Effect of a novel topical immunomodulator, S-28463, on keratinocyte cytokine gene expression and production

Evaluation of Clobetasol and Tacrolimus Treatments in an Imiquimod-Induced Psoriasis Rat Model

Psoriasis is a chronic inflammatory skin disorder characterized by keratinocyte hyperproliferation, inflammation, and aberrant differentiation. Imiquimod-induced psoriasis in rodent models has been widely used to study the pathogenesis of the disease and evaluate potential therapeutic interventions. In this study, we investigated the efficacy of two commonly used treatments, Clobetasol and Tacrolimus, in ameliorating psoriatic symptoms in an Imiquimod-induced psoriasis Wistar rat model. Interestingly, rat models are poorly evaluated in the literature despite rats displaying several advantages in evaluating pharmacological substances. Psoriasis-like skin lesions were induced by topical application of Imiquimod cream on shaved dorsal skin for seven consecutive days. Following induction, rats in the treatment groups received either a Clobetasol or Tacrolimus ointment once daily for one week, while the control group did not receive any application. Disease severity was assessed using clinical scoring, histological examination, and measurement of proinflammatory cytokine levels. Both Clobetasol and Tacrolimus treatments significantly reduced psoriatic lesion severity compared to the control group. Clinical scoring revealed a decrease in erythema, scaling, transepidermal water loss, and thickness of skin lesions in both treatment groups with a more marked effect with Clobetasol. Histological analysis demonstrated reduced epidermal hyperplasia in treated animals compared to controls. Furthermore, Clobetasol led to a significant reduction in the expression levels of the interleukin-17 (IL-17a and IL-17f) proinflammatory cytokines in lesioned skin. Overall, our findings demonstrated the therapeutic efficacy of both Clobetasol and, in a modest manner, Tacrolimus in attenuating Imiquimod-induced psoriasis-like symptoms in a rat model. These results support the clinical use of these agents in the management of psoriasis and mitigating psoriatic inflammation. They also provide insights into the use of rats as a relevant species for the Imiquimod-induced psoriasis model.

Diminution of microRNA-98 alleviates renal fibrosis in diabetic nephropathy by elevating Nedd4L and inactivating TGF-β/Smad2/3 pathway

MicroRNAs (miRNAs) have already been documented to function in diabetic nephropathy (DN), yet little research has focused on the role of miR-98 in this disease. Here, we discuss the mechanism of miR-98 on the renal fibrosis in DN. Recombinant adeno-associated virus carrying miR-98 inhibitor or Nedd4L overexpression plasmid was injected into DN modeled rats to explore their roles in DN. Renal tubular epithelial cell injury models (NRK-52E cells) were induced by high glucose (HG). HG-treated NRK-52E cells were transfected with miR-98 inhibitor or Nedd4L overexpression plasmid for further verification. MiR-98 was upregulated, Nedd4L was downregulated and TGF-β/Smad2/3 signaling was activated in kidney tissues of DN rats and HG-treated NRK-52E cells. miR-98 targeted Nedd4L mRNA 3'UTR. MiR-98 depletion and Nedd4L overexpression inactivated TGF-β/Smad2/3 signaling pathway, alleviated pathological damage and fibrosis, ameliorated inflammation, and depressed cell apoptosis of kidney tissues of DN rats. MiR-98 depletion and Nedd4L overexpression inactivated TGF-β/Smad2/3 signaling pathway, strengthened viability, and limited apoptosis of HG-treated renal tubular epithelial cells. Nedd4L overexpression reversed the effect of up-regulating miR-98 on DN rats and HG-treated renal tubular epithelial cells. Altogether, we find that miR-98 is upregulated in kidney tissues of DN rats, and miR-98 diminution and Nedd4L elevation attenuate renal fibrosis through inactivation of the TGF-β/Smad2/3 pathway, which provides a novel therapy for DN.

Baculovirus Utilizes Cholesterol Transporter NIEMANN-Pick C1 for Host Cell Entry

The dual roles of baculovirus for the control of natural insect populations as an insecticide, and as a tool for foreign gene expression and delivery, have called for a comprehensive understanding of the molecular mechanisms governing viral infection. Here, we demonstrate that the Bombyx mori Niemann-Pick C1 (BmNPC1) is essential for baculovirus infection in insect cells. Both pretreatment of B. mori embryonic cells (BmE) with NPC1 antagonists (imipramine or U18666A) and down-regulation of NPC1 expression resulted in a significant reduction in baculovirus BmNPV (B. mori nuclear polyhedrosis virus) infectivity. Disruption of BmNPC1 could decrease viral entry (2 hpi) rather than reduce the viral binding to the BmE cells. Furthermore, our results showed that NPC1 domain C binds directly and specifically to the viral glycoprotein GP64, which is responsible for both receptor binding and fusion. Antibody blocking assay also revealed that the domain C specific polyclonal antibody inhibited BmNPV infection, indicating that NPC1 domain C most likely plays a role during viral fusion in endosomal compartments. Our results, combined with previous studies identifying an essential role of human NPC1 (hNPC1) in filovirus infection, suggest that the glycoprotein of several enveloped viruses possess a shared strategy of exploiting host NPC1 proteins during virus intracellular entry events.

Resolvin D1 attenuates imiquimod-induced mice psoriasiform dermatitis through MAPKs and NF-κB pathways

BACKGROUND

Resolvin D1 (RvD1), a pro-resolution lipid mediator derived from docosahexaenoic acid (DHA), has been described to promote several kinds of inflammatory resolution. However, the effects and anti-inflammatory mechanisms of RvD1 on psoriasis have not been previously reported.

OBJECTIVE

The present study aimed to determine the protective effects and the underlying mechanisms of RvD1 on imiquimod (IMQ)-induced psoriasiform dermatitis.

METHODS

Mice were topically treated with IMQ to develop psoriasiform dermatitis on their shaved back, pretreated intraperitoneally (i.p.) with or without RvD1 or tert-butoxycarbonyl Met-Leu-Phe peptide (Boc), a lipoxin A4 (ALX) receptor antagonist. The severity was monitored and graded using a modified human scoring system, the Psoriasis Area and Severity Index (PASI), histopathology, and the signature cytokines of psoriasis (IL-23, IL-17, IL-22 and TNF-α). The mRNA and protein levels of inflammatory cytokines were quantified by quantitative real-time PCR (QRT-PCR) and ELISA. The expressions of signaling proteins MAPKs and NF-κB p65 were analyzed using western blotting. Electrophoretic mobility shift assay (EMSA) was used to check NF-κB p65 DNA binding activity.

RESULTS

Our study showed that RvD1 alleviated IMQ-induced psoriasiform dermatitis and improved skin pathological changes. RvD1 markedly inhibited IMQ-induced activation of ERK1/2, p38, JNK (c-Jun N-terminal protein kinase, a subfamily of MAPKs), and NF-κB. Furthermore, pretreatment with Boc, would not exacerbate skin inflammation of IMQ-induced mice, but significantly reversed the beneficial effects of RvD1 on IMQ-induced psoriasiform inflammation.

CONCLUSION

RvD1 can obviously improve skin inflammation in IMQ-induced mice psoriasiform dermatitis. The protective mechanisms might be related to its selective reaction with lipoxin A4 receptor/Formyl-peptide receptor 2 (ALX/FPR2), by downregulating relevant cytokines of the IL-23/IL-17 axis expression, the inhibition of MAPKs and NF-κB signaling transduction pathways. Thus, these results show that RvD1 could be a possible candidate for psoriasis therapy.

Modulation of the Contact Hypersensitivity Response by Æ-941 (Neovastat), a Novel Antiangiogenic Agent

Background:

Æ-941 (Neovastat) is an angiogenesis inhibitor noted to have antiinflammatory properties.

Objective:

We tested Neovastat in a contact hypersensitivity (CHS) model to determine the mechanism of action of its antiinflammatory effects.

Methods:

Neovastat was orally administered (200 mg/kg/day) during the sensitization and challenge phases of a murine CHS assay and inflammatory responses were measured. Subsequent assays were performed on mice treated with Neovastat or Cortisone (120 mg/kg/day, IP) and differential mRNA expression of several pro- and antiinflammatory cytokines was quantified using RT-PCR.

Results:

Neovastat decreased inflammation by 39% when administered during sensitization but did not alter the CHS response when given during the challenge phase. Neovastat significantly induced IL-10 expression in skin and skin-draining lymph nodes (49% and 45%, respectively) and decreased IFNγ expression in the lymph nodes (35%).

Conclusion:

Antiinflammatory effects of Neovastat observed in CHS could be linked to modulation of cytokines early in the sensitization phase.

Topical resiquimod protects against visceral infection with Leishmania infantum chagasi in mice

New prevention and treatment strategies are needed for visceral leishmaniasis, particularly ones that can be deployed simply and inexpensively in areas where leishmaniasis is endemic. Synthetic molecules that activate Toll-like receptor 7 and 8 (TLR7/8) pathways have previously been demonstrated to enhance protection against cutaneous leishmaniasis. We initially sought to determine whether the TLR7/8-activating molecule resiquimod might serve as an effective vaccine adjuvant targeting visceral leishmaniasis caused by infection with Leishmania infantum chagasi. Resiquimod was topically applied to the skin of mice either prior to or after systemic infection with L. infantum chagasi, and parasite burdens were assessed. Surprisingly, topical resiquimod application alone, in the absence of vaccination, conferred robust resistance to mice against future intravenous challenge with virulent L. infantum chagasi. This protection against L. infantum chagasi infection persisted as long as 8 weeks after the final topical resiquimod treatment. In addition, in mice with existing infections, therapeutic treatment with topical resiquimod led to significantly lower visceral parasite loads. Resiquimod increased trafficking of leukocytes, including B cells, CD4(+) and CD8(+) T cells, dendritic cells, macrophages, and granulocytes, in livers and spleens, which are the key target organs of visceralizing infection. We conclude that topical resiquimod leads to systemic immune modulation and confers durable protection against visceralizing L. infantum chagasi infection, in both prophylactic and therapeutic settings. These studies support continued studies of TLR-modulating agents to determine mechanisms of protection and also provide a rationale for translational development of a critically needed, novel class of topical, preventative, and therapeutic agents for these lethal infections.

Human in vitro skin organ culture as a model system for evaluating DNA repair

BACKGROUND

UV-exposures result in accumulation of genetic lesions that facilitate the development of skin cancer. Numerous pharmacologic agents are currently under development to both inhibit formation of DNA lesions and enhance repair. Drugs must be evaluated in vitro, currently performed in cell culture systems, before being tested on humans. Current systems do not account for the architecture and diverse cellularity of intact human skin.

OBJECTIVE

To establish a novel, functionally viable, and reproducible in vitro skin organ culture system for studying the effects of various pharmacologic agents on DNA repair.

METHODS

Human skin was obtained from neonatal foreskins. Intact skin punches derived from foreskins were cultured in vitro prior to exposure to UV-irradiation, and evaluated for DNA-damage using a DNA dot blot. Serial skin biopsies were obtained from patients with actinic keratoses treated with topical imiquimod. Expression of immune-stimulating and DNA repair genes was evaluated in ex vivo and in vitro samples.

RESULTS

DNA dot blots revealed active repair of UV induced lesions in our in vitro skin organ culture. The photo-protective effect of sunscreen was detected, while imiquimod treatment did not enhance DNA repair in vitro. The DNA repair molecules XPA and XPF were up-regulated in the skin of imiquimod treated patients with actinic keratoses and imiquimod treated bone marrow-derived cell lines, but not keratinocytes.

CONCLUSION

Our in vitro human skin organ culture model detected repair of UV-induced DNA lesions, and may be easily adapted to investigate various photo-protective drugs intended to prevent or treat skin cancer.

A comparison of the effects of topical treatment of calcipotriol, camptothecin, clobetasol and tazarotene on an imiquimod-induced psoriasis-like mouse model

The interleukin-23/interleukin 17A (IL-23/IL-17A) cytokine axis plays a critical role in the pathogenesis of psoriasis. In this study, we report the effects of topical calcipotriol, camptothecin, clobetasol and tazarotene on the treatment of imiquimod (IMQ)-induced psoriasis-like inflammation, the development of which is dependent on the IL-23/IL-17A axis. IMQ-induced epidermal hyperplasia and inflammation in the BALB/c mouse ear were significantly inhibited following clobetasol treatment but not calcipotriol, camptothecin or tazarotene treatments. Real-time polymerase chain reaction showed that the mRNA levels of IL-17A, IL-17F, IL-22, IL-1β, IL-6 and TNF-α in ear skin were significantly decreased by clobetasol. In addition, we observed that calcipotriol, camptothecin and tazarotene failed to show any inhibitory effects on the IL-23/IL-17A/IL-22 axis. We also found that clobetasol treatment inhibited the proliferation of γδ T cells and C-C chemokine receptor type 6 (CCR6) expression induced by IMQ. Calcipotriol, camptothecin and tazarotene not only failed to inhibit this proliferation but also enhanced retinoic acid-related orphan receptor γ (RORγ) expression in IMQ-induced psoriasis-like inflammation. In conclusion, we suggest that clobetasol induces the relief of IMQ-induced psoriasis-like inflammation in a mouse model but that calcipotriol, camptothecin and tazarotene cannot. Therefore, we suggest that more in-depth studies on pharmacological effects of tazarotene, camptothecin and calcipotriol should be carried out.

Roles of TLR7 in activation of NF-κB signaling of keratinocytes by imiquimod

Imiquimod is known to exert its effects through Toll-like receptor 7 (TLR7) and/or TLR8, resulting in expression of proinflammatory cytokines and chemokines. Keratinocytes have not been reported to constitutively express TLR7 and TLR8, and the action of imiquimod is thought to be mediated by the adenine receptor, not TLR7 or TLR8. In this study, we revealed the expression of TLR7 in keratinocytes after calcium-induced differentiation. After addition of calcium to cultured keratinocytes, the immunological responses induced by imiquimod, such as activation of NF-κB and induction of TNF-α and IL-8, were more rapid and stronger. In addition, imiquimod induced the expression TLR7, and acted synergistically with calcium to induce proinflammatory cytokines. We confirmed that the responses induced by imiquimod were significantly inhibited by microRNAs suppressing TLR7 expression. These results suggest that TLR7 expressed in keratinocytes play key roles in the activation of NF-κB signaling by imiquimod, and that their modulation in keratinocytes could provide therapeutic potential for many inflammatory skin diseases.

Curcumin inhibits imiquimod-induced psoriasis-like inflammation by inhibiting IL-1beta and IL-6 production in mice

Curcumin, a selective phosphorylase kinase inhibitor, is a naturally occurring phytochemical present in turmeric. Curcumin has been confirmed to have anti-inflammatory properties in addition to the ability to decrease the expression of pro-inflammatory cytokines in keratinocytes. The interleukin-23 (IL-23)/IL-17A cytokine axis plays a critical role in the pathogenesis of psoriasis. Here, we report that topical use of a curcumin gel formulation strongly inhibited imiquimod (IMQ)-induced psoriasis-like inflammation, the development of which was based on the IL-23/IL-17A axis. IMQ-induced epidermal hyperplasia and inflammation in BALB/c mouse ear was significantly inhibited following curcumin treatment. Real-time PCR showed that mRNA levels of IL-17A, IL-17F, IL-22, IL-1β, IL-6 and TNF-α cytokines were decreased significantly by curcumin in ear skin, an effect similar to that of clobetasol. In addition, we found that curcumin may enhance the proliferation of epidermis γδ T cells but inhibit dermal γδ T cell proliferation. We inferred that curcumin was capable of impacting the IL-23/IL-17A axis by inhibiting IL-1β/IL-6 and then indirectly down-regulating IL-17A/IL-22 production. In conclusion, curcumin can relieve the IMQ-induced psoriasis-like inflammation in a mouse model, similar to the effects of clobetasol. Therefore, we have every reason to expect that curcumin will be used in the treatment of psoriasis in the future.

Skin permeating nanogel for the cutaneous co-delivery of two anti-inflammatory drugs

The aim of this study was to develop an effective drug delivery system for the simultaneous topical delivery of two anti-inflammatory drugs, spantide II (SP) and ketoprofen (KP). To achieve this primary goal, we have developed a skin permeating nanogel system (SPN) containing surface modified polymeric bilayered nanoparticles along with a gelling agent. Poly-(lactide-co-glycolic acid) and chitosan were used to prepare bilayered nanoparticles (NPS) and the surface was modified with oleic acid (NPSO). Hydroxypropyl methyl cellulose (HPMC) and Carbopol with the desired viscosity were utilized to prepare the nanogels. The nanogel system was further investigated for in vitro skin permeation, drug release and stability studies. Allergic contact dermatitis (ACD) and psoriatic plaque like model were used to assess the effectiveness of SPN. Dispersion of NPSO in HPMC (SPN) produced a stable and uniform dispersion. In vitro permeation studies revealed increase in deposition of SP for the SP-SPN or SP+KP-SPN in the epidermis and dermis by 8.5 and 9.5 folds, respectively than SP-gel. Further, the deposition of KP for KP-SPN or SP+KP-SPN in epidermis and dermis was 9.75 and 11.55 folds higher, respectively than KP-gel. Similarly the amount of KP permeated for KP-SPN or SP+KP-SPN was increased by 9.92 folds than KP-gel. The ear thickness in ACD model and the expression of IL-17 and IL-23; PASI score and TEWL values in psoriatic plaque like model were significantly less (p < 0.001) for SPN compared to control gel. Our results suggest that SP+KP-SPN have significant potential for the percutaneous delivery of SP and KP to the deeper skin layers for treatment of various skin inflammatory disorders.

Modulation of the allergic asthma transcriptome following resiquimod treatment

Resiquimod is a compound belonging to the imidazoquinoline family of compounds known to signal through Toll-like receptor 7. Resiquimod treatment has been demonstrated to inhibit the development of allergen induced asthma in experimental models. The aim of the present study was to elucidate the molecular processes that were altered following resiquimod treatment and allergen challenge in a mouse model of allergic asthma. Employing microarray analysis, we have characterized the "asthmatic" transcriptome of the lungs of A/J and C57BL/6 mice and determined that it includes genes involved in the control of cell cycle progression, the complement and coagulation cascades, and chemokine signaling. Our results demonstrated that resiquimod treatment resulted in the normalization of the expression of genes involved with airway remodeling, and generally, chemokine signaling. Resiquimod treatment also altered the expression of cell adhesion molecules, and molecules involved in natural killer (NK) cell-mediated cytotoxicity. Furthermore, we have demonstrated that systemic resiquimod administration resulted in the recruitment of NK cells to the lungs and livers of the mice, although no causal relationship between NK cell recruitment and treatment efficacy was found. Overall, our findings identified several genes, important in the development of asthma pathology, that were normalized following resiquimod treatment, thus improving our understanding of the molecular consequences of resiquimod treatment in the lung milieu. The recruitment of NK cells to the lungs may also have application in the treatment of virally induced asthma exacerbations.

Imiquimod-induced psoriasis-like skin inflammation in mice is mediated via the IL-23/IL-17 axis

Topical application of imiquimod (IMQ), a TLR7/8 ligand and potent immune activator, can induce and exacerbate psoriasis, a chronic inflammatory skin disorder. Recently, a crucial role was proposed for the IL-23/IL-17 axis in psoriasis. We hypothesized that IMQ-induced dermatitis in mice can serve as a model for the analysis of pathogenic mechanisms in psoriasis-like dermatitis and assessed its IL-23/IL-17 axis dependency. Daily application of IMQ on mouse back skin induced inflamed scaly skin lesions resembling plaque type psoriasis. These lesions showed increased epidermal proliferation, abnormal differentiation, epidermal accumulation of neutrophils in microabcesses, neoangiogenesis, and infiltrates consisting of CD4(+) T cells, CD11c(+) dendritic cells, and plasmacytoid dendritic cells. IMQ induced epidermal expression of IL-23, IL-17A, and IL-17F, as well as an increase in splenic Th17 cells. IMQ-induced dermatitis was partially dependent on the presence of T cells, whereas disease development was almost completely blocked in mice deficient for IL-23 or the IL-17 receptor, demonstrating a pivotal role of the IL-23/IL-17 axis. In conclusion, the sole application of the innate TLR7/8 ligand IMQ rapidly induces a dermatitis closely resembling human psoriasis, critically dependent on the IL-23/IL-17 axis. This rapid and convenient model allows further elucidation of pathogenic mechanisms and evaluation of new therapies in psoriasis.

Defective innate immunity predisposes murine neonates to poor sepsis outcome but is reversed by TLR agonists

Neonates exhibit an increased risk of sepsis mortality compared with adults. We show that in contrast to adults, survival from polymicrobial sepsis in murine neonates does not depend on an intact adaptive immune system and is not improved by T cell-directed adaptive immunotherapy. Furthermore, neonates manifest an attenuated inflammatory and innate response to sepsis, and have functional defects in their peritoneal CD11b(+) cells. Activation of innate immunity with either a Toll-like receptor 4 (TLR4) or TLR7/8 agonist, but not a TLR3 agonist, increased the magnitude, but abbreviated the early systemic inflammatory response, reduced bacteremia, and improved survival to polymicrobial sepsis. TLR4 agonist pretreatment enhanced peritoneal neutrophil recruitment with increased oxidative burst production, whereas the TLR7/8 agonist also enhanced peritoneal neutrophil recruitment with increased phagocytic ability. These benefits were independent of the adaptive immune system and type I interferon signaling. Improving innate immune function with select TLR agonists may be a useful strategy to prevent neonatal sepsis mortality.

Human Langerhans cells express a specific TLR profile and differentially respond to viruses and Gram-positive bacteria

Dendritic cells (DC) are APCs essential for the development of primary immune responses. In pluristratified epithelia, Langerhans cells (LC) are a critical subset of DC which take up Ags and migrate toward lymph nodes upon inflammatory stimuli. TLR allow detection of pathogen-associated molecular patterns (PAMP) by different DC subsets. The repertoire of TLR expressed by human LC is uncharacterized and their ability to directly respond to PAMP has not been systematically investigated. In this study, we show for the first time that freshly purified LC from human skin express mRNA encoding TLR1, TLR2, TLR3, TLR5, TLR6 and TLR10. In addition, keratinocytes ex vivo display TLR1-5, TLR7, and TLR10. Accordingly, highly enriched immature LC efficiently respond to TLR2 agonists peptidoglycan and lipoteichoic acid from Gram-positive bacteria, and to dsRNA which engages TLR3. In contrast, LC do not directly sense TLR7/8 ligands and LPS from Gram-negative bacteria, which signals through TLR4. TLR engagement also results in cytokine production, with marked differences depending on the PAMP detected. TLR2 and TLR3 ligands increase IL-6 and IL-8 production, while dsRNA alone stimulates TNF-alpha release. Strikingly, only peptidoglycan triggers IL-10 secretion, thereby suggesting a specific function in tolerance to commensal Gram-positive bacteria. However, LC do not produce IL-12p70 or type I IFNs. In conclusion, human LC are equipped with TLR that enable direct detection of PAMP from viruses and Gram-positive bacteria, subsequent phenotypic maturation, and differential cytokine production. This implies a significant role for LC in the control of skin immune responses.

Disease-Independent Skin Recruitment and Activation of Plasmacytoid Predendritic Cells Following Imiquimod Treatment

BACKGROUND

Imiquimod, an immune response modifier that is used topically to treat different types of skin cancer, induces the production of proinflammatory cytokines that stimulate an antitumor immune response. We assessed characteristics of the imiquimod-induced immune activation in epithelial and lymphoproliferative neoplasias of human skin. We focused on plasmacytoid predendritic cells (PDCs), the primary producer of interferon alpha (IFN-alpha) after imiquimod activation in vitro.

METHODS

We used Affymetrix oligonucleotide arrays to compare gene expression profiles from tumors from 16 patients, 10 with superficial basal cell carcinomas (sBCCs), five with cutaneous T-cell lymphomas (CTCLs), and one with Bowen's disease, before and after topical imiquimod treatment. We used quantitative immunohistochemistry with PDC-specific antibodies against BDCA-2 and CD123 to characterize the PDC population before and after imiquimod treatment in these specimens. Activation status of PDCs from four sBCC patients was assessed by intracellular IFN-alpha staining and flow cytometry.

RESULTS

Expression of various IFN-alpha-inducible genes (e.g., CIG5, G1P2, OASL, IFIT1, STAT1, IFI35, OAS1, ISG20, MxA, and IRF7), the so-called IFN-alpha signature, was increased similarly in both sBCC and CTCL lesions after imiquimod treatment. PDCs were recruited and activated in both lesion types, and they produced IFN-alpha after imiquimod treatment in vivo (mean percentage of PDCs producing IFN-alpha = 14.5%, 95% confidence interval [CI] = 4.9% to 24%; range = 3.3%-27%, n = 4 lesions). Imiquimod induced similar immune activation patterns in all three diseases, and these patterns were associated with the number of PDCs recruited to the treatment site. Two imiquimod-treated sBCC patients who did not mount an inflammatory response to imiquimod and whose lesions lacked the IFN-alpha signature after treatment had fewer PDCs in treated lesions compared with other treated patients with such a response.

CONCLUSIONS

Imiquimod induces immune activation patterns that relate to the number of the PDCs recruited to the treatment site, thus supporting the role of PDC in responsiveness to imiquimod in humans.

Imiquimod and resiquimod in a mouse model: adjuvants for DNA vaccination by particle-mediated immunotherapeutic delivery

Imiquimod, an immune response modifier and inducer of cytokines in vitro and in vivo, has been shown to have potent antiviral and antitumour activity and to act as an adjuvant for protein vaccination. We have undertaken studies in mice to investigate the potential of imiquimod and resiquimod to adjuvant DNA vaccination. These imidazoquinolines were administered by subcutaneous injection at the vaccination site immediately after particle-mediated immunotherapeutic delivery of plasmid DNA using a gene gun. Imiquimod was found to increase the number and maturation status of dendritic cells in draining lymph nodes, and to enhance antigen-specific CD4(+) and CD8(+) T cell responses, as assessed by analyses of clonal expansion, and the quantity and kinetics of cytokine production from these cells in lymph nodes and spleens collected after vaccination. A more substantial increase in IFN-gamma-producing, compared with IL-4-producing CD4(+) T cells suggested that imiquimod biased the immune response towards a predominance of Th1 cells. The analogue resiquimod was found to be to produce a similar Th1 biased immune response with a 10-fold reduced dose compared with imiquimod. Collectively, these studies suggest that both imiquimod and resiquimod may be suitable adjuvants for therapeutic DNA vaccines requiring induction of potent cytotoxic T cell responses.

Imiquimod-Induced Interleukin-1α Stimulation Improves Barrier Homeostasis in Aged Murine Epidermis

In response to acute disruption of the permeability barrier of aged mammals there is a diminished capacity for barrier recovery, analogous to other aged organs when stressed. Acute barrier disruption increases levels of epidermal cytokines, and cytokines are known regulators of keratinocyte mitogenesis, as well as lipid synthesis in extracutaneous tissues. Underlying the sluggish barrier recovery in aged skin are diminished mRNA and protein levels for the interleukin-1 cytokine family, and its receptors. To further elucidate the role of the interleukin-1 family of cytokines in the barrier repair response, cytokine production was stimulated in aged murine skin with topical imiquimod application. Imiquimod accelerated barrier recovery after acute insults to aged and young skin. These functional results correlated temporally with increased interleukin-1 alpha production in the epidermis following topical imiquimod administration to murine skin. Furthermore, intracutaneous injections of interleukin-1 alpha accelerated barrier recovery in aged mice. Finally, we showed that interleukin-1 alpha added to cultured human keratinocytes stimulates epidermal lipid synthesis. These studies provide further evidence for the role of reduced interleukin-1 alpha signaling in the decline of permeability barrier function in aged skin, and point to the potential use of cytokine augmentation in barrier dysfunction of the aged.

Immunomodulation as a treatment strategy for genital herpes: review of the evidence

In this review, we discuss the ongoing development of a new treatment option for genital herpes (GH), the disease caused by herpes simplex virus (HSV) types I and II. Following infection, the virus establishes a latent infection in peripheral neurons, which periodically activates to cause recurrent skin lesions or asymptomatic shedding in the anogenital area. A new class of drugs, the immune response modifiers (IRMs), modulates the immune system against viral infection. This approach is currently being tested as a treatment for GH. We first review the effectiveness of treatment of other viral diseases with imiquimod, the first IRM to be licensed (Aldara, imiquimod 5% cream), and one used for the treatment of external anogenital warts. We then focus on resiquimod, an analog of imiquimod, which shows early promise as a new treatment option for GH. The evidence from in vitro and in vivo studies, in particular the guinea pig model of GH, describing the effectiveness and mode of action of this novel immunopharmacological agent is presented. Resiquimod stimulates specific cells of the innate immune system (including monocytes/macrophages, dendritic cells (DC) and B lymphocytes) to produce cytokines (in particular IFN-alpha, IL-12, TNF-alpha and IFN-gamma) that initiate and drive the development of the Th1 acquired immune response against HSV-infected cells. Recent results from clinical trials and in vivo studies in animal models are consistent with the hypothesis that the development of HSV-specific cell-mediated immunity may prove to be the key in providing a long-lasting protection against GH recurrences.

Treatment of external genital warts in men using 5% imiquimod cream applied three times a week, once daily, twice daily, or three times a day

BACKGROUND

Medical therapy for genital warts remains suboptimal. The topical interferon and cytokine inducer, imiquimod, has been proved effective for the treatment of external genital and perianal warts, but there is a substantial difference in the response rates between men and women. When 5% imiquimod cream is applied three times a week up to 16 weeks, approximately two thirds of women treated with imiquimod achieve complete clearance of genital warts, whereas only about one third of men clear completely.

GOAL

This study was undertaken to determine whether more frequent application of topical imiquimod cream would improve the rate of genital wart clearance in men.

STUDY DESIGN

A randomized treatment trial involving adult men with biopsy-proven genital warts was conducted at nine centers in the United States and Canada using four different application frequencies.

RESULTS

Complete clearance rates during the 16-week treatment period were as follows for the different imiquimod treatment frequencies: three times a week (35 %), once daily (28 %), twice daily (24%), and three times a day (27%)(P = 0.88). The four treatment groups all showed comparable reductions in the total lesion area, with a median of more than a 90% reduction in the lesion area by the end of treatment. There was a significant increase in the incidence and severity of local skin reactions including erythema, vesicle formation, ulceration, and excoriation as the dosing frequency increased from three times a week to three times a day.

CONCLUSIONS

In this study, the optimal dosage regimen was the approved three times a week regimen. More frequent application (up to three times a day) did not improve clearance and was associated with an increase in local adverse events.

The cytokine response to physical activity and training

Cytokines are soluble glycoproteins that are produced by and mediate communication between and within immune and nonimmune cells, organs and organ systems throughout the body. Pro- and anti-inflammatory mediators constitute the inflammatory cytokines, which are modulated by various stimuli, including physical activity, trauma and infection. Physical activity affects local and systemic cytokine production at different levels, often exhibiting striking similarity to the cytokine response to trauma and infection. The present review examines the cytokine response to short term exercise stress, with an emphasis on the balance between pro- and anti-inflammatory mechanisms and modulation of both innate and specific immune parameters through cytokine regulation. The effects of long term exercise on cytokine responses and the possible impact on various facets of the immune system are also discussed, with reference to both cross-sectional and longitudinal studies of exercise training. Finally, the validity of using exercise as a model for trauma and sepsis is scruti- nised in the light of physiological changes, symptomatology and outcome, and limitations of the model are addressed. Further studies, examining the effect of exercise, trauma and infection on novel cytokines and cytokine systems are needed to elucidate the significance of cytokine regulation by physical activity and, more importantly, to clarify the health implications of short and long term physical activity with respect to overall immune function and resistance to infection.

Imiquimod therapy for molluscum contagiosum

BACKGROUND

Molluscum contagiosum virus (MCV) is a large double-stranded DNA virus that is a member of the family Poxviridae, and which has a worldwide distribution. As with other poxviruses, MCV does not appear to develop latency but evades the immune system through the production of viral specific proteins.

OBJECTIVE

To evaluate the therapeutic efficacy of imiquimod 5% cream for MCV.

METHODS

Thirteen children >5 and <10 years old, 19 immune-competent adults and four adults with advanced, but stable HIV-1 disease with >10 MCV lesions were treated with topical 5% imiquimod cream three times weekly for up to 16 weeks.

RESULTS

Fourteen of 19 immune-competent adults, four of four adults with HIV-1 disease, and six of 13 children had resolution of their MCV lesions in <16 weeks of imiquimod therapy. Children tended to have more pruritus and inflammatory reactions with imiquimod, although most treated lesions appeared to respond. The development of new MCV lesions resulted in a lower overall resolution of the lesions in children. Imiquimod appeared to be the most efficacious in patients with HIV-1 disease and in the genital area in immune-competent adults.

CONCLUSION

Although topical imiquimod appears to have some efficacy in the therapy of MCV, in children the pruritus correlated relatively well with the development of new lesions. In adults, areas that would be expected to have better penetration appeared to respond more consistently. Although the HIV-1-positive patients had the largest clinical lesions at the onset of therapy, as a group they had the best overall response to therapy.

Antiviral treatment of diseases in pediatric dermatology

Pediatric dermatologic disease that have specific therapies and/or specific prophylactic measures are reviewed. Herpes simplex virus and varicella-zoster virus infections, human papillomavirus infections, and molluscum contagiosum infections are discussed with special emphasis on recent advances of therapy and prophylaxis.

Management of female genital warts with an analog of imiquimod 2% in cream: a randomized, double-blind, placebo-controlled study

The purpose of this randomized, double-blind, placebo-controlled study was to determine the clinical efficacy and tolerability of an analog of imiquimod (2%)in cream to cure genital warts in women. Sixty preselected women, ranging between 18 and 45 years of age (mean 24.3) and having 411 lesions (mean 6.8) with clinical, histopathological and polymerase chain reaction (PCR) confirmed diagnosis of human papilloma virus (HPV) infection were randomized to two parallel groups. Each patient received a precoded 40-g tube and instructions on how to apply the trial medication to their lesions at home two times daily for five consecutive days per week. The active treatment period was six weeks. Patients were evaluated on a weekly basis. A clinically and PCR established total clearance of target warts was recorded as a cure. By the end of the treatment, 43.3% of patients and 42.8% of warts were cured. Code disclosure revealed that imiquimod cream had cured 83.3% of the treated patients and 84.3% of the tested warts, while the placebo healed one subject and four warts (p < 0.0001). Eight patients (13.3%) in the imiquimod group experienced mild to moderate, non-objective, drug-induced symptoms with no dropouts. Among the 26 cured patients, five had a relapse after 11 months. In conclusion, the data presented demonstrate that 2% imiquimod in cream with mild to moderate subjective side effects is significantly more effective than placebo in eliminating genital warts in women.

Cytokine induction in hairless mouse and rat skin after topical application of the immune response modifiers imiquimod and S-28463

ALDARA (imiquimod cream 5%) recently became available for the treatment of genital and perianal warts; however, the topical mechanism of action of imiquimod is not fully understood. Imiquimod, and its analogs R-842, S-27609, and S-28463, are potent anti-viral and anti-tumor agents in animal models. Much of the biologic activity of these compounds can be attributed to the induction of cytokines, including interferon-alpha, tumor necrosis factor-alpha, interleukins-1, -6, -8, and others. This study was performed to characterize the response of mice and rats to topical application of imiquimod and S-28463 and also to evaluate these agents in cultures of murine and human skin cells. Topical administration of imiquimod or S-28463 to the flanks of hairless mice and rats leads to increases in local concentrations of interferon and tumor necrosis factor in the skin. The concentrations of interferon and tumor necrosis factor were higher at the site of drug application than in skin from the contralateral flank or skin from untreated animals. Interferon-alpha mRNA levels were also elevated in the skin of mice after topical application of either imiquimod or S-28463. In vitro, both imiquimod and S-28463 induced increases in interferon and tumor necrosis factor in cultures of cells isolated from hairless mouse skin. Imiquimod also increased interleukin-8 concentrations in human keratinocyte and fibroblast cultures, whereas S-28463 induced increases in tumor necrosis factor in fibroblast cultures. These results demonstrate that imiquimod and S-28463 stimulate production of cytokines in the skin after topical application, which may play a major role in its activity in genital wart patients.