Endogenous IL-27 during toxoplasmosis limits early monocyte responses and their inflammatory activation by pathological T cells

Mice that lack the genes for IL-27, or the IL-27 receptor, and infected with Toxoplasma gondii develop T cell-mediated pathology. Here, studies were performed to determine the impact of endogenous IL-27 on the immune response to T. gondii in wild-type (WT) mice. Analysis of infected mice revealed the early production of IL-27p28 by a subset of Ly6Chi, inflammatory monocytes, and sustained IL-27p28 production at sites of acute and chronic infection. Administration of anti-IL-27p28 prior to infection resulted in an early (day 5) increase in levels of macrophage and granulocyte activation, as well as enhanced effector T cell responses, as measured by both cellularity, cytokine production, and transcriptional profiling. This enhanced acute response led to immune pathology, while blockade during the chronic phase of infection resulted in enhanced T cell responses but no systemic pathology. In the absence of IL-27, the enhanced monocyte responses observed at day 10 were a secondary consequence of activated CD4+ T cells. Thus, in WT mice, IL-27 has distinct suppressive effects that impact innate and adaptive immunity during different phases of this infection.

IMPORTANCE

The molecule IL-27 is critical in limiting the immune response to the parasite Toxoplasma gondii. In the absence of IL-27, a lethal, overactive immune response develops during infection. However, when exactly in the course of infection this molecule is needed was unclear. By selectively inhibiting IL-27 during this parasitic infection, we discovered that IL-27 was only needed during, but not prior to, infection. Additionally, IL-27 is only needed in the active areas in which the parasite is replicating. Finally, our work found that a previously unstudied cell type, monocytes, was regulated by IL-27, which contributes further to our understanding of the regulatory networks established by this molecule.

674 IL-27 signaling drives a type 1 interferon-like gene expression program of immunoregulatory pathways associated with cancer progression

Background

Interleukin (IL)-27 is a heterodimeric immunoregulatory cytokine that signals through the JAK/STAT pathway to increase the expression of coinhibitory receptors on immune cells (e.g. PD-L1, TIM-3, LAG-3) and dampen inflammatory cytokine production. Blockade of IL-27 leads to antitumor activity in preclinical mouse models of lung metastases. A Phase 1 trial of SRF388 (NCT04374877), a first-in-class anti–IL-27 antibody, has demonstrated monotherapy antitumor activity in a patient with non-small cell lung cancer (NSCLC).1 The current study aimed to characterize the immunoregulatory impact of IL-27 signaling by gene expression profiling.

Methods

Gene expression changes induced by IL-27 were examined in activated human CD4+ T cells, human peripheral blood mononuclear cells (PBMCs), and the IL-27RA–expressing lung cancer cell line NCI-H2228 by microarray or single cell RNA-sequencing. The resulting IL-27 signature genes were interrogated by Gene Set Enrichment Analysis (GSEA) using publicly available datasets, including single cell RNA-seq analysis of the tumor microenvironment, from patients with NSCLC.2

Results

IL-27 induced a robust gene expression program in human immune cells that included several inhibitory receptors and canonical interferon regulated genes such as guanylate-binding proteins and interferon regulatory factors. GSEA and interferon signature analysis showed a striking overlap with those genes regulated by interferon-beta, a cytokine known to drive immune suppression associated with chronic viral infection and that is used therapeutically for controlling inflammation associated with the autoimmune disease multiple sclerosis. Moreover, interferon regulated pathways have recently emerged as a mechanism of resistance to immune checkpoint blockade in cancer. Exploration of the IL-27 gene signature in published datasets showed enrichment in macrophage populations associated with progressive disease in patients with NSCLC. While many of the properties of IL-27–mediated immune regulation have focused on hematopoietic cells, IL-27RA is also expressed on tumor cells from NSCLC patients with progressive disease as well as lung cancer cell lines in which IL-27 can upregulate PD-L1, IDO1, and other canonical interferon regulated genes.

Conclusions

These studies elucidate the transcriptional networks that are engaged after IL-27 signaling in immune and cancer cells and highlight the parallels with interferon-associated immune regulation. Blockade of IL-27 provides a novel therapeutic strategy to alleviate a gene transcriptional program implicated in immune suppression and checkpoint resistance.

References

Patnaik A, Morgensztern D, Mantia C, et al. Results of a phase 1 study of SRF388, a first-in-human, first-in-class, high-affinity anti-IL-27 antibody in advanced solid tumors. J Clin Oncol 2021;39:2551–2551.

Maynard A, McCoach CE, Rotow JK, et al. Therapy-induced evolution of human lung cancer revealed by single-cell RNA sequencing. Cell 2020;182:1232–1251.

Abstract 1802: CD39 inhibition shapes the transcriptional landscape of myeloid cells and induces proinflammatory states in the CT26 syngeneic tumor model

Extracellular adenosine triphosphate (ATP) generated by tissue damage or immunogenic cell death initiates proinflammatory responses that are potently restricted by adenosine produced through ATP hydrolysis. The ectonucleotidases CD39 and CD73 limit immune responses by sequentially converting ATP to adenosine monophosphate (AMP) and adenosine, respectively. Increased activity of CD39, the rate-limiting enzyme in ATP hydrolysis in tumor microenvironments (TME), results in significant reductions in extracellular ATP. The subsequent accumulation of adenosine contributes to tumor immune escape, induction of angiogenesis, and metastatic progression. Although pharmacological targeting of CD39 has antitumor effects in preclinical models, the immunological mechanisms of therapeutic CD39 blockade have not been finely parsed. In this study, the immunological effects of CD39 inhibition on tumor infiltrating lymphocytes (TILs) were examined by single-cell transcriptome analysis. Mice bearing syngeneic CT26 tumors were treated with an anti-murine CD39 antibody that blocks the conversion of ATP to AMP. After 3 doses, tumors were harvested on Day 15 post-implant, dissociated, and enriched for CD45+ cells. Isolated TILs were captured in droplets, and single-cell sequencing libraries were generated through standard 10× Genomics protocols. Raw reads were pre-processed through the CellRanger pipeline. Data quality, normalization, integration, and clustering were performed with Seurat. Cell type annotation and differential expression was performed with SingleR and EdgeR, respectively. Several defined immunocyte populations identified in the CT26 TME were conserved across all conditions tested. These cell clusters segregated along the lymphoid/myeloid axis, with many sub-clusters identified for each major lineage. Data for each cell were aggregated in a pseudo-bulk RNA-seq analysis to define broad effects of CD39 blockade, which revealed major changes to immunocyte transcriptional landscapes. Notably, CD39 blockade upregulated several proinflammatory genes, including Gzmf, Gzmg, Cxcl9, and Csf3. Mapping of these changes to single-cell clusters revealed that CD39 blockade predominantly altered the transcriptional profiles of myeloid cell subsets, generally inducing proinflammatory gene modules. This analysis also demonstrated a significant effect of CD39 inhibition on plasmacytoid dendritic cells, inducing Cxcl2, Il1b, Gadd45g, and Fabp4 expression. Interestingly, CD39 blockade repressed Klk1, a kallikrein previously implicated in tumorigenesis. In summary, single-cell RNA-seq of the CT26 syngeneic tumor model suggests that CD39 inhibition predominantly shaped the transcriptional landscape of myeloid cells and generally induced proinflammatory conditions.

Citation Format: Devapregasan Moodley, Mayra Carneiro, Sonia D. Gas, Austin Dulak, Ricard Masia, Secil Koseoglu, Matthew Rausch, Marisella Panduro, Michael C. Warren, John Stagg, Benjamin Lee, Pamela M. Holland, Vito J. Palombella, Andrew C. Lake. CD39 inhibition shapes the transcriptional landscape of myeloid cells and induces proinflammatory states in the CT26 syngeneic tumor model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1802.

Abstract 558: MERTK-specific antibodies that have therapeutic antitumor activity in mice disrupt the integrity of the retinal pigmented epithelium in cynomolgus monkeys

MERTK, a member of the TAM (TYRO3, AXL, MERTK) family of receptor tyrosine kinases, is a pleiotropic immune modulator that controls efferocytosis. Engagement of MERTK with its ligand GAS6, found anchored to phosphatidylserine exposed on the outer membrane of apoptotic cells, triggers MERTK phosphorylation and signaling events that culminate in the removal of apoptotic debris. Recent studies have highlighted the expression of MERTK on tumor-associated macrophages, and Mertk-deficient mice show reduced tumor cell growth accompanied by inflammatory cytokine production and alterations in macrophage activation. Thus, MERTK has emerged as a promising therapeutic target for augmenting innate antitumor immune responses. MERTK is also expressed in retinal pigmented epithelium (RPE) cells of the eye where it mediates phagocytosis of photoreceptor outer segment fragments. Mutations in MERTK that disrupt its expression or kinase activity lead to marked retinal degeneration and blindness in mice, rats, and humans. Due to known differences in blood-retinal permeability, we explored whether therapeutic antibodies targeting MERTK could inhibit macrophage-mediated efferocytosis and promote antitumor activity while sparing RPE toxicity. A diverse panel of high-affinity antibodies was developed to explore MERTK blockade in vitro and in vivo. Multiple antibodies disrupted MERTK-GAS6 binding and blocked human and murine macrophage-mediated efferocytosis. Two antibodies targeting distinct GAS6 binding epitopes were selected for further characterization. Both antibodies demonstrated antitumor activity in murine CT26 and MC38 syngeneic colorectal cancer models and led to alterations in immune cell-related gene expression. To investigate potential effects on RPE biology with MERTK antibodies, a multi-dose, 4-week cynomolgus monkey study with several in-life and post-mortem ophthalmologic endpoints was designed. While no abnormal ophthalmic or electroretinography (ERG) findings were detected, all animals treated with either MERTK antibody at all doses showed histological abnormalities of the retina, including vacuolation of the outer segments of photoreceptors, displacement of RPE cells, and single cell necrosis of the outer nuclear layer. These data suggest that inhibition of efferocytosis by antibody-mediated blockade of MERTK can promote immune activation and inhibit tumor growth in vivo; however, retinal toxicity consistent with histological observations made in Mertk mutant animals is an on-target effect. As several therapeutics that block MERTK function are currently in preclinical development, a thorough evaluation of retinal toxicity is warranted.

Citation Format: Kerry F. White, Matthew Rausch, Jing Hua, Katherine H. Walsh, Christine E. Miller, Christopher C. Wells, Devapregasan Moodley, Benjamin H. Lee, Scott C. Chappel, Pamela M. Holland, Jonathan A. Hill. MERTK-specific antibodies that have therapeutic antitumor activity in mice disrupt the integrity of the retinal pigmented epithelium in cynomolgus monkeys [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 558.

IL-27 and TCR Stimulation Promote T Cell Expression of Multiple Inhibitory Receptors

Inhibitory receptors (IR) are a diverse group of cell surface molecules that modulate T cell activation, but there are gaps in our knowledge of the cell-extrinsic factors that regulate their expression. The present study found that in vivo overexpression of IL-27 in mice led to increased T cell expression of PD-L1, LAG-3, TIGIT, and TIM-3. In vitro, TCR stimulation alone promoted expression of multiple IRs, whereas IL-27 alone induced expression of PD-L1. However, the combination of intermediate TCR stimulation and IL-27 resulted in synergistic induction of LAG-3, CTLA-4, and TIGIT. In vivo, infection with Toxoplasma gondii resulted in parasite-specific effector T cells that expressed high levels of IR, and at local sites of infection where IL-27 production was highest, IL-27 was required for maximal effector cell expression of PD-L1, LAG-3, CTLA-4, and TIGIT. Together, these results affirm the critical role of TCR signals in the induction of IR expression but find that during infection, IL-27 promotes T cell expression of IR.

Sirtuin 1 rs1467568 and rs7895833 in South African Indians with early-onset coronary artery disease

BACKGROUND

Sirtuin 1 (SIRT1), a class III histone deacetylase, has been identified as a candidate molecule affecting the epigenetic mechanisms of cardiovascular disease (CVD). Previous studies have shown that some SIRT1 single-nucleotide polymorphisms (SNPs) are associated with body mass index, diabetes, blood pressure, cholesterol metabolism and coronary artery calcification. We investigated two A>G SIRT1 SNPs, rs1467568 and rs7895833, in young South African (SA) Indians with coronary artery disease (CAD) and compared them to Indian and black controls.

METHODS

For rs1467568, a total of 287 subjects were recruited into this study (104 CAD patients, 99 age-, gender- and race-matched controls, and 84 age- and gender-matched black controls). For rs7895833, a total of 281 subjects were recruited into this study (100 CAD patients, 99 age-, gender- and race-matched controls, and 82 age- and gender-matched black controls). All patients were male, of Indian ethnicity, stable CAD confirmed on angiography, mean age 37.5 years; range 24-45. All subjects were genotyped using TaqMan SNP genotyping assays.

RESULTS

The variant allele for both SNPs was found at a higher frequency in the total Indian group compared to the total black population (rs1467568: 41 vs 18.5%, respectively, p < 0.0001, OR = 3.190, 95% CI: 2.058-40943; and rs7895833: 41 vs 22%, respectively, p < 0.0001, OR = 2.466, 95% CI: 1.620- 3.755). Indian controls presented with a higher frequency for both SNPs compared to black controls (rs1467568: 40 vs 18.5%, respectively, p < 0.0001, OR = 2.996, 95% CI: 1.850- 4.853; and rs7895833: 41 vs 22%, respectively, p < 0.0001, OR = 2.513, 95% CI: 1.578-4.004). No difference was seen in the distribution of both SNPs between CAD patients and either control group. We did not observe any association between the SNPs and clinical parameters in CAD patients and controls.

CONCLUSION

Both SNP variant alleles occurred more frequently in SA Indians than in SA blacks. A larger study group and further analysis is required to assess whether these SIRT1 SNPs may serve as risk factors that contribute to Indians developing early-onset CAD.

Atorvastatin increases miR-124a expression: a mechanism of Gamt modulation in liver cells

Atorvastatin is used to control cholesterol and lipid levels in hyperlipidaemic and hypercholesterolaemic patients. Myopathy and hepatotoxicity, however, have been reported as side effects in a small percentage of statin users. This study aimed to investigate the cytotoxicity and the effect of atorvastatin on microRNA expression in HepG2 cells. The methylthiazol tetrazolium assay was used to assess hepatocyte viability and at 20 μM atorvastatin (24 h) treatment were 82 ± 1.5% viable (P = 0.0002). Levels of intracellular ATP in cells treated with 20 μM atorvastatin were reduced by 1.25-fold, P = 0.002. Cytotoxicity, measured by the release of intracellular lactate dehydrogenase, was increased from 0.95 ± 0.29 units in control cells to 1.12 ± 0.02 units (P = 0.002) in atorvastatin treated cells. A panel of 84-miRNA species was used to evaluate the effect of atorvastatin on miRNA expression. MiR-124a was significantly up-regulated by atorvastatin (12.94-fold). A significant decrease in GAMT expression (3.54-fold) was observed in atorvastatin treated cells following quantitative PCR analysis. In addition, western blotting data showed GAMT protein levels were significantly lower than the controls (3.02-fold) and analysis of creatine levels in treated cells showed a significant decrease in the atorvastatin treated culture supernatant compared to control culture supernatant (32.33 ± 3.51 μM/l vs. 59.67 ± 1.52μM/l, P = 0.0056). This is the first study to show that atorvastatin up-regulates miR-124a levels and consequently modulates GAMT expression in hepatocytes.

Parsing the Interferon Transcriptional Network and Its Disease Associations

Type 1 interferon (IFN) is a key mediator of organismal responses to pathogens, eliciting prototypical "interferon signature genes" that encode antiviral and inflammatory mediators. For a global view of IFN signatures and regulatory pathways, we performed gene expression and chromatin analyses of the IFN-induced response across a range of immunocyte lineages. These distinguished ISGs by cell-type specificity, kinetics, and sensitivity to tonic IFN and revealed underlying changes in chromatin configuration. We combined 1,398 human and mouse datasets to computationally infer ISG modules and their regulators, validated by genetic analysis in both species. Some ISGs are controlled by Stat1/2 and Irf9 and the ISRE DNA motif, but others appeared dependent on non-canonical factors. This regulatory framework helped to interpret JAK1 blockade pharmacology, different clusters being affected under tonic or IFN-stimulated conditions, and the IFN signatures previously associated with human diseases, revealing unrecognized subtleties in disease footprints, as affected by human ancestry.

TB/HIV pleurisy reduces Th17 lymphocyte proportion independent of the cytokine microenvironment

T-helper (Th) 17 cells are a pro-inflammatory subset of CD4(+) effector T-cells critical in mucosal immunity. Imbalances in Th17 cell proportion have been implicated in the pathogenesis of several diseases; however, this has not been adequately explored in tuberculosis (TB) and human immunodeficiency virus (HIV) co-infection. Since Th17 cells are predominantly mucosally associated, we assessed Th17 proportion and associated microenvironment in pleural effusions from patients co-infected with TB/HIV. Our results show that TB(+)HIV(+) pleurisy results in significantly reduced frequency of CD4(+)IL-17(+)RORC(+)STAT3(+) Th17 cells compared to TB(-)HIV(-)ex vivo (p = 0.0054) and was confirmed in conditioned media studies in vitro (p = 0.0001). This was not associated with alterations in Th17 polarising cytokines IL-6, IL-21 and IL-23 or changes in Th17 signature cytokines IL-17A and F. However, the mRNA expression of Th17 signalling molecules, IL-6 (p = 0.0022), IL-6R (p = 0.0247), IL-1β (p = 0.0022) and signal transducer and activator (STAT) 3 (p = 0.0022) were significantly upregulated. Notably, TB(+)HIV(+) pleural fluid contained significantly higher concentrations of IL-1β (p = 0.0008), IL-22 (p = 0.0115), IL-31 (p = 0.0210), TNF-α (p = 0.0251) and IFN-γ (p = 0.0026) than TB(-)HIV(-) pleural fluid ex vivo. Taken together, this suggests a reduced portion of Th17 lymphocytes in TB/HIV pleurisy is independent of locally mediated cytokine polarisation.

The importance of pollinators and autonomous self-fertilisation in the early stages of plant invasions: Banksia and Hakea (Proteaceae) as case studies

Reproduction is a crucial stage in the naturalisation of introduced plant species. Here, using breeding system experiments and observations of floral visitors, we investigate whether a lack of pollinators or an inability to autonomously self-fertilise limits naturalisation in five Australian Banksia species and the co-familial Hakea salicifolia in South Africa. Banksia species were heavily utilised by native insects and nectar-feeding birds. Although Banksia produced fruit when pollinators were excluded, pollinators significantly increased seed set in four of the five species. H. salicifolia flowers were visited by 11 insect species; honeybees (Apis mellifera) were the main visitors. Flowers in naturalised H. salicifolia populations received almost four times the number of visits as flowers in non-naturalised populations; the latter showed both pollen limitation (PLI 0.40) and partial self-incompatibility. This should not prevent invasion, since H. salicifolia produces fruits via autonomous selfing in the absence of pollinators. The results suggest a limited role of breeding systems in mediating naturalisation of introduced Proteaceae species. Other factors, such as features of the recipient environments, appear to be more important. Spatial variation in rates of reproduction might, however, explain variation in the extent and rate of naturalisation of different populations.

Oxidative stress and air pollution exposure during pregnancy: A molecular assessment

Chronic air pollution exposure during pregnancy can cause oxidative stress leading to adverse birth outcomes. The aim of this study was to assess and compare oxidative stress response in peripheral lymphocytes isolated from pregnant women from a highly industrialized locale (south Durban (SD); n = 50) and a control with lower air pollutant levels (north Durban (ND); n = 50). Oxidative stress response was measured by quantifying malondialdehyde (MDA) levels and a SuperArray gene panel. Mitochondrial function (adenosine triphosphate (ATP) levels and mitochondrial depolarization), DNA integrity (comet assay and mitochondrial DNA (mtDNA) viability) and DNA repair (OGG1) were assessed. Antioxidant response was assessed by quantification of glutathione (GSH) and SOD2, nuclear factor erythroid 2-related factor 2 (Nrf2) and uncoupling protein 2 (UCP2) protein and messenger RNA (mRNA) expression. Levels of MDA (p = 0.9), mitochondrial depolarization (p = 0.88), ATP (1.89-fold), SOD2 (1.23-fold) and UCP2 (1.58-fold) gene expression were elevated in the SD group with significantly higher UCP2 protein levels (p = 0.05) and longer comet tail length (p = 0.0004). The expression of Nrf2 protein (p = 0.03) and mRNA levels (-1.37-fold), GSH concentration (p < 0.0001), mtDNA amplification (-2.04-fold) and OGG1 mRNA (-2.78-fold) activity were decreased in the SD group. Of the 84 oxidative stress-related genes evaluated, 26 were differentially regulated. Pregnant women exposed to higher air pollutant levels showed increased markers for oxidative stress and compromised DNA integrity and repair.

Fumonisin B1 induces global DNA hypomethylation in HepG2 cells - An alternative mechanism of action

Fumonisin B1 (FB1), a common mycotoxin contaminant of maize, is known to inhibit sphingolipid biosynthesis and has been implicated in cancer promoting activity in animals and humans. FB1 disrupts DNA methylation and chromatin modifications in human hepatoma (HepG2) cells. We investigated the effect of FB1 on enzymes, DNA methyltransferases and demethylases, involved in chromatin maintenance and gross changes in structural integrity of DNA in HepG2 cells. We measured: (i) the expression of 84 key genes encoding enzymes known to modify genomic DNA and histones (superarray and qPCR); (ii) protein expression of DNA methyltransferases (DNMT1, DNMT3A and DNMT3B) and the major demethylase (MBD2) (western blotting); (iii) degree of DNA methylation by FACS using anti-5-MeCyt and (iv) DNA migration (single cell gel electrophoresis). FB1 significantly decreased the methyltransferase activities of DNMT1, DNMT3A and DNMT3B, and significantly up regulated the demethylases (MBD2 expression and activity, and KDM5B and KDM5C expression). FACS data showed FB1 significantly increased DNA hypomethylation and resulted in gross changes in structural DNA as evidenced by the Comet assay. We conclude that FB1 induces global DNA hypomethylation and histone demethylation that causes chromatin instability and may lead to liver tumourigenesis.

The interleukin-6 -147 g/c polymorphism is associated with increased risk of coronary artery disease in young South African Indian men

BACKGROUND

Interleukin-6 (IL-6) is a proinflammatory cytokine involved in the pathogenesis of chronic inflammatory diseases such as coronary artery disease (CAD). The -174 IL-6 G/C promoter polymorphism influences mRNA levels and protein expression and is implicated in CAD. The Indian population in South Africa, unlike the black community, has a high prevalence of premature CAD. This polymorphism has not been fully explored in this population. The present study assessed the -174 IL-6 G/C polymorphism in young Indian patients with angiographically documented CAD and compared them with age- and gender-matched Indian and black control subjects.

METHODS

Polymorphic variants were assessed by polymerase chain reaction-restriction fragment length polymorphism, and IL-6 levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The -174 IL-6 C allele was found with a higher frequency (23%) in the total Indian group compared to 2% in the black participants [P<0.0001, odds ratio (OR)=0.05, 95% confidence interval (CI) 0.018-0.14). The difference in frequency was more pronounced when Indian controls were compared to black controls (29% vs. 2%, respectively) (P<0.0001, OR=0.05, 95% CI 0.02-0.17). A significant association between the -174 IL-6 G allele and CAD was found in Indian patients compared to Indian controls (84% in cases vs. 71% in Indian controls; P=0.043, OR=0.47 95% CI 0.23-0.95). Levels of IL-6 in circulation were higher in black controls (6.62±0.63 pg/mL) compared to Indian controls (2.51±0.57 pg/mL) and CAD patients (1.46±0.36 pg/mL) (P<0.0001). Levels of IL-6 were higher in all groups with homozygous -174 IL-6 C alleles, but only significant in the healthy Indian control group (GG 3.73±0.94 pg/mL vs. GC/CC 0.89±0.5 pg/mL, P=0.0001).

CONCLUSION

The presence of the IL-6 -174 G allele influences levels of IL-6 and increases the risk of CAD in South African Indians.

A comparative study of central corneal thickness (CCT) and intraocular pressure (IOP) in University of KwaZulu-Natal students of Black and Indian ethnicity*

Thisstudy compared central corneal thickness (CCT) and intraocular pressure (IOP) of Black and Indian students from the University of Kwa-Zulu-Natal. Two hundred (100 Black and 100 Indi-an) participants of both genders aged 18-25 years (mean and standard deviation; 20.1±1.6 years) participated in this study. CCT and IOP were measured for the right eye of each participant using a Tono-Pachymeter (NT530P) and a Goldmann applanation tonometer (GAT) respectively. Data was analyzed with descriptive, t-test and Pearson’s cor-relation statistics. In the total sample (N = 200), the mean CCT value was 519.5 ± 38.6 μm and CCT was higher in the Indians (526.5 ± 37.2 µm) than in the Blacks (512.4 ± 38.9 µm) (p = 0.01).  Also, it was higher in the females (522.3 µm) than in males (516.7 µm), but the difference was insignificant (p = 0.07). The mean CCT was higher in the Indian males (520.1 µm) than in the Black males (513.2 µm), but the difference was insignificant (p=0.39).  However, it was significantly higher in the Indian females (533 µm) than in the Black females (511.6 µm) (p = 0.003). In the total sample, the mean IOP was 14.6 mmHg and IOP was greater in Indiansthan Blacks (mean = 15.3 ± 2.9 mmHg and 13.8 ± 2.6 mmHg respectively) (p = 0.01). Also, the mean IOP (N = 200) value was slightly higher in the females (14.7 mmHg) than in males (14.5 mmHg) (p = 0.51). The mean IOP was higher in the Indian males (15.0 mmHg) than in the Black males (14.0 mmHg) (p = 0.07) and the mean IOP value was higher in the Indian females (15.7 mmHg) than in the Black females (13.6 mmHg) (p < 0.001). The higher mean IOP value in the Indian than Black participants was attributed to the higher mean CCT values. A positive, but inconsistent association between CCT and IOP was found in this study, the coefficient in the total sample (r = 0.382, p = 0.000), in the Blacks (r = 0.196, p = 0.05) and in Indians (r = 0.498, p = 0.000). A national population study comparing CCT and IOP in the various South African ethnic groups is recommended. Cognizance of these differences should be taken in the diagnoses of glaucoma in these ethnic groups. (S Afr Optom 2012 71(4) 171-177)

Association of -308 TNF-alpha promoter polymorphism with viral load and CD4 T-helper cell apoptosis in HIV-1 infected black South Africans

Objective. To determine whether the -308 TNF-α promoter polymorphism is associated with markers of HIV progression in the South African population. Methods. Polymerase chain reaction-restriction fragment length polymorphism was used to detect the -308 TNF-α polymorphism in 75 patients and 76 healthy controls. Serum TNF-α concentrations were measured using ELISA in each cohort. CD4+ T cell apoptosis and HIV-1 RNA viral load were determined using Annexin-V-FITC assay and Nuclisens Easy Q HIV-1 assay respectively. CD4 + T cell counts were measured flow cytometrically. Results. The frequency of -308 G allele was similar in the HIV-1 and control cohorts. The -308GG genotype was associated with lower TNF-α concentrations and markers of increased HIV progression indicated by higher TH lymphocyte apoptosis, lower TH lymphocyte count and higher plasma viral load, irrespective of treatment. Conclusion. The presence of the TNF-α -308 G allele in HIV-1 patients may be associated with increased risk of HIV-1 progression. Further research is required to investigate the nature of this association. S Afr J HIV Med 2012;13(2):72-77.

Initiation but no execution - modulation of peripheral blood lymphocyte apoptosis in rheumatoid arthritis - a potential role for heat shock protein 70

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disease, which causes synovial damage. Persistence of lymphocyte infiltrates in the rheumatoid synovium has been attributed to abnormal apoptosis. While not comprehensively investigated, perturbations in peripheral blood lymphocyte (PBL) apoptosis may also be involved in perpetuation of autoimmune processes in RA.

Methods

We investigated total, CD4+ and CD19+ PBL apoptosis in our study cohort by monitoring the translocation of phosphatidylserine using the Annexin-V assay. To examine the role of death receptor mediated apoptosis as well as activation-induced-cell-death (AICD), PBLs were labeled with CD95/Fas and CD69 markers and enumerated by flow cytometry. Proteolytic activity of initiator and executioner caspases was determined by luminometry. DNA fragmentation assays were used to examine whether apoptotic signals were transduced to the nucleus. Quantitative PCR arrays were used to investigate apoptotic pathways associated with RA-PBLs. Since heat-shock-protein-70 (HSP70) is an inducible protein which modulates apoptotic signals, we determined HSP70 levels by intra-cellular flow cytometry and western blots.

Results

The RA-PBLs showed signs of elevated apoptosis whilst in circulation. These include increases in the loss of plasma membrane asymmetry, indicated by increased externalization of phosphatidylserine (especially in B-lymphocytes). RA-PBLs showed a bias to CD95/Fas mediated apoptotic pathways, but low levels of the CD69 marker suggested that this was not associated with immune activation. Although downstream markers of apoptosis such as caspase-3/7 activity, were increased, no DNA fragmentation was observed in RA-PBLs. Interestingly, elevated levels of apoptosis did not correlate with absolute lymphocyte counts in RA patients. Levels of HSP70 were highly elevated in RA-PBLs compared to controls.

Conclusion

The results suggest that while apoptosis may be initiated in RA-PBLs, they may lack commitment to fully executing the apoptotic program. This may be related to inhibition on apoptotic transduction by HSP70. This study provides evidence that abnormalities in RA-PBLs apoptosis may occur whilst still in circulation and may contribute to pathogenesis of the disease.

Recommendations for the management of adult chronic myeloid leukaemia in South Africa

INTRODUCTION

Chronic myeloid leukaemia (CML) is a chronic myeloproliferative disorder characterised by a chromosomal translocation between the long arms of chromosomes 9 and 22 [corrected] resulting in the formation of the BCR-ABL fusion gene. The management of CML has undergone major changes over the past decade. Novel treatment approaches have had a dramatic impact on patient outcomes and survival. Nevertheless, these outcomes can only be achieved in the context of expert management, careful monitoring of disease response, appropriate management of adverse events and timeous adjustments to therapy when responses are not achieved within stated time-frames.

AIM

With the advent of novel treatments providing molecular responses, both the monitoring and management of CML have become more complicated. The aim of these recommendations was to provide a pragmatic yet comprehensive roadmap to negotiate these complexities.

METHODS

Recommendations were developed based on local expert opinion from both the academic and private medical care arenas after careful review of the relevant literature and taking into account the most widely used international guidelines. About five meetings were held at which these recommendations were discussed and debated in detail.

RESULTS

A comprehensive set of recommendations was compiled with an emphasis on diagnosis, investigation, treatment and monitoring of disease. Careful attention was given to circumstances unique to South Africa, funding constraints, availability and access to laboratory resources, as well as the effects of concurrent HIV infection.

CONCLUSION

Most patients with CML can live a reasonably normal life if their disease is appropriately managed. These recommendations should be of value to all specialists involved in the treatment of haematological disorders.

The effects of Sutherlandia frutescens extracts in cultured renal proximal and distal tubule epithelial cells

Sutherlandia frutescens (SF), a medicinal plant indigenous to South Africa, is traditionally used to treat a diverse range of illnesses, including cancer and viral infections. The biologically active compounds of SF are polar, thus renal elimination increases susceptibility to toxicity in that organ. This study investigated the antioxidant potential, lipid peroxidation, mitochondrial membrane potential and apoptotic induction by SF extracts on proximal and distal tubule epithelial cells. Cell viability was determined using the MTT assay. Mitochondrial membrane potential was determined using a flow cytometric JC-1 Mitoscreen assay. Cellular glutathione and apoptosis were measured using the GSH-Glo™ Glutathione assay and Caspase-Glo® 3/7 assay, respectively. The IC50 values from the cell viability results for LLC-PK1 and MDBK were 15 mg/mL and 7 mg/mL, respectively. SF extracts significantly decreased intracellular glutathione in LLC-PK1 (p less than 0.0001) and MDBK (p less than 0.0001) cells, while lipid peroxidation increased in treated LLC-PK1 (p less than 0.0001) and MDBK (p less than 0.0001) cells. JC-1 analysis showed that SF extracts promoted mitochondrial membrane depolarization in both LLC-PK1 and MDBK cells by up to 80% (p less than 0.0001). The activity of caspase 3/7 increased in both LLC-PK1 (11.9-fold; p less than 0.0001) and MDBK (2.2-fold; p less than 0.0001) cells. SF extracts at high concentrations appear to increase oxidative stress, to alter mitochondrial membrane integrity, and to promote apoptosis in renal tubule epithelia.

Apoptosis-promoting effects of Sutherlandia frutescens extracts on normal human lymphocytes in vitro

Sutherlandia frutescens (SF), an indigenous medicinal plant to South Africa, is traditionally used to treat a diverse range of illnesses. More specifically, the immune-enhancing potential of SF has been recognised to the extent that SF extracts have been recommended as an adjuvant in HIV/AIDS treatment by the South African Ministry of Health, despite a lack of knowledge of its mechanism of action or potential immune toxicity. As yet, unsubstantiated data support the notion of immunostimulatory effects of SF extracts in HIV-infected patients. This was suggested by post-treatment recovery of CD4+ cells brought about by the reduction of the impact of virus-induced apoptosis. This study investigated the apoptotic effects of SF extracts on normal human lymphocytes in vitro. Initially, an acute cytotoxic profile of SF extract was formulated, from which an IC50 of 7.5 mg/mL was calculated and administered for 3 h, 6 h and 12 h to cell populations. At 12 h, SF caused a significant increase in apoptosis in the total lymphocyte population and CD4+ cells as evidenced by increased phosphatidylserine (PS) translocation, caspase-3/7 activity, and decreased ATP content. After 12 h, the SF extract initiated lymphocyte activation in both total lymphocyte and CD4+ subpopulations, indicated by a doubling of the number of cells expressing the CD69 activation marker. The apoptosis observed may thus be the result of activation-induced lymphocyte cell death (AICD). Our results are in conflict with preliminary clinical evidence which has suggested SF extracts are possibly beneficial in the treatment of HIV infection. More extensive evaluations of the effects of SF extracts on the immune system in such subjects are urgently needed.

Cytotoxicity of a dentine bonding agent on four different cell-lines

The aim of this study was to compare the cytotoxicity of a recently available dentine bonding agent on four different cell-lines (three human dental pulp fibroblast cell-lines and one mouse 3T3 fibroblast cell-line).

METHODOLOGY

Three human dental pulp cell-lines from 3 different donors and one established 3T3 mouse cell-line were grown and sub-cultured. Cell viability following exposure to Scothbond was then compared to a similar number of controls using the MTT assay.

RESULTS

Scotchbond 1 was cytotoxic to all four cell-lines. 3T3 cells showed a survival rate of about 60% as compared to two of the human dental pulp cells which showed a significantly lower survival rate (p<0.05, Kruskal-Wallis Multiple-Comparison Test).

CONCLUSION

These findings indicated that is cytotoxic to both human pulp and 3T3 cell-lines. In general, the human pulp cell-lines showed higher sensitivity than the 3T3 cell-lines.

CLINICAL SIGNIFICANCE

Scotchbond 1 cannot be recommended for direct pulp capping techniques and care should be taken when using this dentine bonding agent in cavities where the remaining dentine layer is minimal.

Management of human immunodeficiency virus infection in pregnancy

The HIV global epidemic is having a devastating effect on women of reproductive age; women aged 15-24 years are 2.5 times more likely to be infected than young men in the same age group. Further, mother-to-child transmission (MTCT) accounts for almost two-thirds of the new infections that occur in children world-wide, annually. MTCT of HIV-1 varies widely and is dependent on obstetric practices, mode of delivery, breastfeeding, and the level of the viral load in the mother. Antiretroviral therapy (ARV) in pregnancy is prescribed for two main reasons: (i) women who need ARV medication for their own health; (ii) women who do not need treatment, or do not have access to treatment are offered prophylaxis to prevent MTCT, using one of a number of ARV regimens known to be effective. HIV infection is also associated with significant maternal morbidity and mortality. Clinicians caring for HIV-infected women need to update their knowledge continuously to provide optimal care.

Cytotoxicity of two concentrations of a dentine bonding agent on mouse 3T3 and human pulp fibroblast cell-lines

The objective of this study was to investigate the cytotoxicity and effect of concentration of a recent dentine bonding agent on a mouse fibroblast cell-line (3T3) and four different human pulp fibroblast cell-lines. A mouse fibroblast 3T3 cell-line and 4 different human pulp fibroblast cell lines were used. The cells were grown and subcultured using standard conditions. For the testing of the cytotoxicity of the bonding agent (Prime & Bond NT) it was extracted with DMEM medium and the different cell-lines were exposed to the extraction. The MTT assay was used to establish the number of viable cells. For all 5 pairs (control vs test sample) of cell-lines for 4 microl bonding agent, the mouse and only two of the four human cell-lines showed a statistical significant difference (p < 0.05; Mann-Whitney) due to the cytotoxicity of the bonding agent. However, all 5 pairs showed significant differences (p < 0.05) at the 8 microl concentration level. To investigate the relative effect of concentration (4 microl compared to 8 microl) of a chemical agent (we used a bonding agent, Prime & Bond NT) on the cytotoxicity of these 5 cell-lines, the Kruskal-Wallis Multiple-Comparison test was used on the standardised medians. Statistically significant differences (p < 0.05) were found for various cell-lines between both concentration levels. In general, the tested bonding agent, at a higher concentration level, has an increased cytotoxic effect on all 5 cell-lines. About 69% (median) of 3T3 cells stayed viable with 4 microl (0.94cm2/ml) bonding agent and 61% when 8 microl was used. For the pulp cells the percentages were between 91% and 72% for 4 microl and between 77% and 24% for 8 microl. These findings indicated that the bonding agent Prime and Bond NT was cytotoxic and that different human pulp fibroblast cell-lines should be used in the cytotoxic testing of dental materials and secondly, if only one concentration is to be used it should be in the higher range of that suggested by the ANSI/ADA document (2000, Revision) for recommended standard practices for biological evaluation of dental materials.

Vertical transmission of Mycobacterium tuberculosis in KwaZulu Natal: impact of HIV-1 co-infection

BACKGROUND

Increases in perinatal TB have paralleled the exacerbation of the TB epidemic in KwaZulu Natal. The exact risks for vertical transfer of Mycobacterium tuberculosis (VTRTB) to the baby are unknown, as is the impact of HIV-1 co-infection, which frequently accompanies maternal TB disease in the region.

DESIGN

Prospective case series study of 82 HIV-1-infected and 25 non-infected pregnant mothers, King Edward VIII Hospital, KwaZulu Natal, South Africa.

RESULTS

Perinatal mortality in HIV-1/TB diseased mothers was 85/1000 and associated with maternal anaemia (P = 0.02); 46% of newborns were premature, 66% low birth weight and 49% intrauterine growth restricted. These were significantly higher than overall hospital rates (P < 0.01, OR 4.8, 95%CI 3.2-7.0). Sites of detection of maternal TB, distribution of bacteriologically-proven TB, obstetric comorbidity and perinatal morbidity were similar in HIV-1-infected and non-infected mothers. VTRTB was detected in 16 newborns (16%), occurring similarly in bacteriologically-proven and suspected maternal TB disease, with no difference between HIV-1-infected and non-infected mothers. Eleven newborns with VTRTB were HIV-1 exposed; 64% acquired HIV-1 and died from rapidly progressive disease by 10 months of age. HIV-1-infected mothers and their exposed newborns had significantly lower CD4 counts. No association between perinatal maternal viral load, CD4 count or VTRTB was detected.

CONCLUSION

Mothers with TB disease in pregnancy are at risk for significant perinatal morbidity, mortality and VTRTB.

Dentine bonding agents--a review of adhesion to dentine

Although constant innovation has improved the performance of dentine adhesives, the true mechanism of resin adhesion to dentine is still not clear and the optimal dentinal surface pretreatment has yet to be determined for adhesive integrity of resin to dentine. The integrity of the collagen fibrils left exposed upon acid etching seem to play a major role in the mechanism of adhesion and intermingling of the adhesive monomers with the filigree of collagen fibers or hybrid layer should be considered the paramount dentine bonding mechanism. Definite trends are emerging but more research is necessary before general conclusions can be made about the functions of different bonding agents. The all-in-one self-etching/self-primer bottle systems are relatively new to the market and need more research before they can be advocated as the agent of choice.

Growth in early childhood in a cohort of children born to HIV-1-infected women from Durban, South Africa

This study describes growth in a cohort of black South African children born to HIV-1-infected women in Durban. Children born to HIV-1-seropositive women were followed up from birth to early childhood. At birth and at each visit, growth parameters were measured. Mean Z-scores were calculated for weight-for-length, weight-for-age and length-for-age and, if they were low, the children were regarded as wasted, malnourished or stunted, respectively. At the end of the study, there were 48 infected and 93 uninfected children. There were no significant differences between the two groups at birth. Thereafter, the infected group was found to have early and sustained low mean Z-scores for length-for-age and weight-for-age but not for weight-for-length. The means reached significance at ages 3, 6 and 12 months for length and at 3, 6 and 9 months for weight. Infected children who died early had more severe stunting, wasting and malnutrition than infected children who survived. Infected children born to HIV-positive women have early and sustained stunting and are malnourished but not wasted. Children with rapidly progressive disease have both stunting and wasting and are more severely affected. Early nutritional intervention might help prevent early progression or death in HIV-infected children, particularly in developing countries without access to anti-retroviral therapy in state hospitals.

Interferon-gamma and interleukin-10 production among HIV-1-infected and uninfected infants of HIV-1-infected mothers

Immunologic consequences of exposure to HIV-1 in utero are still poorly understood. This study investigates relationships between type-1 [interferon-gamma (IFN-gamma)] and type-2 (IL-10) cytokine production and maternal-infant HIV-1 transmission. Cord blood leukocytes from deliveries of 71 HIV-1-infected and 11 uninfected mothers were tested for in vitro IFN-gamma and IL-10 production after phytohemagglutinin (PHA) stimulation. The infants of these HIV-1-infected mothers were followed prospectively after birth to determine HIV vertical transmission, and IFN-gamma and IL-10 production was measured again at 6 mo. Median PHA-stimulated IFN-gamma production was 210 pg/mL in cord blood cells from infected and 73 pg/mL from uninfected mothers (p = 0.12), and median PHA-stimulated IL-10 production was 491 pg/mL in cord blood cells from infected and 161 pg/mL from uninfected mothers (p = 0.004). PHA-stimulated IFN-gamma and IL-10 production alone were not significantly associated with transmission, but relationships between the two cytokines differed among infected and uninfected infants of HIV-1-infected mothers. PHA-stimulated IFN-gamma and IL-10 production was positively correlated among infected (r = 0.7, p = 0.12 in cord blood and r = 0.66, p = 0.03 at 6 mo) but not uninfected infants, and stronger relative production of IFN-gamma to IL-10 was observed among exposed uninfected than among infected infants (p = 0.04). Exposure in utero to HIV-1 may augment production of IL-10 detectable in fetal cord blood. Stronger relative production of IFN-gamma to IL-10 in cord blood cells from infants of HIV-1-infected mothers may be associated with protection against perinatal HIV infection.

Pharmacokinetics of zidovudine and lamivudine in neonates following coadministration of oral doses every 12 hours

A phase I, repeat-dose, open-label study was conducted to determine the pharmacokinetics and safety of zidovudine and lamivudine, coadministered orally every 12 hours, in 16 neonates whose mothers were infected with human immunodeficiency virus type 1 (HIV-1). The prospective mothers had been stabilized on a zidovudine/lamivudine regimen since week 36 of pregnancy to prevent mother-to-child transmission of HIV. During 1 week postpartum, the mothers received zidovudine 300 mg plus lamivudine 150 mg every 12 hours and breastfed. Neonatal treatment was initiated 12 hours following birth with 4 mg/kg of zidovudine suspension plus 2 mg/kg of lamivudine solution every 12 hours; this regimen was continued for 1 week. Between days 1 and 7 of neonatal treatment, the neonatal oral clearance (CL/F) of zidovudine and lamivudine increased by 2-fold (p < 0.001) and 1.6-fold (p = 0.004), respectively, possibly reflecting maturation of intestinal hepatic and renal function occurring during the first week of life. Day 7/day 1 ratios for exposure (area under the serum concentration-time curve [AUC]) and maximum observed serum concentration (Cmax) were 0.48 and 0.63, respectively, for zidovudine and 0.64 and 0.73, respectively, for lamivudine. At the time of delivery, the geometric mean cord/maternal concentration ratio was 1.24 for zidovudine and 1.12 for lamivudine, indicating free passage of each drug across the placenta. The maternal and neonatal treatment regimens were well tolerated. The results of this study confirm that in the neonate, a convenient regimen combining zidovudine 4 mg/kg and lamivudine 2 mg/kg, administered orally every 12 hours, provides zidovudine serum exposure very similar to that reported with the standard neonatal zidovudine regimen of 2 mg/kg every 6 hours, as well as lamivudine serum exposure within the range reported in adults receiving lamivudine 150 mg twice a day and children receiving 4 mg/kg twice a day.

Severe, rapidly progressive human immunodeficiency virus type 1 disease in newborns with coinfections

AIM

To describe a severe form of rapidly progressive HIV-1 infection manifesting in the neonatal period.

METHOD

Prospective cohort study, King Edward VIII Hospital, Durban, South Africa. HIV-1-exposed neonates with hepatosplenomegaly, lymphadenopathy or persistent pneumonia within the first 28 days of life were investigated for perinatal infections. Confirmation of neonatal HIV-1 infection, HIV-1 subtype and clinical outcomes were studied.

RESULTS

Twenty-three (72%) of 32 symptomatic HIV-1-exposed neonates recruited at a mean of 15.2 days were HIV-1-infected. HIV-1 infection was detected in 5 patients who were tested within 48 h of birth, confirming congenital infection. Congenital infection was not excluded in any case. Median neonatal viral load at recruitment was 471,932 copies/ml and median CD4 was 777 cells/mm3. The predominant clinical presentation was growth retardation and prematurity. Perinatal infections detected included: tuberculosis (8), syphilis (6) and cytomegalovirus (10). All of the neonates with perinatal tuberculosis were HIV-1-coinfected. Maternal and neonatal viral load and CD4 at recruitment were not statistically different between the groups with tuberculosis vs. other coinfections. Gag gene sequence analysis confirmed closely aligned HIV-1 subtype C in mothers and neonates. Nineteen (83%) died by 9 months, with a mean age at death of 3.5 months.

CONCLUSIONS

A distinct group of HIV-1-infected babies may clinically manifest in the neonatal period with perinatal coinfections, subsequent rapidly progressive HIV-1 and early death.

An evaluation of on-site testing for syphilis

One of the major obstacles to the eradication of perinatal transmission of syphilis is the delay in obtaining the results of syphilis serological tests. The availability of on-site syphilis testing lead to this study which attempted to evaluate on-site syphilis testing performed by nursing staff. The seroprevalence of syphilis by laboratory rapid plasma reagin (RPR) was 8.2% (n=42). Twenty-one of the 42 women were correctly identified by the on-site test. The overall sensitivity of on-site testing was 50% [95% confidence interval (CI)=34.4-65.6]; specificity of 90.9% (95% CI=87.8-93.2). The on-site test correctly identified as uninfected 429 of the 471 women reported as RPR negative by the laboratory, giving a specificity of 91.1% (95% CI=88.1-93.4). The results of the study show that on-site RPR test had a sensitivity of 75% in respect of the clinically important titres of > or = 1:8. The specificity of the on-site test was 91.1% and on-site testing only failed to detect syphilis in those patients with titres of 1:1 and 1:2. On-site testing is a practical and cost-effective option to prevent congenital syphilis, in settings of a high prevalence of syphilis and using skilled testers.

T-helper cell responses to HIV envelope peptides in cord blood: protection against intrapartum and breast-feeding transmission

BACKGROUND

Acquired HIV-specific cell-mediated immune responses have been observed in exposed-uninfected individuals, and it has been inferred, but not demonstrated, that these responses constitute a part of natural protective immunity to HIV. This inference was tested prospectively in the natural exposure setting of maternal-infant HIV transmission in a predominantly breast-fed population.

METHODS

Cord blood from infants of HIV-seropositive women in Durban, South Africa, were tested for in vitro reactivity to a cocktail of HIV envelope peptides (Env) using a bioassay measuring interleukin-2 production in a murine cell line. Infants were followed with repeat HIV RNA tests up to 18 months of age to establish which ones acquired HIV-infection.

RESULTS

T-helper cell responses to Env were detected in 33 out of 86 (38%) cord blood samples from infants of HIV-seropositive women and in none of nine samples from seronegative women (P = 0.02). Among infants of HIV-seropositive mothers, three out of 33 with T-helper responses to Env were already infected before delivery (HIV RNA positive on the day of birth), two were lost to follow-up, and none of the others (out of 28) were found to be HIV infected on subsequent tests. In comparison, six out of 53 infants unresponsive to Env were infected before delivery, and eight out of 47 (17%) of the others were found to have acquired HIV infection intrapartum or post-partum through breast-feeding (P = 0.02).

CONCLUSIONS

T-helper cell responses to HIV envelope peptides were detected in more than one-third of newborns of HIV-infected women; no new infections were acquired by these infants at the time of delivery or post-natally through breast-feeding if these T-helper cell responses were detected in cord blood.

In vitro evaluation of two adhesive systems used with compomer filling materials

AIM

To evaluate and compare the in-vitro shear bond strength, microleakage and dentine-restorative interface of a self-etching/self-priming dentine bonding agent with a three-component dentine-bonding agent.

METHOD

For shear bond strength (SBS) testing 30 non-carious human molars were used of which 15 were tested with Non-Rinse Conditioner (NRC)/Prime&Bond NT (PBNT) and Dyract AP and 15 were tested with Scotchbond Multi-Purpose Plus (SBMP) and F2000. For the microleakage evaluation cavity preparations were made on the facial surfaces of 30 non-carious human premolars of which 15 were restored with NRC and PBNT with Dyract AP and 15 were restored with SBMP and F2000. The dentine-restorative interface was examined through a confocal scanning laser microscope (CSLM).

RESULTS

The mean SBS of PBNT and SBMP were 12.8 and 18.1 MPa, respectively. The microleakage scores showed NRC/PBNT leaked on the dentine side in 13 of the 15 specimens examined. On the enamel side two of the 15 specimens showed microleakage. With SBMP no microleakage was observed on either enamel or dentine sides. The CSLM images show clear resin tag and hybrid layer formation for both the materials examined although SBMP showed better and deeper penetration into the dentine with longer resin tags. SBMP showed resin tags measuring about 150 mm while the hybrid layer measured about 5 mm. The length of the resin tags as well as the thickness of the hybrid layer for PBNT were 20 mm Pounds and 2 mm Pounds, respectively.

CONCLUSIONS

The acid-etch technique of SBMP produced higher bond strength and no microleakage when compared with the self-etching/self-priming 'non-rinse technique' of NRC with PBNT. Thus it can only be speculated that SBMP should be the superior in the clinical situation.

Tissue kallikrein and kinins in renal disease

The renal kallikrein-kinin system is involved in sodium and water homeostasis, blood pressure regulation and inflammation. Tissue kallikrein and kinin levels were measured in the urine of patients with renal disease and in the urine of living related kidney donors prior to uninephrectomy who served as controls. Tissue kallikrein and kinin B1 and B2 receptors were immunolocalised by confocal microscopy in renal biopsy material from patients with renal disease and controls (fresh autopsy material and normal kidney tissue from nephrectomies for malignancy). Urinary tissue kallikrein excretion was significantly decreased in patients with mild renal disease (16.6 +/- 6.7 ng tissue kallikrein (TK)/ng protein; p < 0.05) and more markedly so (1.8 +/- 0.7 ng TK/microg protein; p < 0.01) in patients with severe renal failure requiring dialysis compared to normal controls (78.9 +/- 31.7 ng TK/microg protein). Basal kinin values were unchanged in patients with renal disease (14 +/- 0.8 ng/ml) compared to controls (13.3 +/- 0.56 ng/ml). In control kidney tissue kallikrein was immunolocalised in the distal connecting tubules and collecting ducts whereas decreased immunolabelling was observed with renal disease. Kinin B2 receptor labelling was present in the entire nephron in the normal control kidney but was reduced with renal disease. While kinin B1 receptor immunolabelling was not observed in the control kidneys, labelling of distal tubules and collecting ducts was noted in renal disease, suggesting an upregulation of B1 receptors in renal parenchymal disease.

Mortality in a cohort of children born to HIV-1 infected women from Durban, South Africa

OBJECTIVES

To describe mortality in a cohort of infants with vertically transmitted HIV-1 infection.

PATIENTS AND METHODS

Children of HIV-1 infected women were followed up from birth and a record was made at each visit of growth, development and all illnesses. Details surrounding death were obtained from hospital records.

RESULTS

The final cohort comprised 48 infected and 93 uninfected children; there were 25 deaths, 17 of which (35%) were regarded as being HIV-related. The mean age at death of HIV-related cases was 10.1 months (range 1-48 months), with 83% of HIV-related deaths occurring before the age of 10 months. The commonest diagnoses at the time of death were diarrhoea, pneumonia, failure to thrive and severe thrush. These findings, together with neurological abnormalities, often presaged rapid deterioration and death.

CONCLUSIONS

Mortality among children with vertically acquired HIV infection is high in the first year of life. Death in these subjects was due to the common causes of morbidity and mortality among all children in developing countries. A combination of diarrhoea, pneumonia, failure to thrive, and neurological abnormalities should alert one to the possibility of rapidly progressive disease and death.

HIV type 1 V3 domain serotyping and genotyping in Gauteng, Mpumalanga, KwaZulu-Natal, and Western Cape Provinces of South Africa

More than 20.8 million people are living with HIV/AIDS in sub-Saharan Africa, with southern Africa the worst affected area and accounting for one of the fastest growing AIDS epidemics worldwide. Samples from 81 patients, including 25 from KwaZulu-Natal, 26 from Gauteng, 5 from Mpumalanga, and 25 from Western Cape Province, were serotyped using a competitive V3 peptide enzyme immunoassay (cPEIA). Viral RNA was also isolated from serum and the V3 region amplified by reverse transcriptase polymerase chain reaction (RT-PCR) to obtain a 240-bp product for direct sequencing of 29 samples. CLUSTAL W was used to make multiple sequence alignments. Distance calculation, tree construction methods, and bootstrap analysis were done using TREECON. Subtype C-like V3 loop sequences predominate in all provinces tested in South Africa. Discordant sero- and genotype results were observed in one patient only. The correlation between sero- and genotyping was 96% (24 of 25) in KwaZulu-Natal and 100% in Gauteng and Mpumalanga. In Western Cape Province 18% of patients were identified as sero/genotype B and 82% as sero/genotype C. Our data show that results of the second-generation V3 cPEIA correlated well with V3 sequencing and would be a rapid and affordable screening test to monitor the explosive southern African HIV-1 epidemic.

Pharmacokinetics and antiretroviral activity of lamivudine alone or when coadministered with zidovudine in human immunodeficiency virus type 1-infected pregnant women and their offspring

The safety, pharmacokinetics, and antiretroviral activity of lamivudine alone and in combination with zidovudine was studied in pregnant women infected with human immunodeficiency virus type 1 (HIV-1) and their neonates. Women received the drugs orally from week 38 of pregnancy to 1 week after delivery. Neonate therapy began 12 h after delivery and continued for 1 week. Both treatment regimens were well-tolerated in women and newborns. Lamivudine and zidovudine pharmacokinetics in pregnant women were similar to those in nonpregnant adults. Lamivudine and zidovudine freely crossed the placenta and were secreted in breast milk. Neonatal lamivudine clearance was about half that in pediatric patients; zidovudine clearance was consistent with previous reports. HIV-1 RNA could be quantified in 17 of the 20 women. At the onset of labor/delivery, mean virus load had decreased by approximately 1.5 log10 copies/mL in both treatment cohorts. Although not definitive for HIV-1 infection status, all neonates had HIV-1 RNA levels below the limit of quantification at birth and at ages 1 and 2 weeks.

The early natural history of vertically transmitted HIV-1 infection in African children from Durban, South Africa

Forty-eight children with vertically transmitted HIV-1 infection and 93 uninfected infants were followed up at regular intervals from birth for a mean of 26 months. They were examined physically, growth and development were assessed and illnesses recorded. Seventy per cent of infected infants were symptomatic by 6 months. Relative risks in the infected infants were highest for lymphadenopathy (4.56; CI 2.7-7.7), failure to thrive (4.48; 2.57-7.81), and neurological abnormalities (3.32; 1.9-5.58). The most frequent findings were diarrhoea (78%), pneumonia (76%) and lymphadenopathy (70%). Thrush and pneumonia occurred early but declined over time, whereas diarrhoea and neurological abnormalities occurred later and increased in frequency. A diagnosis of AIDS was made in 44% of infected infants by 12 months of age. Mortality in infected infants was 35.4%, and 76% of deaths occurred within the 1st year. About two-thirds of HIV-infected infants survived into early childhood. In South African children with vertically acquired HIV-1 infection the onset of disease is early and deterioration to AIDS and death are rapid. Infected infants can be easily recognized clinically, the majority by 6 months of age.

Breastfeeding by HIV-1-infected women and outcome in their infants: a cohort study from Durban, South Africa

BACKGROUND

Women in developing countries have the difficult choice of balancing the risk of transmitting HIV through breast milk against the substantial benefits of breastfeeding. It is not known, however, whether the benefits of breastfeeding are the same when the mother is HIV-infected. Therefore, we examined the impact of breastfeeding on infections, growth and mortality in the infants of HIV-1-infected women.

METHODS

Infants of HIV-1-positive women were followed from birth and at each visit they were examined, growth parameters were recorded and notes were made of feeding method, and of current and interim illnesses.

RESULTS

Of the 43 HIV-infected and 90 non-infected infants for whom feeding data were available, 36 infants (27%) were exclusively breastfed, 76 (57%) received mixed feeding, and 21 (16%) received formula only. The HIV transmission rate was 39% in those exclusively breastfed, 24% in those fed exclusively on formula and 32% in those receiving mixed feeding [relative risk (RR), 7.39; 95% confidence interval (CI), 1.67-32.6 between the exclusive breast and formula only groups]. There was a stepwise increase in the transmission rate with duration of exclusive breastfeeding of 1, 2 and 3 months (45%, 64%, and 75%, respectively). Of the infected infants, seven (50%) exclusively breastfed, 13 (51%) of those on mixed feeds and none on formula only developed AIDS; exclusively breastfed infants had a slower rate of progression to AIDS (mean age, 7.5 months versus 5.0 months, P = 0.2242) than those on mixed feeds. Mortality (which occurred in the infected infants only) was 19% in the exclusively breastfed infants; 13% in those on mixed feeds and 0% in those exclusively formula-fed. The frequency of failure to thrive and episodes of diarrhoea and pneumonia were not significantly different between the three groups in both the infected and non-infected infants.

CONCLUSIONS

Exclusive breastfeeding by HIV-infected women does not appear to protect their infants against common childhood illnesses and failure to thrive, nor does it significantly delay progression to AIDS. The implication of the trend towards differential mortality rates according to feeding groups is uncertain and requires further investigation.