Helianthus tuberosus agglutinin directly induces neutrophil migration, which can be modulated/inhibited by resident mast cells.

We investigated the effect of Helianthus tuberosus agglutinin (HTA) on neutrophil migration in vivo and in vitro. The role of resident cells in this effect was analyzed. Peritonitis was induced by injecting stimuli into rat (150-200 g) peritoneal cavities, and in vitro neutrophil chemotaxis was performed using a Boyden microchamber. HTA (80, 200, or 500 microg/mL per cavity) induced significant in vivo neutrophil migration (p < 0.05); in vitro assays showed that this lectin also induced neutrophil chemotaxis, an effect inhibited by the incubation of lectin associated with alpha-D(+)-mannose, its specific binding sugar. Depletion of the resident-cell population by peritoneal lavage did not alter HTA-induced neutrophil migration (200 microg/mL per cavity). The opposite strategy, increasing peritoneal macrophages by intraperitoneally injecting rats with thioglycollate, did not enhance the neutrophil migration produced by HTA (200 microg/mL per cavity). In addition, injection of supernatant from HTA-stimulated macrophage culture (300 microg/mL) into rat peritoneal cavities did not induce neutrophil migration. However, reduction of the peritoneal mast-cell population potentiated the neutrophil migration (p < 0.05) induced by HTA (200 microg/mL per cavity). Lectin from H. tuberosus has a direct neutrophil chemotatic effect that is modulated by mast cells.

Pro-inflammatory effect of Arum maculatum lectin and role of resident cells.

Arum maculatum agglutinin (AMA) is a monocot lectin isolated from tubers of Arum maculatum L. (Araceae) which exhibits different specificity towards oligo-mannosidic-type and N-acetyllactosaminic-type glycans. We have investigated the effect of this lectin on the cells of the immune system. Models of neutrophil migration in vivo, neutrophil chemotaxis in vitro and macrophage cultures were used to study the lectin inflammatory activity. When administered into rat peritoneal cavities, AMA (80, 200 and 500 microg/mL/cavity) induced significant and dose-dependent neutrophil migration. This effect was inhibited by incubation with alpha-methyl-d-mannoside. A 83% depletion in the number of resident cells following peritoneal lavage did not reduce the AMA-induced neutrophil migration, as compared to sham animals (not washed). However, pre-treatment with 3% thioglycolate which increases the peritoneal macrophage population by 236%, enhanced the neutrophil migration induced by AMA (200 microg/mL/cavity) (119%, p < 0.05). Reduction of peritoneal mast cell population by chronic treatment of cavities with compound 48/80 did not modify AMA-induced neutrophil migration. The neutrophil chemotaxy assay in vitro shows that the lectin (300 microg/mL) induces neutrophil chemotaxy (368% p < 0.05) compared to RPMI. Finally, injection into peritoneal cavities of supernatants from macrophage cultures obtained after stimulation with AMA (300 microg/mL) enhanced neutrophil migration (110% p < 0.05). Summarizing, our data suggest that A. maculatum agglutinin presents pro-inflammatory activity, inducing neutrophil migration by two ways, one which is independent on resident cells and another one dependent on the presence of these cells.

The galactose-binding lectin from Vatairea macrocarpa seeds induces in vivo neutrophil migration by indirect mechanism.

To explore the pathways by which lectins induce an inflammatory response, the lectin from Vatairea macrocarpa (VML) seeds was used to induce neutrophil migration in rats. The lectin was shown to cause cell migration, with the effect partially blocked when galactose was added to inhibit lectin activity. Neutrophil migration was also reduced when peritoneal cavity of the animals was depleted of their resident cells beforehand, suggesting that neutrophil migration was mediated by an indirect mechanism. Pre-treatment of rats with thioglycollate increased recruitment of neutrophils while depletion of mast cells by the addition of compound 48/80 had little effect on neutrophil infiltration, suggesting the involvement of macrophages in the inflammatory process induced by the lectin. Inhibition of the cyclooxigenase, leukotriene and PAF activities by indomethacin, MK886 and BN50730, respectively, did not modify the pro-inflammatory effect previously observed. However, dexamethasone and thalidomide significantly reduced the population of neutrophils in the peritoneal cavity after lectin injection. The present study suggests that the effects produced by a galactose-binding lectin do not involve lipoxygenase, cyclooxygenase or PAF mediators that are well known to be involved in the inflammatory process. The blocking actions of dexamethasone and thalidimide suggest that as yet unidentified pro-inflammatory mediators are involved.

Disodium chlodronate prevents bone resorption in experimental periodontitis in rats.

BACKGROUND: Periodontitis is a chronic disease characterized by alveolar bone loss and inflammatory changes. We studied the effect of disodium chlodronate (CD), a bisphosphonate used in metastatic and metabolic bone disease as a bone resorbing drug, in an experimental periodontitis model (EPD) focusing on anti-resorptive and anti-inflammatory parameters. METHODS: A nylon thread ligature was placed around the left maxillary molars of 72 male Wistar rats who were sacrificed after 7 or 11 days. Groups were treated daily with CD (1, 5, or 25 mg/kg/sc) starting at day 0 until day 7 (prophylactic CD) or from day 5 until day 11 (curative CD) after periodontitis induction. Non-treated group (NT) consisted of rats subjected to periodontitis that received no pharmacological treatment. Alveolar bone loss (ABL) was measured as the distance between the cuspid tips and the alveolar bone. The right jaw was used as control. The hemiarcades were processed for histopathologic analysis. RESULTS: In NT group there was significant ABL, severe mononuclear cells influx, and increase in osteoclast numbers. Prophylactic CD treatment decreased the ABL 25.8%, 61.6%, and 75.5% as compared to NT for the 1, 5, and 25 mg/kg CD doses, respectively. Curative CD treatment decreased the ABL 20%, 62%, and 69% as compared to NT for the 1, 5 and 25 mg/kg CD doses, respectively. Both prophylactic and curative CD decreased histological changes, as compared to NT rats (P <0.01). CONCLUSIONS: CD has both bone sparing and anti-inflammatory activity in EPD in rats when administered as a pretreatment or in an ongoing process. The possibility of using CD as an alternative treatment in human periodontitis should be considered.

Bloqueio seletivo da ciclooxigenase tipo 2 inibe a reabsorção óssea inflamatória em ratos / Selective blocking of type 2 cyclooxygenase inhibits inflammatory bone loss in rats

Objetivo - Considerando que as prostaglandinas participam na reabsorção óssea inflamatória e que não se dispõe de modelos in vivo que permitam quantificar macroscopicamente a perda óssea, decidiu-se investigar se um inibidor seletivo da ciclooxigenase do tipo 2 (meloxicam-MLX) seria capaz de alterar a perda óssea alveolar em um modelo de periodontite, bem como comparar seus efeitos sobre a mucosa gástrica em relação aos de um inibidor não seletivo de ciclooxigenase (indometacina-IND). Métodos - Quarenta e oito ratos Wistar foram submetidos à indução da doença periodontal experimental (DPE) através da colocação de um fio de náilon nos molares superiores. A perda óssea foi avaliada em uma hemiarcada como a distância entre a junção amelocementária e o osso alveolar. A outra hemiarcada foi processada para análise histopatológica. Avaliaram-se a curva ponderal e o leucograma. Grupos de animais foram tratados (sc) com IND (n = 6; 0,5, 1 ou 2mg/kg) ou MLX (n=6; 0,75, 1,5 ou 3 mg/kg). Realizou-se análise macroscópica da mucosa gástrica. Resultados - Observou-se no grupo não tratado significante perda óssea, influxo celular, aumento no número de osteoclastos e perda ponderal. IND e MLX reduziram a perda óssea, as alterações histopatológicas, influxo celular e perda ponderal. Os estômagos dos animais tratados com IND (1 e 2mg/kg) apresentaram hemorragia e úlceras, enquanto os animais tratados com MLX exibiram petéquias isoladas apenas com a maior dose (3mg/kg). Conclusão - A inibição de COX preveniu a perda óssea nesse modelo de doença periodontal. MLX apresentou eficácia similar e menor dano à mucosa gástrica do que IND. MLX apresentou melhor relação risco/benefício do que inibidores não seletivos de COX