A novel llama antibody targeting Fn14 exhibits anti-metastatic activity in vivo

Expression of fibroblast growth factor (FGF)-inducible 14 (Fn14), a member of the tumor necrosis factor receptor superfamily, is typically low in healthy adult organisms, but strong Fn14 expression is induced in tissue injury and tissue remodeling. High Fn14 expression is also observed in solid tumors, which is why this receptor is under consideration as a therapeutic target in oncology. Here, we describe various novel mouse-human cross-reactive llama-derived recombinant Fn14-specific antibodies (5B6, 18D1, 4G5) harboring the human IgG1 Fc domain. In contrast to recombinant variants of the established Fn14-specific antibodies PDL192 and P4A8, all three llama-derived antibodies efficiently bound to the W42A and R56P mutants of human Fn14. 18D1 and 4G5, but not 5B6, efficiently blocked TNF-like weak inducer of apoptosis(TWEA K) binding at low concentrations (0.2–2 μg/ml). Oligomerization and Fcγ receptor (FcγR) binding converted all antibodies into strong Fn14 agonists. Variants of 18D1 with enhanced and reduced antibody-dependent cell-mediated cytotoxicity (ADCC) activity were further analyzed in vivo with respect to their effect on metastasis. In a xenogeneic model using human colon carcinoma cancer cells, both antibody variants were effective in reducing metastasis to the liver. In contrast, only the 18D1 variant with enhanced ADCC activity, but not its ADCC-defective counterpart, suppressed lung metastasis in the RE NCA model. In sum, this suggests that Fn14 targeting might primarily act by triggering of antibody effector functions, but also by blockade of TWEA K-Fn14 interaction in some cases

Non-invasive bioluminescence imaging to monitor the immunological control of a plasmablastic lymphoma-like B cell neoplasia after hematopoietic cell transplantation

To promote cancer research and to develop innovative therapies, refined pre-clinical mouse tumor models that mimic the actual disease in humans are of dire need. A number of neoplasms along the B cell lineage are commonly initiated by a translocation recombining c-myc with the immunoglobulin heavy-chain gene locus. The translocation is modeled in the C.129S1-Igha^tm1(Myc)Janz/J mouse which has been previously engineered to express c-myc under the control of the endogenous IgH promoter. This transgenic mouse exhibits B cell hyperplasia and develops diverse B cell tumors. We have isolated tumor cells from the spleen of a C.129S1-Igha^tm1(Myc)Janz/J mouse that spontaneously developed a plasmablastic lymphoma-like disease. These cells were cultured, transduced to express eGFP and firefly luciferase, and gave rise to a highly aggressive, transplantable B cell lymphoma cell line, termed IM380. This model bears several advantages over other models as it is genetically induced and mimics the translocation that is detectable in a number of human B cell lymphomas. The growth of the tumor cells, their dissemination, and response to treatment within immunocompetent hosts can be imaged non-invasively in vivo due to their expression of firefly luciferase. IM380 cells are radioresistant in vivo and mice with established tumors can be allogeneically transplanted to analyze graft-versus-tumor effects of transplanted T cells. Allogeneic hematopoietic stem cell transplantation of tumor-bearing mice results in prolonged survival. These traits make the IM380 model very valuable for the study of B cell lymphoma pathophysiology and for the development of innovative cancer therapies.

Generation of highly effective and stable murine alloreactive Treg cells by combined anti-CD4 mAb, TGF-β, and RA treatment

The transfer of alloreactive regulatory T (aTreg) cells into transplant recipients represents an attractive treatment option to improve long-term graft acceptance. We recently described a protocol for the generation of aTreg cells in mice using a nondepleting anti-CD4 antibody (aCD4). Here, we investigated whether adding TGF-β and retinoic acid (RA) or rapamycin (Rapa) can further improve aTreg-cell generation and function. Murine CD4(+) T cells were cultured with allogeneic B cells in the presence of aCD4 alone, aCD4+TGF-β+RA or aCD4+Rapa. Addition of TGF-β+RA or Rapa resulted in an increase of CD25(+)Foxp3(+)-expressing T cells. Expression of CD40L and production of IFN-γ and IL-17 was abolished in aCD4+TGF-β+RA aTreg cells. Additionally, aCD4+TGF-β+RA aTreg cells showed the highest level of Helios and Neuropilin-1 co-expression. Although CD25(+)Foxp3(+) cells from all culture conditions displayed complete demethylation of the Treg-specific demethylated region, aCD4+TGF-β+RA Treg cells showed the most stable Foxp3 expression upon restimulation. Consequently, aCD4+TGF-β+RA aTreg cells suppressed effector T-cell differentiation more effectively in comparison to aTreg cells harvested from all other cultures, and furthermore inhibited acute graft versus host disease and especially skin transplant rejection. Thus, addition of TGF-β+RA seems to be superior over Rapa in stabilising the phenotype and functional capacity of aTreg cells.

A diagnostic window for the treatment of acute graft-versus-host disease prior to visible clinical symptoms in a murine model

BACKGROUND

Acute graft-versus-host disease (aGVHD) poses a major limitation for broader therapeutic application of allogeneic hematopoietic cell transplantation (allo-HCT). Early diagnosis of aGVHD remains difficult and is based on clinical symptoms and histopathological evaluation of tissue biopsies. Thus, current aGVHD diagnosis is limited to patients with established disease manifestation. Therefore, for improved disease prevention it is important to develop predictive assays to identify patients at risk of developing aGVHD. Here we address whether insights into the timing of the aGVHD initiation and effector phases could allow for the detection of migrating alloreactive T cells before clinical aGVHD onset to permit for efficient therapeutic intervention.

METHODS

Murine major histocompatibility complex (MHC) mismatched and minor histocompatibility antigen (miHAg) mismatched allo-HCT models were employed to assess the spatiotemporal distribution of donor T cells with flow cytometry and in vivo bioluminescence imaging (BLI). Daily flow cytometry analysis of peripheral blood mononuclear cells allowed us to identify migrating alloreactive T cells based on homing receptor expression profiles.

RESULTS

We identified a time period of 2 weeks of massive alloreactive donor T cell migration in the blood after miHAg mismatch allo-HCT before clinical aGVHD symptoms appeared. Alloreactive T cells upregulated α4β7 integrin and P-selectin ligand during this migration phase. Consequently, targeted preemptive treatment with rapamycin, starting at the earliest detection time of alloreactive donor T cells in the peripheral blood, prevented lethal aGVHD.

CONCLUSIONS

Based on this data we propose a critical time frame prior to the onset of aGVHD symptoms to identify alloreactive T cells in the peripheral blood for timely and effective therapeutic intervention.

Tumor necrosis factor receptor 2-dependent homeostasis of regulatory T cells as a player in TNF-induced experimental metastasis

The cytokine tumor necrosis factor (TNF) has pleiotropic functions both in normal physiology and disease. TNF signals by the virtue of two cell surface receptors, TNF receptor 1 (TNFR1) and TNF receptor 2 (TNFR2). Exogenous TNF promotes experimental metastasis in some models, yet the underlying mechanisms are poorly understood. To study the contribution of host TNFR1 and TNFR2 on tumor cell progression and metastasis, we employed a syngeneic B16F10 melanoma mouse model of lung metastasis combined with in vivo bioluminescence imaging. Treatment of tumor-bearing mice with recombinant human TNF resulted in a significant increase in tumor burden and metastatic foci. This correlated with an increase in pulmonary regulatory CD4(+)/Foxp3(+) T cells. TNF caused an expansion of regulatory T (Treg) cells in vitro in a TNFR2-dependent manner. To assess the contribution of immune cell expression of endogenous TNF and its two receptors on B16F10 metastasis, we generated bone marrow chimeras by reconstituting wild-type mice with bone marrow from different knockout mice. Loss of either TNF or TNFR2 on immune cells resulted in decreased B16F10 metastasis and lower numbers of Treg cells within the lungs of these animals. Selective depletion of Treg cells attenuated metastasis even in conjunction with TNF treatment. We propose a novel mechanism in which TNF activates TNFR2 on Treg cells and thereby expands this immunosuppressive immune cell population. Loss of either TNF or TNFR2 prevents the accumulation of Treg cells and results in a less tolerogenic environment, enabling the immune system to control B16F10 tumor metastasis and growth.

Dioxin toxicity, aryl hydrocarbon receptor signaling, and apoptosis-persistent pollutants affect programmed cell death

Exogenous ligands of the aryl hydrocarbon receptor (AhR) such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related substances are highly toxic pollutants ubiquitously present in the environment. They cause a variety of toxic effects to different organs and tissues. Among other effects, TCDD exposure to laboratory animals leads to thymus atrophy and immunosuppression on the one hand, and to tumor formation on the other. Apoptosis appears to be involved in both these toxic effects: AhR activation by TCDD was discussed to induce apoptosis of immune cells, leading to the depletion of thymocytes and ultimately immunosuppression. This mechanism could help to explain the highly immunotoxic actions of TCDD but it is nevertheless under debate whether this is the mode of action for immunosuppression by this class of chemical substances. In other cell types, especially liver cells, TCDD inhibits apoptosis induced by genotoxic treatment. In initiation-promotion studies, TCDD was shown to be a potent liver tumor promoter. Among other theories it was hypothesized that TCDD acts as a tumor promoter by preventing initiated cells from undergoing apoptosis. The exact mechanisms of apoptosis inhibition by TCDD are not fully understood, but both in vivo and in vitro studies consistently showed an involvement of the tumor suppressor p53 in this effect. Various strings of evidence have been established linking apoptosis to the detrimental effects of exogenous activation of the AhR. Within this article, studies elucidating the effects of TCDD and related substances on apoptosis signaling, be it inducing or repressing, is to be reviewed.

Survival of infants in the context of prevention of mother to child HIV transmission in South Africa

AIM

We sought to study the survival of newborn children according to HIV status of the mother, that of the child and the timing of infection.

METHODS

This is a prospective cohort study of 883 mothers (665 HIV-positive and 218 HIV-negative) and their infants. Data were collected using semi-structured questionnaires during home visits between the antenatal period and 36 weeks post-delivery. Infant HIV status was determined at 3, 24 and 36 weeks by HIV DNA PCR.

RESULTS

The majority (81.3%) of infected infants who died were infected by 3 weeks of age. Of the HIV-exposed infants who died, 19 (28.4%) died before 6 weeks and 38 (56.7%) died by 12 weeks. The hazard ratio (HR) of mortality at 36 weeks of age in HIV-infected infants compared with exposed but negative infants was 8.9 (95% CI: 6.7-11.8). There was no significant difference in 36 week survival rates between HIV-non-exposed and HIV-exposed but negative infants (HR: 0.7; 95% CI: 0.3-1.5). The infant being HIV-positive at age 3 weeks (HR: 32 95% CI: 14.0-73.1) and rural site (HR: 4.4 95% CI: 1.2-23.4) were the two independent risk factors for infant death amongst HIV-exposed infants.

CONCLUSION

The prognosis for infants with early HIV infection was very poor in this cohort. A greater focus on prevention of early infection, earlier screening for HIV infection and access to antiretrovirals for eligible infants is recommended.

Russell-Silver syndrome due to paternal H19/IGF2 hypomethylation in a patient conceived using intracytoplasmic sperm injection

Epigenetic alterations at several maternal loci have been associated with imprinting disorders in children conceived using assisted reproductive technologies. To date, epimutations at paternal loci have been observed in the spermatozoa of infertile men, but there is little evidence of paternal epimutations in babies conceived using assisted reproductive treatment. This is a report of a female infant with classic Russell-Silver Syndrome (RSS) who was conceived using intracytoplasmic injection of spermatozoa obtained from testicular aspiration. Methylation studies revealed hypomethylation of the paternally derived H19/IGF2 locus. As far as is known, this is the second assisted reproduction treatment-conceived patient with classic RSS and this epigenotype. This case provides further evidence that epimutations affecting paternal alleles might be associated with assisted reproductive treatment.

Inhibition of UV-C light-induced apoptosis in liver cells by 2,3,7,8-tetrachlorodibenzo-p-dioxin

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a highly toxic pollutant ubiquitously present in the environment. Most of the toxic effects of TCDD are believed to be mediated by high-affinity binding to the aryl hydrocarbon receptor (AhR) and subsequent effects on gene transcription. TCDD causes cancer in multiple tissues in different animal species and is classified as a class 1 human carcinogen. In initiation-promotion studies TCDD was shown to be a potent liver tumor promotor. Among other theories it has been hypothesized that TCDD acts as a tumor promotor by preventing initiated cells from undergoing apoptosis. We examined the effects of TCDD on ultraviolet C (UV-C) light-induced apoptosis in primary rat hepatocytes and Huh-7 human hepatoma cells. TCDD inhibits UV-C light-induced apoptosis in both cell types. This effect is seen with chromatin condensation and fragmentation and appears to be mediated by the AhR in rat hepatocytes. Apoptosis induced by UV-C light in these cells is caspase-dependent and is accompanied by alterations in apoptosis-related gene expression such as up-regulation of proapoptotic bcl-2 family genes like bak and bax, and a marked down regulation of the expression of the antiapoptotic bcl-2. TCDD treatment of irradiated hepatocytes induces the expression of some apoptosis-related genes (birc3, dad1, pycard, tnf). Upstream apoptotic events, namely caspase activation and caspase substrate cleavage are not inhibited by TCDD treatment. We hypothesize that TCDD inhibits late-stage apoptotic events that lead to internucleosomal DNA fragmentation, maintaining chromosomal integrity probably in order to sustain metabolic capacity and hepatic elimination of substrates despite of an initiation of apoptosis.

A health systems assessment of the KwaZulu-Natal tuberculosis programme in the context of increasing drug resistance

SETTING

High mortality and high transmission rates of extensively drug-resistant tuberculosis (XDR-TB) in KwaZulu-Natal Province of South Africa have highlighted the role of hospitals in the spread of TB and drug-resistant TB.

OBJECTIVES

To determine the operational effectiveness of the National TB Programme (NTP) at a regional/district hospital and its referral clinics.

DESIGN

In this multi-faceted retrospective case study, a framework was developed to evaluate the different components of the TB services, their performance in relation to each other and the system as a whole. Different methods used included structured and semi-structured interviews, retrospective medical record reviews and retrospective register reviews.

RESULTS

Only 18% of those diagnosed with smear-positive pulmonary TB (PTB) in the hospital laboratory completed their treatment and 11% were cured. Clinicians did not adhere to the diagnostic guidelines of the NTP. In the TB register, 85% of PTB cases were diagnosed in the absence of sputum microscopy. Chest X-rays alone were used to diagnose PTB in 45% of the records reviewed. In addition, clinicians failed to document a clinical history suggestive of TB. Only 66 (29%) of the hospital's 225 smear-positive PTB patients reached the clinics for completion of their treatment.

CONCLUSION

System failures, together with inadequate knowledge and understanding of clinicians, undermined the effectiveness of the NTP. A reduction in TB and drug-resistant forms of TB is dependent on effective diagnosis, treatment and improved communication systems between the hospital, laboratory and its down-referral clinics.

Infant feeding in the time of HIV: rapid assessment of infant feeding policy and programmes in four African countries scaling up prevention of mother to child transmission programmes

OBJECTIVE

To assess the infant feeding components of prevention of mother to child HIV transmission (PMTCT) programmes.

METHODS

Assessments were performed across Botswana, Kenya, Malawi and Uganda. 29 districts offering PMTCT were selected by stratified random sampling with rural and urban strata. All health facilities in the selected PMTCT district were assessed. The facility level manager and the senior nurse in charge of maternal care were interviewed. 334 randomly selected health workers involved in the PMTCT programme completed self-administered questionnaires. 640 PMTCT counselling observations were carried out and 34 focus groups were conducted amongst men and women.

RESULTS

Most health workers (234/334, 70%) were unable to correctly estimate the transmission risks of breastfeeding irrespective of exposure to PMTCT training. Infant feeding options were mentioned in 307 of 640 (48%) observations of PMTCT counselling sessions, and in only 35 (5.5%) were infant feeding issues discussed in any depth; of these 19 (54.3%) were rated as poor. Several health workers also reported receiving free samples of infant formula in contravention of the International Code on Breastmilk Substitutes. National HIV managers stated they were unsure about infant feeding policy in the context of HIV. Finally, there was an almost universal belief that an HIV positive mother who breastfeeds her child will always infect the child and intentional avoidance of breastfeeding by the mother indicates that she is HIV positive.

CONCLUSION

These findings underline the need to implement and support systematic infant feeding policies and programme responses in the context of HIV programmes.

A European carotenoid database to assess carotenoid intakes and its use in a five-country comparative study

A food frequency questionnaire (FFQ) and carotenoid database with information onα- and β-carotene, lutein, lycopene and β-cryptoxanthin was prepared and used to compare the carotenoid intakes in five European countries: UK, Republic of Ireland, Spain, France and The Netherlands. Eighty, age- (25–45 years) and sex-matched volunteers were recruited in each of the five countries. A FFQ and carotenoid database was prepared of the most commonly consumed carotenoid rich foods in the participating countries and the information was used to calculate frequency and intake of carotenoid-rich foods. The median total carotenoid intake based on the sum of the five carotenoids, was significantly higher (P<0.05) in France (16.1 mg/day) and lower in Spain (9.5 mg/day,) than the other countries, where the average intake was approximately 14 mg/day. Comparison of dietary source of carotenoids showed that carrots were the major source of β-carotene in all countries except Spain where spinach was most important. Likewise, carrots were also the main source ofα-carotene. Tomato or tomato products, were the major source of lycopene. Lutein was mainly obtained from peas in Republic of Ireland and the UK, however, spinach was found to be the major source in other countries. In all countries, β-cryptoxanthin was primarily obtained from citrus fruit. Comparing the data with that from specific European country studies suggests that the FFQ and carotenoid database described in the present paper can be used for comparative dietary intake studies within Europe. The results show that within Europe there are differences in the specific intake of some carotenoids which are related to different foods consumed by people in different countries.

Can lycopene be delivered into semen via prostasomes? In vitro incorporation and retention studies

Lycopene (C(40) H(56)) is a highly lipophilic antioxidant found in human semen in nanomolar concentrations. It has been shown to be one of the most potent carotenoid antioxidant in various human studies. Prostasomes are organelles secreted by glandular prostatic epithelial cells and are known to play an important role in fertility and prostate cancer. They are also known to possess antioxidant activity and aid the functioning of sperm. We studied the ability of these vesicles to adsorb and retain lycopene into their rich lipid environment in vitro. High-performance liquid chromatography analysis confirmed micrograms of lycopene per milligram of prostasomal protein. In view of the prostasomes' lipid-rich nature it is highly likely that these organelles act as delivery vehicles for this highly lipophilic antioxidant substance into human semen.

Confronting Africa's health crisis: more of the same will not be enough

The international community needs to rethink its approach to Africa if it wants to produce sustained improvements in health

Effect of an IMCI intervention on quality of care across four districts in Cape Town, South Africa

AIMS

To measure the change in quality of care provided to sick children as a result of the routine implementation of the IMCI intervention.

METHODS

Structured observations of consultations with sick children, exit interviews with caregivers, and facility reviews were conducted both before and after IMCI intervention in four health districts in Cape Town. Interventions were case management training, orientation courses for supervisors and medical officers, and some reorganisation of management systems.

RESULTS

Twenty one nurses in 21 clinics were observed before and after the IMCI intervention; 90 and 70 child observations were conducted before and after IMCI intervention respectively. There was a marked improvement in assessment of danger signs in sick children (7% before versus 72% after), assessment of co-morbidity (integrated score 5.2 versus 8.2), rational prescribing (62% versus 84%), and starting treatment in the clinic (40% versus 70%). However there was no change in the treatment of anaemia or the prescribing of vitamin A or counselling of caregivers. There was no change in the knowledge of caregivers regarding medication or when to return to the health facility. Facilities were well stocked and supervision regular both before and after IMCI.

CONCLUSION

This study has shown that under normal operating conditions and in a context of good facility infrastructure and management support, IMCI is associated with improvements in some important aspects of care.