Tissue-resident-like CD4+ T cells secreting IL-17 control Mycobacterium tuberculosis in the human lung.

T cell immunity is essential for the control of tuberculosis (TB), an important disease of the lung, and is generally studied in humans using peripheral blood cells. Mounting evidence, however, indicates that tissue-resident memory T cells (Trms) are superior at controlling many pathogens, including Mycobacterium tuberculosis (M. tuberculosis), and can be quite different from those in circulation. Using freshly resected lung tissue, from individuals with active or previous TB, we identified distinct CD4+ and CD8+ Trm-like clusters within TB-diseased lung tissue that were functional and enriched for IL-17-producing cells. M. tuberculosis-specific CD4+ T cells producing TNF-α, IL-2, and IL-17 were highly expanded in the lung compared with matched blood samples, in which IL-17+ cells were largely absent. Strikingly, the frequency of M. tuberculosis-specific lung T cells making IL-17, but not other cytokines, inversely correlated with the plasma IL-1ß levels, suggesting a potential link with disease severity. Using a human granuloma model, we showed the addition of either exogenous IL-17 or IL-2 enhanced immune control of M. tuberculosis and was associated with increased NO production. Taken together, these data support an important role for M. tuberculosis-specific Trm-like, IL-17-producing cells in the immune control of M. tuberculosis in the human lung.

Investigating neutrophil cell death in TB pathogenesis.

Background: Neutrophils are one of the major early role players in antimycobacterial immunity. Upon infection, neutrophils can undergo NETosis, a cell death characterized by release of neutrophil extracellular traps (NETs). The role of NETosis in TB progression remains poorly characterized. We aim to characterize mechanisms underlying NETosis during TB pathogenesis by identifying genes that drive the cell death, and to determine their potential as markers of disease progression in high-risk individuals. Finally, we intend to evaluate neutrophil associated genes as targets for host directed therapy to reduce pathological damage caused by NETosis. Methods: Quantitative PCR will be used to quantify expression of specific genes identified in the blood of individuals with active lung disease (n=30), compared to those from healthy (n=30) and latently infected individuals (LTBI) (n=30). In addition, temporal events associated with NETosis will be measured using live microscopy in a neutrophil in vitro model of Mycobacterium tuberculosis (Mtb) infection. Candidate genes found to be associated with NETosis will be targeted with pharmaceutical inhibitors. Conclusion: Genes associated with neutrophil mediated cell death may serve as potential biomarkers of pathological damage and disease progression, as well as targets for host-directed therapy.

Innate Lymphoid Cell Activation and Sustained Depletion in Blood and Tissue of Children Infected with HIV from Birth Despite Antiretroviral Therapy.

Innate lymphoid cells (ILCs) are important for response to infection and for immune development in early life. HIV infection in adults depletes circulating ILCs, but the impact on children infected from birth remains unknown. We study vertically HIV-infected children from birth to adulthood and find severe and persistent depletion of all circulating ILCs that, unlike CD4+ T cells, are not restored by long-term antiretroviral therapy unless initiated at birth. Remaining ILCs upregulate genes associated with cellular activation and metabolic perturbation. Unlike HIV-infected adults, ILCs are also profoundly depleted in tonsils of vertically infected children. Transcriptional profiling of remaining ILCs reveals ongoing cell-type-specific activity despite antiretroviral therapy. Collectively, these data suggest an important and ongoing role for ILCs in lymphoid tissue of HIV-infected children from birth, where persistent depletion and sustained transcriptional activity are likely to have long-term immune consequences that merit further investigation.

Publisher Correction: Group 3 innate lymphoid cells mediate early protective immunity against tuberculosis.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Group 3 innate lymphoid cells mediate early protective immunity against tuberculosis.

Tuberculosis is the leading cause of death by an infectious disease worldwide1. However, the involvement of innate lymphoid cells (ILCs) in immune responses to infection with Mycobacterium tuberculosis (Mtb) is unknown. Here we show that circulating subsets of ILCs are depleted from the blood of participants with pulmonary tuberculosis and restored upon treatment. Tuberculosis increased accumulation of ILC subsets in the human lung, coinciding with a robust transcriptional response to infection, including a role in orchestrating the recruitment of immune subsets. Using mouse models, we show that group 3 ILCs (ILC3s) accumulated rapidly in Mtb-infected lungs and coincided with the accumulation of alveolar macrophages. Notably, mice that lacked ILC3s exhibited a reduction in the accumulation of early alveolar macrophages and decreased Mtb control. We show that the C-X-C motif chemokine receptor 5 (CXCR5)-C-X-C motif chemokine ligand 13 (CXCL13) axis is involved in Mtb control, as infection upregulates CXCR5 on circulating ILC3s and increases plasma levels of its ligand, CXCL13, in humans. Moreover, interleukin-23-dependent expansion of ILC3s in mice and production of interleukin-17 and interleukin-22 were found to be critical inducers of lung CXCL13, early innate immunity and the formation of protective lymphoid follicles within granulomas. Thus, we demonstrate an early protective role for ILC3s in immunity to Mtb infection.

High-Frequency, Functional HIV-Specific T-Follicular Helper and Regulatory Cells Are Present Within Germinal Centers in Children but Not Adults.

Broadly neutralizing antibodies (bnAbs) against HIV-1 are an effective means of preventing transmission. To better understand the mechanisms by which HIV-specific bnAbs naturally develop, we investigated blood and lymphoid tissue in pediatric infection, since potent bnAbs develop with greater frequency in children than adults. As in adults, the frequency of circulating effector T-follicular helper cells (TFH) in HIV infected, treatment naïve children correlates with neutralization breadth. However, major differences between children and adults were also observed both in circulation, and in a small number of tonsil samples. In children, TFH cells are significantly more abundant, both in blood and in lymphoid tissue germinal centers, than in adults. Second, HIV-specific TFH cells are more frequent in pediatric than in adult lymphoid tissue and secrete the signature cytokine IL-21, which HIV-infected adults do not. Third, the enrichment of IL-21-secreting HIV-specific TFH in pediatric lymphoid tissue is accompanied by increased TFH regulation via more abundant regulatory follicular T-cells and HIV-specific CXCR5+ CD8 T-cells compared to adults. The relationship between regulation and neutralization breadth is also observed in the pediatric PBMC samples and correlates with neutralization breadth. Matching neutralization data from lymphoid tissue samples is not available. However, the distinction between infected children and adults in the magnitude, quality and regulation of HIV-specific TFH responses is consistent with the superior ability of children to develop high-frequency, potent bnAbs. These findings suggest the possibility that the optimal timing for next generation vaccine strategies designed to induce high-frequency, potent bnAbs to prevent HIV infection in adults would be in childhood.

Human and Murine Clonal CD8+ T Cell Expansions Arise during Tuberculosis Because of TCR Selection.

The immune system can recognize virtually any antigen, yet T cell responses against several pathogens, including Mycobacterium tuberculosis, are restricted to a limited number of immunodominant epitopes. The host factors that affect immunodominance are incompletely understood. Whether immunodominant epitopes elicit protective CD8+ T cell responses or instead act as decoys to subvert immunity and allow pathogens to establish chronic infection is unknown. Here we show that anatomically distinct human granulomas contain clonally expanded CD8+ T cells with overlapping T cell receptor (TCR) repertoires. Similarly, the murine CD8+ T cell response against M. tuberculosis is dominated by TB10.44-11-specific T cells with extreme TCRß bias. Using a retro genic model of TB10.44-11-specific CD8+ Tcells, we show that TCR dominance can arise because of competition between clonotypes driven by differences in affinity. Finally, we demonstrate that TB10.4-specific CD8+ T cells mediate protection against tuberculosis, which requires interferon-γ production and TAP1-dependent antigen presentation in vivo. Our study of how immunodominance, biased TCR repertoires, and protection are inter-related, provides a new way to measure the quality of T cell immunity, which if applied to vaccine evaluation, could enhance our understanding of how to elicit protective T cell immunity.

TRIM5α and TRIM22 are differentially regulated according to HIV-1 infection phase and compartment.

UNLABELLED: The antiviral role of TRIM E3 ligases in vivo is not fully understood. To test the hypothesis that TRIM5α and TRIM22 have differential transcriptional regulation and distinct anti-HIV roles according to infection phase and compartment, we measured TRIM5α, TRIM22, and type I interferon (IFN-I)-inducible myxovirus resistance protein A (MxA) levels in peripheral blood mononuclear cells (PBMCs) during primary and chronic HIV-1 infection, with chronic infection samples being matched PBMCs and central nervous system (CNS)-derived cells. Associations with biomarkers of disease progression were explored. The impact of IFN-I, select proinflammatory cytokines, and HIV on TRIM E3 ligase-specific expression was investigated. PBMCs from individuals with primary and chronic HIV-1 infection had significantly higher levels of MxA and TRIM22 than did PBMCs from HIV-1-negative individuals (P < 0.05 for all comparisons). PBMCs from chronic infection had lower levels of TRIM5α than did PBMCs from primary infection or HIV-1-uninfected PBMCs (P = 0.0001 for both). In matched CNS-derived samples and PBMCs, higher levels of MxA (P = 0.001) and TRIM5α (P = 0.0001) in the CNS were noted. There was a negative correlation between TRIM22 levels in PBMCs and plasma viral load (r = -0.40; P = 0.04). In vitro, IFN-I and, rarely, proinflammatory cytokines induced TRIM5α and TRIM22 in a cell type-dependent manner, and the knockdown of either protein in CD4(+) lymphocytes resulted in increased HIV-1 infection. These data suggest that there are infection-phase-specific and anatomically compartmentalized differences in TRIM5α and TRIM22 regulation involving primarily IFN-I and specific cell types and indicate subtle differences in the antiviral roles and transcriptional regulation of TRIM E3 ligases in vivo. IMPORTANCE: Type I interferon-inducible TRIM E3 ligases are a family of intracellular proteins with potent antiviral activities mediated through diverse mechanisms. However, little is known about the contribution of these proteins to antiviral immunity in vivo and how their expression is regulated. We show here that TRIM5α and TRIM22, two prominent members of the family, have different expression patterns in vivo and that the expression pattern depends on HIV-1 infection status and phase. Furthermore, expression differs in peripheral blood versus central nervous system anatomical sites of infection. Only TRIM22 expression correlated negatively with HIV-1 viral load, but gene silencing of both proteins enhances HIV-1 infection of target cells. We report subtle differences in TRIM5α and TRIM22 gene induction by IFN-I and proinflammatory cytokines in CD4(+) lymphocytes, monocytes, and neuronal cells. This study enhances our understanding of antiviral immunity by intrinsic antiviral factors and how their expression is determined.

The role of apoptosis on trophoblast cell invasion in the placental bed of normotensive and preeclamptic pregnancies.

BACKGROUND: Placental development depends on careful coordination of trophoblast proliferation and apoptosis; however, the synchrony of its effect on trophoblast invasion is unknown. OBJECTIVE: To examine the relationship between trophoblast apoptosis and proliferation in placental bed tissue of preeclamptic and normotensive pregnancies. METHODS: Serial sections from archived placental bed biopsies of 12 normotensive (group 1) and 12 preeclamptic (group 2) were immunolabeled with a rabbit anti-Ki67 antibody, a mouse anti-cytokeratin 18 and its neo-epitope, and a monoclonal cytodeath M30 antibody. RESULTS: The immunoexpression of Ki67 for all trophoblast cell subpopulations within the myometrium was non-reactive in both study groups. Smooth muscle cells of the microvasculature reflected a moderate degree of proliferation in both groups. Morphometric image analysis of the wall of the spiral artery revealed a mean area of 31,1729 ± 51,180 µm(2) compared to 35,795 ± 8045 µm(2) in groups 1 and 2, respectively. An elevation of intramural trophoblast was evident within the spiral artery of group 1 (13%). Comparative analyses of M30 distribution on corresponding serial sections were 0.06% versus 0% in groups 1 and 2, respectively. The mean field area percentage of interstitial trophoblast invasion was 10.79% versus 2.87% with corresponding areas of apoptosis been 0.8 % versus 1.9 % in groups 1 and 2, respectively. CONCLUSIONS: This study demonstrates an increased trophoblast apoptosis in placental bed of preeclamptic compared to normotensive pregnancies with concurrent absence of proliferation at term.

The role of podocytes in the early detection of pre-eclampsia.

INTRODUCTION: Pre-eclampsia is a significant cause of maternal and neonatal mortality and morbidity in resource constrained countries. Because the exact aetiology is unknown, treatment of preeclampsia is empiric. Therefore, researchers have been investigating biomarkers for early detection of the syndrome to take steps to prevent complications. The kidney is reported to be affected by the preeclamptic process before clinical signs appear. Podocytes have been suggested as possible markers for this syndrome. However there is debate as to which is the best way to measure the amount of podocyturia. OBJECTIVE: To determine the best method to estimate podocyturia as a biomarker. METHODS: Midstream urine specimens were collected from 18 normotensive healthy primigravidae at their first antenatal visit. Urinary podocyte immunolabelling was performed by two techniques viz., culture and cytospin on urine from normotensive and clinically healthy pregnant women. MAIN OUTCOME MEASURED: Are the podocyte specific proteins, podocalyxin, podocin, nephrin and synaptopodin able to detect pre-eclampsia prior to the development of clinical signs as measured by two separate techniques. RESULTS: The results suggest that the expression of podocyte specific proteins, podocalyxin, podocin, nephrin and synaptopodin, is identifiable and quantifiable from midstream urine in healthy normotensive pregnant women. Cytospin was more efficient in determining the podocyte specific protein expression levels and podocalyxin was the most sensitive marker, with a Kappa coefficient of 0.23. CONCLUSIONS: These findings suggest that immuno-expression of podocyturia are best detected by the cytospin method.

The spectrum of HIV-related nephropathy in children.

BACKGROUND: Despite the burden of human immunodeficiency virus (HIV) disease in Southern Africa, there have been few reports of HIV-related nephropathy in children. This study outlines the spectrum of HIV-1-related kidney diseases of children in KwaZulu-Natal, South Africa. METHODS: A review of the clinical presentation, laboratory and histopathological findings of children diagnosed with HIV-related nephropathy. RESULTS: Forty-nine out of 71 children (1-16 years old) with HIV-1 related nephropathy underwent kidney biopsy. The most common histopathological finding was focal segmental glomerulosclerosis (FSGS), which was present in 32 (65.3%) children; 13 (26.5%) having collapsing glomerulopathy and 19 (38.8%) classic FSGS. The majority of patients showed haematological (86.4%) and electrolyte abnormalities (69.4%). Renal impairment was present in 41% of patients on initial presentation. However, end-stage kidney disease was present in only 4% of these patients. All patients were treated with highly active anti-retroviral therapy (HAART), the majority (79.6%) showed decreased proteinuria with 38.8% having complete remission. CONCLUSIONS: This study, one of the largest series of children reported from Africa, demonstrates that nephrotic syndrome due to HIV-associated nephropathy (HIVAN) is the commonest presentation of HIV-related nephropathy in childhood. Highly active anti-retroviral therapy in combination with angiotensin-converting enzyme antagonists is highly effective in decreasing proteinuria and preserving renal function.