Papel da exposição à Hidroquinona na artrite reumatoide experimental induzida pelo colágeno / Role of Hydroquinone exposure on experimental collagen-induced arthritis

Artrite reumatoide (AR) é uma doença autoimune, que causa inflamação crônica nas membranas sinoviais de diversas articulações. O modelo experimenal de artrite induzida pelo colágeno (AIC) é empregado para investigar os mecanismos da AR e para identificar potenciais agentes terapêuticos. Embora a etiologia da AR ainda seja desconhecida, há evidências que a AR se desenvolve em indivíduos predispostos geneticamente, após exposição a fatores ambientais, como o tabagismo, que se destaca como maior fator de risco para indução da AR e para o agravamento em pacientes com AR já estabelecida. Porém, o mecanismo efetivo da ação dos diversos componentes do cigarros ainda precisa ser elucidado. A Hidroquinona (HQ) é um composto fenólico, encontrada em concentração elevada no cigarro, com maior ativade pró-oxidativa, além de ser produto da biotransformação do benzeno, também encontrado no cigarro. Neste caso, a HQ é responsável pela imunotoxicidade e mielotoxicidade do benzeno. Devido a alta exposição de fumantes à HQ e a associação do tabagismo com a AR, investigamos se a exposição à HQ teria participação no desenvolvimento da AIC em ratos Wistar. Para tanto, animais foram expostos à HQ em diferentes protocolos experimentais, a saber: A - por 35 dias consecutivos, durante fase de indução e desenvolvimento da artrite; B - por 14 dias consecutivos, até a segunda injeção de colágeno, na fase de sensibilização e indução da AIC; C - por 7 dias consecutivos, do 29º ao 35º dia, na fase posterior ao desenvolvimento da AIC. Os resultados obtidos mostraram que a HQ agravou a AR nos 3 grupos experimentais, aumentando os parâmetros clínicos, o número de células no líquido sinovial, a inflamação nas sinóvias, caracterizada por maior influxo de neutrófilos, proliferação de sinoviócitos (histologia por HE e imunohistoquímica), aumento nos níveis de IL-6 e IL-1ß (ELISA) no líquido sinovial e rearranjo do colágeno na sinóvia (microscopia por segundo harmônico). No entanto, os efeitos mais acentuados foram observados em animais dos grupos A e C, que também tiveram perda de peso significativa. Ademais, exposição à HQ, nos 3 grupos experimentais, causou expressão aumentada do receptor aril hidrocarboneto (AhR), um receptor ativado por xenobióticos durante a AR, e aumento nos níveis do fator de transcrição ROR e de IL-17 na sinóvia. Como AhR/ROR/IL-17 em linfócitos e neutrófilos é uma via importante na gênese da AR, ensaios in vitro foram realizados para elucidar o papel da HQ nesta via. A incubação com HQ in vitro de esplenócitos de animais naive elevou a expressão de AhR e de secreção de IL-17 (por citometria de fluxo), as quais foram bloqueadas pelo antagonista de AhR (α-naftoflavona). Em conjunto, os resultados obtidos nos permitem concluir que a HQ, como um importante componente do cigarro agrava a CIA em ratos, e a ativação via AhR/IL-17 é um possível mecanismo da patogênese da artrite

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation in the joint synovial membranes. The experimental model of collagen-induced arthritis (CIA) is used to investigate the involved mechanisms in RA and to identify novel therapeutic agents. The genesis of RA is multifactorial, involving interplay of genetic and environmental factors and smoking is the trigger factor in the development or RA and worsens the pre-existing RA but the mechanisms undlerlying are yet to be elucidated. Hydroquinone (HQ) is a phenolic compound, found in high concentrations in cigarette, where HQ is the major oxidative component. Moreover, HQ is benzene metabolite, which is also found in cigarette smoke, being responsible for the myelotoxicity and immunotoxicity detected during benzene exposure. Due to this association, we aimed to investigate the role of HQ exposure on CIA development in Wistar rats and the involved mechanisms. Animals were exposed to HQ according to different protocols: A - during 35 consecutive days, during the sensitization and devolpment phases of the disease; B - during 14 consecutive days, until the second injection of collagen, during the sensitization phase; C - during 7 consecutive days, from day 29 to 35, after the development phase of CIA. The results showed that HQ worsened the RA in the 3 experimental protocols, HQ elevated the clinical parameters of CIA development, increased inflammation in the synovial membrane, characterized by increased influx of neutrophis, synoviocytes proliferation (visualized by Immunohistochemistry and Histology analysis), augmented the levels of IL-6 and IL-1ß in the synovial fluid (ELISA assay) and led to intense collagen deposition on the synovia. The most pronounced effects where observed in animals from groups A and C, which also had weight body loss. In addition, in the 3 protocols, HQ exposure also increased the expression of AhR receptor, a receptor activated by xenobiotics during RA, and increased the expression of ROR and levels of IL-17 secretion in the synovial membranes. As AhR/ROR/IL-17 in lymphocytes and neutrophils is an important pathway involved in the genesis of RA, in vitro studies have been performed to elucidate the role of HQ exposure in this pathway. The HQ in vitro treatment augmented the expression of AhR and secretion of IL-17 by splenocytes (FACS assay) and the administration of an AhR antagonist (α-naphtoflavone) blocked these effects. Taken together, the results obtained here allow us to conclude that HQ, as an important cigarette component, aggravates CIA in rats, and the activation of AhR/IL-17 pathway is a possible mechanism involved in the RA pathogenesis

Animal models of osteoarthritis: classification, update, and measurement of outcomes.

Osteoarthritis (OA) is one of the most commonly occurring forms of arthritis in the world today. It is a debilitating chronic illness causing pain and immense discomfort to the affected individual. Significant research is currently ongoing to understand its pathophysiology and develop successful treatment regimens based on this knowledge. Animal models have played a key role in achieving this goal. Animal models currently used to study osteoarthritis can be classified based on the etiology under investigation, primary osteoarthritis, and post-traumatic osteoarthritis, to better clarify the relationship between these models and the pathogenesis of the disease. Non-invasive animal models have shown significant promise in understanding early osteoarthritic changes. Imaging modalities play a pivotal role in understanding the pathogenesis of OA and the correlation with pain. These imaging studies would also allow in vivo surveillance of the disease as a function of time in the animal model. This review summarizes the current understanding of the disease pathogenesis, invasive and non-invasive animal models, imaging modalities, and pain assessment techniques in the animals.

Lactobacillus GG bacteria ameliorate arthritis in Lewis rats.

Probiotic bacteria have beneficial effects in infectious and inflammatory diseases, principally in bowel disorders. In the case of chronic progressive autoimmune arthritides, a major goal of treatment is to reduce inflammation. We hypothesized that probiotic bacteria would ameliorate inflammation found in arthritis models. To assess this effect, Lewis rats were injected with 50 microg bovine alpha-tropomyosin (TRM) or complete Freund's adjuvant (CFA) to induce tropomyosin arthritis (TA) or adjuvant arthritis (AA), respectively. In both models, the rats were divided into 6 groups and fed 0.5 mL/d of the following suspensions: 1) heat-killed Lactobacillus GG (LGG) bacteria; 2) live LGG, both 10(11) colony-forming units (cfu)/L; 3) sterilized milk; 4) plain yogurt; 5) yogurt containing 10(11) cfu/L LGG; or 6) sterilized water. In the disease-prevention experiments, feeding started 1 wk before or after disease induction. In the therapeutic experiments, feeding was initiated at the onset of clinical arthritis. In all experiments, there were significant interactions between time and treatment (P < 0.001), except for milk, which had no effect in the therapeutic experiment. Histologically, rats fed yogurt containing LGG had a milder inflammation in all experiments (P < 0.05), whereas rats fed plain yogurt exhibited a moderate inflammatory score only in the prevention experiments. Anti-TRM antibody titers were not affected by any of the treatments in any of the experiments. Ingestion of live or heat-killed human LGG had a clinically beneficial effect on experimental arthritis. Our observation of the remarkable preventive and curative effect on arthritis using commercial yogurts containing lactobacilli, especially LGG, suggests the need for investigation of these agents in arthritic patients.

[Molecular imaging in rheumatoid arthritis]. / Molekulare Bildgebung bei rheumatoider Arthritis.

Advances in molecular biology and technical developments in the field of imaging are increasingly allowing for non-invasive visualization and quantitation of biological processes at the molecular level. Such technologies, defined as molecular imaging, promise early diagnosis and improved classification of the stage and severity of disease, objective assessment of treatment efficacy, and reliable prognosis based on so-called molecular markers. Furthermore, molecular imaging is an important tool for the evaluation of physiological and pathophysiological processes and for drug development. Various different imaging modalities are available, such as conventional radiography (CR), computed tomography (CT), nuclear imaging, magnetic resonance imaging (MRI), ultrasound (US), as well as other methods including fluorescence-based optical imaging. These methods differ with respect to resolution and their potential to gather information at the anatomical, physiological, cellular and molecular level. Therefore, the choice of the imaging modality for molecular imaging depends on the questions that need to be answered. This review discusses the potential of imaging modalities for molecular imaging in rheumatoid arthritis (RA).

Interleukin-1beta in antigen-induced arthritis of the rabbit temporomandibular joint.

The aim was to investigate joint perfusate levels of interleukin-1beta (IL-1beta) in antigen-induced monoarthritis of the rabbit temporomandibular (TMJ) and knee joints. Twenty-four adult male New Zealand White rabbits were divided into three groups: a control group as well as TMJ arthritis and knee joint arthritis groups. After sensitization, unilateral arthritis was induced by intra-articular injection with ovalbumin and the contralateral joint was injected with saline 3 weeks after induction of arthritis. Joints were then perfused continuously with saline and samples were collected at 10-min intervals over a 50-min period. The IL-1beta concentrations in the samples were then analyzed. After killing the animals, the joints were examined histologically. The IL-1beta concentrations in the samples from the arthritic TMJs and knee joints were significantly higher than in the saline-injected and the control joints. Histological signs of chronic arthritis of similar severity were found in both joints. The IL-1beta levels in the samples from the arthritic TM and knee joints correlated with the histological severity of the arthritis, including pannus formation. In conclusion, this study shows that IL-1beta is released in the synovium of rabbit TMJs and knee joints during antigen-induced arthritis, and that high IL-1beta levels in synovial fluid are associated with histological signs of inflammation including, pannus tissue formation.

Susceptibility of DA rats to arthritis induced with adjuvant oil or rat collagen is determined by genes both within and outside the major histocompatibility complex.

Inbred DA rats are remarkably susceptible to arthritis induced both by non-immunogenic mineral oil only (OIA) and by rat collagen II together with mineral oil (rCIA). This fact enables interesting studies concerning which DA genes are associated with the arthritogenicity of adjuvant oil and collagen, respectively. In this paper the authors have investigated the role of genes within and outside the major histocompatibility complex (MHC), in this respect by comparative susceptibility studies in inbred rat strains (DA, LEW) and MHC-congenic strains (DA.1I, DA.1O, DA.1M, DA.1H, LEW.1AV1, PVG.1AV1). The authors confirm earlier reports on the arthritis-promoting nature of the DA MHC haplotype (RT1av1), but demonstrate that neither OIA nor rCIA is restricted to this haplotype or its class II alleles (Ba, Da). A decisive role of non-MHC genes in determining susceptibility is also clear since the PVG.1AV1 strain, with the permissive RT1av1 haplotype, is resistant to both arthritis models. In conclusion, the authors demonstrate that the susceptibility of DA rats to OIA and rCIA is determined similarly, by permissive genes both within and outside the MHC. Second, and more interesting from a general perspective, the investigation demonstrates a notable influence of genes within and outside the MHC on the pathogenic capacity of a non-immunogenic adjuvant oil. This adjuvant is in turn a critical component in provocations leading not only to rCIA but also to many other experimental autoimmune diseases where the influence of 'adjuvant response genes' is rarely considered.

Synthesis of alpha-glucosidase I inhibitors showing antiviral (HIV-1) and immunosuppressive activity.

The synthesis of a series of analogues of the monosaccharide alpha-glucosidase I inhibitor N-decyl-1-deoxynojirimycin (1) is described. With the incorporation of a single oxygen atom particularly at position seven in the N-decyl side chain, i.e. to give N-7-oxadecyl-dNM (4), the therapeutic ratio (alpha-glucosidase I inhibitory activity over toxicity in HepG2 cells) increases considerably. N-7-Oxadecyl-dNM inhibits purified porcine liver alpha-glucosidase I with an IC50 value of 0.28 microM. The position of the oxygen atom in the N-decyl side chain is of importance since N-3-oxadecyl-dNM is less active and, moreover, is toxic to HepG2 cells at 3 mM. Subsequently, the synthesis of a disaccharide inhibitor of alpha-glucosidase I is described. The aminodisaccharide ManNH2 alpha 1,2Glc (12) inhibits alpha-glucosidase I with an IC50 value of 15.7 microM. Two closely related monosaccharide derivatives of 12 did not inhibit the enzyme at low microM concentrations (no inhibition at 5 microM), showing the additional effect of binding of the aglycon fragment of the molecule to the active site of alpha-glucosidase I. Next, the N-alkyl-dNM derivatives were analysed for antiviral and immunomodulatory activity in-vitro. It is found that the most potent alpha-glucosidase I inhibitor from this study, N-7-oxadecyl-dNM (4) inhibits HIV-1 induced syncytia formation and lymphocyte proliferation in-vitro. Finally, compound 4 was also investigated in-vivo. N-7-Oxadecyl-dNM (4) reduced adjuvant-induced arthritis in rats making this compound a potential candidate for treating autoimmune diseases like rheumatoid arthritis.