence identity, structural studies revealed possible different mechanisms of action among species. The PSI induces signaling pathways of defense hormones in vivo and demonstrates broad-spectrum activity against phytopathogens in vitro. Recent characterization of the PSI-tpAP relationship uncovered novel, nonconventional intracellular protein transport pathways and improved tpAP production yields for industrial applications. In spite of research to date, relatively little is known about the structure-function relationships of PSIs. A comprehensive understanding of their biological roles may benefit plant protection strategies against virulent phytopathogens.

Analgesic and anti-inflammatory effects and mechanism of action of borneol on photodynamic therapy of acne

This study aims to explore the analgesic and anti-inflammatory effects of borneol, a traditional Chinese medicine, on photodynamic treatment of acne. Here, we found that borneol significantly decreased the auricular swelling rate and pain threshold of rats. We also showed that borneol noticeably reduced macrophage and lymphocyte infiltration. The number of Th cells was significantly higher in the control PDT group than in the PDT plus borneol treatment group (P < 0.05). The expression of IL-6, TNF-α, and IL-8 mRNA and proteins were noticeably lower in the treatment group in comparison to those of the PDT control group, while PDT plus borneol activated the p38-COX-2-PGE2 signaling pathway, increasing expression in the treatment group. Borneol has significant analgesic and anti-inflammatory effects on PDT of acne, and enhances the healing of acne by activating p38-COX-2-PGE2 signaling pathway.

Potential role of natural bioactive peptides for development of cosmeceutical skin products

In recent years, consumers' demand for cosmeceutical products with protective and therapeutic functions derived from natural sources have caused this industry to search for alternative active ingredients. Bioactive peptides have a wide spectrum of bioactivities, which make them ideal candidates for development of these cosmeceutical products. In vitro studies have demonstrated that bioactive peptides (obtained as extracts, hydrolysates, and/or individual peptides) exhibit biological properties including antioxidant, antimicrobial, and anti-inflammatory activities, in addition to their properties of inhibiting aging-related enzymes such as elastase, collagenase, tyrosinase and hyaluronidase. Some studies report multifunctional bioactive peptides that can simultaneously affect, beneficially, multiple physiological pathways in the skin. Moreover, in vivo studies have revealed that topical application or consumption of bioactive peptides possess remarkable skin protection. These properties suggest that bioactive peptides may contribute in the improvement of skin health by providing specific physiological functions, even though the mechanisms underlying the protective effect have not been completely elucidated. This review provides an overview of in vitro, in silico and in vivo properties of bioactive peptides with potential use as functional ingredients in the cosmeceutical field. It also describes the possible mechanisms involved as well as opportunities and challenges associated with their application.

ANTIMICROBIAL PEPTIDES — A POTENTIAL REPLACEMENT FOR TRADITIONAL ANTIBIOTICS

Antimicrobial peptides are a heterogeneous group of molecules involved in the innate and acquired immune response of various organisms, ranging from prokaryotes to mammals, including humans. They consist of 12–50 amino acid residues; have different physico-chemical and biological properties. The most common feature is their ability to destroy the prokaryotic cell membrane, which causes cell death. In the action, the molecules of antimicrobial peptides are embedded in the target bacteriological cells and change their conformation, forming structures in some cases resembling channels. Some other molecules of antimicrobial peptides can cover the surface of a bacteriological cell and form a carpet, when they reach a critical mass they act like detergents. In addition, being positively charged molecules of such peptides, penetrating through the membranes of parasitic and bacteriological cells, bind to polyanionic RNA and DNA molecules. Among the benefits of antimicrobial peptides is their high metabolic activity, low probability of occurrence of addictions and side effects. In addition, bacteriological pathogens that previously did not have resistance to any antimicrobial peptide are difficult to develop a strategy to control them. In this connection, these peptides are the most promising moleculessubstitutes for traditional antibiotics. The article discusses the approaches and strategies of therapeutic use, the studies of antimicrobial peptides identified in recent years; The most frequently encountered mechanisms of interaction of antimicrobial peptides and a bacteriological membrane are described, the physicochemical properties of peptide molecules are described; the results of studies on the detection of resistance of some strains of bacteria to antimicrobial peptides and antibiotics in general are summarized.

Antimicrobial Peptides and Their Therapeutic Potential for Bacterial Skin Infections and Wounds

Alarming data about increasing resistance to conventional antibiotics are reported, while at the same time the development of new antibiotics is stagnating. Skin and soft tissue infections (SSTIs) are mainly caused by the so called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) which belong to the most recalcitrant bacteria and are resistant to almost all common antibiotics. S. aureus and P. aeruginosa are the most frequent pathogens isolated from chronic wounds and increasing resistance to topical antibiotics has become a major issue. Therefore, new treatment options are urgently needed. In recent years, research focused on the development of synthetic antimicrobial peptides (AMPs) with lower toxicity and improved activity compared to their endogenous counterparts. AMPs appear to be promising therapeutic options for the treatment of SSTIs and wounds as they show a broad spectrum of antimicrobial activity, low resistance rates and display pivotal immunomodulatory as well as wound healing promoting activities such as induction of cell migration and proliferation and angiogenesis. In this review, we evaluate the potential of AMPs for the treatment of bacterial SSTIs and wounds and provide an overview of the mechanisms of actions of AMPs that contribute to combat skin infections and to improve wound healing. Bacteria growing in biofilms are more resistant to conventional antibiotics than their planktonic counterparts due to limited biofilm penetration and distinct metabolic and physiological functions, and often result in chronification of infections and wounds. Thus, we further discuss the feasibility of AMPs as anti-biofilm agents. Finally, we highlight perspectives for future therapies and which issues remain to bring AMPs successfully to the market.

The antimicrobial effect of CEN1HC-Br against Propionibacterium acnes and its therapeutic and anti-inflammatory effects on acne vulgaris

Propionibacterium acnes is a commensal bacterium, which is involved in acne inflammation. An antimicrobial peptide named CEN1HC-Br, which was isolated and characterized form the green sea urchin, has been shown to possess broad-spectrum antibacterial activity. Little is known concerning the potential effects of its antibacterial and anti-inflammatory properties against P. acnes. To examine the potency of CEN1HC-Br in acne treatment, we conducted experiments to analyze the antibacterial and anti-inflammatory activities of CEN1HC-Br both in vitro and in vivo. The antimicrobial activity of CEN1HC-Br was evaluated by minimal inhibitory concentration (MIC) assays using the broth dilution method. To elucidate the in vitro anti-inflammatory effect, HaCaT cells and human monocytes were treated with different concentration of CEN1HC-Br after stimulation by P. acnes. The expression of TLR2 and the secretion of the pro-inflammatory cytokines IL-6, IL-8, IL-1β, TNF-α, IL-12, respectively, were measured by enzyme immunoassays. An evaluation of P. acnes-induced ear edema in rat ear was conducted to compare the in vivo antibacterial and anti-inflammatory effect of CEN1HC-Br, the expression of IL-8, TNF-α, MMP-2 and TLR2 was evaluated by immunohistochemistry and real time-PCR. CEN1HC-Br showed stronger antimicrobial activity against P. acnes than clindamycin. CEN1HC-Br significantly reduced the expression of interleukin IL-12p40, IL-6, IL-1β, TNF-α and TLR2 in monocytes, but they were not influenced by clindamycin. Both CEN1HC-Br and Clindamycin attenuated P. acnes-induced ear swelling in rat along with pro-inflammatory cytokines IL-8, TNF-α, MMP-2 and TLR2. Our data demonstrates that CEN1HC-Br is bactericidal against P. acnes and that it has an anti-inflammatory effect on monocytes. The anti-inflammatory effect may partially occur through TLR2 down-regulation, triggering an innate immune response and the inhibition of pro-inflammatory cytokines.

Friends or Foes? Host defense (antimicrobial) peptides and proteins in human skin diseases

Host defense peptides/proteins (HDPs), also known as antimicrobial peptides/proteins (AMPs), are key molecules in the cutaneous innate immune system. AMPs/HDPs historically exhibit broad-spectrum killing activity against bacteria, enveloped viruses, fungi and several parasites. Recently, AMPs/HDPs were shown to have important biological functions, including inducing cell proliferation, migration and differentiation; regulating inflammatory responses; controlling the production of various cytokines/chemokines; promoting wound healing; and improving skin barrier function. Despite the fact that AMPs/HDPs protect our body, several studies have hypothesized that these molecules actively contribute to the pathogenesis of various skin diseases. For example, AMPs/HDPs play crucial roles in the pathological processes of psoriasis, atopic dermatitis, rosacea, acne vulgaris, systemic lupus erythematosus and systemic sclerosis. Thus, AMPs/HDPs may be a double-edged sword, promoting cutaneous immunity while simultaneously initiating the pathogenesis of some skin disorders. This review will describe the most common skin-derived AMPs/HDPs (defensins, cathelicidins, S100 proteins, ribonucleases and dermcidin) and discuss the biology and both the positive and negative aspects of these AMPs/HDPs in skin inflammatory/infectious diseases. Understanding the regulation, functions and mechanisms of AMPs/HDPs may offer new therapeutic opportunities in the treatment of various skin disorders.