Antibody responses to Porphyromonas gingivalis infection in a murine abscess model--involvement of gingipains and responses to re-infection

BACKGROUND: Porphyromonas gingivalis is one of the most important periodontopathogens. It produces cysteine proteinases named gingipains. We previously examined the effect of gingipains on abscess formation in a murine model. The rgpA rgpB double and kgp mutants induced smaller abscesses than the wild type. Moreover, the rgpA rgpB kgp triple (gingipain-null) mutant hardly showed lesion formation at all under the experimental conditions used, indicating that genes encoding gingipains are important for P. gingivalis virulence. OBJECTIVES: Here, we further report the humoral immune responses induced by P. gingivalis strains. METHODS: After the lesions were apparently cured, sera were collected from the mice and immunoglobulin G (IgG) responses against the whole cell antigens of wild-type P. gingivalis were measured. RESULTS: Wild-type strain was found to induce a strong antibody reaction. On the other hand, the rgpA rgpB kgp triple and kgp mutants induced significantly lower antibody responses compared to the wild type. Western blotting analysis confirmed the differences in antibody production. Next, these mice were re-infected with wild-type strain. Mice that were first infected with wild-type strain showed significantly smaller lesion formation than control mice that were first infected with medium only. On the other hand, mice that were first infected with mutant strains devoid of gingipain activities did not show resistance to re-infection and immunoglobulins directed against gingipains may be protective. CONCLUSIONS: These results suggest that gingipains play an important role in abscess formation in mice, and humoral immune responses seem to be partly responsible for the resistance to re-infection by P. gingivalis.     

Mixed infection of Porphyromonas gingivalis and Bacteroides forsythus in a murine abscess model: involvement of gingipains in a synergistic effect

Several microorganisms including Porphyromonas gingivalis and Bacteroides forsythus have been implicated to be etiologically important agents of periodontal disease. In this study, we determined the ability of combinations of periodontopathogenic microorganisms to cause tissue destruction in a murine abscess model. Although all bacterial combinations used in this study produced larger abscesses than did monoinfection of each bacterium, the combination of P. gingivalis and B.forsythus showed a synergistic effect on abscess formation. Since these two bacteria have been frequently found together in lesions of periodontitis, these results suggest the significance of their co-infection in the progression of periodontitis. P. gingivalis produces extracellular and cell-associated cysteine proteinases (gingipains) which appear to be involved in its virulence. The rgpA rgpB double and kgp mutants induced significantly smaller abscesses than the wild type. Moreover, the rgpA rgpB kgp triple (gingipain-null) mutant hardly showed lesion formation at all with the experimental conditions used in this study, indicating that these genes encoding gingipains are important for virulence of P. gingivalis. Mixed infection of these P. gingivalis mutants with B. forsythus showed an additive effect on abscess formation, indicating that the gingipains of P. gingivalis may play an important role in the pathological synergism between P. gingivalis and B. forsythus.     

Immunohistochemical studies in mite antigen-induced patch test sites in atopic dermatitis

The role of mite allergen in atopic dermatitis is still unclear. In this study, we investigated whether an eczematous reaction could be induced by patch testing with dust mite antigen. We succeeded in reproducing an eczematous lesion and the mite RAST-positive AD group showed a positive reaction much more than the RAST-negative group. Many mite antigen-bearing Langerhans cells, also possessing IgE molecules, were found by the use of an immuno-double labelling technique. By using immunoelectron microscopy, it was observed that the mite antigens were trapped by some macrophages, which were apposed to lymphocytes. To investigate the time-course of the reaction, the patch test reactions were read and biopsied after 1 h, 6 h, 24 h and 48 h. An eczematous reaction developed 24 h after patch testing. The mite antigen-bearing Langerhans cells were seen exclusively in the epidermis after 6 h, and mainly in the dermis after 24 h and 48 h. These results suggested that IgE-mediated contact hypersensitivity to mite antigen may develop and play an important role in AD.     

Alpinetin inhibits neuroinflammation and neuronal apoptosis via targeting the JAK2/STAT3 signaling pathway in spinal cord injury

Background

A growing body of research shows that drug monomers from traditional Chinese herbal medicines have antineuroinflammatory and neuroprotective effects that can significantly improve the recovery of motor function after spinal cord injury (SCI). Here, we explore the role and molecular mechanisms of Alpinetin on activating microglia-mediated neuroinflammation and neuronal apoptosis after SCI.

Methods

Stimulation of microglia with lipopolysaccharide (LPS) to simulate neuroinflammation models in vitro, the effect of Alpinetin on the release of pro-inflammatory mediators in LPS-induced microglia and its mechanism were detected. In addition, a co-culture system of microglia and neuronal cells was constructed to assess the effect of Alpinetin on activating microglia-mediated neuronal apoptosis. Finally, rat spinal cord injury models were used to study the effects on inflammation, neuronal apoptosis, axonal regeneration, and motor function recovery in Alpinetin.

Results

Alpinetin inhibits microglia-mediated neuroinflammation and activity of the JAK2/STAT3 pathway. Alpinetin can also reverse activated microglia-mediated reactive oxygen species (ROS) production and decrease of mitochondrial membrane potential (MMP) in PC12 neuronal cells. In addition, in vivo Alpinetin significantly inhibits the inflammatory response and neuronal apoptosis, improves axonal regeneration, and recovery of motor function.

Conclusion

Alpinetin can be used to treat neurodegenerative diseases and is a novel drug candidate for the treatment of microglia-mediated neuroinflammation.     

Pathophysiology of Medication-overuse Headache: Implications from Animal Studies

Recent animal experiments have shown that chronic medication exposure profoundly affects the function of several areas in the nervous system related to headache pathogenesis. These changes include upregulation of calcitonin gene–related peptide, substance P, and nitric oxide synthase in trigeminal ganglia; expansion of receptive field and decreased nociceptive threshold of central trigeminal neurons; decrease in diffuse noxious inhibitory control; and increased susceptibility to develop cortical spreading depression (CSD). These changes indicate an increase in excitability of cortical and trigeminal neurons. The neuronal hyperexcitability may be the result of derangement of a central, possibly serotonin (5-HT)-dependent, modulating control system. Experiments with animals with low 5-HT showed that the processes of CSD and trigeminal nociception are enhanced in this condition. Derangement in the central 5-HT–dependent modulating system as a result of chronic medication use may underlie the chronification of headache as observed in patients with medication-overuse headache.     

Antibodies specific for a segment of human membrane IgE deplete IgE-producing B cells in humanized mice

IgE-mediated hypersensitivity is central to the pathogenesis of asthma and other allergic diseases. Although neutralization of serum IgE with IgE-specific antibodies is in general an efficacious treatment for allergic asthma, one limitation of this approach is its lack of effect on IgE production. Here, we have developed a strategy to disrupt IgE production by generating monoclonal antibodies that target a segment of membrane IgE on human IgE-switched B cells that is not present in serum IgE. This segment is known as the M1′ domain, and using genetically modified mice that contain the human M1′ domain inserted into the mouse IgE locus, we demonstrated that M1′-specific antibodies reduced serum IgE and IgE-producing plasma cells in vivo, without affecting other immunoglobulin isotypes. M1′-specific antibodies were effective when delivered prophylactically and therapeutically in mouse models of immunization, allergic asthma, and Nippostrongylus brasiliensis infection, likely by inducing apoptosis of IgE-producing B cells. In addition, we generated a humanized M1′-specific antibody that was active on primary human cells in vivo, as determined by its reduction of serum IgE levels and IgE plasma cell numbers in a human PBMC-SCID mouse model. Thus, targeting of human IgE-producing B cells with apoptosis-inducing M1′-specific antibodies may be a novel treatment for asthma and allergy.     

颅内动脉瘤外科治疗500例经验

目的 总结手术治疗动脉瘤的经验。方法 回顾性总结外科治疗的500例Ⅰ-Ⅴ级颅内动脉瘤患者的临床资料,包括动脉瘤的分级、手术时机的选择、控制性低血压麻醉、脑保护剂与载瘤动脉暂时阻断结合应用、经颅多普勒超声动态监测、脑血管痉挛治疗、直接手术中动脉瘤处理技术、血管内动脉瘤栓塞。结果 465例Ⅰ-Ⅳ级颅内动脉瘤患者的手术病死率为27%,1990年前手术的210例病死率为3.8%;1990年后手术的255例病死率为1.9%。35例动脉瘤栓塞的患者无死亡。结论 对颅内动脉瘤采取外科综合治疗措施能有效的改善患者的预后。     

Administration of Fenugreek Seed Extract Produces Better Effects in Glibenclamide-Induced Inhibition in Hepatic Lipid Peroxidation: An in vitro Study

Objective: To evaluate the comparative effects of fenugreek (Trigonella foenum graecum) seed extract (FSE) alone and in combination with an antidiabetic conventional medicine, glibenclamide (GLB), on the inhibition of in vitro lipid peroxidation (LPO) in liver, the major target organ of a drug. Methods: LPO was induced by ferrous sulphate (FeSo4), hydrogen peroxide (H2O2) and carbon tetrachloride (CCl4) and the effects of test seed extract and/or GLB were evaluated. Results: While FeSo4, H2O2 and CCl4 markedly enhanced the hepatic LPO, simultaneous administration of FSE reduced it in a concentration dependent manner. However, when both FSE and GLB were added to the incubation mixture, chemically induced hepatic LPO was further inhibited. The test extract also exhibited high antioxidative activity in 1,1-diphenyl-2-picrylhydrazyl radical and in 2,2''-azino-bis,3-ethylbenzothiazoline-6-sulphonic acid radical scavenging assays. Conclusion: FSE therapy in moderate concentration along with a hypoglycemic drug may prove to be advantageous in ameliorating diabetes mellitus and other diseases that are LPO mediated.