Browsing by Author "Susanne Nylen"

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A molecular signature for CD8+ T cells from visceral leishmaniasis patients
(Blackwell Publishing Ltd, 2019) Bhawana Singh; Shashi Bhushan Chauhan; Rajiv Kumar; Siddharth Sankar Singh; Susanna Ng; Fiona Amante; Fabian de Labastida Rivera; Om Prakash Singh; Madhukar Rai; Susanne Nylen; Shyam Sundar; Christian Engwerda
CD8+ T-cell function is compromised in chronic diseases such as visceral leishmaniasis (VL). However, little is known about the changes in gene expression that cause CD8+ T-cell dysfunction during VL. We used targeted transcriptional profiling of peripheral blood CD8+ T cells from VL patients pre- and post-anti-parasitic drug treatment, and compared them with the same cell population from healthy endemic controls to assess their activation, differentiation and functional status during disease. We found a predominance of downregulated immune genes in CD8+ T cells from VL patients. However, genes encoding several notable immune checkpoint molecules, including LAG-3, TIM-3 and CTLA-4, cytolytic molecules, such as granzymes A, B and H and perforin, as well as SOCS3, STAT1, JAK2 and JAK3 cytokine signalling genes were found to be increasingly expressed by VL patient CD8+ T cells. Additional studies confirmed increased expression of the inhibitory receptors LAG3 and TIM3 on VL patient CD8+ T cells, thereby identifying these molecules as potential targets to improve antigen-specific CD8+ T-cell responses during disease. © 2019 John Wiley & Sons Ltd
A molecular signature for IL-10–producing Th1 cells in protozoan parasitic diseases
(American Society for Clinical Investigation, 2023) Chelsea L. Edwards; Jessica A. Engel; Fabian de Labastida Rivera; Susanna S. Ng; Dillon Corvino; Marcela Montes de Oca; Teija C.M. Frame; Shashi Bhushan Chauhan; Siddharth Sankar Singh; Awnish Kumar; Yulin Wang; Jinrui Na; Pam Mukhopadhyay; Jason S. Lee; Susanne Nylen; Shyam Sundar; Rajiv Kumar; Christian R. Engwerda
Control of visceral leishmaniasis (VL) depends on proinflammatory Th1 cells that activate infected tissue macrophages to kill resident intracellular parasites. However, proinflammatory cytokines produced by Th1 cells can damage tissues and require tight regulation. Th1 cell IL-10 production is an important cell–autologous mechanism to prevent such damage. However, IL-10–producing Th1 (type 1 regulatory; Tr1) cells can also delay control of parasites and the generation of immunity following drug treatment or vaccination. To identify molecules to target in order to alter the balance between Th1 and Tr1 cells for improved antiparasitic immunity, we compared the molecular and phenotypic profiles of Th1 and Tr1 cells in experimental VL caused by Leishmania donovani infection of C57BL/6J mice. We also identified a shared Tr1 cell protozoan signature by comparing the transcriptional profiles of Tr1 cells from mice with experimental VL and malaria. We identified LAG3 as an important coinhibitory receptor in patients with VL and experimental VL, and we reveal tissue-specific heterogeneity of coinhibitory receptor expression by Tr1 cells. We also discovered a role for the transcription factor Pbx1 in suppressing CD4+ T cell cytokine production. This work provides insights into the development and function of CD4+ T cells during protozoan parasitic infections and identifies key immunoregulatory molecules. © 2023, Edwards et al.
Apolipoprotein E Is Upregulated in Blood and Circulating Monocytes of Indian Patients With Visceral Leishmaniasis
(John Wiley and Sons Inc, 2024) Gulafsha Kausar; Shashi B. Chauhan; Ritirupa Roy; Shashi Kumar; Christian Engwerda; Susanne Nylen; Rajiv Kumar; Mary E. Wilson; Shyam Sundar
Apolipoprotein E (ApoE) has been associated with several diseases including Parkinson's disease, Alzheimer's and multiple sclerosis. ApoE also has documented immunomodulatory functions. We investigated gene expression in circulating monocytes and in bone marrows of patients with visceral leishmaniasis (VL) living in an endemic area in Bihar, India, and contrasted these with control healthy subjects or other diagnostic bone marrows from individuals in the same region. Samples from VL patients were obtained prior to initiating treatment. Our study revealed significant upregulated expression of the apoE transcript in patients with VL. Furthermore, the levels of ApoE protein were elevated in serum samples of subjects with VL compared with healthy endemic controls. These observations may provide clues regarding the complex interactions between lipid metabolism and immunoregulation of infectious and inflammatory diseases. © 2024 John Wiley & Sons Ltd.
Combined Immune Therapy for the Treatment of Visceral Leishmaniasis
(Public Library of Science, 2016) Rebecca J. Faleiro; Rajiv Kumar; Patrick T. Bunn; Neetu Singh; Shashi Bhushan Chauhan; Meru Sheel; Fiona H. Amante; Marcela Montes de Oca; Chelsea L. Edwards; Susanna S. Ng; Shannon E. Best; Ashraful Haque; Lynette Beattie; Louise M. Hafner; David Sacks; Susanne Nylen; Shyam Sundar; Christian R. Engwerda
Chronic disease caused by infections, cancer or autoimmunity can result in profound immune suppression. Immunoregulatory networks are established to prevent tissue damage caused by inflammation. Although these immune checkpoints preserve tissue function, they allow pathogens and tumors to persist, and even expand. Immune checkpoint blockade has recently been successfully employed to treat cancer. This strategy modulates immunoregulatory mechanisms to allow host immune cells to kill or control tumors. However, the utility of this approach for controlling established infections has not been extensively investigated. Here, we examined the potential of modulating glucocorticoid-induced TNF receptor-related protein (GITR) on T cells to improve anti-parasitic immunity in blood and spleen tissue from visceral leishmaniasis (VL) patients infected with Leishmania donovani. We found little effect on parasite growth or parasite-specific IFNγ production. However, this treatment reversed the improved anti-parasitic immunity achieved by IL-10 signaling blockade. Further investigations using an experimental VL model caused by infection of C57BL/6 mice with L. donovani revealed that this negative effect was prominent in the liver, dependent on parasite burden and associated with an accumulation of Th1 cells expressing high levels of KLRG-1. Nevertheless, combined anti-IL-10 and anti-GITR mAb treatment could improve anti-parasitic immunity when used with sub-optimal doses of anti-parasitic drug. However, additional studies with VL patient samples indicated that targeting GITR had no overall benefit over IL-10 signaling blockade alone at improving anti-parasitic immune responses, even with drug treatment cover. These findings identify several important factors that influence the effectiveness of immune modulation, including parasite burden, target tissue and the use of anti-parasitic drug. Critically, these results also highlight potential negative effects of combining different immune modulation strategies. © 2016 Almeida et al.
Increased amphiregulin expression by CD4+ T cells from individuals with asymptomatic Leishmania donovani infection
(John Wiley and Sons Inc, 2022) Siddharth Sankar Singh; Shashi Bhushan Chauhan; Susanna SS Ng; Dillon Corvino; Fabian de Labastida Rivera; Jessica A Engel; Nic Waddell; Pamela Mukhopadhay; Rebecca L Johnston; Lambros T Koufariotis; Susanne Nylen; Om Prakash Singh; Christian R Engwerda; Rajiv Kumar; Shyam Sundar
Objectives: There is an urgent need to be able to identify individuals with asymptomatic Leishmania donovani infection, so their risk of progressing to VL and transmitting parasites can be managed. This study examined transcriptional markers expressed by CD4+ T cells that could distinguish asymptomatic individuals from endemic controls and visceral leishmaniasis (VL) patients. Methods: CD4+ T cells were isolated from individuals with asymptomatic L. donovani infection, endemic controls and VL patients. RNA was extracted and RNAseq employed to identify differentially expressed genes. The expression of one gene and its protein product during asymptomatic infection were evaluated. Results: Amphiregulin (AREG) was identified as a distinguishing gene product in CD4+ T cells from individuals with asymptomatic L. donovani infection, compared to VL patients and healthy endemic control individuals. AREG levels in plasma and antigen-stimulated whole-blood assay cell culture supernatants were significantly elevated in asymptomatic individuals, compared to endemic controls and VL patients. Regulatory T (Treg) cells were identified as an important source of AREG amongst CD4+ T-cell subsets in asymptomatic individuals. Conclusion: Increased Treg cell AREG expression was identified in individuals with asymptomatic L. donovani infection, suggesting the presence of an ongoing inflammatory response in these individuals required for controlling infection and that AREG may play an important role in preventing inflammation-induced tissue damage and subsequent disease in asymptomatic individuals. © 2022 The Authors. Clinical & Translational Immunology published by John Wiley & Sons Australia, Ltd on behalf of Australian and New Zealand Society for Immunology, Inc.
Interleukin 2 is an Upstream Regulator of CD4+ T Cells from Visceral Leishmaniasis Patients with Therapeutic Potential
(Oxford University Press, 2019) Shashi Bhushan Chauhan; Rebecca Faleiro; Rajiv Kumar; Susanna Ng; Bhawana Singh; Om Prakash Singh; Siddharth Sankar Singh; Fiona Amante; Fabian De Labastida Rivera; Madhukar Rai; Jaya Chakravarty; David Sacks; Susanne Nylen; Shyam Sundar; Christian Engwerda
Control of visceral leishmaniasis (VL) caused by Leishmania donovani requires interferon-γproduction by CD4+ T cells. In VL patients, antiparasitic CD4+ T-cell responses are ineffective for unknown reasons. In this study, we measured the expression of genes associated with various immune functions in these cells from VL patients and compared them to CD4+ T cells from the same patients after drug treatment and from endemic controls. We found reduced GATA3, RORC, and FOXP3 gene expression in CD4+ T cells of VL patients, associated with reduced Th2, Th17, and FOXP3+CD4+ T regulatory cell frequencies in VL patient blood. Interleukin 2 (IL-2) was an important upstream regulator of CD4+ T cells from VL patients, and functional studies demonstrated the therapeutic potential of IL-2 for improving antiparasitic immunity. Together, these results provide new insights into the characteristics of CD4+ T cells from VL patients that can be used to improve antiparasitic immune responses. © 2019 The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.
Phenotypic and functional characteristics of monocyte subsets in the blood and bone marrow of Indian subjects with Visceral Leishmaniasis
(Public Library of Science, 2024) Gulafsha Kausar; Shashi Bhushan Chauhan; Ritirupa Roy; Vimal Verma; Sundaram Pandey; Aziza Niyaz; Jaya Chakravarty; Christian R. Engwerda; Susanne Nylen; Rajiv Kumar; Mary E. Wilson; Shyam Sundar
Visceral leishmaniasis (VL) is a potentially fatal parasitic infection caused by Leishmania donovani in India. L. donovani is an obligate intracellular protozoan residing mostly in macrophages of the reticuloendothelial system throughout chronic infection. Monocytic phagocytes are critical in the pathogenesis of different forms of leishmaniasis. Subsets of monocytes are distinguished by their surface markers into CD14+CD16-classical monocytes, CD14+CD16+ intermediate monocytes, and CD16++CD14low non-classical monocyte subsets. During cutaneous leishmaniasis (CL), intermediate monocyte are reported to be a source of inflammatory cytokines IL-1β and TNF, and they express CCR2 attracting them to sites of inflammatory pathology. We examined monocyte subsets in the blood and bone marrow of patients with VL from an endemic site in Bihar, India, and found these contrasted with the roles of monocytes in CL. During VL, intermediate and non-classical CD16+ monocyte subsets expressed instead a non-inflammatory phenotype with low CCR2, high CX3CR1 and low microbicidal oxidant generation, making them more similar to patrolling monocytes than inflammatory cells. Bone marrow CD16+ monocyte subsets expressed a phenotype that might be more similar to the inflammatory subsets of CL, although our inability to obtain bone marrow from healthy donors in the endemic region hampered this interpretation Overall the data suggest that CD16+ intermediate monocyte subsets in VL patients express a phenotypes that contributes to an immunosuppressed pathologic immune state, but in contrast to CL, these do not mediate localized inflammatory responses. © 2024, Public Library of Science. All rights reserved.
Tumor necrosis factor alpha neutralization has no direct effect on parasite burden, but causes impaired IFN-γ production by spleen cells from human visceral leishmaniasis patients
(Academic Press, 2016) Neetu Singh; Rajiv Kumar; Christian Engwerda; David Sacks; Susanne Nylen; Shyam Sundar
The pro-inflammatory cytokine tumor necrosis factor (TNF)-α has an important role in control of experimental Leishmania donovani infection. Less is known about the role of TNF-α in human visceral leishmaniasis (VL). Evidence for a protective role is primarily based on case reports of VL development in individuals treated with TNF-α neutralizing antibody. In this study, we have evaluated how TNF-α neutralization affects parasite replication and cytokine production in ex vivo splenic aspirates (SA) from active VL patients. The effect of TNF-α neutralization on cell mediated antigen specific responses were also evaluated using whole blood cultures. Neutralization of TNF-α did not affect parasite numbers in SA cultures. Interferon (IFN)-γ levels were significantly reduced, but interleukin (IL)-10 levels were unchanged in these cultures. Leishmania antigen stimulated SA produced significant TNF-α which suggests that TNF-α is actively produced in VL spleen. Further it stimulates IFN-γ production, but no direct effect on parasite replication. © 2016 Elsevier Ltd
Type I Interferons Suppress Anti-parasitic Immunity and Can Be Targeted to Improve Treatment of Visceral Leishmaniasis
(Elsevier B.V., 2020) Rajiv Kumar; Patrick T. Bunn; Siddharth Sankar Singh; Susanna S. Ng; Marcela Montes de Oca; Fabian De Labastida Rivera; Shashi Bhushan Chauhan; Neetu Singh; Rebecca J. Faleiro; Chelsea L. Edwards; Teija C.M. Frame; Meru Sheel; Rebecca J. Austin; Steven W. Lane; Tobias Bald; Mark J. Smyth; Geoffrey.R. Hill; Shannon E. Best; Ashraful Haque; Dillon Corvino; Nic Waddell; Lambross Koufariotis; Pamela Mukhopadhay; Madhukar Rai; Jaya Chakravarty; Om Prakash Singh; David Sacks; Susanne Nylen; Jude Uzonna; Shyam Sundar; Christian R. Engwerda
CD4+ T cells are critical for control of intracellular parasites such as Leishmania donovani. Kumar et al. show that type I interferons (IFNs) suppress Th1 cells and promote IL-10-producing CD4+ T cells during visceral leishmaniasis (VL). Thus, manipulation of type I IFN signaling may improve disease outcome in VL patients. © 2020 The Authors; Type I interferons (IFNs) play critical roles in anti-viral and anti-tumor immunity. However, they also suppress protective immune responses in some infectious diseases. Here, we identify type I IFNs as major upstream regulators of CD4+ T cells from visceral leishmaniasis (VL) patients. Furthermore, we report that mice deficient in type I IFN signaling have significantly improved control of Leishmania donovani, a causative agent of human VL, associated with enhanced IFNγ but reduced IL-10 production by parasite-specific CD4+ T cells. Importantly, we identify a small-molecule inhibitor that can be used to block type I IFN signaling during established infection and acts synergistically with conventional anti-parasitic drugs to improve parasite clearance and enhance anti-parasitic CD4+ T cell responses in mice and humans. Thus, manipulation of type I IFN signaling is a promising strategy for improving disease outcome in VL patients. © 2020 The Authors