Altered Patterns of Gene Expression Underlying the Enhanced Immunogenicity of Radiation-Attenuated Schistosomes

Schistosoma mansoni is a blood-dwelling parasitic worm that causes schistosomiasis in humans throughout Africa and parts of South America. A vaccine would enhance attempts to control and eradicate the disease that currently relies on treatment with a single drug. Although a manufactured vaccine has yet to generate high levels of protection, this can be achieved with infective parasite larvae that have been disabled by exposure to radiation. How these weakened parasites are able to induce protective immunity when normal parasites do not, is the question addressed by our experiments. We have used a technique of gene expression profiling to compare the patterns in normal and disabled parasites, over the period when they would trigger an immune response in the host. We found that only a handful of genes were differentially expressed, all of them diminished in the disabled parasite. However, a more sensitive technique to examine groups of genes revealed that those involved in nervous system and muscle function were depressed in the disabled parasites. We suggest that reduced mobility of these larvae permits them longer contact with the immune system, thus enabling a strong protective immune response to develop

Do schistosome vaccine trials in mice have an intrinsic flaw that generates spurious protection data?

The laboratory mouse has been widely used to test the efficacy of schistosome vaccines and a long list of candidates has emerged from this work, many of them abundant internal proteins. These antigens do not have an additive effect when co-administered, or delivered as SWAP homogenate, a quarter of which comprises multiple candidates; the observed protection has an apparent ceiling of 40–50 %. We contend that the low level of maturation of penetrating cercariae (~32 % for Schistosoma mansoni) is a major limitation of the model since 68/100 parasites fail to mature in naïve mice due to natural causes. The pulmonary capillary bed is the obstacle encountered by schistosomula en route to the portal system. The fragility of pulmonary capillaries and their susceptibility to a cytokine-induced vascular leak syndrome have been documented. During lung transit schistosomula burst into the alveolar spaces, and possess only a limited capacity to re-enter tissues. The acquired immunity elicited by the radiation attenuated (RA) cercarial vaccine relies on a pulmonary inflammatory response, involving cytokines such as IFNγ and TNFα, to deflect additional parasites into the alveoli. A principal difference between antigen vaccine protocols and the RA vaccine is the short interval between the last antigen boost and cercarial challenge of mice (often two weeks). Thus, after antigen vaccination, challenge parasites will reach the lungs when both activated T cells and cytokine levels are maximal in the circulation. We propose that “protection” in this situation is the result of physiological effects on the pulmonary blood vessels, increasing the proportion of parasites that enter the alveoli. This hypothesis will explain why internal antigens, which are unlikely to interact with the immune response in a living schistosomulum, plus a variety of heterologous proteins, can reduce the level of maturation in a non-antigen-specific way. These proteins are “successful” precisely because they have not been selected for immunological silence. The same arguments apply to vaccine experiments with S. japonicum in the mouse model; this schistosome species seems a more robust parasite, even harder to eliminate by acquired immune responses. We propose a number of ways in which our conclusions may be tested

Completion surgery after concomitant chemoradiation in obese women with locally advanced cervical cancer: Evaluation of toxicity and outcome measures

BACKGROUND: This study aims at comparing the morbidity and oncologic outcomes in normal weight, overweight, and obese women with locally advanced cervical cancers (LACC) submitted to radical surgery after chemoradiation. METHODS: A review of LACC patients with body mass index (BMI) 65 18.5 kg/m(2) who underwent neoadjuvant chemoradiation followed by radical surgery between January 1996 and December 2010 was performed. BMI categories were created according to the World Health Organization (WHO) classification. RESULTS: Two hundred sixty-eight women met the inclusion criteria: 118 (44.0%) were normal weight, 100 (37.3%) overweight and 50 (18.7%) obese. The median follow-up was 42 months. Higher BMI was associated with older age (p = 0.0041), while there were no differences among the three groups in Charlson comorbidity score, tumor characteristics, radiotherapy dosing, type of surgery, and pathological response. There were no differences among the three groups in the intraoperative and postoperative complications as well as rate of patients requiring adjuvant treatments: 21 (7.8%) patients experienced grade 3-4 toxicity, including six normal weight, 12 overweight and three obese patients (p = 0.14). Only the rate of grade 1-2 skin toxicity was higher in obese (14%) with respect to overweight (1%) and normal women (0%) (p = 0.00001). There were no differences in the five-year DFS (74%, 77%, and 84% for normal weight, overweight, and obese women, respectively, p = n.s.), and five-year OS (76%, 78%, and 78% for normal weight, overweight, and obese women, respectively, p = n.s.). CONCLUSIONS: The role of obesity should not be overestimated when evaluating the chance of enrolment of LACC patients into preoperative chemoradiation protocols