Clinical presentation and diagnosis of toxoplasmic encephalitis in Japan

Distinguishing life-threatening toxoplasmic encephalitis (TE) from brain lymphoma in patients with acquired immunodeficiency syndrome (AIDS) may be difficult. Empiric anti-toxoplasmosis treatment is often initiated because of the reluctance in performing brain biopsies, which may delay the diagnosis and treatment of brain lymphoma in Japan. In this study, we retrospectively examined the clinical characteristics of 13 AIDS patients with TE in Japan, including magnetic resonance imaging and thallium 201 (201TI) single photon emission computed tomography (SPECT) findings, cerebral spinal fluid analysis, serology, and polymerase chain reaction (PCR) results. All patients improved on anti-toxoplasmosis treatment. Of the 11 patients who underwent serological testing, 6 (55%) had a positive serological result. Of the 7 patients who underwent PCR testing, 3 (42.9%) had a positive PCR result. Nine of 11 patients with TE (81.8%) had multiple lesions. Analysis of the sites of TE lesions did not reveal a difference in site predilection between TE and brain lymphoma. Uptake was negative in all 9 patients who underwent 201Tl SPECT. The study findings suggest that toxoplasma serostatus and PCR may be used to discriminate TE from brain lymphoma. No focal accumulation of 201TI is strongly suggestive of TE in patients with AIDS in Japan.     

The role of astrocytes in the immunopathogenesis of toxoplasmic encephalitis

Challenge with the parasite Toxoplasma gondii eventually leads to persistent infection characterised by the presence of tissue cysts in the brain of the host. In immunocompetent individuals the parasite rarely leads to disease but in the immunocompromised host reactivation of these cysts can lead to toxoplasmic encephalitis. It is known that both CD4(+) and CD8(+) T cells are important in preventing reactivation of the parasite, however there is also evidence that astrocytes, a subset of glial cells dominant in the CNS, may be important in resistance to T. gondii. The aim of this paper is to review what is known about the immune functions of astrocytes, and the possible role they may play during toxoplasmic encephalitis.     

Importance of endogenous IFN-gamma for prevention of toxoplasmic encephalitis in mice

The importance of endogenous IFN-gamma for prevention of toxoplasmic encephalitis was studied in mice chronically infected with Toxoplasma gondii by using a mAb to this lymphokine. Control mice chronically infected with the ME49 strain that received saline or normal IgG had slight inflammation in their brains whereas those that received the mAb developed severe encephalitis. In contrast to control mice, the mAb-treated mice had many areas of acute focal inflammation and infiltration of large numbers of inflammatory cells in the meninges and parenchyma of their brains. In the areas of acute focal inflammation, tachyzoites and Toxoplasma Ag were demonstrated by immunoperoxidase staining with the use of rabbit anti-Toxoplasma antibody, suggesting that the focal inflammation was induced by Toxoplasma organisms. Acute inflammation was also observed around cysts of Toxoplasma. Immunohistologic staining revealed tachyzoites and Toxoplasma Ag surrounding the periphery of these cysts suggesting cyst disruption had occurred. Mice treated with mAb against IFN-gamma had five times the numbers of cysts in their brains as did control mice. These results clearly indicate that endogenous IFN-gamma plays a significant and important role in prevention of encephalitis in mice chronically infected with Toxoplasma. The mAb-treated mice had the same Toxoplasma antibody titers and the same degree of macrophage killing of Toxoplasma as did untreated controls. These results suggest that IFN-gamma may have a direct role in preventing cyst rupture and toxoplasmic encephalitis.     

Respiratory cryptococcosis in HIV positive patients.

Although the lungs are the portal of entry of the infection, respiratory manifestations of AIDS related cryptococcosis have not been very well studied. The lack of typical findings in clinical and roentgenographic studies and the difficulties in the interpretation of the isolation of Cryptococcus neoformans from bronchial secretions, is probably the explanation for the lack of interest on this subject. The clinical and microbiological findings of 22 HIV positive patients, who presented C. neoformans in their respiratory tract clinical samples, are presented. Seventeen were males and 5 females, their age average was 30.8 years (21-50 years) and the following risk factors for HIV infection were detected: intravenous drug abuse 18, heterosexuals with several sexual partners two, one female prostitute and 1 homosexual man. All patients, except three, showed less than 100 CD4+ cells per microl. The following symptoms were observed: fever, cough, mucoid expectoration and chest ache. Roengenographic studies presented diffuse infiltrative patches in eleven cases, pulmonary cavities in three, pseudotumoral nodules in two, pneumonic infiltration in two and pleural effusion in four patients. C. neoformans was observed and/or isolated from sputum in nine patients, from bronchoalveolar lavage in seven, from lung biopsy in one and from pleural effusion in four cases. Blood cultures for C. neoformans were positive in 13 cases, urine cultures in 10 and in 11 patients C. neoformans was isolated from C.S.F. The latex agglutination tests for C. neoformans capsular polysaccharide rendered positive results in serum samples from 19 patients and from C.S.F. in 14 cases. Seven cases also presented active tuberculosis. According to these findings, it seems that the isolation of C. neoformans from bronchial secretion of HIV positive patients is a signal of disseminated cryptococcosis. It is important to isolate C. neoformans or detect its capsular antigen from other clinical samples in order to confirm the diagnosis of disseminated cryptococcosis. As observed in other studies, pleuropulmonary cryptococcosis does not present a typical clinical pattern.     

HIV抗体阳性合并马尔尼菲青霉菌感染的临床特点

目的 对HIV阳性合并马尔尼菲青霉菌的临床特点进行分析,揭示免疫能力递减的程度,易感马尔尼菲青霉菌之间的关系,给临床诊断提供帮助。方法 以我院收治的3例HIV阳性合并马尔尼菲青霉菌感染患者为例,总结分析其生物学特点。结果 三位患者都为中年男性,以间断发热、呼吸困难、干咳为主要临床表现,肺部影像学提示双肺弥漫性病变,外院治疗无效后转入我院,确诊为HIV阳性,经血培养诊断为马尔尼菲青霉菌感染。患者血CD4+ T细胞计数后,CD4+ T细胞均＜2%（正常值31%~60%）。结论 HIV阳性时,不明原因发热,肺部感染,免疫功能受损到一定程度时,易合并马尔尼菲青霉菌感染,临床症状较重并有很高的死亡率。     

Pattern of neuropsychological performance among HIV positive patients in Uganda

Background  

Few studies have examined cognitive functioning of HIV positive patients in sub-Saharan Africa. It cannot be assumed that HIV positive patients in Africa exhibit the same declines as patients in high-resource settings, since there are differences that may influence cognitive functioning including nutrition, history of concomitant disease, and varying HIV strains, among other possibilities. Part of the difficulty of specifying abnormalities in neuropsychological functioning among African HIV positive patients is that there are no readily available African normative databases. The purpose of the current study was to evaluate the pattern of neuropsychological performance in a sample of HIV positive patients in comparison to HIV negative control subjects in Uganda.     

Analysis of behavior and trafficking of dendritic cells within the brain during toxoplasmic encephalitis

Under normal conditions the immune system has limited access to the brain; however, during toxoplasmic encephalitis (TE), large numbers of T cells and APCs accumulate within this site. A combination of real time imaging, transgenic reporter mice, and recombinant parasites allowed a comprehensive analysis of CD11c+ cells during TE. These studies reveal that the CNS CD11c+ cells consist of a mixture of microglia and dendritic cells (DCs) with distinct behavior associated with their ability to interact with parasites or effector T cells. The CNS DCs upregulated several chemokine receptors during TE, but none of these individual receptors tested was required for migration of DCs into the brain. However, this process was pertussis toxin sensitive and dependent on the integrin LFA-1, suggesting that the synergistic effect of signaling through multiple chemokine receptors, possibly leading to changes in the affinity of LFA-1, is involved in the recruitment/retention of DCs to the CNS and thus provides new insights into how the immune system accesses this unique site.     

尿液中细菌L型检出情况及耐药性分析

目的 了解泌尿感染患者尿液标本细菌L型的检出情况,分析尿常规结果、病原菌分布情况及耐药性特点,为临床提供诊疗依据。方法 对2014年1月至2015年12月1 532例住院和门诊泌尿感染患者的清洁中段尿标本的尿常规结果和微生物培养结果进行回顾性分析。严格按照《全国临床检验操作规程》要求采集患者尿液标本,2 h内完成尿液普通培养、高渗培养、尿常规检查及尿液离心后沉渣镜检。培养出细菌L型进行菌株鉴定和药敏试验,结果采用SPSS 13.0统计软件进行分析处理。结果 共检出细菌L型132例,检出率为8.6%。132例细菌L型阳性病例中,白细胞酯酶阳性19例,阳性率14.4%;尿沉渣镜检白细胞阳性105例,阳性率79.5%。细菌L型检出率排名前三位的分别为大肠埃希菌、粪肠球菌、葡萄球菌,分别占40.9%、22.7%、12.1%。大肠埃希菌对氨苄西林、环丙沙星、左氧氟沙星、氨苄西林/舒巴坦、头孢唑啉、复方新诺明耐药率较高;粪肠球菌对克林霉素、奎奴普丁/达福普汀、红霉素、四环素耐药率较高;葡萄球菌对青霉素G、红霉素、头孢西丁、甲氧西林、环丙沙星耐药率较高。结论 尿常规、尿沉渣镜检有助于细菌L型感染的辅助诊断,临床医生应根据尿培养结果合理、足疗程选用抗菌药物。     

Treatment with anti-L3T4 (CD4) monoclonal antibody reduces the inflammatory response in toxoplasmic encephalitis

Toxoplasma gondii is an important cause of disease of the central nervous system in patients with AIDS. Among the variety of immunologic disorders encountered by AIDS patients is a depletion of CD4+ subpopulation of lymphocytes. In order to determine the role of this population of T lymphocytes in the generation of toxoplasmic encephalitis, mice chronically infected with T. gondii were treated with mAb GK1.5 directed against the cell surface glycoprotein L3T4 (CD4) of T lymphocytes. Histopathologic sections of brains of control and treated animals were examined at regular intervals during and after completion of treatment. The results demonstrated significantly less inflammation in brains of mice during treatment with GK1.5 mAb. In addition, recrudescence of the inflammatory process occurred after discontinuation of treatment. Similar results were observed in experiments in which different strains of mice and T. gondii were used.     

Serotypes of Candida albicans isolated from HIV positive patients.

Twenty-one HIV-positive patients in different stages of the disease were studied to evaluate candidosis in the oral cavity. All patients in clinical category C were infected with Candida. The most frequently observed clinical forms were pseudomembranous and hypertrophic, in contrast to reports by other authors. Candida albicans was the species isolated in these HIV-positive patients. Alterations of cell-mediated immunity were reflected in the negativity of intradermal test. The predominant serotype of C. albicans in these patients was A, in agreement with what has been found in non-immunosuppressed patients in Venezuela. There was no correlation between the serotype of C. albicans and the clinical forms of candidosis. Based in our results and those of other authors, no conclusions can be drawn concerning a particular serotype as an indicator of immunosuppression.     

In vitro correlates of Ld-restricted resistance to toxoplasmic encephalitis and their critical dependence on parasite strain

Resistance to murine toxoplasmic encephalitis has been precisely and definitively mapped to the L(d) class I gene. Consistent with this, CD8(+) T cells can adoptively transfer resistance to toxoplasmic encephalitis. However, cytotoxic CD8(+) T cells, capable of killing class I-matched, infected target cells, are generated during the course of Toxoplasma gondii infection even in mice lacking the L(d) gene. L(d)-restricted killing could not be demonstrated, and the functional correlate of the L(d) gene has therefore remained elusive. Herein, L(d)-restricted killing of T. gondii-infected target cells is demonstrated for the first time. L(d)-restricted killing is critically dependent on the strain of T. gondii and is observed with all the derivatives of type II strains tested, but not with a type I strain. These results have important implications for vaccine development.     

Host response profile of human brain proteome in toxoplasma encephalitis co-infected with HIV

Background

Toxoplasma encephalitis is caused by the opportunistic protozoan parasite Toxoplasma gondii. Primary infection with T. gondii in immunocompetent individuals remains largely asymptomatic. In contrast, in immunocompromised individuals, reactivation of the parasite results in severe complications and mortality. Molecular changes at the protein level in the host central nervous system and proteins associated with pathogenesis of toxoplasma encephalitis are largely unexplored. We used a global quantitative proteomic strategy to identify differentially regulated proteins and affected molecular networks in the human host during T. gondii infection with HIV co-infection.

Results

We identified 3,496 proteins out of which 607 proteins were differentially expressed (≥1.5-fold) when frontal lobe of the brain from patients diagnosed with toxoplasma encephalitis was compared to control brain tissues. We validated differential expression of 3 proteins through immunohistochemistry, which was confirmed to be consistent with mass spectrometry analysis. Pathway analysis of differentially expressed proteins indicated deregulation of several pathways involved in antigen processing, immune response, neuronal growth, neurotransmitter transport and energy metabolism.

Conclusions

Global quantitative proteomic approach adopted in this study generated a comparative proteome profile of brain tissues from toxoplasma encephalitis patients co-infected with HIV. Differentially expressed proteins include previously reported and several new proteins in the context of T. gondii and HIV infection, which can be further investigated. Molecular pathways identified to be associated with the disease should enhance our understanding of pathogenesis in toxoplasma encephalitis.

Electronic supplementary material

The online version of this article (doi:10.1186/1559-0275-11-39) contains supplementary material, which is available to authorized users.     

Detection of infectious prions in urine

Prions are the infectious agents responsible for prion diseases, which appear to be composed exclusively by the misfolded prion protein (PrP(Sc)). The mechanism of prion transmission is unknown. In this study, we attempted to detect prions in urine of experimentally infected animals. PrP(Sc) was detected in approximately 80% of the animals studied, whereas no false positives were observed among the control animals. Semi-quantitative calculations suggest that PrP(Sc) concentration in urine is around 10-fold lower than in blood. Interestingly, PrP(Sc) present in urine maintains its infectious properties. Our data indicate that low quantities of infectious prions are excreted in the urine. These findings suggest that urine is a possible source of prion transmission.