The Maresin 1-LGR6 axis decreases respiratory syncytial virus-induced lung inflammation.

The resolution of infection is an active process with specific molecular and cellular mechanisms that temper inflammation and enhance pathogen clearance. Here, the specialized pro-resolving mediator (SPM) Maresin 1 (MaR1) inhibited respiratory syncytial virus (RSV)-induced inflammation. inlerleukin-13 production from type 2 innate lymphoid cells (ILC) and CD4 T helper type 2 cells was decreased by exogenous MaR1. In addition, MaR1 increased amphiregulin production and decreased RSV viral transcripts to promote resolution. MaR1 also promoted interferon-ß production in mouse lung tissues and also in pediatric lung slices. MaR1 significantly inhibited the RSV-triggered aberrant inflammatory phenotype in FoxP3-expressing Tregs. The receptor for MaR1, leucine-rich repeat-containing G protein-coupled receptor 6 (LGR6), was constitutively expressed on Tregs. Following RSV infection, mice lacking Lgr6 had exacerbated type 2 immune responses with an increased viral burden and blunted responses to MaR1. Together, these findings have uncovered a multi-pronged protective signaling axis for MaR1-Lgr6, improving Tregs's suppressive function and upregulating host antiviral genes resulting in decreased viral burden and pathogen-mediated inflammation, ultimately promoting restoration of airway mucosal homeostasis.

Intranasal administration of nucleus-deliverable GATA3-TMD alleviates the symptoms of allergic asthma.

Although the T helper 2 (Th2) subset is a critical player in the humoral immune response to extracellular parasites and suppression of Th1-mediated inflammation, Th2 cells have been implicated in allergic inflammatory diseases such as asthma, allergic rhinitis, and atopic dermatitis. GATA binding protein 3 (GATA3) is a primary transcription factor that mediates Th2 differentiation and secretion of Th2 cytokines, including IL-4, IL-5, and IL-13. Here, a nucleus-deliverable form of GATA3-transcription modulation domain (TMD) (ndG3-TMD) was generated using Hph-1 human protein transduction domain (PTD) to modulate the transcriptional function of endogenous GATA3 without genetic manipulation. ndG3-TMD was shown to be efficiently delivered into the cell nucleus quickly without affecting cell viability or intracellular signaling events for T cell activation. ndG3-TMD exhibited a specific inhibitory function for the endogenous GATA3-mediated transcription, such as Th2 cell differentiation and Th2-type cytokine production. Intranasal administration of ndG3-TMD significantly alleviated airway hyperresponsiveness, infiltration of immune cells, and serum IgE level in an OVA-induced mouse model of asthma. Also, Th2 cytokine secretion by the splenocytes isolated from the ndG3-TMD-treated mice substantially decreased. Our results suggest that ndG3-TMD can be a new therapeutic reagent to suppress Th2-mediated allergic diseases through intranasal delivery.

Protective effects of CRTH2 suppression in dry age-related macular degeneration.

Age-related macular degeneration (AMD) is the leading cause of central vision loss in the elderly. Oxidative stress-induced retinal pigment epithelium (RPE) cell apoptosis is a crucial pathogenic hallmark in AMD. Chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2), a prostaglandin (PG) D2 receptor, has been implicated in various pathophysiological events, especially inflammation and stress-induced cell apoptosis. However, its specific role in AMD is not fully understood. Here we studied the effect of CRTH2 on AMD. Our results showed that when stimulated by H2O2, CRTH2 mRNA expression in cells tended to increase. Flow cytometry revealed that the CRTH2 inhibitor could protect the RPE from apoptosis. After NaIO3 injection, a larger area of retinal degeneration was observed in wild-type mice than in CRTH2-/- mice. Optical coherence tomography (OCT) and Hematoxylin and Eosin (H&E) staining of retinal sections showed that sodium iodate-induced loss of photoreceptor cells was reduced in CRTH2-/- mice after treatment; TUNEL-positive cells were mostly found in the outer nuclear layer. In the control group, NaIO3 stimulation increased the number of TUNEL-positive cells, whereas the percentage of TUNEL-positive cells was significantly lower in CRTH2-/- mice. Similarly, the CRTH2 receptor inhibitor CAY10471 similarly inhibited sodium iodate-induced retinal damage. Our results suggest that targeting CRTH2 is a promising therapeutic strategy for the treatment of progressive retinal degeneration in AMD.

Poly-ADP ribose polymerase-14 limits severity of allergic skin disease.

Poly-ADP ribose polymerase-14 (PARP14 or ARTD8) was initially identified as a transcriptional co-activator for signal transducer and activator of transcription 6 (Stat6), where the presence of interleukin-4 (IL-4) and activated Stat6 induces the enzymatic activity of PARP14 that promotes T helper type 2 differentiation and allergic airway disease. To further our understanding of PARP14 in allergic disease, we studied the function of PARP14 in allergic inflammation of skin using mice that express constitutively active Stat6 in T cells (Stat6VT) and develop spontaneous inflammation of the skin. We mated Stat6VT mice to Parp14-/- mice and observed that approximately 75% of the Stat6VT × Parp14-/- mice develop severe atopic dermatitis (AD)-like lesions, compared with about 50% of Stat6VT mice, and have increased morbidity compared with Stat6VT mice. Despite this, gene expression in the skin and the cellular infiltrates was only modestly altered by the absence of PARP14. In contrast, we saw significant changes in systemic T-cell cytokine production. Moreover, adoptive transfer experiments demonstrated that decreases in IL-4 production reflected a cell intrinsic role for PARP14 in Th2 cytokine control. Hence, our data suggest that although PARP14 has similar effects on T-cell cytokine production in several allergic disease models, the outcome of those effects is distinct, depending on the target organ of disease.

Priming with high and low respiratory allergen dose induces differential CD4+ T helper type 2 cells and IgE/IgG1 antibody responses in mice.

Sensitization of allergic patients normally takes place over several years and is the result of repeated exposure to low levels of allergen. Most mouse asthma models use a high dose of allergen administered over a short period. We have investigated the role of dose in the immune response to an inhaled respiratory allergen (Blomia tropicalis). We observed the effect of priming dose on the allergic response in mice intranasally immunized with low (0·5 µg) and high (50 µg) doses of B. tropicalis extract and killed 1 day after the last challenge. For both doses of allergen, T helper type 2 (Th2) cells and Th2 cytokines were evident as well as eosinophilic inflammation accompanied by mucus hyper-secretion. By contrast, IgE and IgG1 antibody responses were normally only detected at high-dose priming. To investigate the mechanism for these effects, we found group 2 innate lymphoid cells (ILC2s) were increased 48 hr after challenge in the low-dose-treated but not the high-dose-treated mice. Furthermore, we determined whether repeated low-dose exposure with different priming protocols could induce an antibody response. Repeated low-dose exposure to 0·5 µg three times weekly for 4 weeks (cumulative 6 µg) had the same effect as a shorter high-dose exposure (cumulative 80 µg) and increasing cumulative dose induced antibody responses. These data indicate that low doses of allergen are sufficient to prime Th2 cells and ILC2s, but insufficient to induce antibody responses. Cumulative exposure to small amounts of allergen induces both Th2 and antibody responses and may better reflect natural sensitization.

Lung CD200 Receptor Activation Abrogates Airway Hyperresponsiveness in Experimental Asthma.

In allergic asthma, homeostatic pathways are dysregulated, which leads to an immune response toward normally innocuous antigens. The CD200-CD200 receptor pathway is a central regulator of inflammation, and CD200 expression was recently found to be down-regulated in circulating leukocytes of patients with asthma. Given the antiinflammatory properties of CD200, we investigated whether local delivery of recombinant CD200 (rCD200) could reinstate lung homeostasis in an experimental model of asthma. Brown Norway rats were sensitized with ovalbumin (OVA) and alum. rCD200 was intratracheally administered 24 hours before OVA challenge, and airway responsiveness to methacholine was measured 24 hours after the allergen challenge. Inflammation was also assessed by measuring cell recruitment and cytokine levels in bronchoalveolar lavages, as well as lung and draining lymph node accumulation of dendritic cells (DCs) and T cells. In sensitized rats, rCD200 abolished airway hyperresponsiveness, whereas the sham treatment had no effect. In addition, rCD200 strongly reduced OVA-induced lung accumulation of myeloid DCs, CD4(+) T cells, and T helper type 2 cells. This was associated with a strong reduction of OVA-induced IL-13 level and with an increase of IL-10 in supernatants of bronchoalveolar lavages. Lung eosinophilia and draining lymph node accumulation of myeloid DCs and T cells were not affected by rCD200. Overall, these data reveal that rCD200 can inhibit airway hyperresponsiveness in a model of asthma by a multistep mechanism associated with local alterations of the T cell response and the cytokine milieu.

Indomethacin inhibits eosinophil migration to prostaglandin D2 : therapeutic potential of CRTH2 desensitization for eosinophilic pustular folliculitis.

Indomethacin is a cyclo-oxygenase inhibitor, and shows therapeutic potential for various eosinophilic skin diseases, particularly eosinophilic pustular folliculitis. One of the unique characteristics of indomethacin is that, unlike other non-steroidal anti-inflammatory drugs, it is a potent agonist of chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2), a receptor for prostaglandin D2 (PGD2 ). This study investigated the pharmacological actions of indomethacin on eosinophil migration to clarify the actual mechanisms underlying the therapeutic effects of indomethacin on eosinophilic pustular folliculitis. Eosinophils exhibited chemokinetic and chemotactic responses to both PGD2 and indomethacin through CRTH2 receptors. Pre-treatment of eosinophils with indomethacin greatly inhibited eosinophil migration to PGD2 and, to a much lesser extent, to eotaxin (CCL11); these effects could be mediated by homologous and heterologous desensitization of eosinophil CRTH2 and CCR3, respectively, by agonistic effects of indomethacin on CRTH2. Indomethacin also cancelled a priming effect of Δ(12) -PGJ2 , a plasma metabolite of PGD2 , on eosinophil chemotaxis to eotaxin. Indomethacin down-modulated cell surface expression of both CRTH2 and CCR3. Hair follicle epithelium and epidermal keratinocytes around eosinophilic pustules together with the eccrine apparatus of palmoplantar lesions of eosinophilic pustular folliculitis were immunohistochemically positive for lipocalin-type PGD synthase. Indomethacin may exert therapeutic effects against eosinophilic skin diseases in which PGD2 -CRTH2 signals play major roles by reducing eosinophil responses to PGD2 .

One-Step Automatic Radiosynthesis and Evaluation of [18F]TM-30089 as GPR44 Radiotracer.

Recently, a G-protein coupled receptor 44 (GPR44) was discovered to play a significant role in the process of inflammation-related diseases, including cancer and diabetes. However, the precise role of GPR44 has yet to be fully elucidated. Currently, there is a strong and urgent need for the development of GPR44 radiotracers as a non-invasive methodology to explore the exact mechanism of GPR44 on inflammation-related diseases and monitor the progress of therapy. TM-30089 is a potent GPR44 antagonist that exhibits a high specificity and selectivity for GPR44. Its structure contains a fluorine nuclide, which could potentially be replaced with 18F. In the present study, we successfully took a highly effective synthesis strategy that pretreated the unprotected carboxylic acid group of the precursor and developed a feasible one-step automatic radiosynthesis strategy for [18F]TM-30089 with a high radiochemical purity and a good radiochemical yield. We further evaluated this radiotracer using mice models implanted with 1.1 B4 cell lines (GPR44-enriched cell lines) and human islets (high GPR44 expression), respectively. The results revealed the persistent and specific uptake of [18F]TM-30089 in GPR44 region, indicating that [18F]TM-30089 is a promising candidate for targeting GPR44. Further evaluation is ongoing.

Pruritus as a Distinctive Feature of Type 2 Inflammation.

Pruritus is a common symptom of several skin diseases, both inflammatory and neoplastic. Pruritus might have a tremendous impact on patients' quality of life and strongly interfere with sleep, social, and work activities. We review the role of type-2 inflammation and immunity in the pathogenesis of chronic pruritic conditions of the skin. Type 2 cytokines, including IL-4, IL-13, thymic stromal lymphopoietin, periostin, IL-31, IL-25, and IL-33 are released by mast cells, innate lymphoid cells 2, keratinocytes, and type 2 T lymphocytes, and are master regulators of chronic itch. These cytokines might act as direct pruritogen on primary sensory neurons (pruriceptors) or alter the sensitivity to other itch mediators Type 2 inflammation- and immunity-dominated skin diseases, including atopic dermatitis, prurigo nodularis, bullous pemphigoid, scabies, parasitic diseases, urticaria, and Sézary syndrome are indeed conditions associated with most severe pruritus. In contrast, in other skin diseases, such as scleroderma, lupus erythematosus, hidradenitis suppurativa, and acne, type 2 inflammation is less represented, and pruritus is milder or variable. Th2 inflammation and immunity evolved to protect against parasites, and thus, the scratching response evoked by pruritus might have developed to alert about the presence and to remove parasites from the skin surface.

Acute hepatitis B virus infection model within the host incorporating immune cells and cytokine responses.

We formulate and analyze a within-host hepatitis B viral mathematical model for hepatitis B in the acute phase of infection. The model incorporates hepatocytes, hepatitis B virus, immune system cells and cytokine dynamics using a system of ordinary differential equations. We use the model to demonstrate the trends of the hepatitis B infection qualitatively without the effects of immune cells and cytokines. Using these trends, we tested the effects of incorporating the immune cells only and immune cells with cytokine responses at low and high inhibitions on the hepatitis B virus infection. Our results showed that it is impossible to have the immune cells work independently from cytokines when there is an acute hepatitis B virus infection. Therefore, our results suggest that incorporating immune cells and cytokine dynamics in the acute hepatitis B virus infection stage delays infection in the hepatocytes and excluding such dynamics speeds up infection during this phase. Results from this study are useful in developing strategies for control of hepatocellular carcinoma which is caused by hepatitis B virus infection.

Elevated circulating Th2 but not group 2 innate lymphoid cell responses characterize canine atopic dermatitis.

Atopic dermatitis (AD) is an allergic skin disease that causes significant morbidity and affects multiple species. AD is highly prevalent in companion dogs, and the clinical management of the disease remains challenging. An improved understanding of the immunologic and genetic pathways that lead to disease could inform the development of novel treatments. In allergic humans and mouse models of AD, the disease is associated with Th2 and group 2 innate lymphoid cell (ILC2) activation that drives type 2 inflammation. Type 2 inflammation also appears to be associated with AD in dogs, but gaps remain in our understanding of how key type 2-associated cell types such as canine Th2 cells and ILC2s contribute to the pathogenesis of canine AD. Here, we describe previously uncharacterized canine ILC2-like cells and Th2 cells ex vivo that produced type 2 cytokines and expressed the transcription factor Gata3. Increased circulating Th2 cells were associated with chronic canine AD. Single-cell RNA sequencing revealed a unique gene expression signature in T cells in dogs with AD. These findings underline the importance of pro-allergic Th2 cells in orchestrating AD and provide new methods and pathways that can inform the development of improved therapies.

The evolution of the EGFRvIII (rindopepimut) immunotherapy for glioblastoma multiforme patients.

Glioblastoma Multiforme (GBM) is the most common type of brain tumor and it is uniformly fatal. The community standard of treatment for this disease is gross or subtotal resection of the tumor, followed by radiation and temozolomide. At recurrence bevacizumab can be added for increased progression free survival. Many challenges are encountered while trying to devise new drugs to treat GBM, such as the presence of the blood brain barrier which is impermeable to most drugs. Therefore in the past few years attention was turned to immunological means for the treatment of this devastating disease. EGFRvIII targeting has proven a good way to attack glioblastoma cells by using the immune system. Although in still in development, this approach holds the promise as a great first step toward immune-tailored drugs for the treatment of brain cancers.

Reversible expression of CD138 on mature follicular B cells is downregulated by IL-4.

CD138, known as a marker of plasma cells, was reported to be expressed to an intermediate level in the murine bone marrow precursor B cells. Here an intermediate level of CD138 expression was also noted in a subpopulation of splenic follicular B cells, which were distinguishable from CD138(high) plasma cells, whereas the majority of transitional or marginal zone B cells did not express CD138. These CD138(int) B cells were IgM(low)IgD(high) mature B cells, located within follicular B cell zone, and expressed a lower level of CD21 than CD138(-) follicular B cells. During in vitro culture of splenic cells, the proportion of CD138(int) B cells increased, which was noticeably reversed by the addition of IL-4 to the culture. The experiments with sorted CD138(int) cells showed that IL-4-mediated regulation of the CD138 expression was B cell-intrinsic and independent of in vitro B cell death. Our results demonstrate that mouse CD138(int) B cells characterize a subpopulation of IgM(low)IgD(high) mature follicular B cells. The CD138 expression on follicular B cells may represent a reversible status, reflecting a dynamic state probably influenced by IL-4.