Possible relationship between neurocysticercosis and hematological malignancies

Spirocerca lupi Proteomics and Its Role in Cancer Development: An Overview of Spirocercosis-Induced Sarcomas and Revision of Helminth-Induced Carcinomas

Spirocerca lupi is a parasitic nematode of canids that induces a myriad of clinical manifestations in its host and, in 25% of infections, leads to the formation of sarcomas. The description of the protein composition of the excretory and secretory products (Sl-ESP) of S. lupi has shed light on its possible interactions with the host environment, including migration within the host and mechanisms of immunomodulation. Despite this, the process by which S. lupi induces cancer in the dog remains poorly understood, and some hypotheses have arisen regarding these possible mechanisms. In this review, we discuss the role of specific ESP from the carcinogenic helminths Clonorchis sinensis, Opisthorchis viverrini and Schistosoma haematobium in inducing chronic inflammation and cancer in their host’s tissues. The parasitic worms Taenia solium, Echinococcus granulosus, Heterakis gallinarum, Trichuris muris and Strongyloides stercoralis, which have less-characterized mechanisms of cancer induction, are also analyzed. Based on the pathological findings in spirocercosis and the mechanisms by which other parasitic helminths induce cancer, we propose that the sustained inflammatory response in the dog´s tissues produced in response to the release of Sl-ESP homologous to those of other carcinogenic worms may lead to the malignant process in infected dogs.

Neglected Agent Eminent Disease: Linking Human Helminthic Infection, Inflammation, and Malignancy

Helminthic parasitic infection is grossly prevalent across the globe and is considered a significant factor in human cancer occurrence induced by biological agents. Although only three helminths (Schistosoma haematobium, Clonorchis sinensis, and Opisthorchis viverrini) so far have been directly associated with carcinogenesis; there are evidence suggesting the involvement of other species too. Broadly, human helminthiasis can cause chronic inflammation, genetic instability, and host immune modulation by affecting inter- and intracellular communications, disruption of proliferation-anti-proliferation pathways, and stimulation of malignant stem cell progeny. These changes ultimately lead to tumor development through the secretion of soluble factors that interact with host cells. However, the detailed mechanisms by which helminths introduce and promote malignant transformation of host cells are still not clear. Here, we reviewed the current understanding of immune-pathogenesis of helminth parasites, which have been associated with carcinogenesis, and how these infections initiate carcinogenesis in the host.

Association between cysticercosis and neoplasia: a study based on autopsy findings

Chronic infections including the cysticercosis induce inflammatory cells to produce free radicals and synthesize carcinogenic toxins. The cells with genetic mutations proliferate in a disorganized manner, leading to the development of neoplasia. The aim of the present study was to demonstrate the relation between cysticercosis and neoplasia. Patients autopsied were divided into 4 groups: patients with neoplasia and cysticercosis (NC), patients with neoplasia only (NN), patients with cysticercosis only (CC), and patients without neoplasia or cysticercosis (WW). Of 2012 autopsy reports analyzed, 0.4 showed NC. In groups CC and NC, the most common location of the parasite was the brain. There was a predominance of three or more cysticerci in groups NC and CC. In the NC group, all had malignant neoplasms, and was predominance of benign neoplasm in NN group. The digestive system was the most frequent neoplasia. By calculating odds ratio, rate of neoplasia in patients with cysticercosis was 0.74. In conclusion, the demographic profile of patients with cysticercosis and neoplasia is similar to that of patients with cysticercosis alone. The incidence of cysticercosis and neoplasia was greater in older patients suggesting that immunosenescence may contribute to development of neoplasia promoted by cysticercosis.

Genotoxicity induced by Taenia solium and its reduction by immunization with calreticulin in a hamster model of taeniosis

Genotoxicity induced by neurocysticercosis has been demonstrated in vitro and in vivo in humans. The adult stage of Taenia solium lodges in the small intestine and is the main risk factor to acquire neurocysticercosis, nevertheless its carcinogenic potential has not been evaluated. In this study, we determined the genotoxic effect of T. solium infection in the hamster model of taeniosis. In addition, we assessed the effect of oral immunization with recombinant T. solium calreticulin (rTsCRT) plus cholera toxin as adjuvant on micronuclei induction, as this protein has been shown to induce 33-44% protection in the hamster model of taeniosis. Blood samples were collected from the orbital venous plexus of noninfected and infected hamsters at different days postinfection, as well as from orally immunized animals, to evaluate the frequency of micronucleated reticulocytes as a measure of genotoxicity induced by parasite exposure and rTsCRT vaccination. Our results indicate that infection with T. solium caused time-dependent DNA damage in vivo and that rTsCRT immunization reduced the genotoxic damage induced by the presence of the tapeworms.

Clinical manifestations associated with neurocysticercosis: a systematic review

BACKGROUND

The clinical manifestations of neurocysticercosis (NCC) are poorly understood. This systematic review aims to estimate the frequencies of different manifestations, complications and disabilities associated with NCC.

METHODS

A systematic search of the literature published from January 1, 1990, to June 1, 2008, in 24 different electronic databases and 8 languages was conducted. Meta-analyses were conducted when appropriate.

RESULTS

A total of 1569 documents were identified, and 21 included in the analysis. Among patients seen in neurology clinics, seizures/epilepsy were the most common manifestations (78.8%, 95%CI: 65.1%-89.7%) followed by headaches (37.9%, 95%CI: 23.3%-53.7%), focal deficits (16.0%, 95%CI: 9.7%-23.6%) and signs of increased intracranial pressure (11.7%, 95%CI: 6.0%-18.9%). All other manifestations occurred in less than 10% of symptomatic NCC patients. Only four studies reported on the mortality rate of NCC.

CONCLUSIONS

NCC is a pleomorphic disease linked to a range of manifestations. Although definitions of manifestations were very rarely provided, and varied from study to study, the proportion of NCC cases with seizures/epilepsy and the proportion of headaches were consistent across studies. These estimates are only applicable to patients who are ill enough to seek care in neurology clinics and likely over estimate the frequency of manifestations among all NCC cases.

A systematic review of the frequency of neurocyticercosis with a focus on people with epilepsy

BACKGROUND

The objective of this study is to conduct a systematic review of studies reporting the frequency of neurocysticercosis (NCC) worldwide.

METHODS/PRINCIPAL FINDINGS

PubMed, Commonwealth Agricultural Bureau (CAB) abstracts and 23 international databases were systematically searched for articles published from January 1, 1990 to June 1, 2008. Articles were evaluated for inclusion by at least two researchers focusing on study design and methods. Data were extracted independently using standardized forms. A random-effects binomial model was used to estimate the proportion of NCC among people with epilepsy (PWE). Overall, 565 articles were retrieved and 290 (51%) selected for further analysis. After a second analytic phase, only 4.5% of articles, all of which used neuroimaging for the diagnosis of NCC, were reviewed. Only two studies, both from the US, estimated an incidence rate of NCC using hospital discharge data. The prevalence of NCC in a random sample of village residents was reported from one study where 9.1% of the population harboured brain lesions of NCC. The proportion of NCC among different study populations varied widely. However, the proportion of NCC in PWE was a lot more consistent. The pooled estimate for this population was 29.0% (95%CI: 22.9%-35.5%). These results were not sensitive to the inclusion or exclusion of any particular study.

CONCLUSION/SIGNIFICANCE

Only one study has estimated the prevalence of NCC in a random sample of all residents. Hence, the prevalence of NCC worldwide remains unknown. However, the pooled estimate for the proportion of NCC among PWE was very robust and could be used, in conjunction with estimates of the prevalence and incidence of epilepsy, to estimate this component of the burden of NCC in endemic areas. The previously recommended guidelines for the diagnostic process and for declaring NCC an international reportable disease would improve the knowledge on the global frequency of NCC.

The role of helminth infections in carcinogenesis

This review examines the significant literature on the role of helminth infections in carcinogenesis. Both parasitic infections and cancer have complex natural histories and long latent periods during which numerous exogenous and endogenous factors interact to obfuscate causality. Although only two helminths, Schistosoma haematobium and Opisthorchis viverrini, have been proven to be definitely carcinogenic to humans, others have been implicated in facilitating malignant transformation. The known mechanisms of helminth-induced cancer include chronic inflammation, modulation of the host immune system, inhibition of intracellular communication, disruption of proliferation-antiproliferation pathways, induction of genomic instability and stimulation of malignant stem cell progeny. Approximately 16% of all cancer cases worldwide are attributable to pathogenic agents, including schistosomes and liver flukes. This equates to 1,375,000 preventable cancer deaths per year. Means to reduce the incidence of helminth-associated malignancies are discussed.

Cysticercosis in the elderly

The immunosenescence, a peculiarity of the aging process, increases the susceptibility of elderly individuals to neoplasia, infections, and parasitosis, among them, cysticercosis. The aim of this study was to compare the epidemiological and anatomopathological characteristics of cysticercosis in elderly or nonelderly patients. We reviewed 72 autopsies, protocols and specimens, performed in the School Hospital of the Triangulo Mineiro Federal University. We selected 3 groups: elderly with cysticercosis, nonelderly with cysticercosis, and control group without cysticercosis. From the patients with cysticercosis, 27.8% were elderly. Of these, 80% presented with neurocysticercosis and 20% cardiac cysticercosis. In the elderly, the early stages of the parasitic development, vesicular and colloidal vesicular, prevailed (75%). In relationship with the causes of death, death in 40% of the elderly was by neoplasic and 35% by cardiovascular, whereas for the nonelderly, death in 63.5% was by cardiovascular and 25% by infectious. There was a significant difference between groups with relation to neoplasic and cardiovascular causes. Therefore, cysticercosis was frequent in elderly patients, and probably patients are continuously infected with cysticercosis as they age. Perhaps, decurrence of the immunosenescence associated with immunological alterations caused by cysticercosis form favorable conditions to the development of neoplasias in the elderly attacked by the parasitosis.

Oral cysticercosis: a collaborative study of 16 cases

Cysticercosis is a potentially fatal parasitic disease that rarely involves the oral region in humans. This study includes 21 lesions seen in 16 Latin American patients. There were 8 men and 8 women, with an age range from 6 to 67 years (mean 33.6 years). Most cases appeared as asymptomatic submucosal nodules that resembled mucous cysts or benign mesenchymal neoplasms. Most were found in the tongue (11 cases), followed by buccal mucosa and the lower lip (4 cases each) and upper lip (2 cases). These were well circumscribed, and ranged in size from 1 to 2.5 cm in diameter. Typical histologic features of viable cysticerci were observed in 15 cases, and the presence of colloid degeneration and granular mineralization were detected in only 1 case. In all cases, simple surgical excision was sufficient to ensure complete removal of the lesions without postoperative complications. It is important to carry out a detailed study in every case, in order to exclude the presence of the parasite in other sites.

Genotoxicity of vesicular fluid and saline extract of Taenia solium metacestodes in somatic cells of Drosophila melanogaster

Neurocysticercosis, the most common parasitic disease of the central nervous system, is caused by cysticerci of the helminth Taenia solium, which is prevalent in developing countries and is reemerging in affluent societies. This helminth is associated with brain tumors and hematological malignancies in humans. In the present study, we analyzed the genotoxicity of vesicular fluid (VF) and a saline extract (SE) of T. solium metacestodes in the Drosophila melanogaster wing somatic mutation and recombination test (SMART). Third-instar larvae derived from standard and high bioactivation crosses were treated for approximately 48 hr with 12.5, 25.0, and 50.0 microg/ml of VF and SE of T. solium metacestodes. Negative (phosphate buffered saline) and positive (10 mM urethane) controls were also included. The results showed that the two test compounds were genotoxic in both crosses of Drosophila. Nevertheless, further research is needed to determine the genotoxic potential of specific compounds present in VF and SE and their role in the development of cancer.

Positive reaction for cysticercosis and multicentric anaplastic oligoastrocytoma

INTRODUCTION

An unusual case of positive immunological testing for cysticercosis in the cystic fluid obtained from an anaplastic oligoastrocytoma is presented.

CASE REPORT

A 15-year-old boy was admitted with multiple brain lesions. The biggest was a cyst with a mural node and neurocysticercosis was suspected. In order to relieve intracranial pressure, the cyst was punctured and the immunological testing for cysticercosis was positive, reinforcing the clinical suspicion and leading to a clinical trial with albendazole and steroids. As the patient deteriorated the cystic lesion was removed and the diagnosis of anaplastic oligoastrocytoma was established. A second lesion was eventually approached and the histopathological diagnosis of both specimens concurred.

DISCUSSION

Although some authors believe that chronic inflammatory changes following neurocysticercosis could induce the formation of brain tumors, this association may be a mere coincidence. In our case no clinical evidence of a prior infestation by Cysticercus was found. In fact, an exhaustive examination of the specimens did not reveal any areas of inflammatory reaction. We believe that the similarity of the glioma and cysticercosis antigens may be the cause of the positive reactions in the cystic fluid.

Role of infectious diseases in human carcinogenesis

The burden of human infectious diseases remains a public health problem worldwide. At least 2 billion people are affected by viral infections, and a similar number by bacteria or helminths. The long-term effects of these maladies have raised particular concern since some infectious agents have been associated with chronic human diseases, especially cancer. It is estimated that 13-20% of the world cancer cases are associated with some virus, bacteria, or helminth, e.g., human papillomavirus, Helicobacter pylori, and Schistosoma haematobium that cause cervical, stomach, and urinary bladder cancer, respectively. Certain associations between infection and malignancy are strong and irrefutable; others are still speculative. This article reviews the infectious agents that have been associated with cancer and current knowledge about the mechanisms underlying these associations.

Induction of DNA damage in human lymphocytes treated with a soluble factor secreted by Taenia solium metacestodes

We have previously reported that a factor secreted by the metacestode of Taenia solium (MF) is able to transform Syrian hamster embryo cells. The aim of this study was to analyze the genotoxicity of MF in cultured human lymphocytes using the micronucleus assay. Results show a significantly high frequency of micronucleated cells in lymphocyte cultures treated with MF. Although further experiments are needed to determine whether this factor is also secreted by T. solium metacestodes in humans, analysis of the frequency of micronucleus induced in cultured human lymphocytes indicates that DNA instability induced by MF could represent a risk for malignant transformation.

Neurocysticercosis: regional status, epidemiology, impact and control measures in the Americas

The analysis of epidemiological data concerning human cysticercosis point to important advances in understanding the magnitude and distribution of this parasitic disease in Latin America, as well as the relationship of the elements that conform the life cycle of Taenia solium. The data indicate that the main risk factor for acquiring human neurocysticercosis and swine cysticercosis is the presence of the tapeworm carrier in the household. Therefore, several intervention measures for the control of cysticercosis have been evaluated: mass treatment in order to cure tapeworm carriers, health education towards understanding the risk factors, pig control by restraining them, experimental vaccination of pigs and treatment of swine cysticercosis. In this paper, we review the information obtained in these areas. We hope it will be useful in other endemic countries that wish to elaborate an action plan for the control and ultimate eradication of T. solium.

Neurocysticercosis: an update

Taeniosis and cysticercosis, diseases caused by the parasitic tapeworm Taenia solium, are distributed worldwide where pigs are eaten and sanitation is poor, and also in the more developed countries as a result of increasing migration. Neurocysticercosis is the commonest parasitic disease of the human nervous system. Immunological assays detect positivity for human cysticercosis in 8-12% of people in some endemic regions, which indicates the presence of antibodies against the parasite but not necessarily active or central-nervous-system infection. The only reliable tool for diagnosis of neurocysticercosis is imaging by CT or MRI. The presence of viable cysts with a mural nodule, associated with degenerative cysts and calcifications, is typical. Classification of neurocysticercosis into active, transitional, and inactive forms gives a good clinical-imaging correlation and facilitates medical and surgical treatment. The main clinical manifestations of neurocysticercosis are seizures, headache, and focal neurological deficits, and it can have such sequelae as epilepsy, hydrocephalus, and dementia. Treatment should be individually fitted for each patient, with antiepileptic drugs, analgesics, corticosteroids, or a combination of these. Anthelmintic drugs (praziquantel and albendazole) are used routinely, but so far no controlled clinical trial has established specific indications or definitive doses of treatment. Parenchymal forms of neurocysticercosis have a good prognosis in terms of clinical remission. The most effective approach to taeniosis and cysticercosis is prevention, which should be a primary public-health focus for less developed countries.

Do helminths play a role in carcinogenesis?

Chronic helminthiasis is recognized as a significant factor in cancer development in humans. However, the mechanisms by which helminths initiate and promote malignant transformation of host cells are still not understood fully. Human helminthiasis can cause genetic instability and affect inter- and intracellular communication, ultimately leading to tumour development through inflammation, modulation of the host immune system, and secretion of soluble factors that interact with host cells.

Taenia solium disease in humans and pigs: an ancient parasitosis disease rooted in developing countries and emerging as a major health problem of global dimensions

This article reviews current knowledge on human and porcine cysticercosis caused by Taenia solium. It highlights the conditions favorable for its prevalence and transmission, as well as current trends in research on its natural history, epidemiology, immunopathology, diagnosis, treatment and prevention. Our opinions on the most urgent needs for further research are also presented.

Neurocysticercosis and oncogenesis

Recent studies suggest that neurocysticercosis may be a risk factor for human cancer. Pathogenetic mechanisms explaining possible oncogenic effects of cysticerci include the following: (a) parasite-induced modulation of the host immune response that may be associated with loss of regulatory mechanisms implicated in the immunological surveillance against cancer; (b) transfer of genetic material from the parasite to the host, causing DNA damage and malignant transformation of host cells, and (c) chronic inflammation with liberation of nitric oxide and inhibition of tumor suppressor genes. Further research is needed to confirm the potential role of cysticercosis in the development of cancer. These studies should determine the presence of cysticercotic factors responsible for the transfer of genetic material and potential mutations in the tumor suppressor genes in proliferating astrocytes surrounding cysticercotic lesions. Additionally, the complex interaction between the immune state of the host with variable cytokine release and the presence of inflammatory cells releasing nitric oxide that cause DNA damage and impair tumor suppressive mechanisms needs to be investigated.

Possible association between Taenia solium cysticercosis and cancer: increased frequency of DNA damage in peripheral lymphocytes from neurocysticercosis patients

Helminths, particularly some Schistosoma species, have been associated with cancer in humans. Neurocysticercosis, produced by cysticerci of the helminth Taenia solium, has been associated with the emergence of brain tumours and haematological malignancies. Local tumours, such as glioblastoma, could be explained by the induction of DNA damage in cells surrounding the cysticercus and chronically exposed to an inflammatory host response. However, systemic effects such as haematological malignancies are not easy to understand. The present work was conducted in Mexico to find out whether DNA damage arises in peripheral lymphocytes in patients with neurocysticercosis. We utilized a highly sensitive technique to analyse chromosomal aberrations, in-situ hybridization with probes against chromosomes 1, 2 and 4, and in addition the blocked-cytokinesis technique was used to determine the formation of micronuclei, a peculiar form of DNA damage. The study was made in lymphocytes from 8 patients before and after the administration of praziquantel, 1 of the 2 drugs used for neurocysticercosis treatment. The frequencies of chromosome aberrations and micronuclei in peripheral blood lymphocytes were higher in the infected patients as compared to those observed both in healthy donors and in the group of patients after praziquantel therapy. Our results suggest that chromosome aberrations induced in peripheral cells during neurocysticercosis could be associated with the development of haematological neoplasias.