Silencing of PD-L2/B7-DC by Topical Application of Small Interfering RNA Inhibits Elicitation of Contact Hypersensitivity

Injectable and Photocurable Gene Scaffold Facilitates Efficient Repair of Spinal Cord Injury

RNA interference-based gene therapy has led to a strategy for spinal cord injury (SCI) therapy. However, there have been high requirements regarding the optimal gene delivery vector for siRNA-based SCI gene therapy. Here, we developed an injectable and photocurable lipid nanoparticle GelMA (PLNG) hydrogel scaffold for controlled dual siRNA delivery at the SCI wound site. The prepared PLNG scaffold could efficiently protect and retain the bioactivity of the siRNA nanocomplex. It facilitated sustainable siRNA release along with degradation in 7 days. After loading dual siRNA targeting phosphatase and tensin homologue (PTEN) and macrophage migration inhibitory factor (MIF) simultaneously, the locally administered siRNAs/PLNG scaffold efficiently improved the Basso mouse scale (BMS) score and recovered ankle joint movement and plantar stepping after treatment with only three doses. We further proved that the siRNAs/PLNG scaffold successfully regulated the activities of neurons, microglia, and macrophages, thus promoting neuron axon regeneration and remyelination. The protein array results suggested that the siRNAs/PLNG scaffold could increase the expression of growth factors and decrease the expression of inflammatory factors to regulate neuroinflammation in SCI and create a neural repair environment. Our results suggested that the PLNG scaffold siRNA delivery system is a potential candidate for siRNA-based SCI therapy.

Endothelial Protein C Receptor and 3K3A-Activated Protein C Protect Mice from Allergic Contact Dermatitis in a Contact Hypersensitivity Model

Endothelial protein C receptor (EPCR) is a receptor for the natural anti-coagulant activated protein C (aPC). It mediates the anti-inflammatory and barrier-protective functions of aPC through the cleavage of protease-activated receptor (PAR)1/2. Allergic contact dermatitis is a common skin disease characterized by inflammation and defective skin barrier. This study investigated the effect of EPCR and 3K3A-aPC on allergic contact dermatitis using a contact hypersensitivity (CHS) model. CHS was induced using 1-Fluoro-2,4-dinitrobenzene in EPCR-deficient (KO) and matched wild-type mice and mice treated with 3K3A-aPC, a mutant form of aPC with diminished anti-coagulant activity. Changes in clinical and histological features, cytokines, and immune cells were examined. EPCRKO mice displayed more severe CHS, with increased immune cell infiltration in the skin and higher levels of inflammatory cytokines and IgE than wild-type mice. EPCR, aPC, and PAR1/2 were expressed by the skin epidermis, with EPCR presenting almost exclusively in the basal layer. EPCRKO increased the epidermal expression of aPC and PAR1, whereas in CHS, their expression was reduced compared to wild-type mice. 3K3A-aPC reduced CHS severity in wild-type and EPCRKO mice by suppressing immune cell infiltration/activation and inflammatory cytokines. In summary, EPCRKO exacerbated CHS, whereas 3K3A-aPC could reduce the severity of CHS in both EPCRKO and wild-type mice.

T cell co-stimulatory and co-inhibitory pathways in atopic dermatitis

The use of immune checkpoint inhibitors (ICIs) targeting the T cell inhibitory pathways has revolutionized cancer treatment. However, ICIs might induce progressive atopic dermatitis (AD) by affecting T cell reactivation. The critical role of T cells in AD pathogenesis is widely known. T cell co-signaling pathways regulate T cell activation, where co-signaling molecules are essential for determining the magnitude of the T cell response to antigens. Given the increasing use of ICIs in cancer treatment, a timely overview of the role of T cell co-signaling molecules in AD is required. In this review, we emphasize the importance of these molecules involved in AD pathogenesis. We also discuss the potential of targeting T cell co-signaling pathways to treat AD and present the unresolved issues and existing limitations. A better understanding of the T cell co-signaling pathways would aid investigation of the mechanism, prognosis evaluation, and treatment of AD.

The performance and perspectives of dendritic cell vaccines modified by immune checkpoint inhibitors or stimulants

Therapeutic dendritic cell (DC) vaccines stimulate the elimination of tumor cells by the immune system. However, while antigen-specific T cell responses induced by DC vaccines are commonly observed, the clinical response rate is relatively poor, necessitating vaccine optimization. There is evidence that the suppression of DC function by immune checkpoints hinders the anti-tumor immune responses mediated by DC vaccines, ultimately leading to the immune escape of the tumor cells. The use of immune checkpoint inhibitors (ICIs) and immune checkpoint activators (ICAs) has extended the immunotherapeutic range. It is known that both inhibitory and stimulatory checkpoint molecules are expressed by most DC subsets and can thus be used to manipulate the effectiveness of DC vaccines. Such manipulation has been investigated using strategies such as chemotherapy, agonistic or antagonistic antibodies, siRNA, shRNA, CRISPR-Cas9, soluble antibodies, lentiviruses, and adenoviruses to maximize the efficacy of DC vaccines. Thus, a deeper understanding of immune checkpoints may assist in the development of improved DC vaccines. Here, we review the actions of various ICIs or ICAs shown by preclinical studies, as well as their potential application in DC vaccines. New therapeutic interventional strategies for blocking and stimulating immune checkpoint molecules in DCs are also described in detail.

Differential Involvement of Programmed Cell Death Ligands in Skin Immune Responses

PD-1 is an immunoregulatory receptor that can bind PD-L1 or PD-L2 expressed on stimulated antigen-presenting cells. In this study, isolated antigen-presenting cells (macrophages and dendritic cells) were cultured with IFN-γ, IL-4, or IL-17A, and the expression of PD-L1 and PD-L2 was compared by flow cytometry. Strong upregulation of PD-L1 expression was observed on IFN-γ stimulation of both antigen-presenting cells as well as in response to IL-17A stimulation of macrophages compared with the expression in unstimulated controls. In contrast, only stimulation with IL-4 could upregulate PD-L2 expression on both antigen-presenting cells. Therefore, experiments were performed in murine models, including DNFB-induced contact hypersensitivity, calcipotriol-induced atopic dermatitis-like skin inflammation, and imiquimod-induced psoriasis-like dermatitis models, to trigger IFN-γ‒mediated T helper type (Th)1-, IL-4‒mediated Th2-, and IL-17A‒mediated Th17-type responses, respectively. In both Th1- and Th17-type immunity models, changes in ear thickness were more severe in Pd-l1‒deficient mice than in wild-type or Pd-l2‒deficient mice. In the Th2-type immunity model, changes in thickness in Pd-l2‒deficient mice were more severe than that in wild-type or Pd-l1‒deficient mice. Collectively, PD-L1 has predominant roles in Th1 and Th17 type immunity, whereas PD-L2 is involved in Th2-type immunity.

Augmentation of lenvatinib efficacy by topical treatment of miR-634 ointment in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is one of the most lethal types of human tumors. Lenvatinib can improve the disease control and prognosis in patients with ATC. However, there is an unmet need to develop a therapeutically safer and non-invasive strategy that improves the efficacy of lenvatinib for advanced ATC tumors, which grow larger close to the skin. We previously demonstrated that the topical application of an ointment incorporating tumor suppressive microRNA (TS-miR), miR-634, is a useful strategy as a TS-miR therapeutics. Here, we found that the overexpression of miR-634 synergistically increased lenvatinib-induced cytotoxicity by concurrently downregulating multiple genes related to cytoprotective processes, including ASCT2, a glutamine transporter, in ATC cell lines. Furthermore, the topical application of a miR-634 ointment on subcutaneous tumors effectively augmented the anti-tumor effects of lenvatinib in an ATC xenograft mouse model. Thus, we propose topical treatment of a miR-634 ointment as a rational strategy for improving lenvatinib-based therapy for ATC.

Overexpression of PD-L1 in gingival basal keratinocytes reduces periodontal inflammation in a ligature-induced periodontitis model

Background

The immune checkpoint programmed cell death 1 (PD‐1): PD‐1 ligand 1 (PD‐L1) pathway plays a crucial role in maintaining immune tolerance and preventing tissue damages by excessive immune responses. PD‐L1 is physiologically expressed and upregulated in keratinocytes (KCs) in the oral cavity. We here investigated the contribution of PD‐L1 that was overexpressed in gingival basal KCs in a ligature‐induced periodontitis model.

Methods

Wild‐type (WT) BALB/c and K14/PD‐L1 transgenic (tg) mice, in which PD‐L1 was overexpressed in basal KCs under control of the keratin 14 promoter, were used. To induce periodontitis, a 9‐0 silk ligature was placed around the upper right second molar, and lipopolysaccharide from Porphyromonas gingivalis was applied on the suture. Gingival tissues were collected on day 7, after which histological analyses were performed, including by hematoxylin and eosin and tartrate‐resistant acid phosphate staining (TRAP) and quantitative PCR for proinflammatory cytokines and bone metabolism‐related genes. Alveolar bone loss at 7 weeks after ligature placement was assessed by micro‐computed tomography analysis.

Results

PD‐L1 was overexpressed in the basal KCs of all gingival epithelia in K14/PD‐L1tg mice. Early ligature‐induced periodontal inflammation, as assessed based on histological changes, elevation of proinflammatory cytokine (IL‐1β, IL‐6, TNF‐α) expression, periodontal ligament degeneration, and osteoclastogenesis as assessed by Rankl and Opg expression and TRAP+ cells, was markedly impaired in K14/PD‐L1tg mice. Alveolar bone resorption at a late time point was also clearly minimized in K14/PD‐L1tg mice.

Conclusion

Overexpression of PD‐L1 in gingival basal keratinocytes in K14/PD‐L1tg mice reduces periodontal inflammation and alveolar bone resorption in a ligature‐induced periodontitis model.

Improving the Efficacy of EGFR Inhibitors by Topical Treatment of Cutaneous Squamous Cell Carcinoma with miR-634 Ointment

For cutaneous squamous cell carcinoma (cSCC), topical treatment is an essential option for patients who are not candidates for, or who refuse, surgery. Epidermal growth factor receptor (EGFR) plays a key role in the development of cSCC, but EGFR tyrosine kinase inhibitors (TKIs), such as gefitinib, have shown only partial clinical benefit in this disease. Thus, there is an unmet need to develop novel strategies for improving the efficacy of TKIs in cSCC. We previously demonstrated that the tumor-suppressive microRNA (miRNA) miR-634 functions as a negative modulator of the cytoprotective cancer cell survival processes and is a useful anticancer therapeutic agent. In the present study, we found that topical application of an ointment containing miR-634 inhibited in vivo tumor growth without toxicity in a cSCC xenograft mouse model and a 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced papilloma mouse model. Functional validation revealed that miR-634 overexpression reduced glutaminolysis by directly targeting ASCT2, a glutamine transporter. Furthermore, overexpression of miR-634 synergistically enhanced TKI-induced cytotoxicity by triggering severe energetic stress in vitro and in vivo. Thus, we propose that topical treatment with miR-634 ointment is a useful strategy for improving for EGFR TKI-based therapy for cSCC.

Cannabinoid Receptor 2 Modulates Maturation of Dendritic Cells and Their Capacity to Induce Hapten-Induced Contact Hypersensitivity

Contact hypersensitivity (CHS) is an established animal model for allergic contact dermatitis. Dendritic cells (DCs) play an important role in the sensitization phase of CHS by initiating T cell responses to topically applied haptens. The cannabinoid receptors 1 (CB1) and 2 (CB2) modulate DC functions and inflammatory skin responses, but their influence on the capacity of haptenized DCs to induce CHS is still unknown. We found lower CHS responses to 2,4-dinitro-1-fluorobenzene (DNFB) in wild type (WT) mice after adoptive transfer of haptenized Cnr2^-/- and Cnr1^-/-/Cnr2^-/- bone marrow (BM) DCs as compared to transfer of WT DCs. In contrast, induction of CHS was not affected in WT recipients after transfer of Cnr1^-/- DCs. In vitro stimulated Cnr2^-/- DCs showed lower CCR7 and CXCR4 expression when compared to WT cells, while in vitro migration towards the chemokine ligands was not affected by CB2. Upregulation of MHC class II and co-stimulatory molecules was also reduced in Cnr2^-/- DCs. This study demonstrates that CB2 modulates the maturation phenotype of DCs but not their chemotactic capacities in vitro. These findings and the fact that CHS responses mediated by Cnr2^-/- DCs are reduced suggest that CB2 is a promising target for the treatment of inflammatory skin conditions.