Lysosomal degradation of PD-L1 is associated with immune-related adverse events during anti-PD-L1 immunotherapy in NSCLC patients.

Background: Immune checkpoint inhibitors (ICIs) can induce immune-related adverse events (irAEs). Liquid biomarkers to predict irAE occurrence are urgently needed. We previously developed an ELISA system to specifically detect soluble PD-L1 (sPD-L1) with PD-1-binding capacity (bsPD-L1). Here, we investigated the relationship between sPD-L1 and bsPD-L1 in gastric cancer (GC) and non-small cell lung cancer (NSCLC) treated with PD-1/PD-L1 blockade and their association with irAEs. Methods: We examined sPD-L1, bsPD-L1, matrix metalloproteinases (MMPs), and proinflammatory cytokine levels by ELISA in plasma samples from 117 GC patients prior to surgery and 72 NSCLC patients prior to and at 2 months after ICI treatment (anti-PD-1, n = 48; anti-PD-L1, n = 24). In mice treated with anti-PD-1/PD-L1 antibodies (Abs), sPD-L1 levels and localization of Abs were examined by ELISA and immunohistochemistry, respectively. Results:sPD-L1 was detected with higher frequency in GC patients than in NSCLC patients, whereas bsPD-L1 was detected with similar frequencies in GC and NSCLC patients. sPD-L1 levels were correlated with IL-1α, IL-1ß, TNF-α, and IL-6 levels, while bsPD-L1 levels were correlated with MMP13, MMP3, and IFN-γ levels. In NSCLC patients, anti-PD-L1, but not anti-PD-1, treatment increased sPD-L1, which was associated with irAE development, but not with clinical outcomes. In mice, trafficking of anti-PD-L1 Abs to lysosomes in F4/80+ macrophages resulted in sPD-L1 production, which was suppressed by treatment with lysosomal degradation inhibitor chloroquine and macrophage depletion. Conclusion: Anti-PD-L1-mediated lysosomal degradation induces sPD-L1 production, which can serve as an indicator to predict irAE development during anti-PD-L1 treatment.

Interleukin 21 promotes IgG1+ plasma cell differentiation instead of class switching to IgE via Blimp1 expression.

IgE is induced by the presence of IL-4 by class switching from IgM through IgG1 to IgE. IL-21 inhibits the IgE class switch by induction of Blimp1 leading to Stat6 and AID downregulation, and plasmablast/plasma cell differentiation.

Combination of plasma MMPs and PD-1-binding soluble PD-L1 predicts recurrence in gastric cancer and the efficacy of immune checkpoint inhibitors in non-small cell lung cancer.

Background: The tumor microenvironment (TME) impacts the therapeutic efficacy of immune checkpoint inhibitors (ICIs). No liquid biomarkers are available to evaluate TME heterogeneity. Here, we investigated the clinical significance of PD-1-binding soluble PD-L1 (bsPD-L1) in gastric cancer (GC) patients and non-small cell lung cancer (NSCLC) patients treated with PD-1/PD-L1 blockade. Methods: We examined bsPD-L1, matrix metalloproteinases (MMPs), and IFN-γ levels in plasma samples from GC patients (n = 117) prior to surgery and NSCLC patients (n = 72) prior to and 2 months after ICI treatment. We also examined extracellular matrix (ECM) integrity, PD-L1 expression, and T cell infiltration in tumor tissues from 25 GC patients by Elastica Masson-Goldner staining and immunohistochemical staining for PD-L1 and CD3, respectively. Results: bsPD-L1 was detected in 17/117 GC patients and 16/72 NSCLC patients. bsPD-L1 showed strong or moderate correlations with plasma MMP13 or MMP3 levels, respectively, in both GC and NSCLC patients. bsPD-L1 expression in GC was associated with IFN-γ levels and intra-tumoral T cell infiltration, whereas MMP13 levels were associated with loss of ECM integrity, allowing tumor cells to access blood vessels. Plasma MMP3 and MMP13 levels were altered during ICI treatment. Combined bsPD-L1 and MMP status had higher predictive accuracy to identify two patient groups with favorable and poor prognosis than tumor PD-L1 expression: bsPD-L1+MMP13high in GC and bsPD-L1+(MMP3 and MMP13)increased in NSCLC were associated with poor prognosis, whereas bsPD-L1+MMP13low in GC and bsPD-L1+(MMP3 or MMP13)decreased in NSCLC were associated with favorable prognosis. Conclusion: Plasma bsPD-L1 and MMP13 levels indicate T cell response and loss of ECM integrity, respectively, in the TME. The combination of bsPD-L1 and MMPs may represent a non-invasive tool to predict recurrence in GC and the efficacy of ICIs in NSCLC.

Inhibition of IL-33 signaling ameliorate hepatic fibrosis with decreasing MCP-1 in a mouse model of diabetes and non-alcoholic steatohepatitis; comparison for luseogliflozin, an SGLT2 inhibitor.

Non-alcoholic fatty liver disease (NAFLD) is increasing globally, and seeking therapeutic molecule targets is urgent. Several studies have demonstrated that IL-33 plays an important role in the progression of Non-alcoholic steatohepatitis (NASH) with fibrosis and the proliferation of hepatocellular carcinoma (HCC). However, whether the inhibition of IL-33 signaling prevents NAFLD from progressing to NASH and HCC has not been clarified. We investigated the effects of a novel antibody, IL-33RAb, and luseogliflozin, a SGLT2 inhibitor, when administered to a model mouse for NASH and HCC, and their effects were compared to investigate the mechanisms of how IL-33 is involved in the pathogenesis of NASH progression. Compared with the positive control of luseogliflozin, inhibition of IL-33 signaling ameliorated decreasing hepatic fibrosis via decreasingαSMA and MCP-1, and also partially suppressed the progression of the HCC cell line in in vitro experiments. These findings suggest that inhibition of IL-33 possibly prevents progression from NASH to HCC, and their effect may be a newly arrived therapeutic agent.

Fine-tuning of antigen-specific immune responses by regulatory T cells activated via antigen recognition-independent and humoral factor-dependent mechanisms.

CD4+ CD25+ Foxp3+ regulatory T cells (Tregs) are highly sensitive to IL-2, one of the many cytokines produced during immune responses, for their development, survival and functions. Although the effects of IL-2 administration on Tregs in vivo are well characterized, the effects on Tregs elicited by IL-2 produced during an immune response have not been elucidated. Hence, in this study, Treg behaviour during IL-2-producing immune responses was explored using in vivo and in vitro murine systems. The use of murine mixed lymphocyte culture (MLC) revealed that a large proportion of Tregs increased in size, accompanied by both cell death and proliferation status. Further, these large Tregs, which were found to not recognize specific antigens, were observed in MLCs as being functionally activated by various cytokines, including IL-2, produced by antigen-specific T cells. This 'bystander Treg activation' was also observed in mice with graft-versus-host reactions (GvHRs). Alternatively, effector cells from Treg-depleted MLCs exhibited lower antigen-specific responses or higher cross-reactivity as compared to control MLCs with Tregs. Taken together, these results suggest that Tregs are activated by cytokines, mainly IL-2, released from T cells that are activated by a specific antigen. Subsequently, these activated bystander Tregs contribute to the fine-tuning of highly antigen-specific immune responses.

IL-21 and IL-5 coordinately induce surface IgA+ cells.

Intestinal IgA is induced by microbes and food antigens. Peyer's patches (PPs) are known as one of the inductive sites for intestinal IgA production. However, the precise mechanism of IgA induction is as yet unknown. IgA secretion was induced from IgD+ B cells in vitro by stimulus with lipopolysaccharide in the presence of only retinoic acid (RA) and low doses of TGF-ß1. Surface IgA+ cells were effectively induced from IgD+ B cells in vitro by the mixture of RA and the cytokines TGF-ß1, APRIL, IL-5 and IL-21. rIL-21 upregulated surface IgA+ but impaired the proliferation of stimulated B cells in the presence of rTGF-ß1, RA and rAPRIL, in vitro. The addition of rIL-5 restored the impaired proliferation by rIL-21, resulting in the expansion of IgA+ cells. rIL-21 induced the expression of Aicda and Prdm1, and impaired Rel in IgD+ B cells. Blockade of IL-21R signaling by a neutralizing mAb in vivo led to lower frequencies of IgA+ and IgG2b+ cells and lower germinal center B cells in PPs in a homeostatic condition. Although amounts of small intestinal IgA and titers of anti-dsDNA, the major target of intestinal IgA, in these mice were not altered, anti-OVA IgA titers induced by OVA drinking in OVA-specific T-cell receptor (TCR) transgenic mice were decreased. PP-deficient TCR transgenic mice showed diminished anti-OVA IgA induction. Blockade of IL-5R signaling in vivo led to similar results with relatively weaker effects than that of IL-21R mAb administration. These results suggest that IL-21 and IL-5 play cooperative roles in surface expression of IgA in PPs.

Peyer's patches contain abundant isotype-switched B cells with activated phenotypes and are inductive sites for T-independent anti-DNA IgA.

Peyer's patches (PPs) are inductive sites for IgA production; however, the induction mechanism of IgA remains largely unknown. We found that the activated phenotypes of isotype-switched PP B cells were more abundant than those of splenic B cells. Immunoglobulins (Igs) from PP B cells reacted to several substances, including DNA and diet extract. Hybridomas established from PP B cells of untreated mice revealed that IgA mainly react with DNA. PP-deficient mice revealed that PPs were dispensable for a total intestinal IgA amount but were required for intestinal anti-diet extract and anti-DNA IgA. Antibiotic-treated mice and CD4+ T cell-depleted mice demonstrated that the intestinal anti-DNA IgA was induced by microbiota in a T-independent manner. Interestingly, the oral administration of IgA led to the expansion of intestinal bacteria in a reactivity-independent manner. Our findings suggest that PPs are unique and efficient inductive sites for IgA, particularly against T-independent antigens.

Tumor necrosis factor superfamily member (TNFSF) 13 (APRIL) and TNFSF13B (BAFF) downregulate homeostatic immunoglobulin production in the intestines.

Intestinal immunoglobulins (Igs) protect against microbes. However, the regulation of intestinal Ig production is poorly understood. In this study, we have investigated the roles of APRIL (tumor necrosis factor superfamily member [TNFSF] 13) and BAFF (TNFSF13B) in intestinal Ig induction. Peyer's patches (PPs) are, at least in part, an inductive site for Igs, including IgA. Introducing APRIL and BAFF in vivo lowered the frequency of IgG1+ or IgG2b+ B cells in PPs. Administration of TACI-Fc upregulated the frequency of IgG1+, IgG2b+, and IgA+ B cells in PPs, suggesting that APRIL and BAFF attenuate Ig production in these regions. TACI-Fc also upregulated intestinal IgA levels and expanded germinal center B cells in PPs. These results indicate that APRIL and BAFF paradoxically downregulate homeostatic Ig production in the intestines.

The exon 38-containing ARHGEF11 splice isoform is differentially expressed and is required for migration and growth in invasive breast cancer cells.

Breast cancer invasion involves the loss of cell-cell junctions and acquisition of an invasive, migratory phenotype, and breast cancer cells of the basal intrinsic subtype are more invasive and metastatic than breast cancer cells of other subtypes. ARHGEF11 is a RhoGEF that was previously shown to bind to the tight junction protein ZO-1 at perijunctional actomyosin ring (PJAR), a network of cortically organized actin and myosin filaments associated with junctional complexes that regulates cell-cell adhesion and polarization. We show here that ARHGEF11 shows splice isoform expression that differs according to the intrinsic subtype of breast cancer cells and that controls their invasive phenotype. Luminal subtype breast cancer cells express the isoform of ARHGEF11 lacking exon 38 (38-), which binds to ZO-1 at PJAR and is necessary for formation and maintenance of cell-cell junctions. Basal subtype breast cancer cells express the isoform of ARHGEF11 containing exon 38 (38+), which does not bind to ZO-1 and which drives cell migration and motility. Depletion of ARHGEF11 in basal subtype breast cancer cells is sufficient to alter cell morphology from a mesenchymal stellate form with extensive cell protrusions to a cobblestone-like epithelial form, and to suppress growth and survival both in vitro and in vivo. These findings show that the expression of the particular splice isoform of ARHGEF11 is critically linked to the malignant phenotype of breast cancer cells, identifying ARHGEF11 exon 38(+) as a biomarker and target for therapy of breast cancer.

Peyer's patch innate lymphoid cells regulate commensal bacteria expansion.

Anatomical containment of commensal bacteria in the intestinal mucosa is promoted by innate lymphoid cells (ILCs). However, the mechanism by which ILCs regulate bacterial localization to specific regions remains unknown. Here we show that Peyer's patch (PP) ILCs robustly produce IL-22 and IFN-γ in the absence of exogenous stimuli. Antibiotic treatment of mice decreased both IL-22+ and IFN-γ+ cells in PPs. Blockade of both IL-2 and IL-23 signaling in vitro lowered IL-22 and IFN-γ production. PP ILCs induced mRNA expression of the antibacterial proteins RegIIIß and RegIIIγ in intestinal epithelial cells. Furthermore, in vivo depletion of ILCs rather than T cells altered bacterial composition and allowed bacterial proliferation in PPs. Collectively, our results show that ILCs regulate the expansion of commensal bacteria in PPs.

IL-33 activates eosinophils of visceral adipose tissue both directly and via innate lymphoid cells.

Eosinophils are multifunctional leukocytes involved in allergic reactions as well as adipose tissue regulation. IL-5 is required for eosinophil survival; however, the in vivo mechanisms of eosinophil regulation are not fully understood. A tg mouse model with il5 promoter-driven EGFP expression was established for detecting the IL-5-producing cells in vivo. Il5-egfp tg mice expressed high levels of EGFP in gonadal adipose tissue (GAT) cells. EGFP(+) cells in GAT were mainly group 2 innate lymphoid cells (ILCs). IL-33 preferentially expanded EGFP(+) cells and eosinophils in GAT in vivo. EGFP(+) ILCs were found to upregulate prg2 mRNA expression in GAT eosinophils. These results demonstrate that ILCs activate eosinophils in GAT. The blockage of IL-33Rα, on the other hand, did not impair EGFP(+) ILC numbers but did impair eosinophil numbers in vivo. GAT eosinophils expressed IL-33Rα and IL-33 expanded eosinophil numbers in CD90(+) cell-depleted mice. IL-33 was further observed to induce the expression of retnla and epx mRNA in eosinophils. These findings demonstrate that IL-33 directly activates eosinophils in GAT, and together with our other findings described above, our findings show that IL-33 has dual pathways via which it activates eosinophils in vivo: a direct activation pathway and a group 2 ILC-mediated pathway.

NFκB attenuates IL-5 production and upregulates T-box transcription factors in Th2-like T cells.

IL-5 plays important roles in eosinophil differentiation, expansion, and recruitment. The regulation of IL-5 seems critical for the treatment of eosinophil-mediated allergic reactions. However, the precise mechanisms for IL-5 regulation remain unknown. In this study, we investigated how IL-5 production is regulated. The transduction of GATA-3 into a murine T cell hybridoma resulted in acquiring the ability to produce IL-5 in response to an antigenic stimulus like Th2 cells. This production was dependent on the cAMP-PKA pathway, but not on p38 activation. Transduction of NIK largely impaired IL-5 production. RelA and RelB similarly impaired IL-5 production. RelA decreased not only IL-5 protein amount but mRNA. RelA also inhibited Il5-luciferase reporter activity. The transduction of GATA-3 decreased the expression of Tbx21 and Eomes, but the additional transduction of RelA abrogated the decreased expression of GATA-3-induced Tbx21 and Eomes. Furthermore, the transduction of T-bet or Eomes into the GATA-3-transduced T cell hybridoma impaired IL-5 production. These results suggested that strong enhancement of the NFκB pathway downregulates IL-5 production and upregulates T-box protein expression to shift an immune response from Th2 to inflammatory Th1.

CD2-mediated regulation of peripheral CD4(+) CD25(+) regulatory T-cell apoptosis accompanied by down-regulation of Bim.

Extensive studies on CD4(+)  CD25(+) regulatory T (Treg) cells suggest that they are important in regulating immune responses. However, mechanisms of peripheral Treg cell homeostasis are unknown. We found that stromal cells isolated from secondary lymphoid organs such as spleen and lymph nodes could support the survival of Treg cells. This was dependent on CD2 engagement and a direct interaction between Treg cells and stromal cells. In the presence of stromal cells, Bim, a pro-apoptotic factor, was partially decreased in Treg cells. This effect could be inhibited by anti-CD2 blocking antibodies, indicating that stimulation through CD2 on Treg cells regulates Bim expression, which may be relevant to Treg cell apoptosis. Therefore, Treg cell interactions with stromal cells through CD2 may be essential for Treg cell survival. Surprisingly, the expression of CD2 ligands on stromal cells was not detected. Hence, it is not clear how CD2 on Treg cells contributes to a direct interaction with the stromal cells and participates in survival support for Treg cells. Taken together, CD2 stimuli were mandatory for Treg cell survival with reduced Bim expression, but CD2 may not function as a direct receptor for molecules on stromal cells.

Intact B7-H3 signaling promotes allograft prolongation through preferential suppression of Th1 effector responses.

Ligands of the B7 family provide both positive and negative costimulatory signals to the CD28 family of receptors on T lymphocytes, the balance of which determines the immune response. B7-H3 is a member of the B7 family whose function in T-cell activation has been the subject of some controversy: in autoimmunity and tumor immunity, it has been described as both costimulatory and coinhibitory, while in transplantation, B7-H3 signaling is thought to contribute to graft rejection. However, we now demonstrate results to the contrary. Signaling through a putative B7-H3 receptor prolonged allograft survival in a fully MHC-mismatched cardiac model and promoted a shift toward a Th2 milieu; conversely, B7-H3 blockade, achieved by use of a blocking antibody, resulted in accelerated rejection, an effect associated with enhanced IFN-γ production. Finally, graft prolongation achieved by CTLA4 Ig was shortened both by B7-H3 blockade and the absence of recipient B7-H3. These findings suggest a coinhibitory role for B7-H3. However, experience with other CD28/B7 family members suggests that immune redundancy plays a crucial role in determining the functions of various pathways. Given the abundance of conflicting data, it is plausible that, under differing conditions, B7-H3 may have both positive and negative costimulatory functions.

Antibodies against B7-DC with differential binding properties exert opposite effects.

Programmed cell death 1 (PD-1) is an immunoregulatory receptor on T cells that binds two ligands, B7-H1 and B7-DC. Although accumulating reports suggest a critical role for the B7-H1:PD-1 pathway in peripheral tolerance, the actual involvement of B7-DC has not been well confirmed. Here, we established a new MAb against mouse B7-DC (MIH37) and compared its functional properties with a previously established anti-B7-DC MAb (TY25). Binding analyses using flow cytometry demonstrated that MIH37 showed an approximately four-fold higher binding affinity to B7-DC and stronger inhibitory effects on B7-DC:PD-1 binding. In contrast to the effects of TY25, treatment with MIH37 at both sensitization and challenge inhibited hapten-induced contact hypersensitivity reactions. Furthermore, the addition of MIH37 inhibited OVA-specific T cell responses in vitro. The inhibitory effects of MIH37 were counteracted by co-blockade with PD-1 and absent in PD-1-deficient mice, suggesting PD-1-dependent action of MIH37. Our present results suggest that greater complexities of PD-1-mediated functions are induced via ligand binding for controlling immunity and tolerance.

Naïve CD4+ T cells of Peyer's patches produce more IL-6 than those of spleen in response to antigenic stimulation.

Peyer's patches (PPs) are potential sites where specific mucosal immune responses and oral tolerance are induced. The unique features of these immune responses are thought to occur in micromilieu and are largely affected by antigen-presenting cells (APCs) such as dendritic cells. In this study, we investigated the cytokine profiles induced by the activation of CD4(+) T cells of PPs. PP cells from TCR transgenic mice secreted greater amounts of IL-5 and IL-6 than spleen cells after antigenic stimulation. IL-5 was mainly produced by PP non-T cells, whereas IL-6 was secreted by PP CD4(+) cells. PPs contained two major populations including naïve and memory/activated CD4(+) cells; both populations secreted IL-6 upon activation. We also found that CD4(+)/CD62L(hi) naïve cells from PPs secreted a greater amount of IL-6 after stimulation than those from the spleen. Furthermore, subtraction and qPCR analyses revealed that PP CD4(+)/CD62L(hi) cells express a greater amount of transcripts of GA-binding protein ß subunit 1 than those of the spleen. These results suggest that naïve T cells as well as non-T cells and activated/memory T cells from PPs are distinct from their splenic counterparts and thus cause unique immune responses the in intestine.

Immunoregulatory molecule B7-H1 (CD274) contributes to skin carcinogenesis.

B7-H1 (CD274), a member of the B7 family of coinhibitory molecules, is often induced in human tumors and its expression is closely correlated with a poor prognosis or higher malignancy grade. Tumor-associated B7-H1 is implicated in mechanisms of immune escape. Under inflammatory conditions, B7-H1 is also inducible in normal epithelial cells, but little is known about its involvement in the conversion of normal cells to tumor cells. We recently found that skin-specific expression of B7-H1 accelerates chemically induced carcinogenesis of squamous cell carcinoma (SCC), despite impaired skin inflammatory responses, in B7-H1 transgenic (B7-H1tg) mice. B7-H1tg-derived keratinocytes (KC) and SCCs exhibited a marked reduction of E-cadherin, and B7-H1tg-originated SCCs showed elevated expression of the transcription factors Slug and Twist, suggesting that B7-H1 overexpression in KCs promotes the epithelial-mesenchymal transition and accelerates carcinogenesis. This review discusses the diverse functions of B7-H1 in carcinogenesis and cancer progression, and considers future directions for developing cancer therapy targeting B7-H1.

B7-H1 overexpression regulates epithelial-mesenchymal transition and accelerates carcinogenesis in skin.

B7-H1 (CD274) is a T-cell coinhibitory molecule that is also often induced on human carcinoma cells, where its expression has been implicated in immune escape. Under inflammatory conditions, B7-H1 is also inducible in normal epithelial cells but little is known about its involvement in conversion of normal cells to tumor cells. Here, we show that skin-specific expression of B7-H1 accelerates inflammatory carcinogenesis in a methylcholantrene (MCA)-induced model of squamous cell carcinoma (SCC). Inflammatory responses induced by MCA or phorbol ester TPA were clearly inhibited in B7-H1 transgenic mice (B7-H1tg mice). Antibody-mediated blockade of either B7-H1 or the related molecule PD-1 revealed that their ability to limit inflammation relied on ligand interactions made by B7-H1 or PD-1. Skin keratinocytes derived from B7-H1tg mice exhibited constitutive reduction of E-cadherin, and SCC induced in B7-H1tg mice also showed loss of E-cadherin along with elevated expression of the transcription factors Slug and Twist that drive epithelial-mesenchymal transition (EMT). Our results indicate that upregulation of B7-H1 in skin epithelial cells promotes EMT and accelerates carcinogenesis, revealing insights into the significance of B7-H1 overexpression on solid tumor cells and hinting at a close relationship between EMT and immune escape signaling pathways in cancer.

Keratinocyte-associated B7-H1 directly regulates cutaneous effector CD8+ T cell responses.

Keratinocytes (KCs) may play important roles for maintenance of peripheral tolerance in the upper layers of the skin. Coinhibitory signals mediated via the programmed death (PD)-1 and its ligand B7-H1 (PD-L1/CD274) are crucial for the downregulation of T cell immune responses and for the maintenance of peripheral tolerance. In this study, to investigate the role of KC-expressed B7-H1 in the regulation of T cell immune responses, we generated transgenic (tg) mice overexpressing B7-H1 under the control of keratin 14 (K14) promoter (K14-B7-H1 tg). K14-B7-H1 tg mice displayed impaired contact hypersensitivity (CH) responses to primary and secondary hapten challenges. The K14-B7-H1 tg mice did not exhibit substantial impairment of cutaneous dendritic cell migration after sensitization and of hapten-specific proliferation and IFN-gamma production of CD4(+) and CD8(+) T cells in the draining lymph nodes, suggesting that overexpression of B7-H1 on KCs did not affect the induction phase of the CH response. The systemic or s.c. injection of hapten-sensitized T cells into the K14-B7-H1 tg mice did not efficiently induce the CH response. IFN-gamma expression and apoptosis of KCs in the challenged ears were impaired in K14-B7-H1 tg mice. IFN-gamma production by presensitized CD8(+) T cells stimulated with hapten-pulsed KCs was markedly impaired for the KCs obtained from the K14-B7-H1 tg mice but was restored by the addition of an anti-B7-H1 mAb. These results suggest that KC-associated B7-H1 directly downregulates the effector function of CD8(+) T cells by associating with PD-1 at local inflammatory sites and that it plays a role in peripheral T cell tolerance against exogenous Ags.

Topical application of siRNA targeting cutaneous dendritic cells in allergic skin disease.

RNA interference is a promising method for silencing specific genes and has great potential for therapeutic applications. However, the major hurdle for therapeutic application is the limited stability of double-strand RNA (dsRNA) and the absence of a reliable delivery method to target cells. Skin appears to be a favorable target for small interfering RNA (siRNA) therapy. Dendritic cells (DCs) exist in the skin and mucosae on the front lines of defense; these cells capture antigens and play a crucial role in inducing immunity and tolerance.In our recent work, we have shown a successful treatment using CD86 siRNA targeting cutaneous DCs. A costimulatory molecule, CD86, is induced on DCs in situ after antigen uptake, and CD86-expressing DCs migrate to the regional lymph nodes to present antigens to T cells. Topical application of cream-emulsified CD86 siRNA ameliorated the clinical manifestations in murine contact hypersensitivity (CH) and atopic dermatitis (AD)-like disease. Our method may be advantageous for the treatment of allergic skin diseases.