Cytokine production in rhesus monkeys infected with Plasmodium coatneyi

Validity of a combination of periodontal pathogens and salivary biomarkers as predictors of periodontitis

OBJECTIVE

Chronic periodontitis is caused by multiple risk factors. To predict chronic periodontitis in older people, we evaluated the association between a combination of major periodontal pathogens and salivary biomarkers and the presence of periodontitis.

METHODS

Stimulated saliva samples were collected to analyze the prevalence of Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Prevotella intermedia, as well as four biomarkers: interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), and prostaglandin E2 (PGE2). A total of 201 Japanese patients were recruited. Oral examinations ware performed to determine chronic periodontitis as measured by Community Periodontal Index. The sociodemographic and behavioral characteristics were also obtained, and the parameters were adjusted as potential confounders to employ statistical models.

RESULTS

The odds ratio (OR) for the presence of P. gingivalis and the third tertile level of IL-1β as compared with the absence of P. gingivalis and the lowest tertile of IL-1β was highest in individuals with periodontitis (OR = 13.98; 95% confidence interval [CI] 3.87-50.52) with the best level (0.79) of area under the curve (AUC) based on the receiver operating characteristic curve. The OR for the presence of P. gingivalis and the third tertile of PGE2 was 7.76 (CI 1.89-31.91) with an AUC of 0.78. The coexistence of more than two periodontal bacteria and the third tertile of PGE2 was also strongly associated with chronic periodontitis (OR = 9.23, 95% CI 2.38-35.79) with an AUC of 0.76.

CONCLUSIONS

The combined information of the presence of P. gingivalis in stimulated saliva, and higher levels of salivary IL-1β may play a vital role in the detection and prediction of chronic periodontitis in older adults.

Association between declines in objective masticatory performance and salivary stress markers: The Suita study

Dentists often encounter patients suffering from psychological and social stress due to declines in masticatory performance, making this a critical issue to manage. We aimed to clarify the relationships between salivary stress markers as objective indices of chronic stress and objective masticatory performance in a general urban Japanese population. Data from 880 participants (mean age, 65.8 years) in the Suita study were used. Salivary interleukin (IL)-6 and cortisol concentrations were measured by enzyme-linked immunosorbent assay. Objective masticatory performance was determined by measuring the increase in surface area test gummy jelly after 30 times chewing. Participants were divided into two groups based on masticatory performance: a decreased group (lowest quartile) and a non-decreased group (second to fourth quartiles). Odds ratios (ORs) of higher salivary levels of stress markers (highest quartile) according to masticatory performance were estimated using logistic regression analysis adjusting for age, sex, periodontal status, salivary flow rate and smoking habit. Salivary IL-6 level was significantly higher in the decreased group than in the non-decreased group. Logistic regression analysis showed the adjusted OR for higher salivary IL-6 was significantly higher in the decreased group than in the non-decreased group (OR = 1.92; 95% confidence interval = 1.33-2.76; P < .001). No significant associations were found between salivary cortisol and decreased masticatory performance in any analyses. Declines in objective masticatory performance may correlate with higher salivary IL-6 level as an objective index of chronic stress.

A Review of Plasmodium coatneyi-Macaque Models of Severe Malaria

Malaria remains one of the most significant public health concerns in the world today. Approximately half the human population is at risk for infection, with children and pregnant women being most vulnerable. More than 90% of the total human malaria burden, which numbers in excess of 200 million annually, is due to Plasmodium falciparum. Lack of an effective vaccine and a dwindling stockpile of antimalarial drugs due to increased plasmodial resistance underscore the critical need for valid animal models. Plasmodium coatneyi was described in Southeast Asia 50 years ago. This plasmodium of nonhuman primates has been used sporadically as a model for severe malaria, as it mimics many of the pathophysiologic features of human disease. This review covers the reported macroscopic, microscopic, ultrastructural, and molecular pathology of P. coatneyi infection in macaques, specifically focusing on the rhesus macaque, as well as describing the critical needs still outstanding in the validation of this crucial model of human disease.

Salivary inflammatory cytokines may be novel markers of carotid atherosclerosis in a Japanese general population: the Suita study

OBJECTIVE

Salivary biomarkers have been recently useful of periodontal disease, which is also risk factor of atherosclerosis. However, there are few studies of the association between salivary inflammatory cytokines and carotid atherosclerosis. We aimed to clarify the association between salivary inflammatory cytokines and periodontal disease and carotid atherosclerosis in a general urban population.

METHODS

We studied 608 Japanese men and women (mean age: 65.4 years) in the Suita study. Carotid atherosclerosis was evaluated by high-resolution ultrasonography with atherosclerotic indexes of intima-media thickness (IMT). Periodontal status was evaluated by the Community Periodontal Index (CPI). Salivary levels of interleukin-1β, interleukin-6, tumor necrosis factor-α (TNF-α), and prostaglandin E2 (PGE2) were measured by enzyme linked immunosorbent assay. The risks of carotid atherosclerosis (≥75th percentiles of mean- [0.88 mm] and Max-IMT [1.50 mm]) according to the quartiles of salivary inflammatory cytokines were compared using of adjusted-logistic regression models.

RESULTS AND CONCLUSION

All salivary inflammatory cytokines were positively associated with CPI. The adjusted odds ratios for carotid atherosclerosis of mean-IMT in the highest quartile of interleukin-6 and TNF-α were higher than those in the lowest quartiles (OR = 2.32 and 2.88; 95% confidence intervals = 1.19-4.51 and 1.51-5.49, respectively). The adjusted odds ratio for carotid atherosclerosis of mean-IMT in the highest quartile of PGE2 was greater than those in the lowest quartile in women (OR = 2.78; 95% confidence intervals = 1.11-6.95). In conclusion, higher levels of salivary inflammatory cytokines were associated with both periodontal disease and carotid atherosclerosis. Selected salivary inflammatory cytokines may be useful screening markers for periodontal disease and carotid atherosclerosis.

Plasmodium coatneyi in rhesus macaques replicates the multisystemic dysfunction of severe malaria in humans

Severe malaria, a leading cause of mortality among children and nonimmune adults, is a multisystemic disorder characterized by complex clinical syndromes that are mechanistically poorly understood. The interplay of various parasite and host factors is critical in the pathophysiology of severe malaria. However, knowledge regarding the pathophysiological mechanisms and pathways leading to the multisystemic disorders of severe malaria in humans is limited. Here, we systematically investigate infections with Plasmodium coatneyi, a simian malaria parasite that closely mimics the biological characteristics of P. falciparum, and develop baseline data and protocols for studying erythrocyte turnover and severe malaria in greater depth. We show that rhesus macaques (Macaca mulatta) experimentally infected with P. coatneyi develop anemia, coagulopathy, and renal and metabolic dysfunction. The clinical course of acute infections required suppressive antimalaria chemotherapy, fluid support, and whole-blood transfusion, mimicking the standard of care for the management of severe malaria cases in humans. Subsequent infections in the same animals progressed with a mild illness in comparison, suggesting that immunity played a role in reducing the severity of the disease. Our results demonstrate that P. coatneyi infection in rhesus macaques can serve as a highly relevant model to investigate the physiological pathways and molecular mechanisms of malaria pathogenesis in naïve and immune individuals. Together with high-throughput postgenomic technologies, such investigations hold promise for the identification of new clinical interventions and adjunctive therapies.

Overview of known non-human primate pathogens with potential to affect colonies used for toxicity testing

The increased demand for non-human primates (NHPs) in biomedical research has resulted in alternative sources of animals being used, which has allowed for importation of animals with varying background incidences of bacterial, viral, parasitic, and fungal pathogens. This can be of minimal consequence when animals from different sources are kept isolated. However, when NHPs from different sources with varying incidences of primary and opportunistic pathogens are mixed, there can be a rapid spread of these pathogens and an increase in the seroconversion of susceptible animals. If this process occurs during the conduct of a study, interpretation of that study can be confounded. Furthermore, NHPs imported from areas enzootic for pathogens such as Plasmodium or with high incidences of human diseases such as measles and tuberculosis can introduce diseases that can be a threat to colony health, have zoonotic risk, and can severely impact study outcome. Thus, knowledge of the common primary and opportunistic NHP infections, as well as reemerging pathogens, enables the toxicologist to use information on disease status for pre-study animal selection and intelligent study design. This is particularly important when immunomodulatory compounds are being investigated. Moreover, the toxicologic pathologist well versed in the common spontaneous infections, opportunistic pathogens, and background lesions in NHPs is able to assess possible drug-related effects in drug safety studies. This review identifies the common primary and opportunistic pathogens, as well as newly emerging infections of NHPs, that can directly or indirectly affect colony health and the interpretation of drug safety studies.

Mamu-A01/K(b) transgenic and MHC Class I knockout mice as a tool for HIV vaccine development

We have developed a murine model expressing the rhesus macaque (RM) Mamu-A01 MHC allele to characterize immune responses and vaccines based on antigens of importance to human disease processes. Towards that goal, transgenic (Tg) mice expressing chimeric RM (alpha1 and alpha2 Mamu-A01 domains) and murine (alpha3, transmembrane, and cytoplasmic H-2K(b) domains) MHC Class I molecules were derived by transgenesis of the H-2K(b)D(b) double MHC Class I knockout strain. After immunization of Mamu-A01/K(b) Tg mice with rVV-SIVGag-Pol, the mice generated CD8(+) T-cell IFN-gamma responses to several known Mamu-A01 restricted epitopes from the SIV Gag and Pol antigen sequence. Fusion peptides of highly recognized CTL epitopes from SIV Pol and Gag and a strong T-help epitope were shown to be immunogenic and capable of limiting an rVV-SIVGag-Pol challenge. Mamu-A01/K(b) Tg mice provide a model system to study the Mamu-A01 restricted T-cell response for various infectious diseases which are applicable to a study in RM.

Transcriptome profile of dendritic cells during malaria: cAMP regulation of IL-6

Dendritic cells (DCs) have been proposed as mediators of immunity against malaria parasites, as well as a target for inhibition of cellular responses. Here we describe the transcriptomic analysis of spleen DCs in response to Plasmodium infection in a rodent model. We identified a high number of unique transcripts modulated in DCs upon infection. Many cellular functions suffer extensive genomic regulation including the cell cycle, the glycolysis and purine metabolism pathways and also defence responses. Only a small fraction of the regulated genes are coincident with the response induced by other pathogens, suggesting that Plasmodium induces a unique genetic re-programming of DCs. We confirmed regulation of a number of cytokines at the mRNA level including IL-6, IL-10 and IFN-gamma. We further dissected a signalling pathway regulating Plasmodium-induced expression of IL-6 by DCs, which is mediated by release of PGE2, increases in intracellular cAMP and activation of PKA and p38-MAPK.

Infection of Saimiri boliviensis monkeys with Plasmodium coatneyi

Abundant, apparently normally developing, liver-stage parasites of Plasmodium coatneyi were demonstrated following injection of sporozoites dissected from the salivary glands of Anopheles dirus mosquitoes. Erythrocytic development was not demonstrated.

Potentiation of the antimalarial action of chloroquine in rodent malaria by drugs known to reduce cellular glutathione levels

Ferriprotoporphyrin IX (FP) is released inside the food vacuole of the malaria parasite during the digestion of host cell hemoglobin. FP is detoxified by its biomineralization to hemozoin. This process is effectively inhibited by 4-aminoquinolines. As a result FP accumulates in the membrane fraction and associates with enzymes of infected cells in parallel with parasite killing. Free FP is degraded by reduced glutathione (GSH). This degradation is inhibited by chloroquine (CQ) and amodiaquine (AQ) but not by quinine (Q) or mefloquine (MQ). Increased GSH levels in Plasmodium falciparum-infected cells confer resistance to CQ and vice versa, and sensitize CQ-resistant Plasmodium berghei by inhibiting the synthesis of glutathione. Some drugs are known to reduce GSH in body tissues when used in excess, either due to their pro-oxidant activity or their ability to form conjugates with GSH. We show that acetaminophen, indomethacin and disulfiram were able to potentiate the antimalarial action of sub-curative doses of CQ and AQ in P. berghei- or Plasmodium vinckei petteri-infected mice, but not that of Q and MQ. In contrast, N-acetyl-cysteine which is expected to increase the cellular levels of GSH, antagonized the action of CQ. Although these results imply that alteration in GSH are involved, measurement of total glutathione either in uninfected or P. berghei-infected mice, treated with these drugs did not reveal major changes. In conclusion, experimental evidences provided in this study suggest that some off the counter drugs can be used in combination with some antimalarials to which the parasite has become resistant.

Increased plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell molecule-1 (sVCAM-1) associated with disease severity in a primate model for severe human malaria: Plasmodium coatneyi-Infected Japanese macaques (Macaca fuscata)

In the present study, we investigated plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1) in seven Japanese macaques (Macaca fuscata) infected with Plasmodium coatneyi. Concentrations of sICAM-1 and sVCAM-1 were significantly elevated in the severe phase; the levels were maximally increased up to six times and three times those before infection, respectively. We subsequently examined kinetic profiles of sICAM-1 and sVCAM-1 concentration in plasma obtained from two infected monkeys. Both infected monkeys had markedly increased levels of these adhesion molecules when they exhibited severe clinical signs correlated with rapid increase in parasitemia. These results suggest that the elevation of levels of sICAM-1 and sVCAM-1 is a critical step in the pathogenesis of severe malaria in vivo.

Quantitation of simian cytokine and beta-chemokine mRNAs, using real-time reverse transcriptase-polymerase chain reaction: variations in expression during chronic primate lentivirus infection

Cytokines and beta-chemokines are important mediators of the immune system and are expressed in many infectious diseases. To study cytokine and beta-chemokine profiles during pathogenesis of lentiviral infection and progression to AIDS in rhesus macaques, we established new quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) assays based on TaqMan chemistry. Using synthetic RNA standards, we quantified mRNAs of IL-2, IL-4, IL-6, IL-10, IL-12 p40, interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), RANTES, macrophage inflammatory protein 1 alpha (MIP-1 alpha), and MIP-1 beta in unstimulated peripheral blood mononuclear cells (PBMCs) and lymph nodes from macaques chronically infected with SIV or SHIV. Viremic monkeys with decreased CD4(+) T cell counts (<500 cells/microl) had significantly higher IL-10 mRNA expression than uninfected controls, which parallels the findings in HIV-1-infected humans. In addition, MIP-1 alpha, MIP-1 beta, and RANTES mRNA expression increased in viremic monkeys with decreased CD4(+) T cell counts; gene expression was inversely correlated with CD4(+) T cell counts, but not viral load. The newly established quantitative real-time RT-PCR assays will allow the determination of cytokine and beta-chemokine patterns in rhesus macaques in studies of microbial pathogenesis or vaccine development.