Suppressive Effect of Two Cucurbitane-Type Triterpenoids from Momordica charantia on Cutibacterium acnes-Induced Inflammatory Responses in Human THP-1 Monocytic Cell and Mouse Models

Octahydroindolizine alkaloid Homocrepidine A from Dendrobium crepidatum attenuate P. acnes-induced inflammatory in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Dendrobium crepidatum Lindl. ex Paxton is a perennial epiphyte of Dendrobium genus, distributed in southern China, and utilized as the traditional Chinese medicine "Shihu" in Yunnan Province. Due to its heat-clearing and detoxicating properties, it is formulated as the "XiaoCuoWan" as recorded in the China Pharmacopoeia, and specially used to treat chronic skin inflammatory diseases, such as acne.

AIM OF THE STUDY

This research aimed to estimate impact of the octahydroindoline alkaloid Homocrepidine A (HCA), isolated from D. crepidatum, on acne inflammation using both human THP-1 cells and mouse models. Furthermore, the potential anti-inflammatory mechanism of HCA has been analyzed through molecular biology methods and computer simulation.

MATERIALS AND METHODS

THP-1 cells and mouse models induced by live Propionibacterium acnes (P. acnes) were employed to evaluate the anti-inflammatory properties of crude extract of D. crepidatum (DCE) and HCA. ELISA was utilized to detect the release of inflammatory cytokines in both cellular and murine ear tissues. RNAseq was used to screen the pathways associated with HCA-mediated inflammatory inhibition, while Western blot, RT-qPCR, and immunofluorescence were utilized to detect the expression of relevant proteins. Additionally, molecular docking simulations and cellular thermal shift assays were employed to confirm the target of HCA.

RESULTS

Our research shows that DCE and HCA can effectively alleviate acne inflammation. HCA inhibits TLR2 expression by interacting with amino acid residues in the TIR domain of hTLR2, including Pro-681, Asn-688, Trp-684, and Ile-685. Moreover, HCA disrupts inflammatory signal transduction mediated by MAPK and NF-κB pathways through MyD88-dependent pathway. Additionally, HCA treatment facilitates Nrf2 nuclear translocation and upregulates HO-1 expression, thereby inhibiting NLRP3 inflammasomes activation. In vivo experiments further revealed that HCA markedly attenuated erythema and swelling caused by P. acnes in mice ears, while also decreasing the expression of pro-inflammatory cytokines IL-1β and IL-8.

CONCLUSIONS

Our research highlights the protective effects of D. crepidatum and its bioactive compound HCA against acne inflammation, marking the first exploration of its potential in this context. The discoveries indicate that HCA treatment may represent a promising functional approach for acne therapy.

Extraction methods, multiple biological activities, and related mechanisms of Momordica charantia polysaccharide: A review

Momordica Charantia Polysaccharide (MCP) is a key bioactive compound derived from bitter melon fruit. This review summarizes the advancements in MCP research, including extraction techniques, biological activities, and mechanisms. MCP can be extracted using various methods, and has demonstrated hypoglycemic, antioxidant, anti-inflammatory, and immunoregulatory effects. Research suggests that MCP may regulate metabolic enzymes, oxidative stress reactions, and inflammatory pathways. The review highlights the potential applications of MCP in areas such as anti-diabetes, antioxidant, anti-inflammatory, and immunoregulatory research. Future research should focus on elucidating the molecular mechanisms of MCP and optimizing extraction methods. This review provides a foundation for further research and utilization of MCP.

Lipid Metabolism Reprogramming of Immune Cells in Acne: An Update

Acne vulgaris is one of the most widespread skin conditions and the main reason for visiting a dermatologist. Inflammatory response and abnormal infiltrations of immune cells are the main pathogenesis of acne. The increased lipid is the prerequisite for the acne, and the perturbation of lipid composition and content is consistent with the severity of acne. Furthermore, the increased lipid production not only contributes to the occurrence and development of acne, but also sensitizes the function of immune cells. The lipid metabolic dysfunction aggravates the severity of local tissue and provides pro-inflammatory-cytokine cues, which indicates the crucial roles of lipid metabolism on immune cells. Recent advances have demonstrated the lipid metabolism reprogramming of various immune cells in acne lesion. The abnormal lipid accumulation, lipolysis, and fatty acid oxidation lead to the activation and differentiation of immune cells, which promotes the pro-inflammatory cytokines production. Thus, this review discusses the emerging role of lipid metabolism reprogramming of immune cells in the progress of acne and aims to constitute food for others' projects involved in acne research.

Cytotoxic and Anti-Inflammatory Triterpenoids in the Vines and Leaves of Momordica charantia

The vines and leaves of Momordica charantia L. are used as herbal medicines to treat inflammation-related disorders. However, their safety profile remains uncharacterized, and the constituents in their extracts that exert anti-inflammatory and adverse effects remain unclear. This study isolated the characteristic cucurbitane-type triterpenoid species in the vines and leaves of M. charantia L. and analyzed their cytotoxicity, anti-inflammatory effects, and underlying mechanisms. Four structurally related triterpenoids—momordicines I, II, IV, and (23E) 3β,7β,25-trihydroxycucurbita-5,23-dien-19-al (TCD)—were isolated from the triterpenoid-rich fractions of extracts from the vines and leaves of M. charantia. Momordicine I was cytotoxic on normal cells, momordicine II exerted milder cytotoxicity, and momordicine IV and TCD had no obvious adverse effects on cell growth. TCD had anti-inflammatory activity both in vivo and in vitro. In lipopolysaccharide-stimulated RAW 264.7 cells, TCD inhibited the inhibitor kappa B kinase/nuclear factor-κB pathway and enhanced the expression of nuclear factor erythroid 2-related factor 2, heme oxygenase-1, and glutamate-cysteine ligase modifier subunit through the extracellular signal-regulated kinase1/2 and p38. Thus, the vines and leaves of M. charantia should be used with caution. An extraction protocol that can enrich TCD but remove momordicine I would likely enhance the safety of the extract.

Characterization of Weissella viridescens UCO-SMC3 as a Potential Probiotic for the Skin: Its Beneficial Role in the Pathogenesis of Acne Vulgaris

Previously, we isolated lactic acid bacteria from the slime of the garden snail Helix aspersa Müller and selected Weissella viridescens UCO-SMC3 because of its ability to inhibit in vitro the growth of the skin-associated pathogen Cutibacterium acnes. The present study aimed to characterize the antimicrobial and immunomodulatory properties of W. viridescens UCO-SMC3 and to demonstrate its beneficial effect in the treatment of acne vulgaris. Our in vitro studies showed that the UCO-SMC3 strain resists adverse gastrointestinal conditions, inhibits the growth of clinical isolates of C. acnes, and reduces the adhesion of the pathogen to keratinocytes. Furthermore, in vivo studies in a mice model of C. acnes infection demonstrated that W. viridescens UCO-SMC3 beneficially modulates the immune response against the skin pathogen. Both the oral and topical administration of the UCO-SCM3 strain was capable of reducing the replication of C. acnes in skin lesions and beneficially modulating the inflammatory response. Of note, orally administered W. viridescens UCO-SMC3 induced more remarkable changes in the immune response to C. acnes than the topical treatment. However, the topical administration of W. viridescens UCO-SMC3 was more efficient than the oral treatment to reduce pathogen bacterial loads in the skin, and effects probably related to its ability to inhibit and antagonize the adhesion of C. acnes. Furthermore, a pilot study in acne volunteers demonstrated the capacity of a facial cream containing the UCO-SMC3 strain to reduce acne lesions. The results presented here encourage further mechanistic and clinical investigations to characterize W. viridescens UCO-SMC3 as a probiotic for acne vulgaris treatment.