Application Of Imiquimod Research Articles

LncRNA MEG3 suppresses PI3K/AKT/mTOR signalling pathway to enhance autophagy and inhibit inflammation in TNF-α-treated keratinocytes and psoriatic mice.

Psoriasis is a common chronic inflammatory skin disorder that causes patches of thick red skin and silvery scales and affects 1-3% of the population, which reduces patient's quality of life. Understanding the pathogenesis of psoriasis is crucial for developing novel therapeutic strategies. HaCaT and NHEK cells were treated with TNF-α in vitro. A mouse model of psoriasis was established by topical imiquimod application on back skin. LncRNA MEG3 was cloned into the pcDNA3.1 vector and transfected in TNF-α-treated HaCaT and NHEK cells to overexpress its expression. Liposome-encapsulated pcDNA3.1-MEG3 was injected into imiquimod-treated mice via tail vein. RT-qPCR and western blot assays were used to examine the expression of lncRNA MEG3, IL-6, IL-8, IFN-γ, IL-1β, LC3, Beclin 1, p62, p-p65, p65, NLRP3, p-PI3K, PI3K, p-AKT, AKT, p-mTOR, mTOR respectively. The secretion of IL-6, IL-8, IFN-γ and IL-1β was determined using ELISA assay. Immunofluorescence and immunohistochemistry methods were performed for analyzing the expression of LC3 and NLRP3 in cells and skin tissues respectively. LY294002 was used to block the PI3K/AKT/mTOR signalling. MTT assay was applied to test the toxicity of LY294002 to HaCaT and NHEK cells. LncRNA MEG3 expression levels were downregulated in TNF-α-treated HaCaT and NHEK cells and skin tissues of psoriatic mice model. TNF-α treatment enhanced inflammation and suppressed autophagy in HaCaT and NHEK cells, which were largely reversed by overexpression of lncRNA MEG3. Autophagy puncta and NLRP3 inflammasome assembly showed the same patterns with the expression of inflammation and autophagy markers in TNF-α-treated HaCaT and NHEK cells with or without lncRNA MEG3 overexpression. TNF-α-induced activation of the PI3K/AKT/mTOR signalling was abolished by lncRNA MEG3 overexpression in HaCaT and NHEK cells. Blocking the PI3K/AKT/mTOR signalling inhibited TNF-α-induced inflammation and restored autophagy level in TNF-α-treated HaCaT and NHEK cells. Overexpression of lncRNA MEG3 suppressed inflammation, promoted autophagy and inhibited the activation of the PI3K/AKT/mTOR signalling in a mouse model of psoriasis. LncRNA MEG3 facilitates autophagy and suppresses inflammation in TNF-α-treated keratinocytes and psoriatic mice, which is dependent on the PI3K/AKT/mTOR signalling pathway. Our study enhances the understanding of psoriasis and provides potential therapeutic targets for psoriasis.

Methodological shortcomings in the reports of the imiquimod psoriatic model.

Psoriasis is a chronic inflammatory skin disease affecting about 2-3% of the worldwide population. More of the knowledge of psoriasis is due to the in vitro and in vivo models tried to reproduce the disease and to know the mechanisms of pathogenesis, as well as to develop new therapies. One of the more simple, cheap and more used models is the imiquimod model based on the application of imiquimod in the depilated skin of mice. Several studies describing the methodology employed to develop an animal disease model does not present all the details about the model more especially related to the use of one sex or another and other methodological aspects that are relevant for researchers and to consider the accuracy of the study. In this review, we have selected 100 papers published in the last five years using the imiquimod psoriatic model recording different data such as animal, strain, sex, dose of imiquimod, area of administration, housing information, anaesthesia/euthanasia information, number of animals per group and control details among others. Our results revealed several methodological shortcomings in the models of imiquimod to study psoriasis namely sex bias and discrepancies in dose applied or time of imiquimod application among others. As long as these discrepancies exist in animal methodologies, there will be a poor translation from animal studies to clinical applications in dermatology and in other areas.

Acute induction of psoriasis-like skin inflammation disturbes vascular tone and provokes a rapid blood pressure response in mice

Abstract Background Psoriasis is the most common chronic skin disease worldwide. Furthermore, it is an independent cardiovascular risk factor. Several genetic and inducible murine models reproduce specific aspects of the human disease. In mice genetically overexpressing IL-17A in keratinocytes or dendritic cells, we coulod show both aspects of the disease: cutaneous hallmarks and the vascular phenotype. The most popular inducible model consists of topical application of Imiquimod (IMQ), a Toll-like receptor 7/8 agonist. In this model, cardiovascular aspects have not been studied yet. Therefore, we examined vascular and hemodynamic effects in this most popular murine psoriasis model. Methods C57BL/6J mice were treated with 5% IMQ or sham cream. During treatment, we measured bodyweight, skin thickness and skin water loss. After 10 days, aortic relaxation studies were performed. For assessment of vascular inflammation, inflammatory cell infiltration into the aortic tissue was investigated by flow cytometric analysis. To record physical activity, blood pressure and heart rate, carotid catheters were implanted two weeks before treatment with IMQ. Blood pressure and heart rate were continuously recorded by receiver platforms. Results IMQ treatment resulted in severe skin inflammation and induced a skin barrier defect resulting in a 7-fold increase of transcutaneous water loss (from 11±6 ml/m2h to 77±30 ml/m2h). Physical activity decreased more than 50% after d1 of treatment and normalized at d7. Telemetric recording revealed a reflex tachycardia at 1d of IMQ-application (from 492±21 bpm to 524±20 bpm) followed by a significant reduction of heart rate for the next two days (456±18bpm). Systolic blood pressure showed a similar trend: after a fast increase (from 120±13 mmHg to 127±18 mmHg), blood pressure dropped below baseline at d2/3 with a subsequent recovery. We could display a highly significant positive correlation between blood pressure and heart rate during the treatment (R=0.6; p≤0.0001). Aortas from animals after 10d of IMQ-treatment showed an increased infiltration of CD45+ and CD11b+ inflammatory cells but no change of responsiveness to endothelium dependent and independent vasodilators in organ chamber studies. Conclusion Skin treatment with IMQ had severe implications on the hemodynamic system: After an initial peak of heart rate and blood pressure, mice showed significantly lower values for two days with a subsequent full recovery. Moreover, bodyweight and physical activity were significantly altered during treatment. Our data indicate that skin inflammation and inflammatory skin barrier disruption by IMQ forces a compensatory whole-body response. 10 days of IMQ-treatment resulted in vascular inflammation without mediating vascular dysfunction. In summary, we could reveal that IMQ-induced psoriasis, as the most popular murine psoriasis model worldwide, has extensive effects on the cardiovascular system. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Boehringer Ingelheim Foundation “Novel and neglected cardiovascular risk factors: molecular mechanisms and therapeutic implications”German Federal Ministry for Education and Research (BMBF EDU-V24)

Imiquimod induced vitiligo-like lesions-A consequence of modified melanocyte function.

IntroductionImiquimod plays an important role in the management of condyloma and premalignant lesions. Successively, an increase of hypopigmented lesions following imiquimod application has been reported. However, the mechanisms of imiquimod on melanocytes remain unclear. This study was designed to assess the effect of Imiquimod on the functions of melanocytes in vitro.MethodsPrimary cultured melanocytes were isolated from normal control skin tissue. After incubation with imiquimod for 48 h in vitro, cell viability was analyzed by cell counting kit‐8 assay. Apoptosis was detected using the Annexin V‐fluorescein‐5‐isothiocyanate flow cytometry assay. Melanin content and tyrosinase activity in melanocytes were measured by colorimetric method and the modified dopachrome method. The production of inflammatory cytokine interleukin 8 (IL‐8), IL‐6, and soluble ICAM‐1 (soluble Intercellular Adhesion Molecule‐1[sICAM‐1]) in melanocytes were measured by enzyme‐linked immunosorbent assay (ELISA). Toll‐like receptor 7 (TLR7), toll‐like receptor 9 (TLR9) protein, and autophagy‐related proteins microtubule‐associated protein 1A/1B‐light chain 3 (LC3‐II), p62, mechanistic target of rapamycin (mTOR), and Atg5 were assessed using western blot analysis.ResultsImiquimod significantly inhibited the activity of tyrosinase activity and decreased melanin content in melanocytes and significantly increased apoptosis and IL‐6, IL‐8, and sICAM‐1 production in melanocytes. Moreover, the expression of TLR7 and TLR9 proteins were significantly increased, and the expression of mTOR, p62 protein were markedly decreased, but the expression of LC3II/I and Atg5 protein were significantly increased in melanocytes after incubating with imiquimod.ConclusionsThis study shows that imiquimod directly inhibits melanogenesis and increases melanocyte apoptosis rates. These effects combined with the upregulation of TLR7 and TLR9 together with increased autophagy activity and inflammatory cytokines production, might be the main reasons leading to hypopigmented lesions after imiquimod application.

201 Decreased efficacy of regulatory T cells in the absence of HCA2 is due to overexpression of IL-6

The suppressive activity of regulatory T cells (Treg) in the absence of the G-protein coupled receptor 109a (HCA2, Puma) is significantly reduced as demonstrated in the contact hypersensitivity model. Here we asked whether the same phenomenon can be observed in other skin inflammatory models. To address this issue, we used the psoriasis like imiquimod (IMQ)-induced skin inflammation model in mice. Application of IMQ on the skin of HCA2- knock out (KO) or wild type (WT) animals resulted in psoriasiform skin (skin thickening, erythema, scales).

CME Dermatology 24/Answers: Porokeratosis

CME Dermatology 24/Answers: Porokeratosis Abstract. Porokeratoses are a heterogeneous group of cornification disorders with the characteristic histological feature of the cornoid lamellae in the area of the marginal ridge. It is a rare but characteristic disease that occurs primarily in adulthood. Men are slightly more likely to be affected. The etiopathogenesis that leads to the transformation of the keratinocytes remains unclear; associations with genetic mutations and trigger factors such as UV rays and immunosuppression were observed. Due to the risk of malignant degeneration, consistent sun protection and regular clinical controls should take place. Cryotherapy, ablative laser therapy, curettage, photodynamic therapy or topical application of fluorouracil (5-FU), imiquimod and retinoids can be used to treat itchy, painful or cosmetically disturbing porokeratoses, depending on the location and severity.

Repurposing the anthelmintic praziquantel to treat psoriasis.

The anthelmintic drug praziquantel has been used as a standard treatment for schistosomiasis for over 40 years. This study aimed to repurpose praziquantel to treat psoriasis. Psoriasis-like skin inflammation was induced in mice (C57 and Balb/C) by topical application of imiquimod or intradermal injection of recombinant IL-23. Praziquantel was either orally or topically administered during the psoriasis induction period. Mice treated with either oral or topical praziquantel exhibited markedly improved psoriasiform skin symptoms when compared with control mice, as judged by disease severity score, epidermal thickening, inflammatory cell infiltration and spleen size. Flow cytometric analysis of infiltrating immune cells from mouse skin displayed reduced infiltration of Th17 cells. In vitro experiments revealed that praziquantel inhibited STAT3 phosphorylation and RORγt expression in splenic CD4+ T-cells. Praziquantel also decreased STAT3 phosphorylation in HEK-A/F cells. Down-regulation of STAT3 phosphorylation in these cells accounts for the decreased number of Th17 cells and keratinocytes. These results provide the first preclinical evidence that praziquantel may effectively treat psoriasis, and suggest that praziquantel alleviates symptoms in mice by inhibiting STAT3 phosphorylation, thereby suppressing Th17 immune responses.

CME Dermatology 24: Porokeratosis

CME Dermatology 24: Porokeratosis Abstract. Porokeratoses are a heterogeneous group of cornification disorders with the characteristic histological feature of the cornoid lamellae in the area of the marginal ridge. It is a rare but characteristic disease that occurs primarily in adulthood. Men are slightly more likely to be affected. The etiopathogenesis that leads to the transformation of the keratinocytes remains unclear; associations with genetic mutations and trigger factors such as UV rays and immunosuppression were observed. Due to the risk of malignant degeneration, consistent sun protection and regular clinical controls should take place. Cryotherapy, ablative laser therapy, curettage, photodynamic therapy or topical application of fluorouracil (5-FU), imiquimod and retinoids can be used to treat itchy, painful or cosmetically disturbing porokeratoses, depending on the location and severity.

Curcumin alleviates imiquimod-induced psoriasis in progranulin-knockout mice

Recent advances have revealed that progranulin (PGRN) is related to the aetiology of psoriasis. Moreover, curcumin, a compound derived from turmeric, has been proposed as a potential therapeutic approach in psoriasis-like dermatitis, but it is still unclear whether curcumin affects the development of psoriasis-like skin lesions under PGRN-deficient conditions. Therefore, in this study, we developed a mouse model of psoriatic skin lesions using topical application of imiquimod (IMQ) in both wild type and PGRN-knockout mice to test this possibility. We observed that PGRN deficiency not only increased proinflammatory cytokine IL-17A levels and aggravated psoriasis-like damaged appearance and epidermal thickening but also directly mediated changes in keratinocyte proliferation (Krt 14, cyclinD1 and c-Myc) and differentiation (Krt 10 and Filaggrin) associated gene expression following IMQ challenge, compared to those in the control group. Furthermore, curcumin treatment (50 mg/kg and 200 mg/kg, intragastrically) for 21 consecutive days suppressed the IMQ exposure-induced increase in PGRN expression. Importantly, curcumin treatment significantly alleviated the PGRN deficiency-induced exacerbation of psoriatic appearance, histological features and keratinocyte proliferation after IMQ exposure. In summary, these results demonstrate the direct regulation of PGRN in keratinocyte proliferation and differentiation in psoriatic lesions and demonstrate the protective effect of curcumin on PGRN deficiency-induced psoriatic skin lesion exacerbation.

IFN-κ Is a Rheostat for Development of Psoriasiform Inflammation

Psoriasis is a common, inflammatory autoimmune skin disease. Early detection of an IFN-1 signature occurs in many psoriasis lesions, but the source of IFN production remains debated. IFN-κ is an important source of IFN-1 production in the epidermis. We identified a correlation between IFN-regulated and psoriasis-associated genes in human lesional skin. We thus wanted to explore the effects of IFN-κ in psoriasis using the well-characterized imiquimod psoriasis model. Three mouse strains aged 10 weeks were used: wild-type C57Bl/6, C57Bl/6 that overexpress Ifnk in the epidermis (i.e., transgenic), and total body Ifnk-/- (i.e., knockout) strain. Psoriasis was induced by topical application of imiquimod on both ears for 8 consecutive days. Notably, the severity of skin lesions and inflammatory cell infiltration was more significantly increased in transgenic than in wild-type than in knockout mice. Gene expression analysis identified greater upregulation of Mxa, Il1b, Tnfa, Il6, Il12, Il23, Il17, and Ifng in transgenic compared to wild-type compared to knockout mice after imiquimod treatment. Furthermore, imiquimod increased CD8+ and CD4+ T-cell infiltration more in transgenic than in wild-type than in knockout mice. In summary, we identified IFN-κ as a rheostat for initiation of psoriasiform inflammation. This suggests that targeting IFN-1s early in the disease may be an effective way of controlling psoriatic inflammation.

HPV-16 E6/E7 DNA tattoo vaccination using genetically optimized vaccines elicit clinical and immunological responses in patients with usual vulvar intraepithelial neoplasia (uVIN): a phase I/II clinical trial

BackgroundUsual vulvar intraepithelial neoplasia (uVIN) is a premalignancy caused by persistent infection with high-risk types of human papillomavirus (HPV), mainly type 16. Even though different treatment modalities are available (eg,...

Long-term efficacy and safety of imiquimod 5% and fluorouracil 1% creams in medical monotherapy of complex eyelid basal cell carcinomas.

To study the long-term efficacy and safety of local application of imiquimod 5% and fluorouracil 1% creams in complex eyelid basal cell carcinomas (BCCs). A retrospective, non-comparative study in biopsy-proven, complex (involving canthi or >50% of eyelid length) eyelid BCC patients who were medically unfit for surgical procedures. All patients were medically treated with either of the creams using fixed-dose regimens for a minimum of 3 months. All received oral vitamin C 500 mg QID for 3 months as an adjunct for collagen healing. A minimum of "post-treatment" follow-up of 12 months was observed. Of total 30 patients, imiquimod 5% and fluorouracil 1% were used in 16 and 14 patients, respectively. The mean age of our patients was 70.5 years. The co-morbidities included - severe coronary artery disease using blood-thinners (n = 19), poorly controlled diabetes (n = 12), poorly controlled hypertension (n = 6), on nebulization (n = 3), and tuberculosis with pulmonary fibrosis (n = 2). Complete clinical tumor resolution was noted in 10 and 8 patients over 12 and 16.5 weeks, respectively, in imiquimod and fluorouracil groups. Periocular skin erythema, chemical conjunctivitis, and skin depigmentation were seen in all the patients of imiquimod group. On the other hand, the local side-effect profile in fluorouracil patients was limited. The medical treatment of complex eyelid BCC is a useful alternative to surgery in the elderly with significant co-morbidities. It provides a promising long-term relief with a tolerable side-effect profile. A prospective, randomized, double-blinded trial would provide stronger evidence for the efficacy of these drugs.

Seasonal trivalent inactivated influenza vaccine with topical imiquimod in immunocompromised patients: A randomized controlled trial

BackgroundThe effect of the Toll-like receptor 7 agonist imiquimod before intradermal (ID) or intramuscular (IM) influenza vaccine in immunocompromised hosts is unknown. MethodsIn this open-label randomized controlled trial, kidney transplant recipients (KT) and people living with HIV (PLWH) were randomized to receive IM trivalent inactivated influenza vaccine alone (IM), IM vaccine after topical imiquimod (imi+IM) or ID vaccine after topical imiquimod (imi+ID). Immunogenicity was assessed by hemagglutination inhibition assay. The primary outcome was vaccine response, defined as seroconversion to at least one viral strain at day 21. ResultsSeventy patients (35 KT and 35 PLWH) received IM (24), imi+IM (22), or imi+ID (24) vaccine. Vaccine response was 61% (14/23) with IM, 59% (13/22) with imi+IM, and 65% (15/23) with imi+ID vaccine (P = 0.909). Vaccine response was associated with HIV infection compared to kidney transplantation (adjusted-OR 3.74, 95% CI 1.25 – 11.23, P = 0.019), but not with imiquimod application nor ID injection. After vaccination, seroprotection to all viral strains was 79% (19/24) with IM, 68% (15/22) with imi+IM, and 70% (16/23) with imi+ID (P = 0.657). We did not observe any vaccine-related severe adverse event. ConclusionsIn our study, topical imiquimod did not improve the immunogenicity of influenza vaccine in KT and in PLWH.

A Sensitization-Free Dimethyl Fumarate Prodrug, Isosorbide Di-(Methyl Fumarate), Provides a Topical Treatment Candidate for Psoriasis

Dimethyl fumarate (DMF) is an effective oral treatment for psoriasis administered in Europe for nearly 60 years. However, its potential has been limited by contact dermatitis that prohibits topical application. This paper characterizes a DMF derivative, isosorbide DMF (IDMF), which was designed to have antipsoriatic effects without skin-sensitizing properties. We show that IDMF exhibits neither genotoxicity nor radiation sensitivity in skin fibroblasts and is nonirritating and nonsensitizing in animal models (rat, rabbit, guinea pig). Microarray analysis of cytokine-stimulated keratinocytes showed that IDMF represses the expression of genes specifically upregulated in psoriatic skin lesions but not those of other skin diseases. IDMF also downregulated genes induced by IL-17A and TNF in keratinocytes as well as predicted targets of NF-κB and the antidifferentiation noncoding RNA (i.e., ANCR). IDMF further stimulated the transcription of oxidative stress response genes (NQO1, GPX2, GSR) with stronger NRF2/ARE activation compared to DMF. Finally, IDMF reduced erythema and scaling while repressing the expression of immune response genes in psoriasiform lesions elicited by topical application of imiquimod in mice. These data show that IDMF exhibits antipsoriatic activity that is similar or improved compared with that exhibited by DMF, without the harsh skin-sensitizing effects that have prevented topical delivery of the parent molecule.

Anoctamin1 Induces Hyperproliferation of HaCaT Keratinocytes and Triggers Imiquimod-Induced Psoriasis-Like Skin Injury in Mice.

Psoriasis, a long-lasting and multifactorial skin disease, is related to comorbidities such as metabolic disease, depression, and psoriatic arthritis. Psoriasis occurs due to a variety of factors including keratinocyte hyperproliferation, inflammation, and abnormal differentiation. Proinflammatory cytokines upregulated by increased activation of keratinocytes and immune cells in the skin trigger progression of psoriasis. This study aimed to investigate the effects of anoctamin1 (ANO1) on psoriasis development in vitro and in vivo. We analyzed the proliferation of HaCaT keratinocytes and ANO1-related ERK and AKT signaling pathways after ANO1 inhibitor (T16Ainh-A01 and Ani9) treatment and knock-down of ANO1. Furthermore, after applying imiquimod (IMQ) cream or coapplying IMQ cream and T16Ainh-A01 on mouse ears, we not only observed psoriatic symptoms, including ear thickening, but also quantified the effects of treatment on ERK and AKT signaling-involved proteins and proinflammatory cytokines. Inhibition of ANO1 attenuated the proliferation of HaCaT cells and induced reduction of pERK1/2. Coapplication of IMQ and T16Ainh-A01 on ears of mice reduced not only symptoms of IMQ-induced psoriasis such as thickening and erythema, but also expression of ANO1 and pERK1/2 compared to that of application of IMQ alone. In addition, the expression levels of IL-17A, IL-17F, IL-22, IL-23, IL-6, IL-1β, and TNF-α increased after applying IMQ and were significantly reduced by coapplying IMQ and T16Ainh-A01. These results aid in understanding the underlying mechanisms of ANO1 in epidermal layer keratinocyte hyperproliferation and suggest the potential of ANO1 as a target to treat psoriasis.

Central Nervous System-Endogenous TLR7 and TLR9 Induce Different Immune Responses and Effects on Experimental Autoimmune Encephalomyelitis.

Innate receptors, including Toll like receptors (TLRs), are implicated in pathogenesis of CNS inflammatory diseases such as multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). TLR response to pathogens or endogenous signals includes production of immunoregulatory mediators. One of these, interferon (IFN)β, a Type I IFN, plays a protective role in MS and EAE. We have previously shown that intrathecal administration of selected TLR ligands induced IFNβ and infiltration of blood-derived myeloid cells into the central nervous system (CNS), and suppressed EAE in mice. We have now extended these studies to evaluate a potential therapeutic role for CNS-endogenous TLR7 and TLR9. Intrathecal application of Imiquimod (TLR7 ligand) or CpG oligonucleotide (TLR9 ligand) into CNS of otherwise unmanipulated mice induced IFNβ expression, with greater magnitude in response to CpG. CD45+ cells in the meninges were identified as source of IFNβ. Intrathecal CpG induced infiltration of monocytes, neutrophils, CD4+ T cells and NK cells whereas Imiquimod did not recruit blood-derived CD45+ cells. CpG, but not Imiquimod, had a beneficial effect on EAE, when given at time of disease onset. This therapeutic effect of CpG on EAE was not seen in mice lacking the Type I IFN receptor. In mice with EAE treated with CpG, the proportion of monocytes was significantly increased in the CNS. Infiltrating cells were predominantly localized to spinal cord meninges and demyelination was significantly reduced compared to non-treated mice with EAE. Our findings show that TLR7 and TLR9 signaling induce distinct inflammatory responses in the CNS with different outcome in EAE and point to recruitment of blood-derived cells and IFNβ induction as possible mechanistic links between TLR9 stimulation and amelioration of EAE. The protective role of TLR9 signaling in the CNS may have application in treatment of diseases such as MS.

Supplemental Leuconostoc mesenteroides strain NTM048 attenuates imiquimod-induced psoriasis in mice.

Psoriasis, a chronic inflammatory skin disease, is associated with altered intestinal microbiota. Here, we investigated the ameliorative effect of Leuconostoc mesenteroides NTM048 strain in imiquimod (IMQ)-induced psoriasis in mice. Mice were administered NTM048 for 21 days alongside the topical application of IMQ on the dorsal skin for 6 consecutive days. IMQ induced psoriatic symptoms such as erythema and scaling and also upregulated interleukin (IL)-17, a key effector cytokine of psoriasis, in the skin. Supplemental NTM048 suppressed these abnormalities, increased the levels of plasma deoxycholic acid (DCA), a secondary bile acid and altered the faecal microbiota composition, as indicated by the increased abundance of Akkermansia and decreased abundance of Staphylococcus and Streptococcus. Notably, DCA treatment of murine splenocytes reduced IL-17 production. The NTM048-mediated reduction of psoriasis was shown to involve the downregulation of IL-17 in mouse skin, which was possibly associated with the plasma DCA derived from intestinal microbiota. Our findings propose not only a novel approach for psoriasis reduction but also a crosstalk between the skin and intestine in psoriasis.

Abnormal\ufeff composition of microbiota in the gut and skin of imiquimod-treated mice

Psoriasis is a chronic, inflammatory skin disease. Although the precise etiology of psoriasis remains unclear, gut–microbiota axis might play a role in the pathogenesis of the disease. Here we investigated whether the composition of microbiota in the intestine and skin is altered in the imiquimod (IMQ)-treated mouse model of psoriasis. Topical application of IMQ to back skin caused significant changes in the composition of microbiota in the intestine and skin of IMQ-treated mice compared to control mice. The LEfSe algorithm identified the species Staphylococcus lentus as potential skin microbial marker for IMQ group. Furthermore, there were correlations for several microbes between the intestine and skin, suggesting a role of skin–gut–microbiota in IMQ-treated mice. Levels of succinic acid and lactic acid in feces from IMQ-treated mice were significantly higher than control mice. Moreover, the predictive functional analysis of the microbiota in the intestine and skin showed that IMQ caused alterations in several KEGG pathways. In conclusion, the current data indicated that topical application with IMQ to skin alters the composition of the microbiota in the gut and skin of host. It is likely that skin–gut microbiota axis plays a role in pathogenesis of psoriasis.

Role of Benzo (a) Pyrene in exacerbating the skin inflammation in Psoriatic mouse model

Emerging evidence suggests that environmental chemicals, mainly the organic pollutants like polycyclic hydrocarbons (PAHs), could contribute to the pathophysiology of several chronic inflammatory skin diseases like atopic dermatitis and psoriasis. Benzo[a]pyrene (BaP), the main source of atmospheric PAH, is generated mainly from cigarette smoke, wood-burning and automobile exhaust. Several reports suggest that the inflammatory effects exerted by BaP could be mediated via the aryl hydrocarbon receptor (AhR) signaling pathway. AhR ligands exert the antioxidative pathway triggered by injury and inflammation, and could activate the nuclear factor-erythroid 2-related factor-2 (NRF2). Pathology of Psoriasis includes acanthosis, hyperkeratosis, and parakeratosis of the epidermis, invasion of neutrophils into the epidermis as well as an inflammatory response. BaP exposure could exacerbate the inflammatory pathology of psoriasis; however, comprehensive studies to assess this and decipher the molecular mechanisms involved, remain elusive. In the present study, we evaluated the effect of BaP on mouse skin psoriasis. For generating psoriasis, the dorsal skin of C57BL/6 male and female mice was shaved and exposed to 62.5mg of 5% imiquimod (IMQ) cream once daily for five days. To study the effect of BaP in the exacerbation of IMQ- induced psoriasis, mice were exposed to 64µg BaP in 50µl acetone for five days before IMQ application [BaP+IMQ] or for five days together with the IMQ [(BaP+IMQ)] application. Histopathological analysis showed that BaP exposure together with IMQ exacerbated IMQ-induced psoriatic inflammatory lesions including the skin bi-fold thickness, epidermal and dermal thickness, acanthosis, hyperkeratosis, dermal fibrosis and neutrophil infiltration. Our ongoing molecular studies show that the exposure of BaP in IMQ-induced psoriatic mice elevated the expression of inflammatory markers like COX-2, MMP9, myeloperoxidase (maker of neutrophil infiltration) and NRF2. Increased expression of these markers suggests that BaP could activate inflammatory pathways and further elevate the skin inflammation in IMQ induced psoriasis. Further mechanistic studies are underway to evaluate the pathways involved in BaP-induced exacerbation of psoriasis.

Improved imiquimod-induced psoriasis like dermatitis using microneedles in mice

Psoriasis is a chronic inflammatory skin disease, in which the key features are epidermis hyperplasia, hyper-keratinization, leading to low drug absorption. As an approach of transdermal drug delivery, the microneedle (MN) has received increasing attentions for its painless penetration and efficient administration. In this study, we fabricated polylactic acid polymer MNs with hot-press method and established a psoriasis-like skin inflammation model in ear and dorsal skin of mice by topical application of imiquimod (IMQ). The dynamometer and insertion test of MNs into parafilm and skin of mice were done, revealing that the MNs have sufficient mechanical properties to insert parafilm and skin of mice. The two methods (apply calcipotriol (CAL) directly and pre-treat with MNs before applying CAL) were used to treat psoriasis and observe the skin inflammation, including skin and epidermal thickening, spleen weight gain, inflammatory cell infiltration, and expression of inflammatory cytokines of TNF-α. Both methods have a therapeutic effect and the effect of the MN pretreatment group is better. In addition, there are statistical differences between the two groups (P < 0.05). These features indicated that the MNs may be promising in future clinical applications in improving the imiquimod-induced psoriasis like dermatitis.