Silicone gel and octamethylcyclotetrasiloxane (D4) enhances antibody production to bovine serum albumin in mice

Autoinflammatory/autoimmunity syndrome induced by adjuvants (ASIA; Shoenfeld's syndrome): A new flame

In the present review, recent findings regarding autoimmune/inflammatory syndrome by adjuvants (ASIA) are described. Patients with ASIA present with complaints such as fatigue, cognitive impairment, arthralgias, myalgias, pyrexia, dry eyes and dry mouth. During the last few years, it has been postulated that these symptoms in patients with foreign body implants are due to a chronic inflammatory process and an adjuvant effect of the implanted biomaterial. Ultimately, these inflammatory reactions result in (an increase of) allergies, autoimmune diseases, immune deficiency and/or lymphomas. Pre-existent allergic disease has been found to be an important risk factor for the development of ASIA after foreign body implantation. Explantation of the foreign body results in the majority of patients in an amelioration of the symptoms. There is an urgent need to start adequately adjusted epidemiological studies to obtain better evidence which percentage of patients does develop symptoms and/or diseases such as ASIA, immune deficiency, and/or autoimmune diseases after implant surgery.

Pilot for the Australian Breast Device Registry (ABDR): a national opt-out clinical quality registry for breast device surgery

PURPOSE

To establish a pilot clinical quality registry (CQR) to monitor the quality of care and device performance for breast device surgery in Australia.

PARTICIPANTS

All patients having breast device surgery from contributing hospitals in Australia. A literature review was performed which identified quality indicators for breast device surgery.

FINDINGS TO DATE

A pilot CQR was established in 2011 to capture prospective data on breast device surgery. An interim Steering Committee and Management Committee were established to provide clinical governance, and guide quality indicator selection. The registry's minimum dataset was formulated in consultation with stakeholder groups; potential quality indicators were assessed in terms of (1) importance and relevance, (2) usability, (3) feasibility to collect and (4) scientific validity. Data collection was by a two-sided paper-based form with manual data entry. Seven sites were recruited, including one public hospital, four private hospitals and two day surgeries. Patients were recruited and opt-out consent used.

FUTURE PLANS

The pilot breast device registry provides high-quality population-based data. It provides a model for developing a national CQR for breast devices; its minimum dataset and quality indicators reflect the opinions of the broad range of stakeholders. It is easily scalable, and has formed the basis for other international surgical groups establishing similar registries.

Toxicology of octamethylcyclotetrasiloxane (D4)

Octamethylcyclotetrasiloxane (D₄) is a volatile cyclic siloxane used primarily as a monomer or intermediate in the production of some silicon-based polymers widely used in industrial and consumer applications and may be present as a residual impurity in a variety of consumer products. A robust toxicological data set exists for D_4. Treatment-related results from a chronic inhalation study conducted in rats are limited to mild effects on the respiratory tract, increases in liver weight, increases in the incidence of uterine endometrial epithelial hyperplasia, and a dose-related trend in the incidence of endometrial adenomas. The observed increases in liver weight appear to be related to the induction of hepatic metabolizing enzymes, similar to those that are induced in the presence of phenobarbital. D₄ is not mutagenic or genotoxic in standard in vitro and in vivo tests; therefore, the benign uterine tumors observed likely occur by a non-genotoxic mechanism. Results from mechanistic studies suggest that D₄ has very weak estrogenic and antiestrogenic activity, as well as dopamine agonist-like activity. In rats, D₄ exposure delays ovulation and hypothesized to prolong exposure of the uterine endometrium to endogenous estrogen. Though this mode of action may play a role in the development of benign uterine tumors in the rat, it is considered unlikely to occur in the human due to the marked differences in cycle regulatory mechanisms. Reproductive effects were observed following D₄ exposure in female rats. These effects appear to be related to a delay of the luteinizing hormone (LH) surge, which fails to induce complete ovulation in the rat. However, based on differences in ovulatory control in rats and humans, it appears these effects may be species-specific with no risk or relevance to human health. Results from pharmacokinetic studies indicate that dermal absorption of D₄ is limited, due to its high volatility and, if absorbed via dermal, oral or inhalation exposure, the majority of D₄ is rapidly cleared from the body, indicating bioaccumulation is unlikely.

Octamethylcyclotetrasiloxane (D4)

Octamethylcyclotetrasiloxane (D4; CAS No. 556-67-2) is used as a monomer in the manufacture of polymeric materials, which are widely used in various industrial and/or medical applications, such as breast implants. D4 has a relatively low order of toxicity following acute administration via the oral, dermal, and inhalation routes of exposure and is not considered to be a dermal or eye irritant or to be a dermal sensitizer. There is no appreciable dermal absorption of D4 based on results from in vivo and in vitro studies. D4 has not been shown to be genotoxic/mutagenic when tested in a number of short-term in vitro and in vivo assays. Overall, studies have demonstrated adverse effects on specific female reproductive endpoints at higher exposure concentrations; however, no D4 exposure-specific effects were noted with respect to developmental endpoints. Inhalation exposure of rats to 700 ppm D4 for up to 24 months produced effects in the liver, kidney, and uterus (weight changes, hepatocellular hypertrophy, endometrial hyperplasia, and nephropathy). Changes in the nasal epithelium (eosinophilic globules) were also noted at 150 and 700 ppm. Despite 24 months of exposure, only mild to minimal inflammatory responses were found at 150 ppm, and overall, the basic integrity of the respiratory tract was unchanged at this dose. At 700 ppm, there was an increased incidence of endometrial adenomas in female rats. Based on the adverse changes in the respiratory tract, kidney, and female reproductive tract in the chronic inhalation study, 150 ppm was determined to be the no-observed-adverse-effect level (NOAEL) and was selected as the point of departure for the derivation of the workplace environmental exposure level (WEEL®) value. The inhalation NOAEL was adjusted to account for interindividual variability and residual uncertainty regarding upper respiratory tract changes still occurring at 150 ppm. An 8-h time-weighted average WEEL value of 10 ppm is expected to provide a significant margin of safety against any potential adverse health effects in workers exposed to airborne D4.

Silicone implants and lymphoma: The role of inflammation

The risk of hematological malignancies is mainly determined by genetic background, age, sex, race and ethnicity, geographic location, exposure to certain chemicals and radiation; along with the more recently proposed immune factors such as chronic inflammation, immunodeficiencies, autoimmunity, and infections. Paradigmatic examples include the development of lymphoma in Sjögren's syndrome and Hashimoto thyroiditis, gastric MALT lymphoma in Helicobacter pylori infection, or lymphomas associated with infections by Epstein-Barr virus, human herpes virus 8 (HHV 8) and leukemia/lymphoma virus 1 (HTLV-1). A growing number of reports indicates an increased risk of lymphoma, particularly of the anaplastic large cell (ALCL) type. The implants, specifically those used in the past, elicit chronic stimulation of the immune system against the prosthetic material. This is particularly the case in genetically susceptible hosts. We suggest that polyclonal activation may result in monoclonality in those at risk hosts, ultimately leading to lymphoma. We suggest that patients with an inflammatory response against silicone implants be monitored carefully.

Antibodies to squalene in Gulf War syndrome

Gulf War Syndrome (GWS) is a multisystemic illness afflicting many Gulf War-era veterans. The molecular pathological basis for GWS has not been established. We sought to determine whether the presence of antibodies to squalene correlates with the presence of signs and symptoms of GWS. Participants in this blinded cohort study were individuals immunized for service in Desert Shield/Desert Storm during 1990-1991. They included 144 Gulf War-era veterans or military employees (58 in the blinded study), 48 blood donors, 40 systemic lupus erythematosus patients, 34 silicone breast implant recipients, and 30 chronic fatigue syndrome patients. Serum antibodies to squalene were measured. In our small cohort, the substantial majority (95%) of overtly ill deployed GWS patients had antibodies to squalene. All (100%) GWS patients immunized for service in Desert Shield/Desert Storm who did not deploy, but had the same signs and symptoms as those who did deploy, had antibodies to squalene. In contrast, none (0%) of the deployed Persian Gulf veterans not showing signs and symptoms of GWS have antibodies to squalene. Neither patients with idiopathic autoimmune disease nor healthy controls had detectable serum antibodies to squalene. The majority of symptomatic GWS patients had serum antibodies to squalene.

Toxicology and humoral immunity assessment of octamethylcyclotetrasiloxane (D4) following a 28-day whole body vapor inhalation exposure in Fischer 344 rats

Octamethylcyclotetrasiloxane, D4, is a low viscosity, silicone fluid consisting of four dimethyl-siloxy units ((CH3)2SiO)4 in a cyclic structure. It is primarily used as a building block in the industrial synthesis of long chain silicone polymers. The combination of D4 with decamethylcyclopentasiloxane (D5) is commonly referred to as cyclomethicone which has a wide range of applications as a formulation aid in personal care products. To extend the existing database regarding the biological activities of D4, a 28 day whole body vapor inhalation study was conducted using Fischer 344 rats at 0 (room air), 7, 20, 60, 180 and 540 ppm for 6 hours/day, 5 days/week. Parameters measured included body weights, organ weights, gross pathology, histopathology, serum chemistries, and urinalysis. In addition to these standard toxicological endpoints, the ability of D4 exposed animals to mount an IgM antibody response was evaluated by a splenic antibody forming cell (AFC) assay and a serum enzyme-linked immunosorbant assay (ELISA). The results of this 28-day inhalation study indicate that D4 exposure caused no adverse effects on body weight, food consumption, or urinalysis parameters. In addition, there were no exposure related histopathological alterations at any site for any exposure group. A statistically significant increase in liver weight and the liver to body weight ratio was observed in both male (180-540 ppm) and female (20-540 ppm) rats, which was not observed in the 14-day recovery group animals. There were no other significant organ weight changes. Although statistically significant changes were observed in several hematological and serum chemistry parameters in both the terminal and 14-day recovery animals, the changes were marginal and within the normal range of values for the rat. Under these experimental conditions, there were no alterations noted in immune system function at any of the D4 exposure levels.

The immunopathology of siliconosis. History, clinical presentation, and relation to silicosis and the chemistry of silicon and silicone

Recent evidence confirms the fundamental involvement of the human immune system in the reaction to implantation of silicone-based medical devices. An as yet-to-be particularized epitope of many complex substances sharing siloxane structures is presented through the MHC-II apparatus with development and retention of T cell memory. This memory can be tested for in practical terms using one or more forms of silica, which links the immuno-histopathology and autoimmune attributes of "silicosis" with those of "siliconosis." The lesions of siliconosis are typical of those for persistent antigens and delayed, cell mediated hypersensitivity. The basic descriptive pathology of the reaction to silicone has been known since soon after introduction of silicones in medical procedures, with the exception of some details related to the more recent discoveries on the role of cytokines in the immunopathic process. The clinical consequences of siliconosis are common and can be severe in some individuals implanted with silicone devices.