Lipoxin A4 impairs effective bacterial control and potentiates joint inflammation and damage caused by Staphylococcus aureus infection.

Staphylococcus aureus is the main cause of septic arthritis in humans, a disease associated with high morbidity and mortality. Inflammation triggered in response to infection is fundamental to control bacterial growth but may cause permanent tissue damage. Here, we evaluated the role of Lipoxin A4 (LXA4 ) in S aureus-induced arthritis in mice. Septic arthritis was induced by S aureus injection into tibiofemoral joints. At different time points, we evaluated cell recruitment and bacterial load in the joint, the production of pro-inflammatory molecules, and LXA4 in inflamed tissue and analyzed joint damage and dysfunction. LXA4 was investigated using genetically modified mice or by pharmacological blockade of its synthesis and receptor. CD11c+ cells were evaluated in lymph nodes by confocal microscopy and flow cytometry and dendritic cell chemotaxis using the Boyden chamber. Absence or pharmacological blockade of 5-lipoxygenase (5-LO) reduced joint inflammation and dysfunction and was associated with better control of infection at 4 to 7 days after the infection. There was an increase in LXA4 in joints of S aureus-infected mice and administration of LXA4 reversed the phenotype in 5-LO-/- mice. Blockade or absence of the LXA4 receptor FPR2 has a phenotype similar to 5-LO-/- mice. Mechanistically, LXA4 appeared to control migration and function of dendritic cells, cells shown to be crucial for adequate protective responses in the model. Thus, after the first days of infection when symptoms become evident therapies that inhibit LXA4 synthesis or action could be useful for treatment of S aureus-induced arthritis.

Maresin-2 inhibits inflammatory and neuropathic trigeminal pain and reduces neuronal activation in the trigeminal ganglion.

Pain is a common symptom associated with disorders involving the orofacial structures. Most acute orofacial painful conditions are easily recognized, but the pharmacological treatment may be limited by the adverse events of current available drugs and/or patients' characteristics. In addition, chronic orofacial pain conditions represent clinical challenges both, in terms of diagnostic and treatment. There is growing evidence that specialized pro-resolution lipid mediators (SPMs) present potent analgesic effects, in addition to their well characterized role in the resolution of inflammation. Maresins (MaR-1 and MaR-2) were the last described members of this family, and MaR-2 analgesic action has not yet been reported. Herein the effect of MaR-2 in different orofacial pain models was investigated. MaR-2 (1 or 10 ng) was always delivered via medullary subarachnoid injection, which corresponds to the intrathecal treatment. A single injection of MaR-2 caused a significant reduction of phases I and II of the orofacial formalin test in rats. Repeated injections of MaR-2 prevented the development of facial heat and mechanical hyperalgesia in a model of post-operative pain in rats. In a model of trigeminal neuropathic pain (CCI-ION), repeated MaR-2 injections reversed facial heat and mechanical hyperalgesia in rats and mice. CCI-ION increased c-Fos positive neurons and CGRP+ activated (nuclear pNFkB) neurons in the trigeminal ganglion (TG), which were restored to sham levels by MaR-2 repeated treatment. In conclusion, MaR-2 showed potent and long-lasting analgesic effects in inflammatory and neuropathic pain of orofacial origin and the inhibition of CGRP-positive neurons in the TG may account for MaR-2 action.

Ovarian toxicity by fusariotoxins in pigs: Does it imply in oxidative stress?

Mycotoxins are natural contaminants of food and feed occurring worldwide. Deoxynivalenol (DON) and fumonisin B1 (FB1) are the most frequent fusariotoxins and induce immune and intestinal toxicity in humans and animals. Recently, an association between mycotoxins exposure and impaired fertility has been suggested. However, the effects of these mycotoxins on the reproductive system are not well established. This study aimed to evaluate the effects of FB1 and DON, in combination or alone, on the ovarian morphology and oxidative responses using porcine explants. Seventy-two explants were obtained from six pigs and submitted to the following treatments: control (MEM medium), DON (10 µM), FB1 (100 µM FB1), and DON + FB1 (10 µM + 100 µM). Histological and immunohistochemical assays were performed to evaluate ovarian changes, cell proliferation, and apoptosis. Oxidative stress response was evaluated through lipid peroxidation and antioxidant capacity response assays. The exposure to mycotoxins induced significant histological changes in the ovaries, which were characterized by a decrease in viable follicles and increase in degenerated follicles. A significant decrease in granulosa cell proliferation was observed in explants exposed to all mycotoxins. In addition the multi-contaminated treatment was responsible for an increase in the cell apoptosis index of growing follicles. On the other hand, the FB1 and multi-contaminated treatments induced a significant decrease in lipid peroxidation accompanied by an increase in antioxidant responses. Altogether, our results indicate a reproductive toxicity induced by fusariotoxins. Moreover, mycotoxins, alone or in combination, modulate oxidative stress response, interfering with the production of free radicals and affecting the reproductive capacity of pigs.

Influência do armazenamento de suspensão bacteriana na respostainflamatória em camundongos / Influence of bacterial suspension storage in the inflammatory response in mice

O preparo de suspensão bacteriana é procedimento importante para avaliação da inflamação e podeser obtida por diferentes métodos que precisam ou não do passo de armazenamento. O objetivo destetrabalho foi investigar a influência do armazenamento de suspensão de Staphylococcus aureus na viabilidade bacteriana e sua influência na inflamação in vivo. A suspensão bacteriana de S. aureus ATCC 6538 foi preparada visualmente seguindo o grau 4 da Escala de McFarland. A viabilidade bacteriana nessa solução foi determinada pela contagem de UFC, a qual foi utilizada para induzir artrite séptica e peritonite. O armazenamento por 24 h reduziu as UFC de S. aureus. Essa redução da viabilidadebacteriana resultou em diminuição da hiperalgesia mecânica, edema e recrutamento leucocitário na artriteséptica, e recrutamento leucocitário e produção de citocinas na peritonite bacteriana. Estes resultadosdemonstraram que o armazenamento de suspensão bacteriana afetou sua viabilidade, resultando emdiminuição da resposta inflamatória in vivo, sugerindo a importância de padronizar procedimentos parao preparo de suspensão bacteriana. Uma abordagem concebível seria determinar o número de UFC em um específico grau da Escala de McFarland, o qual permitirá o preparo e o uso de uma suspensão bacteriana no mesmo dia para os testes in vivo.

The preparation of bacterial suspension is an important procedure used in laboratories for inflammatoryevaluation protocols and can be obtained by different methods that need or not need step storage. The aimof this work was investigate the influence of storage of Staphylococcus aureus suspension in bacterialviability and its influence in bacteria-induced inflammation in vivo. The bacterial suspension of S. aureus ATCC 6538 was prepared accordingly to 4th degree of McFarland’s Scale by visual comparison. This suspension was used to determine by CFU counting the bacterial viability and for administration to the animals to induce septic arthritis and peritonitis. Twenty four hours of storage reduced the S. aureus CFU. As a consequence of reduced bacterial viability, was detected reduced mechanical hyperalgesia, edema and leukocyte recruitment in septic arthritis and leukocyte recruitment and cytokine production bacterial peritonitis. These results demonstrate that storage of bacterial suspension affected bacterialviability, which resulted in diminished inflammatory response in vivo, raising the importance of standardprocedures for bacterial suspension preparation. A conceivable approach would be to determine the number of CFU at a specific McFarland’s scale degree, which will allow the preparation and use a bacterial suspension in the same day for in vivo testing.