Enhancement of ovalbumin-specific Th1, Th2, and Th17 immune responses by amorphous silica nanoparticles.

Nanomaterials present in cosmetics and food additives are used for industrial applications. However, their safety profile is unclear. Amorphous silica nanoparticles (nSPs) are a widely used nanomaterial and have been shown to induce inflammatory cytokines following intratracheal administration in mice. The current study investigated the adjuvant effect of nSP30 (nSP with a diameter of 33 nm) on T helper (Th)1, Th2, and Th17 immune responses as well as immunoglobulin (Ig) levels in mice. BALB/c mice were intraperitoneally administered ovalbumin (OVA) with or without varying doses and varying sizes of nSPs. The adjuvant effect of nSPs was investigated by measuring OVA-specific IgG antibodies in sera, OVA-specific proliferative responses of splenocytes, and the production of Th1, Th2, and Th17 cytokines. Aluminum hydroxide was used as a positive adjuvant control. Anti-OVA IgG production, splenocyte proliferative responses, and secretion of IFN-γ, IL-2, IL-4, IL-5, and IL-17 were increased significantly in mice receiving a combined injection of nSP30 (30 or 300 µg) with OVA compared with OVA alone or a combined injection with nSP30 (3 µg). The responses were nSP30 dose-dependent. When different sized nSPs were used (with 30, 100, and 1000 nm diameters), the responses to OVA were enhanced and were size-dependent. The smaller sized nSP particles had a greater adjuvant effect. nSPs appear to exert a size-dependent adjuvant effect for Th1, Th2, and Th17 immune responses. Understanding the mechanisms of nSP adjuvanticity might lead to the development of novel vaccine adjuvants and therapies for allergic diseases caused by environmental factors.

Amorphous nanosilica particles block induction of oral tolerance in mice.

The mucosal immune system is exposed to non-self antigens in food and the gut microbiota. Therefore, the recognition of orally ingested non-self antigens is suppressed in healthy individuals to avoid excessive immune responses in a process called "oral tolerance". The breakdown of oral tolerance has been cited as a possible cause of food allergy, and amorphous silica nanoparticles (nSP) have been implicated in this breakdown. As nSP are widely used in foodstuffs and other products, exposure to them is increasing; thus, investigations of any effects of nSP on oral tolerance are urgent. This study evaluated the effects of nSP30 (particle diameter = 39 nm) on immunological unresponsiveness induced in mice with oral ovalbumin (OVA). Specifically, production of OVA-specific antibodies, splenocyte proliferation in response to OVA, and effects on T-helper (TH)-1, TH2, and TH17 responses (in terms of cytokine and IgG/IgE subclass expression) were evaluated. nSP30 increased the levels of OVA-specific IgG in OVA-tolerized mice and induced the proliferation of OVA-immunized splenocytes in response to OVA in a dose-related manner. nSP30 also increased the expression of OVA-specific IgG1, IgE, and IgG2a, indicating stimulation of the TH1 and TH2 responses. The expression of interferon (IFN)-γ (TH1), interleukin (IL)-4 and IL-5 (TH2), and IL-17 (TH17) was also stimulated in a dose-related manner by nSP30 in splenocytes stimulated ex vivo with OVA. The induction of tolerance by OVA, the production of anti-OVA IgG antibodies, and proliferation of splenocytes in response to OVA was inhibited by nSP30 in conjunction with OVA and was dose-related. The nSP30 enhanced TH1 and TH2 responses that might prevent the induction of oral tolerance. Overall, this study showed that the abrogation of OVA-induced oral tolerance in mice by exposure to nSP30 was dose-related and that nSP30 stimulated TH1, TH2, and TH17 responses.

Intra-/inter-laboratory validation study on reactive oxygen species assay for chemical photosafety evaluation using two different solar simulators.

A previous multi-center validation study demonstrated high transferability and reliability of reactive oxygen species (ROS) assay for photosafety evaluation. The present validation study was undertaken to verify further the applicability of different solar simulators and assay performance. In 7 participating laboratories, 2 standards and 42 coded chemicals, including 23 phototoxins and 19 non-phototoxic drugs/chemicals, were assessed by the ROS assay using two different solar simulators (Atlas Suntest CPS series, 3 labs; and Seric SXL-2500V2, 4 labs). Irradiation conditions could be optimized using quinine and sulisobenzone as positive and negative standards to offer consistent assay outcomes. In both solar simulators, the intra- and inter-day precisions (coefficient of variation; CV) for quinine were found to be below 10%. The inter-laboratory CV for quinine averaged 15.4% (Atlas Suntest CPS) and 13.2% (Seric SXL-2500V2) for singlet oxygen and 17.0% (Atlas Suntest CPS) and 7.1% (Seric SXL-2500V2) for superoxide, suggesting high inter-laboratory reproducibility even though different solar simulators were employed for the ROS assay. In the ROS assay on 42 coded chemicals, some chemicals (ca. 19-29%) were unevaluable because of limited solubility and spectral interference. Although several false positives appeared with positive predictivity of ca. 76-92% (Atlas Suntest CPS) and ca. 75-84% (Seric SXL-2500V2), there were no false negative predictions in both solar simulators. A multi-center validation study on the ROS assay demonstrated satisfactory transferability, accuracy, precision, and predictivity, as well as the availability of other solar simulators.

Establishment and intra-/inter-laboratory validation of a standard protocol of reactive oxygen species assay for chemical photosafety evaluation.

A reactive oxygen species (ROS) assay was previously developed for photosafety evaluation of pharmaceuticals, and the present multi-center study aimed to establish and validate a standard protocol for ROS assay. In three participating laboratories, two standards and 42 coded chemicals, including 23 phototoxins and 19 nonphototoxic drugs/chemicals, were assessed by the ROS assay according to the standardized protocol. Most phototoxins tended to generate singlet oxygen and/or superoxide under UV-vis exposure, but nonphototoxic chemicals were less photoreactive. In the ROS assay on quinine (200 µm), a typical phototoxic drug, the intra- and inter-day precisions (coefficient of variation; CV) were found to be 1.5-7.4% and 1.7-9.3%, respectively. The inter-laboratory CV for quinine averaged 15.4% for singlet oxygen and 17.0% for superoxide. The ROS assay on 42 coded chemicals (200 µm) provided no false negative predictions upon previously defined criteria as compared with the in vitro/in vivo phototoxicity, although several false positives appeared. Outcomes from the validation study were indicative of satisfactory transferability, intra- and inter-laboratory variability, and predictive capacity of the ROS assay.