Gallbladder Cancer Risk and Indigenous South American Mapuche Ancestry: Instrumental Variable Analysis Using Ancestry-Informative Markers

A strong association between the proportion of indigenous South American Mapuche ancestry and the risk of gallbladder cancer (GBC) has been reported in observational studies. Chileans show the highest incidence of GBC worldwide, and the Mapuche are the largest indigenous people in Chile. We set out to assess the confounding-free effect of the individual proportion of Mapuche ancestry on GBC risk and to investigate the mediating effects of gallstone disease and body mass index (BMI) on this association. Genetic markers of Mapuche ancestry were selected based on the informativeness for assignment measure, and then used as instrumental variables in two-sample Mendelian randomization analyses and complementary sensitivity analyses. Results suggested a putatively causal effect of Mapuche ancestry on GBC risk (inverse variance-weighted (IVW) risk increase of 0.8% per 1% increase in Mapuche ancestry proportion, 95% CI 0.4% to 1.2%, p = 6.7 × 10-5) and also on gallstone disease (3.6% IVW risk increase, 95% CI 3.1% to 4.0%), pointing to a mediating effect of gallstones on the association between Mapuche ancestry and GBC. In contrast, the proportion of Mapuche ancestry showed a negative effect on BMI (IVW estimate -0.006 kg/m2, 95% CI -0.009 to -0.003). The results presented here may have significant implications for GBC prevention and are important for future admixture mapping studies. Given that the association between the individual proportion of Mapuche ancestry and GBC risk previously noted in observational studies appears to be free of confounding, primary and secondary prevention strategies that consider genetic ancestry could be particularly efficient.

Development and internal validation of a multifactorial risk prediction model for gallbladder cancer in a high-incidence country

Since 2006, Chile has been implementing a gallbladder cancer (GBC) prevention program based on prophylactic cholecystectomy for gallstone patients aged 35 to 49 years. The effectiveness of this prevention program has not yet been comprehensively evaluated. We conducted a retrospective study of 473 Chilean GBC patients and 2137 population-based controls to develop and internally validate three GBC risk prediction models. The Baseline Model accounted for gallstones while adjusting for sex and birth year. Enhanced Model I also included the non-genetic risk factors: body mass index, educational level, Mapuche surnames, number of children and family history of GBC. Enhanced Model II further included Mapuche ancestry and the genotype for rs17209837. Multiple Cox regression was applied to assess the predictive performance, quantified by the area under the precision-recall curve (AUC-PRC) and the number of cholecystectomies needed (NCN) to prevent one case of GBC at age 70 years. The AUC-PRC for the Baseline Model (0.44%, 95%CI 0.42-0.46) increased by 0.22 (95%CI 0.15-0.29) when non-genetic factors were included, and by 0.25 (95%CI 0.20-0.30) when incorporating non-genetic and genetic factors. The overall NCN for Chileans with gallstones (115, 95%CI 104-131) decreased to 92 (95%CI 60-128) for Chileans with a higher risk than the median according to Enhanced Model I, and to 80 (95%CI 59-110) according to Enhanced Model II. In conclusion, age, sex and gallstones are strong risk factors for GBC, but consideration of other non-genetic factors and individual genotype data improves risk prediction and may optimize allocation of financial resources and surgical capacity.

Identification of Circulating lncRNAs Associated with Gallbladder Cancer Risk by Tissue-Based Preselection, Cis-eQTL Validation, and Analysis of Association with Genotype-Based Expression

Long noncoding RNAs (lncRNAs) play key roles in cell processes and are good candidates for cancer risk prediction. Few studies have investigated the association between individual genotypes and lncRNA expression. Here we integrate three separate datasets with information on lncRNA expression only, both lncRNA expression and genotype, and genotype information only to identify circulating lncRNAs associated with the risk of gallbladder cancer (GBC) using robust linear and logistic regression techniques. In the first dataset, we preselect lncRNAs based on expression changes along the sequence "gallstones → dysplasia → GBC". In the second dataset, we validate associations between genetic variants and serum expression levels of the preselected lncRNAs (cis-lncRNA-eQTLs) and build lncRNA expression prediction models. In the third dataset, we predict serum lncRNA expression based on individual genotypes and assess the association between genotype-based expression and GBC risk. AC084082.3 and LINC00662 showed increasing expression levels (p-value = 0.009), while C22orf34 expression decreased in the sequence from gallstones to GBC (p-value = 0.04). We identified and validated two cis-LINC00662-eQTLs (r² = 0.26) and three cis-C22orf34-eQTLs (r² = 0.24). Only LINC00662 showed a genotyped-based serum expression associated with GBC risk (OR = 1.25 per log2 expression unit, 95% CI 1.04-1.52, p-value = 0.02). Our results suggest that preselection of lncRNAs based on tissue samples and exploitation of cis-lncRNA-eQTLs may facilitate the identification of circulating noncoding RNAs linked to cancer risk.

Epigenome-Wide Analysis of Methylation Changes in the Sequence of Gallstone Disease, Dysplasia, and Gallbladder Cancer

BACKGROUND AND AIMS

Gallbladder cancer (GBC) is a highly aggressive malignancy of the biliary tract. Most cases of GBC are diagnosed in low-income and middle-income countries, and research into this disease has long been limited. In this study we therefore investigate the epigenetic changes along the model of GBC carcinogenesis represented by the sequence gallstone disease → dysplasia → GBC in Chile, the country with the highest incidence of GBC worldwide.

APPROACH AND RESULTS

To perform epigenome-wide methylation profiling, genomic DNA extracted from sections of formalin-fixed, paraffin-embedded gallbladder tissue was analyzed using Illumina Infinium MethylationEPIC BeadChips. Preprocessed, quality-controlled data from 82 samples (gallstones n = 32, low-grade dysplasia n = 13, high-grade dysplasia n = 9, GBC n = 28) were available to identify differentially methylated markers, regions, and pathways as well as changes in copy number variations (CNVs). The number and magnitude of epigenetic changes increased with disease development and predominantly involved the hypermethylation of cytosine-guanine dinucleotide islands and gene promoter regions. The methylation of genes implicated in Wnt signaling, Hedgehog signaling, and tumor suppression increased with tumor grade. CNVs also increased with GBC development and affected cyclin-dependent kinase inhibitor 2A, MDM2 proto-oncogene, tumor protein P53, and cyclin D1 genes. Gains in the targetable Erb-B2 receptor tyrosine kinase 2 gene were detected in 14% of GBC samples.

CONCLUSIONS

Our results indicate that GBC carcinogenesis comprises three main methylation stages: early (gallstone disease and low-grade dysplasia), intermediate (high-grade dysplasia), and late (GBC). The identified gradual changes in methylation and CNVs may help to enhance our understanding of the mechanisms underlying this aggressive disease and eventually lead to improved treatment and early diagnosis of GBC.

Gallstones, Body Mass Index, C-Reactive Protein, and Gallbladder Cancer: Mendelian Randomization Analysis of Chilean and European Genotype Data

BACKGROUND AND AIMS

Gallbladder cancer (GBC) is a neglected disease with substantial geographical variability: Chile shows the highest incidence worldwide, while GBC is relatively rare in Europe. Here, we investigate the causal effects of risk factors considered in current GBC prevention programs as well as C-reactive protein (CRP) level as a marker of chronic inflammation.

APPROACH AND RESULTS

We applied two-sample Mendelian randomization (MR) using publicly available data and our own data from a retrospective Chilean and a prospective European study. Causality was assessed by inverse variance weighted (IVW), MR-Egger regression, and weighted median estimates complemented with sensitivity analyses on potential heterogeneity and pleiotropy, two-step MR, and mediation analysis. We found evidence for a causal effect of gallstone disease on GBC risk in Chileans (P = 9 × 10-5 ) and Europeans (P = 9 × 10-5 ). A genetically elevated body mass index (BMI) increased GBC risk in Chileans (P = 0.03), while higher CRP concentrations increased GBC risk in Europeans (P = 4.1 × 10-6 ). European results suggest causal effects of BMI on gallstone disease (P = 0.008); public Chilean data were not, however, available to enable assessment of the mediation effects among causal GBC risk factors.

CONCLUSIONS

Two risk factors considered in the current Chilean program for GBC prevention are causally linked to GBC risk: gallstones and BMI. For Europeans, BMI showed a causal effect on gallstone risk, which was itself causally linked to GBC risk.

ABCB1/4 gallbladder cancer risk variants identified in India also show strong effects in Chileans

BACKGROUND

The first large-scale genome-wide association study of gallbladder cancer (GBC) recently identified and validated three susceptibility variants in the ABCB1 and ABCB4 genes for individuals of Indian descent. We investigated whether these variants were also associated with GBC risk in Chileans, who show the highest incidence of GBC worldwide, and in Europeans with a low GBC incidence.

METHODS

This population-based study analysed genotype data from retrospective Chilean case-control (255 cases, 2042 controls) and prospective European cohort (108 cases, 181 controls) samples consistently with the original publication.

RESULTS

Our results confirmed the reported associations for Chileans with similar risk effects. Particularly strong associations (per-allele odds ratios close to 2) were observed for Chileans with high Native American (=Mapuche) ancestry. No associations were noticed for Europeans, but the statistical power was low.

CONCLUSION

Taking full advantage of genetic and ethnic differences in GBC risk may improve the efficiency of current prevention programs.

High CD8+ and absence of Foxp3+ T lymphocytes infiltration in gallbladder tumors correlate with prolonged patients survival

BACKGROUND

Gallbladder cancer (GBC), although infrequent in industrialized countries, has high incidence rates in certain world regions, being a leading cause of death among elderly Chilean women. Surgery is the only effective treatment, and a five-year survival rate of advanced-stage patients is less than 10%. Hence, exploring immunotherapy is relevant, although GBC immunogenicity is poorly understood. This study examined the relationship between the host immune response and GBC patient survival based on the presence of tumor-infiltrating lymphocytes at different disease stages.

METHODS

Tumor tissues from 80 GBC patients were analyzed by immunohistochemistry for the presence of CD3+, CD4+, CD8+, and Foxp3+ T cell populations, and the results were associated with clinical stage and patient survival.

RESULTS

The majority of tumor samples showed CD3+ T cell infiltration, which correlated with better prognosis, particularly in advanced disease stages. CD8+, but not CD4+, T cell infiltration correlated with improved survival, particularly in advanced disease stages. Interestingly, a < 1 CD4+/CD8+ T cell ratio was related with increased survival. Additionally, the presence of Foxp3+ T cells correlated with decreased patient survival, whereas a ≤ 1 Foxp3+/CD8+ T cell ratio was associated with improved patient survival.

CONCLUSIONS

Depending on the disease stage, the presence of CD8+ and absence of Foxp3+ T cell populations in tumor tissues correlated with improved GBC patient survival, and thus represent potential markers for prognosis and management of advanced disease, and supports testing of immunotherapy.

Polyarthritis and membranoproliferative glomerulonephritis as paraneoplastic manifestation of Hodgkin's lymphoma: A case report and literature review

Paraneoplastic syndromes can be presented in multiple ways, which include endocrinological, hematologic, rheumatologic and nephrologic manifestations. While most of the publications described solid tumors as responsible for these manifestations, hematologic neoplasms are important cause to consider as part of the differential diagnosis. We report the case of a 46 year-old man with seronegative symmetric polyarthritis of large and small joints associated with membranoproliferative glomerulonephritis with deposits of immune complexes and acute impairment of renal function, as part of a paraneoplastic syndrome secondary of a classical Hodgkin lymphoma with bone marrow invasion, which reversed completely with chemotherapy treatment.

Modulation induced by estradiol in the acute phase of Trypanosoma cruzi infection in mice

We investigated the effect of 17beta-estradiol on mice resistant to infection by Trypanosoma cruzi. Infected Balb/C, C3H and C57BL/6 female mice had a longer survival time than males, C57BL/6 showing the highest difference (50% cumulative mortality in females versus 100% in males). This lineage was treated with estradiol (from 0.05 microg to 500 microg/mouse) 1 day before infection. Treatment with 50 microg or 500 microg estradiol/ mouse increased mortality and parasitaemia. Low doses had no effect or tended to reduce both parameters. Given that estradiol presented no in vitro effect on trypomastigotes or epimastigotes, the involvement of a direct hormonal effect on the parasite is improbable. Alterations in the humoral T. cruzi-specific response were also discarded, since the kinetics and concentration of anti-T. cruzi IgG were not affected by the treatment. Females infected during an estradiol-descending phase (meta-oestrus) survived longer than those infected during other phases of the oestrous cycle. We confirmed that estradiol interferes with T. cruzi infection.

Percutaneous colonoscopic cecostomy for management of chronic constipation in children

BACKGROUND

Chronic constipation and encopresis are common problems in children with spina bifida and anorectal anomalies. Commonly used therapies include complicated bowel regimens and antegrade continence enemas delivered via surgically placed appendicostomies and radiologically placed cecostomies.

METHODS

A technique is described for percutaneous placement of cecostomies for the delivery of continence enemas or venting.

RESULTS

Percutaneous cecostomies were placed in 12 patients. Improvement in bowel management occurred in all patients.

CONCLUSIONS

Percutaneous endoscopic cecostomy is a safe and effective method for the treatment of intractable constipation.

Prolonged duration of response to infliximab in early but not late pediatric Crohn's disease

OBJECTIVES

Tumor necrosis factor-alpha plays a central role in chronic intestinal inflammation of Crohn's disease. Targeting this cytokine with the chimeric monoclonal antibody infliximab has emerged as an effective form of therapy in adult Crohn's disease patients. We sought to determine whether infliximab treatment would benefit pediatric patients with medically refractory Crohn's disease. We also assessed the duration of response, comparing children with early disease to children with long-standing (late) Crohn's disease.

METHODS

Fifteen consecutive children (mean age 12.8 +/- 3.2 yr) with medically refractory Crohn's disease were enrolled in a prospective, open-label trial of a single, 5-mg/kg infliximab intravenous infusion. Medically refractory disease was defined as an inability to taper steroids, lack of response to immunomodulator therapy over 4 months, and active disease as measured by the Pediatric Crohn's Disease Activity Index (PCDAI). Primary endpoints included measurements of disease activity (PCDAI), steroid use, and duration of clinical response.

RESULTS

In all, 14/15 children (94%) improved after infliximab infusion, with a significant decrease of both PCDAI and daily steroid use by 4 wk. Ten patients (67%) achieved complete remission by 10 wk. Among the 14 patients who responded, three of six children (50%) with early disease maintained clinical response through the 12-month trial period, compared to none of eight children with late disease. There were no serious complications associated with the use of infliximab in any of the patients.

CONCLUSIONS

Infliximab is safe and effective in the short-term treatment of medically refractory pediatric Crohn's disease. More importantly, there is a remarkably prolonged duration of response after infliximab therapy in children with early compared to late Crohn's disease.

Deficient iNOS in inflammatory bowel disease intestinal microvascular endothelial cells results in increased leukocyte adhesion

Microvascular endothelial cells play a key role in inflammation by undergoing activation and recruiting circulating immune cells into tissues and foci of inflammation, an early and rate-limiting step in the inflammatory process. We have previously [Binion et al., Gastroenterology112:1898-1907, 1997] shown that human intestinal microvascular endothelial cells (HIMEC) isolated from surgically resected inflammatory bowel disease (IBD) patient tissue demonstrate significantly increased leukocyte binding in vitro compared to normal HIMEC. Our studies [Binion et al., Am. J. Physiol.275 (Gastrointest. Liver Physiol. 38):G592-G603, 1998] have also demonstrated that nitric oxide (NO) production by inducible nitric oxide synthase (iNOS) normally plays a key role in downregulating HIMEC activation and leukocyte adhesion. Using primary cultures of HIMEC derived from normal and IBD patient tissues, we sought to determine whether alterations in iNOS-derived NO production underlies leukocyte hyperadhesion in IBD. Both nonselective (N(G)-monomethyl-L-arginine) and specific (N-Iminoethyl-L-lysine) inhibitors of iNOS significantly increased leukocyte binding by normal HIMEC activated with cytokines and lipopolysaccharide (LPS), but had no effect on leukocyte adhesion by similarly activated IBD HIMEC. When compared to normal HIMEC, IBD endothelial cells had significantly decreased levels of iNOS mRNA, protein, and NO production following activation. Addition of exogenous NO by co-culture with normal HIMEC or by pharmacologic delivery with the long-acting NO donor detaNONOate restored a normal leukocyte binding pattern in the IBD HIMEC. These data suggest that loss of iNOS expression is a feature of chronically inflamed microvascular endothelial cells, which leads to enhanced leukocyte binding, potentially contributing to chronic, destructive inflammation in IBD.

Kashin-Beck osteoarthropathy in rural Tibet in relation to selenium and iodine status

BACKGROUND AND METHODS

Kashin-Beck disease is a degenerative osteoarticular disorder that is endemic to certain areas of Tibet, where selenium deficiency is also endemic. Because selenium is involved in thyroid hormone metabolism, we studied the relation among the serum selenium concentration, thyroid function, and Kashin-Beck disease in 575 subjects 5 to 15 years of age in 12 villages around Lhasa, Tibet, including 1 control village in which no subject had Kashin-Beck disease. Clinical, radiologic, and biochemical data were collected.

RESULTS

Among the 575 subjects, 280 (49 percent) had Kashin-Beck disease, 267 (46 percent) had goiter, and 7 (1 percent) had cretinism. Of the 557 subjects in whom urinary iodine was measured, 66 percent had a urinary iodine concentration of less than 2 microg per deciliter (157 nmol per liter; normal, 5 to 25 microg per deciliter [394 to 1968 nmol per liter]). The mean urinary iodine concentration was lower in subjects with Kashin-Beck disease than in control subjects (1.2 vs. 1.8 microg per deciliter [94 vs. 142 nmol per liter], P<0.001) and hypothyroidism was more frequent (23 percent vs. 4 percent, P=0.01). Severe selenium deficiency was documented in all villages; 38 percent of subjects had serum concentrations of less than 5 ng per milliliter (64 nmol per liter; normal, 60 to 105 ng per milliliter [762 to 1334 nmol per liter]). When age and sex were controlled for in a multivariate analysis, low urinary iodine, high serum thyrotropin, and low serum thyroxine-binding globulin values were associated with an increased risk of Kashin-Beck disease, but a low serum selenium concentration was not.

CONCLUSIONS

In areas where severe selenium deficiency is endemic, iodine deficiency is a risk factor for Kashin-Beck disease.

Maternal Trypanosoma cruzi-specific antibodies and worsening of acute infection in mouse offspring

The role of antibodies in the previously demonstrated harmful effect of Trypanosoma cruzi-infected mothers on progeny infection was studied by injecting either serum from chronically infected animals or purified T. cruzi-specific antibodies into uninfected mice during gestation and lactation periods. It was verified that injected antibodies were transferred to offspring. Pregnant or lactating animals exhibited lower circulating antibody levels than nonpregnant or pregnant but nonlactating mice, respectively, suggesting that such antibody transfer occurred in both fetuses and suckling offspring. When infected two months after birth, offspring of mice treated with chronic serum or purified antibodies displayed significantly higher parasitemia than offspring from mothers receiving control serum or immunoglobulins unrelated to T. cruzi. These results indicate that soluble factors contained in sera of infected mice, and particularly antibodies, when transferred from mothers to their young, are able to worsen T. cruzi acquired infection in the offspring.

High circulating levels of fibronectin and antibodies against its RGD adhesion site during mouse Trypanosoma cruzi infection: relation to survival

The levels of fibronectin (FN), a multifunctional glycoprotein known to mediate in vitro Trypanosoma cruzi-host cell adhesion, were measured in the plasma of T. cruzi-infected BALB/c mice. The infection induced a long-lasting increase of fibronectin levels during the acute parasitemic phase of the disease. Immunoblotting analysis showed the occurrence of lower-molecular-size FN fragments in the plasma of acutely infected animals, suggesting an infection-related FN degradation. FN levels were found to be significantly lower in dying mice harboring higher parasitemias than in surviving animals. A weak level of natural IgM against the RGD adhesion site of FN was detected before and during the first 3 weeks of infection. The level was significantly higher in surviving mice. From the fourth week postinfection, a significant increase in the levels of anti-RGD antibodies coincided with a decrease of circulating FN. These antibodies were mainly of the IgM, IgG1, and IgG2a isotypes. Taken together, these data suggest that both FN and anti-FN antibodies may contribute to the outcome of T. cruzi infection in mice.

High tumor necrosis factor alpha (TNF-alpha) production in Trypanosoma cruzi-infected pregnant mice and increased TNF-alpha gene transcription in their offspring

Since tumor necrosis factor alpha (TNF-alpha) is known to be involved in the feto-maternal relationship, this cytokine was studied in Trypanosoma cruzi-infected pregnant BALB/c mice and their fetuses and offspring. Pregnant chronically infected mice displayed significantly higher levels of circulating TNF-alpha than animals either only infected or only pregnant. TNF-alpha was undetectable in sera of uninfected and nonpregnant mice as well as in breast milk obtained from infected and uninfected animals. Fetuses from infected mice exhibited significantly more cells containing TNF-alpha mRNA in their thymus than fetuses from uninfected mothers. When infected 2 months after birth, offspring born to infected and uninfected mothers displayed similar amounts of circulating TNF-alpha during chronic infection, whereas this cytokine was only weakly detectable during the acute phase of the disease. An intravenous injection of lipopolysaccharide during acute infection strongly increased the production of TNF-alpha in offspring born to infected mothers to levels higher than those in progeny from uninfected mice. These results suggest that TNF-alpha is an important cytokine in the feto-maternal relationship during T. cruzi infection and that fetuses and offspring of infected mothers are primed to produce elevated levels of TNF-alpha.

[Pre-transplantation evaluation with echo-Doppler of the receptor's vascular risk factors]

A total of 51 potential recipients of a renal transplant (RT) have been evaluated with an Eco-Doppler study of the posterior femoral, popliteal and posterior tibial corteries. Acceleration (AC), mean rate (MR), maximum systolic rate (MXSR) and minimal diastolic rate (MNDR), as well as pulsatility (PI) and resistance index (RI) were measured. Arterial high blood pressure (HBP), smoking, time in haemodialysis (HD) and cholesterol and triglycerides levels, were evaluated as vascular risk factors. RI and PI were maximal, and MXSR, MR and AC minimal at the popliteal artery level. Smoking (number of cigarettes/day) (R = 0.77), systolic blood pressure (BP) (R = 0.43), time of HBP evolution (R = 0.044), cholesterol level (R = 0.43) and time in HD (R = 0.35) correlate with Eco-Doppler parameters. Fifteen of these 51 patients underwent transplantation, and increased RR and PR with decreased MR and MXSR were seen post-RT in the ipsilateral popliteal and posterior tibial arteries. Eco-Doppler is a useful technique to evaluate the vascular risk of potential RT recipients.

Trypanosoma cruzi infection in mice induces a polyisotypic hypergammaglobulinaemia and parasite-specific response involving high IgG2a concentrations and highly avid IgG1 antibodies

Trypanosoma cruzi infection in BALB/c mice induced a reversible polyisotypic hypergammaglobulinaemia, with particularly high levels of IgG2a, IgM and IgE. Hypergammaglobulinaemia started during the acute phase of infection and persisted during chronic disease until 11-13 weeks post-infection (w.p.i.), when immunoglobulin levels, with the exception of IgE, returned near normal values. Parasite-specific antibodies counted for 14 to 23% of gammaglobulinaemia, in acute and chronic infection respectively. The titres of IgM antibodies rose from two w.p.i. IgA, IgE and IgG subclass antibodies built up gradually over the time of parasite clearance (i.e., between three and six w.p.i.). All antibody isotypes, including IgM reached significant and stable titres throughout chronic infection. IgG2a, IgG1 and IgM antibodies had constantly higher titres than the other antibody isotypes. The dominance of IgG2a antibodies was due to their high plasma concentrations, around 70% of all antibodies available in the chronic infection. IgG1 had the highest functional avidity, whereas its concentration corresponded to only 10% of the whole antibody fraction. These results indicate that T. cruzi infection in mice induces a polyisotypic humoral immune response, dominated by some antibody isotypes, with major differences in concentrations and functional avidities. This could be of crucial importance in determining the outcome of infection.

Modulation of T-cell responsiveness during Trypanosoma cruzi infection: analysis in different lymphoid compartments

Spleen and lymph node cells of Trypanosoma cruzi-infected mice were studied for mitogen-induced responsiveness in terms of proliferation and lymphokine production (IL-2, IFN-gamma). Splenocyte (SP) as well as lymph node cell (LN) proliferation and IL-2 production were depressed during the acute phase of the infection. Proliferative capacity of LN cells recovered completely and that of SP partially during the chronic phase. In contrast to these suppressive effects, the mitogen-induced IFN-gamma response was enhanced. In vitro co-incubation of normal SP or LN cells with trypomastigotes resulted in a reduced mitogen-induced cell proliferation and IL-2 secretion, similar to those seen with cells taken from infected mice. In contrast, trypomastigotes exerted a stimulatory activity on the mitogen-induced IFN-gamma response of both SP and LN cells. Addition of lymph node cells from T. cruzi-infected mice (LN-I) to lymph node cells of control mice (LN-C) suppressed strongly the mitogen-induced responsiveness of such cocultures. A marginal level of suppression was recorded in cocultures of spleen cells from infected mice (SP-I) and control spleen cells (SP-C). The potent suppressive cells within LN-I populations were identified as macrophage-like and such cells were absent in SP-C and peritoneal exudate cells from T. cruzi infected animals.

An Fc gamma RII-, Fc gamma RIII-specific monoclonal antibody (2.4G2) decreases acute Trypanosoma cruzi infection in mice

In order to study the role of Fc gamma Rs in Trypanosoma cruzi infection in mice, the 2.4G2 monoclonal antibody (MAb), specific to the extracellular domains of Fc gamma RII and Fc gamma RIII, was injected intraperitoneally into mice. Flow cytometry studies of uninfected mice showed that 2.4G2 MAb bound to peritoneal and lymph node cells, respectively, on days 2 and 6 after injection. Repeating 2.4G2 injections every 3 to 4 days decreased the availability of Fc gamma Rs on peritoneal, lymph node, and spleen cells. Injections of 2.4G2 MAb into T. cruzi-infected mice, at days -1, 3, 7, 11, 16, 20, and 24 relative to infection, reduced mortality in comparison with that in infected animals injected with an unrelated MAb (50 versus 93.3% mortality; P < 0.01). Parasitemia in 2.4G2-treated mice was significantly (three times) lower than in control animals on days 21 and 24 postinfection (P < 0.05), before parasite-specific antibodies were detectable at significant levels. Immunoglobulin and T. cruzi-specific antibody levels were similar in all groups of mice. These results indicate that repeated injections of 2.4G2 MAb administered to acutely infected mice reduce the in vivo infection level, suggesting that Fc gamma Rs play a role in the early host invasion by T. cruzi parasites.

Trypanosoma cruzi infection in mice enhances the membrane expression of low-affinity Fc receptors for IgG and the release of their soluble forms

The membrane expression of low-affinity Fc receptors for IgG (Fc gamma RII/III) on cells and the number of Fc gamma RII/III(+) cells were studied by flow cytometry, using the 2.4G2 MoAb, in mice infected by Trypanosoma cruzi. Cells from spleen, mesenteric lymph nodes and peritoneum were collected on days 10, 20, 30 and 40 post infection (p.i.). The in vivo serum level of soluble Fc gamma RII/III, as well as its in vitro release by cells from infected mice were studied. Parasitaemia and IgG1, IgG2a and IgG2b T. cruzi-specific antibody titres were also recorded. Both the expression of Fc gamma R on cell membrane and the absolute number of Fc gamma R(+) cells increased in spleen and in mesenteric lymph nodes, but not in peritoneum. The modifications in spleen occurred in the early and late parasitaemic phase of infection, i.e., before and after detection of T. cruzi-specific antibodies (from day 10 to 40 p.i.). In mesenteric lymph nodes, the variations were observed only in the early acute infection, when antibodies were not yet detectable at significant levels (on days 10 and 20 p.i.). Higher levels of soluble Fc gamma R were detected in sera and in culture supernatants of spleen and lymph node cells from day 20 to 40 p.i. These results show that T. cruzi infection in mice upregulates the expression and the release of Fc gamma RII/III, in the acute phase of infection, before as well as after the rise of antibody response.

Trypanosoma cruzi: enhanced alpha-macroglobulin levels correlate with the resistance of BALB/cj mice to acute infection

Trypanosoma cruzi proteinases are very likely involved in host-cell invasion. Physiological plasma-proteinase inhibitors from the macroglobulin (MG) family, among them alpha-2-macroglobulin (A2M), are found in tissues and in the plasma of mammals. By complexing to all classes of proteinases, MGs inhibit their action on high-molecular-weight substrates. In vitro studies have shown that A2M impairs T. cruzi proteases and, consequently, the parasite's ability to invade host cells and enhances the phagocytic and microbicidal actions of resident macrophages against T. cruzi. To test the hypothesis of a putative "protective" effect for MG, we quantified it in BALB/cj mice during the course of an experimental T. cruzi infection, comparing a posteriori the levels in mice that died with those in animals that survived, which were considered as being susceptible and resistant to the infection, respectively. The results showed that surviving mice showed an increase in plasma concentrations of MG during the first few weeks after the infection, whereas the levels in mice that died during the acute phase did not differ significantly from those in non-infected mice. These findings and the previous in vitro data indicate a role for physiological proteinase inhibitors, particularly alpha-macroglobulins, in resistance to T. cruzi infection, whereby a balance between parasite proteases and host protease inhibitors may be crucial. MG may thus participate in the complex network of reactions involved in the early acute phase of the disease and contribute by conferring to the host an ability to survive the infection.

Direct identification of Trypanosoma cruzi natural clones in vectors and mammalian hosts by polymerase chain reaction amplification

The polymerase chain reaction was used to amplify the highly variable region of the kinetoplast minicircle of Trypanosoma cruzi directly in biological samples (feces of infected Triatomine bugs, blood samples of experimentally infected mice, and artificially infected human blood samples). Hybridization of the amplified DNAs with reference stocks representing different genotypes (natural clones) enabled us to characterize the stocks infecting the biological samples under study. The main interest of this new approach is the diagnosis of T. cruzi infection and simultaneous direct identification of the different natural clones circulating in vectors and mammalian blood without isolation of the stocks. The suitability of this technique for epidemiologic studies is also discussed.

Chagas' disease: decreased resistance to Trypanosoma cruzi acquired infection in offspring of infected mice

The course of Trypanosoma cruzi infection was studied in an experimental model, using the offspring of mice that were chronically infected with T. cruzi. When infected two months after birth, a higher mortality rate in heavily parasitized mice occurred in these offspring than in controls born to uninfected mothers. The harmful maternal influence reached a maximum when offspring were exposed both to prenatal (placental) and postnatal (lactating) influences. It was a reversible phenomenon that led to a T. cruzi-specific failure of the offspring to control the acute phase of the infection. Such features are suggestive of a maternally-induced impairment of the immune response of the offspring.

Endogenous IFN-gamma is required for resistance to acute Trypanosoma cruzi infection in mice

In order to study the role of endogenous IFN-gamma in Trypanosoma cruzi infection in mice, a potent murine IFN-gamma-specific mAb was injected i.p. on days -1, 7, and 14, relative to infection. Irrespective of the parasite inocula (100 or 25,000), groups of antibody-treated mice had significantly greater cumulative mortality rates than did appropriate controls. In antibody-treated mice, mean survival times were also significantly shorter, and maximum mean parasitemia levels were significantly higher, than in controls. Moreover, the number of amastigote nests in tissues was higher than in control mice and attained a maximum at the same time as parasitemia. As evident from kinetic studies of neutralizing activity, injected mAb were rapidly consumed in infected, but not in noninfected, mice, which is suggestive of massive IFN-gamma production during the early parasitemic phase of the disease. Nevertheless, IFN-gamma remained undetectable in the sera of infected but untreated mice. Unexpectedly, however, a peak of IFN-like antiviral activity, characterizable as a mixture of IFN-gamma and IFN-beta, appeared in mAb-treated mice that survived to infection at a time when neutralizing activity of injected mAb had drastically decreased in the circulation. We hypothesize that this high level of artificially induced endogenous IFN-gamma, not neutralized by the amounts of injected mAb, was due to the more intense parasite multiplication occurring in mAb-treated mice, which in turn may have induced an increased amount of various cytokines. TNF-alpha was not found in the serum of our mice. The humoral immune response entered its exponential phase at a time point later than that when protection by endogenous IFN-gamma was evident. Treatment with IFN-gamma-specific antibody, as applied in our study, failed to affect the level of different Ig isotypes or of T. cruzi-specific antibodies. Our study clearly indicates that IFN-gamma is produced early in acute T. cruzi infection and exerts a protective effect that is probably independent from the humoral immune response.

Endogenous IFN-gamma is required for resistance to acute Trypanosoma cruzi infection in mice

In order to study the role of endogenous IFN-gamma in Trypanosoma cruzi infection in mice, a potent murine IFN-gamma-specific mAb was injected i.p. on days -1, 7, and 14, relative to infection. Irrespective of the parasite inocula (100 or 25,000), groups of antibody-treated mice had significantly greater cumulative mortality rates than did appropriate controls. In antibody-treated mice, mean survival times were also significantly shorter, and maximum mean parasitemia levels were significantly higher, than in controls. Moreover, the number of amastigote nests in tissues was higher than in control mice and attained a maximum at the same time as parasitemia. As evident from kinetic studies of neutralizing activity, injected mAb were rapidly consumed in infected, but not in noninfected, mice, which is suggestive of massive IFN-gamma production during the early parasitemic phase of the disease. Nevertheless, IFN-gamma remained undetectable in the sera of infected but untreated mice. Unexpectedly, however, a peak of IFN-like antiviral activity, characterizable as a mixture of IFN-gamma and IFN-beta, appeared in mAb-treated mice that survived to infection at a time when neutralizing activity of injected mAb had drastically decreased in the circulation. We hypothesize that this high level of artificially induced endogenous IFN-gamma, not neutralized by the amounts of injected mAb, was due to the more intense parasite multiplication occurring in mAb-treated mice, which in turn may have induced an increased amount of various cytokines. TNF-alpha was not found in the serum of our mice. The humoral immune response entered its exponential phase at a time point later than that when protection by endogenous IFN-gamma was evident. Treatment with IFN-gamma-specific antibody, as applied in our study, failed to affect the level of different Ig isotypes or of T. cruzi-specific antibodies. Our study clearly indicates that IFN-gamma is produced early in acute T. cruzi infection and exerts a protective effect that is probably independent from the humoral immune response.

[Osteoarticular infections associated with catheterization of the subclavian vein]

Access to a central way through catheterization of the subclavian vein is a widely used technique. Not uncommonly, the procedure is followed by infective complications among which clavicular osteomyelitis and septic sternoclavicular arthritis represent a rare eventuality. We report two cases of staphylococcic bacteremia produced after subclavian vein catheterization. Both patients presented septic sternoclavicular arthritis and osteomyelitis of the sternal manubrium. The isolated microorganisms were Staphylococcus aureus and Staphylococcus epidermidis methicillin-resistant, respectively. The clinical course under antibiotic therapy was satisfactory in both cases. Septic metastases appear to be the most likely pathogenic mechanism for the osteoarticular complications.

Immunotactoid glomerulopathy associated with mycosis fungoides

A patient with mycosis fungoides developed a nephrotic syndrome. Renal biopsy revealed deposits of a highly organized fibrillar material which did not stain with the typical amyloid stains; this picture was consistent with the diagnosis of non-amyloidotic fibrillary glomerulopathy or immunotactoid glomerulopathy. We believe this is the first case reported of immunotactoid glomerulopathy associated with mycosis fungoides. Possible pathogenetic implications are discussed with reference to previous publications.

Interactions between chronic murine Trypanosoma cruzi infection and pregnancy: fetal growth retardation

Fetal growth, reproductive capacity, and parasitemia were studied in three groups of BALB/c mice: pregnant and chronically infected with Trypanosoma cruzi, non-pregnant but similarly infected, and pregnant but noninfected. The pregnant mice were killed on day 17 of pregnancy. Comparisons of the two pregnant groups showed significant differences in fetal weights and x18 magnified ossification lengths of radius and cubitus, whereas placental weights were not modified. The results indicate that intrauterine growth retardation occurs during chronic murine T. cruzi infection. No difference was noted between the reproductive capacities of the two pregnant groups. Parasitemias were similar in infected pregnant and control groups. Mice of all groups survived infection until killing. Pregnancy, therefore, does not influence chronic murine T. cruzi infection. Parasites were never found in fetal blood, indicating a very low, if any, frequency of transplacental transmission of parasite during the chronic phase of infection.

Pregnancy and humoral immune response in mice chronically infected by Trypanosoma cruzi

The effect of pregnancy on the humoral immune response induced by Trypanosoma cruzi was studied in groups of chronically infected and pregnant mice (IP) or chronically infected and nonpregnant mice (INP) of strain BALB/c. Groups of noninfected and nonpregnant mice (NINP) or noninfected and pregnant mice (NIP) served as controls. The pregnant mice were killed on day 17 of pregnancy. Anti-T. cruzi immunoglobulin G (IgG) and IgM antibodies, detected by immunofluorescence or enzyme-linked immunosorbent assay or both, underwent a pregnancy-associated decrease of 20 to 40%, whereas complement-mediated lytic antibodies were unaffected by pregnancy. Immunoblotting analysis indicated identical specificities of the anti-T. cruzi antibodies in IP and INP groups. The levels of all the immunoglobulin isotypes (particularly IgG2a and IgG3), circulating immune complexes, rheumatoid-like factor, and anti-DNA antibodies were considerably increased during chronic infection (NINP versus INP), which could be related to the high degree of polyclonal B-cell activation occurring in T. cruzi infection. However, pregnancy significantly decreased (by 20 to 60%) such parameters. IgG levels were particularly affected (by 40 to 60%), and the decreases could be ordered as follows: IgG3 greater than IgG2a greater than IgG1 greater than IgG2b for IP versus INP. Comparisons between the noninfected groups indicated differences only in IgG levels. These results indicate the following. (i) The specific humoral anti-T. cruzi immune response is weakly affected by pregnancy, which is not sufficient to modify the course of the mother's infection. (ii) Pregnancy does not modify the expression of the anti-T. cruzi antibody repertory. (iii) Pregnancy reduces the polyclonal B-cell activation, particularly the levels of the IgG isotypes undergoing the greatest activation.