miR-146a Inhibits Biofilm-Derived Cutibacterium acnes-Induced Inflammatory Reactions in Human Keratinocytes

Progress on Multiomics Research on Acne Vulgaris: A Literature Review

Acne vulgaris, a prevalent chronic inflammatory disease of the pilosebaceous unit, continues to present with a complex pathogenesis that is not fully understood. The advent of high-throughput sequencing technologies has revolutionized biomedical research, enabling the comprehensive use of multiomics analyses to study diseases with intricate mechanisms, such as acne. This review summarizes the progress in genomics, epigenomics, transcriptomics, proteomics, and metabolomics research on acne. By providing a comprehensive overview, we aim to enhance our understanding of acne pathogenesis and identify potential therapeutic targets that could inspire the prevention and treatment of acne.

Comprehensive microRNA analyses using vitreous humor of ocular sarcoidosis

PURPOSE

MicroRNAs (miRNAs) are non-coding RNAs which have attracted attention as biomarkers in a variety of diseases. However, extensive unbiased analysis of miRNA in vitreous humor of sarcoidosis patients has not been reported. In the present study, we comprehensively analyzed the dysregulated miRNAs in ocular sarcoidosis to search for potential biomarkers.

MATERIALS AND METHODS

This study included seven patients diagnosed with ocular sarcoidosis (five definite and two presumed). Five patients with unclassified uveitis and 24 with non-inflammatory diseases served as controls. MicroRNA expression levels in vitreous humor samples were measured by microarray, and differentially expressed miRNAs between sarcoidosis and other diseases were explored. Next, pathway enrichment analysis was performed to evaluate the functions of the dysregulated miRNAs, and machine learning was used to search for candidate biomarkers.

RESULTS

A total of 614 upregulated miRNAs and 8 downregulated miRNAs were detected in vitreous humor of patients with ocular sarcoidosis compared with patients with unclassified uveitis and non-inflammatory diseases. Some dysregulated miRNAs were involved in the TGF-β signaling pathway. Furthermore, we identified miR-764 as the best predictor for ocular sarcoidosis using Boruta selection.

CONCLUSIONS

In this study, comprehensive miRNA analysis of vitreous humor samples identified dysregulated miRNAs in ocular sarcoidosis. This study suggests new insights into molecular pathogenetic mechanisms of sarcoidosis and may provide useful information toward developing novel diagnostic biomarkers and therapeutic targets for sarcoidosis.

Epigenetic Regulatory Processes Involved in the Establishment and Maintenance of Skin Homeostasis-The Role of Microbiota

Epigenetic mechanisms are central to the regulation of all biological processes. This manuscript reviews the current understanding of diverse epigenetic modifications and their role in the establishment and maintenance of normal skin functions. In healthy skin, these mechanisms allow for the precise control of gene expression, facilitating the dynamic balance between cell proliferation and differentiation necessary for effective barrier function. Furthermore, as the skin ages, alterations in epigenetic marks can lead to impaired regenerative capacity and increased susceptibility to environmental stressors. The interaction between skin microbiota and epigenetic regulation will also be explored, highlighting how microbial communities can influence skin health by modulating the host gene expression. Future research should focus on the development of targeted interventions to promote skin development, resilience, and longevity, even in an ever-changing environment. This underscores the need for integrative approaches to study these complex regulatory networks.

Autocrine IL-8 Contributes to Propionibacterium Acnes-induced Proliferation and Differentiation of HaCaT Cells via AKT/FOXO1/ Autophagy

OBJECTIVE

Proprionibacterium acnes (P. acnes)-induced inflammatory responses, proliferation and differentiation of keratinocytes contribute to the progression of acne vulgaris (AV). P. acnes was found to enhance the production of interleukin-8 (IL-8) by keratinocytes. This study aimed to investigate the role of IL-8 in P. acnes-induced proliferation and differentiation of keratinocytes and the underlying mechanism.

METHODS

The P. acnes-stimulated HaCaT cell (a human keratinocyte cell line) model was established. Western blotting and immunofluorescence were performed to detect the expression of the IL-8 receptors C-X-C motif chemokine receptor 1 (CXCR1) and C-X-C motif chemokine receptor 2 (CXCR2) on HaCaT cells. Cell counting kit-8 (CCK-8) assay, 5-ethynyl-20-deoxyuridine (EdU) assay and Western blotting were performed to examine the effects of IL-8/CXCR2 axis on the proliferation and differentiation of HaCaT cells treated with P. acnes, the IL-8 neutralizing antibody, the CXCR2 antagonist (SB225002), or the CXCR1/CXCR2 antagonist (G31P). Western blotting, nuclear and cytoplasmic separation, CCK-8 assay, and EdU assay were employed to determine the downstream pathway of CXCR2 after P. acnes-stimulated HaCaT cells were treated with the CXCR2 antagonist, the protein kinase B (AKT) antagonist (AZD5363), or the constitutively active forkhead box O1 (FOXO1) mutant. Finally, autophagy markers were measured in HaCaT cells following the transfection of the FOXO1 mutant or treatment with the autophagy inhibitor 3-methyladenine (3-MA).

RESULTS

The expression levels of CXCR1 and CXCR2 were significantly increased on the membrane of HaCaT cells following P. acnes stimulation. The IL-8/CXCR2 axis predominantly promoted the proliferation and differentiation of P. acnes-induced HaCaT cells by activating AKT/FOXO1/autophagy signaling. In brief, IL-8 bound to its receptor CXCR2 on the membrane of keratinocytes to activate the AKT/FOXO1 axis. Subsequently, phosphorylated FOXO1 facilitated autophagy to promote the proliferation and differentiation of P. acnes-induced keratinocytes.

CONCLUSION

This study demonstrated the novel autocrine effect of IL-8 on the proliferation and differentiation of P. acnes-induced keratinocytes, suggesting a potential therapeutic target for AV.

A microRNA focus on acne

Acne (syn. acne vulgaris) is a common inflammatory skin disorder associated with puberty and adolescence. The disease is characterized by comedoneous lesions, papules, pustules, and nodules that are mostly found on the face. These lesions are caused by intricate interactions between the pilosebaceous unit and the Cutibacterium acnes (C. acnes) bacteria. Unhealthy acne and its aftereffects, like pigment changes and scarring, have a detrimental impact on one's quality of life. Recent years have seen a sharp increase in the approval of nucleic acid therapies (NATs), such as antisense oligonucleotides and short-interfering RNA medications, for rare diseases for which there are few or no effective treatments. These developments suggest that NATs may be useful in acne treatment plans down the road, as do clinical trials for microRNA (miRNA) modulation in skin contexts. We highlight promising miRNA targets for anti-acne therapy in this review. We outline the pathophysiology of acne in brief and emphasize the functions of C. acnes. Next, we concentrate on the distinct impacts of biofilm and planktonic C. acnes on a Toll-like receptor 2 axis that spans miR-146a-5p, which was recently discovered. Before discussing the potential contributions of miR-21-5p, miR-233-3p, and miR-150-5p to inflammatory axes in acne, we evaluate miR-146a-5p in sebocytes. Finally, we address patient involvement in miRNA-related acne research and translational perspectives.

The m6A reader HNRNPC promotes glioma progression by enhancing the stability of IRAK1 mRNA through the MAPK pathway

Glioma is the most common and aggressive type of primary malignant brain tumor. The N6-methyladenosine (m6A) modification widely exists in eukaryotic cells and plays an important role in the occurrence and development of human tumors. However, the function and mechanism of heterogeneous nuclear ribonucleoprotein C (HNRNPC), an RNA-binding protein and m6A reader in gliomas remains to be comprehensively and extensively explored. Herein, we found that HNRNPC mRNA and protein overexpression were associated with a poor prognosis for patients with gliomas, based on the data from TCGA, the CGGA, and the TMAs. Biologically, HNRNPC knockdown markedly repressed malignant phenotypes of glioma in vitro and in vivo, whereas ectopic HNRNPC expression had the opposite effect. Integrative RNA sequencing and MeRIP sequencing analyses identified interleukin-1 receptor-associated kinase 1 (IRAK1) as a downstream target of HNRNPC. The glioma public datasets and tissue microarrays (TMAs) data indicated that IRAK1 overexpression was associated with poor prognosis, and IRAK1 knockdown significantly repressed malignant biological behavior in vitro. Mechanistically, HNRNPC maintains the mRNA stability of IRAK1 in an m6A-dependent manner, resulting in activation of the mitogen-activated protein kinase (MAPK) signaling pathway, which was necessary for the malignant behavior of glioma. Our findings demonstrate the HNRNPC-IRAK1-MAPK axis as a crucial carcinogenic factor for glioma and the novel underlying mechanism of IRAK1 upregulation, which provides a rationale for therapeutically targeting epitranscriptomic modulators in glioma.

Utilizing the photodynamic properties of curcumin to disrupt biofilms in Cutibacterium acnes: A promising approach for treating acne

BACKGROUND

The treatment of acne vulgaris is often challenging due to the antibiotic resistance frequently observed in Cutibacterium acnes (C.acnes), a prevalent bacterium linked to this condition.

OBJECTIVE

The objective of this research was to examine the impact of curcumin photodynamic therapy (PDT) on the survival of C.acnes and activity of biofilms produced by this microorganism.

METHODS

Following the Clinical and Laboratory Standards Institute (CLSI) guidelines, we assessed the drug sensitivity of 25 clinical C.acnes strains to five antibiotics (erythromycin, clindamycin, tetracycline, doxycycline, minocycline) and curcumin by implementing the broth microdilution technique. In addition, we established C.acnes biofilms in a laboratory setting and subjected them to curcumin-PDT(curcumin combined with blue light of 180 J/cm2). Afterwards, we evaluated their viability using the XTT assay and observed them using confocal laser scanning microscopy.

RESULTS

The result revealed varying resistance rates among the tested antibiotics and curcumin, with erythromycin, clindamycin, tetracycline, doxycycline, minocycline, and curcumin exhibiting resistance rates of 72 %, 44 %, 36 %, 28 %, 0 %, and 100 %, respectively. In the curcumin-PDT inhibition tests against four representative antibiotic-resistant strains, it was found that the survival rate of all strains of planktonic C. acnes was reduced, and the higher the concentration of curcumin, the lower the survival rate. Furthermore, in the biofilm inhibition tests, the vitality and three-dimensional structure of the biofilms were disrupted, and the inhibitory effect became more significant with higher concentrations of curcumin.

CONCLUSION

The results emphasize the possibility of using curcumin PDT as an alternative approach for the treatment of C.acnes, especially in instances of antibiotic-resistant variations and infections related to biofilms.

Hsa_circ_0105040 promotes Cutbacterium acnes biofilm induced inflammation via sponge miR-146a in human keratinocyte

Acne is a chronic inflammatory skin disease, and the pathogenesis of acne induced by Cutibacterium acnes (C.acnes) is not well understood. Recently, circular RNAs (circRNAs) have attracted much attention because of its involvement in various diseases. However, the mechanisms by which circRNAs regulated acne have rarely been reported. We identified several differentially expressed circRNAs by sequencing patient-derived acne tissues. Among them, hsa_circ_0105040 was determined to be low expressed in acne tissues and localized in the cytoplasm of human primary keratinocytes. We established a C.acnes biofilms model of acne in vitro and showed that hsa_circ_0105040 promoted inflammation via MAPK and NF-κB pathway. Mechanistically, hsa_circ_0105040 could directly bind to miR-146a and inhibit the expression of miR-146a. Moreover, hsa_circ_0105040 promoted the expression of IRAK1 and TRAF6 by sponging miR-146a, thereby elevating the level of inflammation in acne. Collectively, our data suggested that hsa_circ_0105040- miR-146a -IRAK1/TRAF6 axis was involved in regulating the inflammatory response in acne, which provided a potential therapeutic target for acne and a novel insight into the pathogenesis of inflammatory acne.

Identification of differentially methylated genes for severe acne by genome-wide DNA methylation and gene expression analysis

Severe acne is a chronic inflammatory skin condition that is affected by both genetic and environmental factors. DNA methylation is associated with a variety of inflammatory skin diseases, but its role in severe acne is unclear. In this study, we conducted a two-stage epigenome correlation study using 88 blood samples to identify disease-related differential methylation sites. We found close associations between the DNA methylation at 23 differentially methylated sites (DMSs) and severe acne, including PDGFD, ARHGEF10, etc. Further analysis revealed that differentially methylated genes (PARP8 and MAPKAPK2) were also expressed differently between severe acne and health control groups. These findings lead us to speculation that epigenetic mechanisms may play an important role in the pathogenesis of severe acne.

The updates and implications of cutaneous microbiota in acne

Acne is a chronic inflammatory skin disorder that profoundly impacts the quality of life of patients worldwide. While it is predominantly observed in adolescents, it can affect individuals across all age groups. Acne pathogenesis is believed to be a result of various endogenous and exogenous factors, but the precise mechanisms remain elusive. Recent studies suggest that dysbiosis of the skin microbiota significantly contributes to acne development. Specifically, Cutibacterium acnes, the dominant resident bacterial species implicated in acne, plays a critical role in disease progression. Various treatments, including topical benzoyl peroxide, systemic antibiotics, and photodynamic therapy, have demonstrated beneficial effects on the skin microbiota composition in acne patients. Of particular interest is the therapeutic potential of probiotics in acne, given its direct influence on the skin microbiota. This review summarizes the alterations in skin microbiota associated with acne, provides insight into its pathogenic role in acne, and emphasizes the potential of therapeutic interventions aimed at restoring microbial homeostasis for acne management.

Analysis of differentially expressed microRNAs in bovine mammary epithelial cells treated with lipoteichoic acid

Mastitis is one of the most common diseases of dairy cattle and can be caused by physical stress, chemicals and microbial infection. Staphylococcus aureus is the most common pathogens that induce mastitis in dairy cattle. In this study, bovine mammary epithelial cells (BMECs) were treated either with lipoteichoic acid (LTA, 30 µg/ml) or 1 × phosphate-buffer saline (PBS, control) and RNA-Seq was applied to explore the effect of LTA on the expression microRNAs (miRNAs) in BMECs. Compared to the control group, 43 miRNAs were significantly up-regulated and eight miRNAs were significantly down-regulated. Additionally, 724 genes were significantly up-regulated and 13 genes were significantly down-regulated in LTA group relative to the control group. Bta-miR-196a, bta-miR-2285aj-5p, bta-miR-143, bta-miR-2433, bta-miR-2284f and bta-miR-2368-3p were selected from 51 differentially expressed miRNAs and are discussed in this manuscript. Target gene prediction revealed that the target genes of these six miRNAs were all differentially expressed, including MT1E, SPDYA, FGL1, TLR2, PAPOLG, ZDHHC17 and SMC4. Subsequently, the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the target genes with differentially expressed miRNAs were enriched in mitogen-activated protein kinase (MAPK) signalling pathway, rheumatoid arthritis and cancer. Therefore, the results of this study provided new evidences for the molecular mechanism of LTA-induced mastitis, which may provide new targets for the diagnosis and treatment of mastitis in dairy cattle.

Low curcumin concentrations combined with blue light inhibits cutibacterium acnes biofilm-induced inflammatory response through suppressing MAPK and NF-κB in keratinocytes

BACKGROUND

Curcumin has been employed as a photosensitizer agent during photodynamic therapy (PDT). Cutibacterium acnes (C. acnes) can cause an inflammatory response in human keratinocytes; however, no research has been conducted to determine whether curcumin and its photodynamic properties can prevent this inflammatory reaction.

OBJECTIVE

We hypothesized that curcumin may control the C. acnes biofilm-induced inflammatory response in keratinocytes, either alone or in combination with blue light photodynamic therapy.

METHODS

Following C. acnes biofilm stimulation, human primary keratinocytes were treated with 20 μM curcumin solution alone or 5 μM curcumin with combined blue light irradiation. The amount of secreted protein was measured using an ELISA kit. The expression levels of Toll-like receptor 2 (TLR2) and its downstream proteins were determined using western blot.

RESULTS

Treatment with 20 μM curcumin, but not 5 μM curcumin, reduced the inflammatory response to C. acnes biofilms in keratinocytes by blocking the TLR2/MAPK/NF-κB pathway. Interestingly, 5 μM curcumin combined with blue light also reduced the C. acnes biofilm-induced inflammation indicated above by blocking the TLR2/MAPK/NF-κB pathway.

CONCLUSION

Curcumin alone, in sufficient concentrations, or low-concentration curcumin with blue light had anti-inflammatory activity on keratinocytes stimulated by C. acnes biofilms through inhibition of MAPK and NF-κB signaling pathways by downregulating TLR2 expression.

Anti-Inflammatory microRNAs for Treating Inflammatory Skin Diseases

Skin inflammation occurs due to immune dysregulation because of internal disorders, infections, and allergic reactions. The inflammation of the skin is a major sign of chronic autoimmune inflammatory diseases, such as psoriasis, atopic dermatitis (AD), and lupus erythematosus. Although there are many therapies for treating these cutaneous inflammation diseases, their recurrence rates are high due to incomplete resolution. MicroRNA (miRNA) plays a critical role in skin inflammation by regulating the expression of protein-coding genes at the posttranscriptional level during pathogenesis and homeostasis maintenance. Some miRNAs possess anti-inflammatory features, which are beneficial for mitigating the inflammatory response. miRNAs that are reduced in inflammatory skin diseases can be supplied transiently using miRNA mimics and agomir. miRNA-based therapies that can target multiple genes in a given pathway are potential candidates for the treatment of skin inflammation. This review article offers an overview of the function of miRNA in skin inflammation regulation, with a focus on psoriasis, AD, and cutaneous wounds. Some bioactive molecules can target and modulate miRNAs to achieve the objective of inflammation suppression. This review also reports the anti-inflammatory efficacy of these molecules through modulating miRNA expression. The main limitations of miRNA-based therapies are rapid biodegradation and poor skin and cell penetration. Consideration was given to improving these drawbacks using the approaches of cell-penetrating peptides (CPPs), nanocarriers, exosomes, and low-frequency ultrasound. A formulation design for successful miRNA delivery into skin and target cells is also described in this review. The possible use of miRNAs as biomarkers and therapeutic modalities could open a novel opportunity for the diagnosis and treatment of inflammation-associated skin diseases.

Anti-Inflammatory and Anti-Acne Effects of Hamamelis virginiana Bark in Human Keratinocytes

Cutibacterium acnes (C. acnes) is recognized as one of the main triggers of the cutaneous inflammatory response in acne vulgaris, a chronic skin disorder with a multifactorial origin. Witch hazel (Hamamelis virginiana L.) is a plant widely used for skin inflammatory conditions, with some preliminary anti-inflammatory evidence on the skin, but lacking data on acne conditions. This study aimed to evaluate the effect of a glycolic extract from Hamamelis virginiana bark (HVE) versus C. acnes-induced inflammation in human keratinocytes (HaCaT). Phytochemical investigations of HVE identified hamamelitannin (HT) and proanthocyanidins as the most abundant compounds (respectively, 0.29% and 0.30% w/w_extract). HVE inhibited C. acnes-induced IL-6 release (IC₅₀: 136.90 μg/mL), by partially impairing NF-κB activation; however, no antibacterial or antibiofilm activities were found. In addition, HVE showed greater anti-inflammatory activity when TNF-α was used as a proinflammatory stimulus (IC₅₀ of 38.93 μg/mL for IL-8 release), partially acting by antioxidant mechanisms, as shown for VEGF inhibition. The effects of HVE are primarily based on the proanthocyanidin content, as HT was found inactive on all the parameters tested. These results suggest further investigations of HVE in other inflammatory-based skin diseases.

Suppression of Cutibacterium acnes-Mediated Inflammatory Reactions by Fibroblast Growth Factor 21 in Skin

Cutibacterium acnes (C. acnes) is a common commensal bacterium that is closely associated with the pathogenesis of acne. Fibroblast growth factor 21 (FGF21), as a favorable regulator of glucose and lipid metabolism and insulin sensitivity, was recently shown to exert anti-inflammatory effects. The role and mechanism of FGF21 in the inflammatory reactions induced by C. acnes, however, have not been determined. The present study shows that FGF21 in the dermis inhibits epidermal C. acnes-induced inflammation in a paracrine manner while it functions on the epidermal layer through a receptor complex consisting of FGF receptor 1 (FGFR1) and β-Klotho (KLB). The effects of FGF21 in heat-killed C. acnes-induced HaCaT cells and living C. acnes-injected mouse ears were examined. In the presence of C. acnes, FGF21 largely counteracted the activation of Toll-like receptor 2 (TLR2), the downstream nuclear factor-κB (NF-κB), and mitogen-activated protein kinase (MAPK) signaling pathways induced by C. acnes. FGF21 also significantly reduced the expression of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α. Taken together, these findings indicate that FGF21 suppresses C. acnes-induced inflammation and might be used clinically in the management and treatment of acne.

MicroRNA Cross-Involvement in Acne Vulgaris and Hidradenitis Suppurativa: A Literature Review

Acne Vulgaris (AV) and Hidradenitis suppurativa (HS) are common chronic inflammatory skin conditions that affect the follicular units that often coexist or are involved in differential diagnoses. Inflammation in both these diseases may result from shared pathways, which may partially explain their frequent coexistence. MicroRNAs (miRNAs) are a class of endogenous, short, non-protein coding, gene-silencing or promoting RNAs that may promote various inflammatory diseases. This narrative review investigates the current knowledge regarding miRNAs and their link to AV and HS. The aim is to examine the role of these molecules in the pathogenesis of AV and HS and to identify possible common miRNAs that could explain the similar characteristics of these two diseases. Five miRNA (miR-155 miR-223-, miR-21, and miRNA-146a) levels were found to be altered in both HS and AV. These miRNAs are related to pathogenetic aspects common to both pathologies, such as the regulation of the innate immune response, regulation of the Th1/Th17 axis, and fibrosis processes that induce scar formation. This review provides a starting point for further studies aimed at investigating the role of miRNAs in AV and HS for their possible use as diagnostic-therapeutic targets.

Spleen tyrosine kinase regulates keratinocyte inflammasome activation and skin inflammation induced by UVB irradiation

UVB can induce inflammatory responses contributing to diverse skin damage. UVB-triggered inflammasome activation of human keratinocytes underlies UVB-induced skin sunburn reaction. Pleiotropic functions of spleen tyrosine kinase (Syk) have rendered it as a potential therapeutic target. In immunocytes, Syk modulates immunoreceptor signaling and NLRP3 inflammasome activation. In skin, Syk mediates EGFR signaling, regulates keratinocyte differentiation and is involved in inflammatory disorders. However, roles of Syk in UVB-induced inflammasome activation in keratinocytes remain elusive. We investigated roles of keratinocyte Syk in UVB-triggered photo-responses. Primary normal human epidermal keratinocytes (NHEKs) isolated from skin were used. Syk knockdown or Syk inhibitor R406 was applied to investigate functions of keratinocyte Syk in UVB photobiology. The possible in vivo role of Syk was evaluated by checking UVB-induced skin damage in R406-treated mice. UVB was able to induce Syk phosphorylation in NHEKs that could be regulated by reactive oxygen species (ROS) generation and EGFR. Syk knockdown or Syk inhibitor (R406) treatment reduced UVB-triggered apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC) crosslinking, procaspase-1 cleavage, active IL-1β formation, and gasdermin D activation, indicating roles of Syk in UVB-triggered inflammasome activation in keratinocytes. UVB-induced production of IL-8, TNF-α, ROS, and phosphorylation of JNK and p38 were attenuated after Syk knockdown or inhibition. R406 ameliorated UVB-induced mouse skin damage, including erythema and transepidermal water loss (TEWL). Thus, Syk participated in UVB-induced inflammasome activation and inflammatory response in vitro and in vivo, suggesting potential photo-protective effects of Syk inhibition in UVB-induced skin inflammation.

Synergistic antibacterial combination of Sapindoside A and B changes the fatty acid compositions and membrane properties of Cutibacterium acnes

Sapindus saponins extracted from S. mukorossi have been reported to exert antibacterial activities against skin pathogenic bacteria, but their antibacterial mechanism is still at an exploratory stage. The objective of this study was to explore the synergistic antibacterial mechanism of the combination of two Sapindus saponins, namely Sapindoside A and B (SAB) against Cutibacterium acnes (C. acnes) 6919 via targeting the fatty acid compositions and membrane properties. After exposure to SAB, C. acnes cells increased the cell surface hydrophobicity and reduced the cell membrane fluidity by changing the composition of membrane fatty acids. In the fatty acid compositions, the content of two main fatty acids 12-methyl-tetradecanoic acid (isoC15:0) and octadecanoic acid (C18:0) reduced and improved respectively with the addition of SAB, and fatty acid biosynthesis-related genes were significantly down-regulated (p < 0.05). Further, molecular docking demonstrated that SAB interacted with FabD, which is an essential enzyme for bacterial type II fatty acid synthesis, via hydrogen bonds and hydrophobic interactions. In the above results, the contribution of SA to SAB was greater than that of SB. In summary, the results revealed that SAB changed the fatty acid compositions of C. acnes, further disrupting the cell membrane properties, and SA played a major role, suggesting that SAB could be a natural antiacne additive against C. acnes-associated infections.

miR-146a modulates TLR1/2 and 4 induced inflammation and links it with proliferation and lipid production via the indirect regulation of GNG7 in human SZ95 sebocytes

Activation of Toll-like receptors (TLR) 1/2 and 4 are central in inducing inflammation in sebocytes by regulating the expression of protein coding mRNAs, however the microRNA (miRNA) profile in response to TLR activation and thus the possible role of miRNAs in modulating sebocyte functions has not been elucidated. In this work we identified miR-146a to have the highest induction in the TLR1/2 and 4 activated SZ95 sebocytes and found that its increased levels led to the down-regulation of IL-8 secretion, decreased the chemoattractant potential and stimulated the proliferation of sebocytes. Assessing the gene expression profile of SZ95 sebocytes treated with a miR-146a inhibitor, the induction of GNG7 was one of the highest, while when cells were treated with a miR-146a mimic, the expression of GNG7 was down-regulated. These findings correlated with our in situ hybridization results, that compared with control, miR-146a showed an increased, while GNG7 a decreased expression in sebaceous glands of acne samples. Further studies revealed, that when inhibiting the levels of GNG7 in SZ95 sebocytes, cells increased their lipid content and decreased their proliferation. Our findings suggest, that miR-146a could be a potential player in acne pathogenesis by regulating inflammation, inducing proliferation and, through the indirect down-regulation of GNG7, promoting the lipid production of sebocytes.

Knockdown of H19 Inhibits the Pathogenesis of Acne Vulgaris by Targeting the miR-196a/TLR2/NF-κB Axis

Acne vulgaris (AV) is a chronic inflammatory disease of the pilosebaceous unit, and Propionibacterium acnes (P. acnes) has been implicated in acne inflammation. Numerous studies have shown that non-coding RNAs play important roles in regulating the pathophysiological processes of acne. In addition, the first imprinted long non-coding RNA (lncRNA) identified, H19, plays a critical role in inflammatory disease. However, the expression and role of H19 in AV remain unclear. In this study, we investigated the effects of H19 in keratinocytes and explored the regulatory mechanisms underlying these effects. H19 was upregulated in keratinocytes treated with P. acnes in a concentration-dependent manner. The phosphorylated forms of the nuclear factor (NF)-κB-related proteins IκBα (p-IκBα) and p65 (p-P65) were significantly upregulated after P. acnes treatment. Additionally, secretion of the proinflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-8 was upregulated in a concentration-dependent manner. Knockdown of H19 inhibited the expression of p-IκBα and p-P65 as well as the secretion of TNF-α, IL-6, and IL-8 in keratinocytes treated with P. acnes. Moreover, H19 was found to exert its proinflammatory effects by activating NF-κB. H19, which was localized mainly in the cytoplasm of keratinocytes, facilitated Toll-like receptor 2 (TLR2) expression by acting as a miR-196a sponge. H19 thus promoted the activation of NF-κB and the secretion of inflammatory cytokines through the miR-196a/TLR2 axis. These findings provide novel insight into the pathogenesis of AV.

A Janus-Faced Bacterium: Host-Beneficial and -Detrimental Roles of Cutibacterium acnes

The bacterial species Cutibacterium acnes (formerly known as Propionibacterium acnes) is tightly associated with humans. It is the dominant bacterium in sebaceous regions of the human skin, where it preferentially colonizes the pilosebaceous unit. Multiple strains of C. acnes that belong to phylogenetically distinct types can co-exist. In this review we summarize and discuss the current knowledge of C. acnes regarding bacterial properties and traits that allow host colonization and play major roles in host-bacterium interactions and also regarding the host responses that C. acnes can trigger. These responses can have beneficial or detrimental consequences for the host. In the first part of the review, we highlight and critically review disease associations of C. acnes, in particular acne vulgaris, implant-associated infections and native infections. Here, we also analyse the current evidence for a direct or indirect role of a C. acnes-related dysbiosis in disease development or progression, i.e., reduced C. acnes strain diversity and/or the predominance of a certain phylotype. In the second part of the review, we highlight historical and recent findings demonstrating beneficial aspects of colonization by C. acnes such as colonization resistance, immune system interactions, and oxidant protection, and discuss the molecular mechanisms behind these effects. This new insight led to efforts in skin microbiota manipulation, such as the use of C. acnes strains as probiotic options to treat skin disorders.

Apatinib-Induced Hand-Foot Skin Reaction in Chinese Patients With Liver Cancer

Apatinib, an anti-tumor drug selectively targeting VEGFR2 (Vascular Endothelia Growth Factor Recpetor-2), has been proven effective in Chinese patients with liver cancer. Generally, treatment with apatinib achieves 16.1% of the overall objective remission rate (ORR) and 55.83% of the disease control rate (DCR) in Chinese patients with liver cancer. However, the prevalence of apatinib-induced hand–foot skin reaction (AI-HFSR) is noticeably high. The incidence of AI-HFSR is about 50.5%, of which Grades 1/2 and 3 are 38.8 and 11.6%, respectively. In addition, potential molecular mechanisms underlying the development of AI-HFSR are poorly understood and urgently needed to be investigated histologically. In this review, we summarize and review the current efficacy of apatinib and the prevalence of AI-HFSR in Chinese patients with liver cancer. Besides, we postulate the potential mechanisms underlying the development of AI-HFSR and discuss the optimal clinical management for this unwanted cutaneous side effect.

Elucidating the immune infiltration in acne and its comparison with rosacea by integrated bioinformatics analysis

BACKGROUND

Acne vulgaris and rosacea are common inflammatory complications of the skin, both characterized by abnormal infiltration of immune cells. The two diseases can be differentiated based on characteristic profile of the immune cell infiltrates at the periphery of disease lesions. In addition, dysregulated infiltration of immune cells not only occur in the acne lesions but also in non-lesional areas of patients with the disease, thus characterizing the immune infiltration in these sites can further enhance our understanding on the pathogenesis of acne.

METHODS

Five microarray data-sets (GSE108110, GSE53795, GSE65914, GSE14905 and GSE78097) were downloaded from Gene Expression Omnibus. After removing the batch effects and normalizing the data, we applied the CIBERSORT algorithm combined with signature matrix LM22, to describe 22 types of immune cells' infiltration in acne less than 48 hour (H) old, in comparation with non-lesional skin of acne patients, healthy skin and rosacea (including erythematotelangiectatic rosacea, papulopustular rosacea and phymatous rosacea) and we compared gene expression of Th1 and Th17-related molecules in acne, rosacea and healthy control.

RESULTS

Compared with the non-lesional skin of acne patients, healthy individuals and rosacea patients, there is a significant increase in infiltration of neutrophils, monocytes and activated mast cells around the acne lesions, less than 48 H after their development. Contrarily, few naive CD4+ T cells, plasma cells, memory B cells and resting mast cells infiltrate acne sites compared to the aforementioned groups of individuals. Moreover, the infiltration of Regulatory T cells (Tregs) in acne lesions is substantially lower, relative to non-lesional sites of acne patients and skin of healthy individuals. In addition, non-lesional sites of acne patients exhibit lower infiltration of activated memory CD4+ T cells, plasma cells, memory B cells, M0 macrophages, neutrophils, resting mast cells but higher infiltration of Tregs and resting dendritic cells relative to skin of healthy individuals. Intriguingly, we found that among the 3 rosacea subtypes, the immune infiltration profile of papulopustular rosacea is the closest to that of acne lesions. In addition, through gene expression analysis of acne, rosacea and skin tissues of healthy individuals, we found a higher infiltration of Th1 and Th17 cells in acne lesions, relative to non-lesional skin areas of acne patients.

CONCLUSIONS

Our study provides new insights into the inflammatory pathogenesis of acne, and the difference between acne and rosacea, which helps in differentiating the two diseases. Our findings also guide on appropriate target therapy of the immune cell infiltrates in the two disease conditions.

Cutibacterium acnes as an Opportunistic Pathogen: An Update of Its Virulence-Associated Factors

Cutibacterium acnes is a member of the skin microbiota found predominantly in regions rich in sebaceous glands. It is involved in maintaining healthy skin and has long been considered a commensal bacterium. Its involvement in various infections has led to its emergence as an opportunist pathogen. Interactions between C. acnes and the human host, including the human skin microbiota, promote the selection of C. acnes strains capable of producing several virulence factors that increase inflammatory capability. This pathogenic property may be related to many infectious mechanisms, such as an ability to form biofilms and the expression of putative virulence factors capable of triggering host immune responses or enabling C. acnes to adapt to its environment. During the past decade, many studies have identified and characterized several putative virulence factors potentially involved in the pathogenicity of this bacterium. These virulence factors are involved in bacterial attachment to target cells, polysaccharide-based biofilm synthesis, molecular structures mediating inflammation, and the enzymatic degradation of host tissues. C. acnes, like other skin-associated bacteria, can colonize various ecological niches other than skin. It produces several proteins or glycoproteins that could be considered to be active virulence factors, enabling the bacterium to adapt to the lipophilic environment of the pilosebaceous unit of the skin, but also to the various organs it colonizes. In this review, we summarize current knowledge concerning characterized C. acnes virulence factors and their possible implication in the pathogenicity of C. acnes.

MicroRNA-490-3p inhibits inflammatory responses in LPS-induced acute lung injury of neonatal rats by suppressing the IRAK1/TRAF6 pathway

Acute lung injury (ALI) is a main reason for neonatal death. Studying the molecular mechanism behind neonatal ALI is critical for the development of therapeutic strategies. The present study explored microRNA (miR)-490-3p-mediated regulatory effects on lipopolysaccharide (LPS)-induced neonatal ALI. Initially, LPS (10 mg/kg body weight) was injected to 3-8 day old neonatal SD rats to induce ALI, and LPS (100 ng/ml) was used to treat lung epithelial cells to construct an ALI model in vitro. Next, miR-490-3p, pro-inflammatory factors (that included IL-1β, IL-6 and TNFα), interleukin 1 receptor associated kinase 1 (IRAK1) and TNF receptor associated factor 6 (TRAF6) mRNA expression levels in lung tissues and epithelial cells were assessed via reverse transcription-quantitative PCR. In addition, miR-490-3p mimics were adopted to construct its overexpressed cell model, and Cell Counting Kit-8 and BrdU assays were conducted to assess cell viability. Furthermore, the miR-490-3p target, IRAK was predicted by bioinformatics analysis and verified via Dual-luciferase reporter gene assay. The results revealed that miR-490-3p was markedly downregulated in an LPS-induced rat ALI model, while IL-1β, IL-6, TNFα, IRAK1 and TRAF6 were all upregulated and negatively correlated with miR-490-3p expression. Moreover, overexpressed miR-490-3p significantly inhibited LPS-induced lung epithelial cell injury and inflammatory response. Mechanistically, miR-490-3p targeted and attenuated IRAK1 expression, which thus inactivated the LPS-mediated TRAF6/NF-κB pathway. Overall, the present study indicated that miR-490-3p overexpression significantly inhibited LPS-induced ALI and inflammatory responses by restricting the IRAK1/TRAF6 pathway.