IL-10–producing Tfh cells accumulate with age and link inflammation with age-related immune suppression

Aging results in profound immune dysfunction, resulting in the decline of vaccine responsiveness previously attributed to irreversible defects in the immune system. In addition to increased interleukin-6 (IL-6), we found aged mice exhibit increased systemic IL-10 that requires forkhead box P3–negative (FoxP3−), but not FoxP3+, CD4+T cells. Most IL-10–producing cells manifested a T follicular helper (Tfh) phenotype and required the Tfh cytokines IL-6 and IL-21 for their accrual, so we refer to them as Tfh10 cells. IL-21 was also required to maintain normal serum levels of IL-6 and IL-10. Notably, antigen-specific Tfh10 cells arose after immunization of aged mice, and neutralization of IL-10 receptor signaling significantly restored Tfh-dependent antibody responses, whereas depletion of FoxP3+ regulatory and follicular regulatory cells did not. Thus, these data demonstrate that immune suppression with age is reversible and implicate Tfh10 cells as an intriguing link between “inflammaging” and impaired immune responses with age

Decreased frequency and secretion of CD₆ promotes disease progression in Indian post kala-azar dermal Leishmaniasis

Purpose: Leishmania, the causative organisms for leishmaniasis, reside in host macrophages and survive by modulating the microbicidal pathways via attenuation of the oxidative burst and/or suppression of cell-mediated immunity. As post kala-azar dermal leishmaniasis (PKDL), the dermal sequela of visceral leishmaniasis, has no animal model, the underlying mechanism(s) that nullify the microbicidal effector mechanisms remain poorly understood. This study was aimed at assessing the status of dipeptidyl peptidase CD26, a co-stimulatory molecule that is essential for T-cell signal activation. Methods: The frequency/expression of CD26 and CD45RO/RA was evaluated by flow cytometry, while levels of soluble CD26 (sCD26), CXCL-10, RANTES, IL-10 and TGF-β along with adenosine deaminase (ADA) activity were measured using ELISA. Results: In patients with PKDL vis-a-vis healthy individuals, there was a significant decrease in the frequency and expression of CD26 on CD3⁺CD8⁺ T-cells, which was accompanied by a significant lowering of plasma levels of sCD26. Furthermore, these patients showed a significant decrease in the frequency of CD45RO⁺/CD8⁺ T-cells, concomitant with a significant increase in the proportion of CD45RA⁺/CD8⁺ T-cells. This could collectively translate into reduced formation of the immunological synapse of CD26, CD45RO, and ADA, and lead to an attenuation of the Th1 responses. The decreased levels of CD26 and sCD26 correlated negatively with raised levels of Th2 cytokines, IL-10, and TGF-β along with the lesional parasite load, indicating disease specificity. Conclusions: Taken together, the decreased expression and secretion of CD26 in patients with PKDL resulted in impairment of the CD26-ADA interaction, and thereby possibly contributed to T-cell unresponsiveness, emphasizing the need to develop immunomodulatory therapies against PKDL and by extension, the leishmaniases

Can systemically generated reactive oxygen species help to monitor disease activity in generalized vitiligo? A pilot study

Background: Generalized vitiligo is a disease with unpredictable bursts of activity, goal of treatment during the active phase being to stabilize the lesions. This emphasizes the need for a prospective marker for monitoring disease activity to help decide the duration of therapy. Aims and Objectives: In the present study, we examined whether reactive oxygen species (ROS) generated in erythrocytes can be translated into a marker of activity in vitiligo. Materials and Methods: Level of intracellular ROS was measured flow cytometrically in erythrocytes from venous blood of 21 patients with generalized vitiligo and 21 healthy volunteers using the probe dichlorodihydrofluorescein diacetate. Results: The levels of ROS differed significantly between patients and healthy controls, as well as between active versus stable disease groups. In the active disease group, ROS levels were significantly lower in those being treated with systemic steroids than those that were not. ROS levels poorly correlated with disease duration or body surface area involved. Conclusion: A long-term study based on these findings can be conducted to further validate the potential role of ROS in monitoring disease activity vitiligo

Inadequacy of 12-week miltefosine treatment for Indian post-kala-azar dermal leishmaniasis

Post-kala-azar dermal leishmaniasis (PKDL) is a chronic dermatosis that generally occurs after apparent cure of visceral leishmaniasis caused by Leishmania donovani. In view of the prolonged treatment regimens necessary for PKDL, noncompliance is a major limitation; an optimal regimen is yet to be defined, but 12 weeks of therapy with miltefosine is generally recommended. We performed a single-arm open-label trial of miltefosine administered daily for 16 weeks in 27 patients in Kolkata with PKDL. After 4 weeks of treatment, nine patients were lost to follow-up because of unacceptable side effects, including severe abdominal pain, nausea, and vomiting. Of the 18 remaining patients, seven completed 12 weeks of therapy and 11 completed 16 weeks of therapy. Three of the seven who received 12 weeks of therapy and none of the 11 who received 16 weeks of therapy experienced disease relapse. Our results suggest that a 16-week course of miltefosine is required for reliable cure of PKDL. Further, the study highlighted the urgent need for a multicentric randomized controlled trial of 12 versus 16 weeks of treatment with miltefosine for PKDL so as to achieve the goal of elimination of leishmaniasis in south Asia

Iron trafficking in patients with Indian Post kala-azar dermal leishmaniasis.

BACKGROUND:During infections involving intracellular pathogens, iron performs a double-edged function by providing the pathogen with nutrients, but also boosts the host's antimicrobial arsenal. Although the role of iron has been described in visceral leishmaniasis, information regarding its status in the dermal sequel, Post Kala-azar Dermal Leishmaniasis (PKDL) remains limited. Accordingly, this study aimed to establish the status of iron within monocytes/macrophages of PKDL cases. METHODOLOGY/PRINCIPAL FINDINGS:The intramonocytic labile iron pool (LIP), status of CD163 (hemoglobin-haptoglobin scavenging receptor) and CD71 (transferrin receptor, Tfr) were evaluated within CD14+ monocytes by flow cytometry, and soluble CD163 by ELISA. At the lesional sites, Fe3+ status was evaluated by Prussian blue staining, parasite load by qPCR, while the mRNA expression of Tfr (TfR1/CD71), CD163, divalent metal transporter-1 (DMT-1), Lipocalin-2 (Lcn-2), Heme-oxygenase-1 (HO-1), Ferritin, Natural resistance-associated macrophage protein (NRAMP-1) and Ferroportin (Fpn-1) was evaluated by droplet digital PCR. Circulating monocytes demonstrated elevated levels of CD71, CD163 and soluble CD163, which corroborated with an enhanced lesional mRNA expression of TfR, CD163, DMT1 and Lcn-2. Additionally, the LIP was raised along with an elevated mRNA expression of ferritin and HO-1, as also iron exporters NRAMP-1 and Fpn-1. CONCLUSIONS/SIGNIFICANCE:In monocytes/macrophages of PKDL cases, enhancement of the iron influx gateways (TfR, CD163, DMT-1 and Lcn-2) possibly accounted for the enhanced LIP. However, enhancement of the iron exporters (NRAMP-1 and Fpn-1) defied the classical Ferritinlow/Ferroportinhigh phenotype of alternatively activated macrophages. The creation of such a pro-parasitic environment suggests incorporation of chemotherapeutic strategies wherein the availability of iron to the parasite can be restricted

M2 polarization of monocytes-macrophages is a hallmark of Indian post kala-azar dermal Leishmaniasis

The high level of functional diversity and plasticity in monocytes/macrophages has been defined within in vitro systems as M1 (classically activated), M2 (alternatively activated) and deactivated macrophages, of which the latter two subtypes are associated with suppression of cell mediated immunity, that confers susceptibility to intracellular infection. Although the Leishmania parasite modulates macrophage functions to ensure its survival, what remains an unanswered yet pertinent question is whether these macrophages are deactivated or alternatively activated. This study aimed to characterize the functional plasticity and polarization of monocytes/macrophages and delineate their importance in the immunopathogenesis of Post kala-azar dermal leishmaniasis (PKDL), a chronic dermatosis of human leishmaniasis. Monocytes from PKDL patients showed a decreased expression of TLR-2/4, along with an attenuated generation of reactive oxidative/nitrosative species. At disease presentation, an increased mRNA expression of classical M2 markers CD206, ARG1 and PPARG in monocytes and lesional macrophages indicated M2 polarization of macrophages which was corroborated by increased expression of CD206 and arginase-1. Furthermore, altered vitamin D signaling was a key feature in PKDL, as disease presentation was associated with raised plasma levels of monohydroxylated vitamin D3 and vitamin D3- associated genes, features of M2 polarization. Taken together, in PKDL, monocyte/macrophage subsets appear to be alternatively activated, a phenotype that might sustain disease chronicity. Importantly, repolarization of these monocytes to M1 by antileishmanial drugs suggests that switching from M2 to M1 phenotype might represent a therapeutic opportunity, worthy of future pharmacological consideration

Impaired activation of lesional CD8(+) T-cells is associated with enhanced expression of Programmed Death-1 in Indian Post Kala-azar Dermal Leishmaniasis

Post Kala-azar dermal leishmaniasis (PKDL), caused by Leishmania donovani is the dermal sequel of Visceral Leishmaniasis and importantly, is the proposed disease reservoir. The survival of Leishmania parasites within monocytes/macrophages hinges on its ability to effectively nullify immune activation mechanisms. Thus, delineating the disease-promoting immune mechanisms can facilitate development of immunotherapeutic strategies. Accordingly, in the absence of an animal model, this study aimed to delineate the status of CD8(+) T-cells in patients with PKDL. At disease presentation, the absence of CD4(+) T-cells at lesional sites was concomitant with an overwhelming infiltration of CD8(+) T-cells that demonstrated an absence of Perforin, Granzyme and Zap-70, along with an enhanced expression of Programmed Death-1 (PD-1) and the skin-homing CCL17. Additionally, the lesional CCR4(+) CD8(+) population was associated with an enhanced expression of IL-10 and IL-5. In circulation, the enhanced CD8(+) CCR4(+) T-cell population and raised levels of CCL17/22 was associated with an increased frequency of PD-1, while CD127 was decreased. Taken together, in PKDL, the enhanced plasma and lesional CCL17 accounted for the dermal homing of CD8(+) CCR4(+) T-cells, that along with a concomitant upregulation of PD-1 and IL-10 mediated immune inactivation, emphasizing the need for designing immunotherapies capable of reinvigorating T-cell potency

TNF-Signaling Modulates Neutrophil-Mediated Immunity at the Feto-Maternal Interface During LPS-Induced Intrauterine Inflammation

Accumulation of activated neutrophils at the feto-maternal interface is a defining hallmark of intrauterine inflammation (IUI) that might trigger an excessive immune response during pregnancy. Mechanisms responsible of this massive neutrophil recruitment are poorly investigated. We have previously showed that intraamniotic injection of LPS in rhesus macaques induced a neutrophil predominant inflammatory response similar to that seen in human IUI. Here, we demonstrate that anti-TNF antibody (Adalimumab) inhibited ~80% of genes induced by LPS involved in inflammatory signaling and innate immunity in chorio-decidua neutrophils. Consistent with the gene expression data, TNF-blockade decreased LPS-induced neutrophil accumulation and activation at the feto-maternal interface. We also observed a reduction in IL-6 and other pro-inflammatory cytokines but not prostaglandins concentrations in the amniotic fluid. Moreover, TNF-blockade decreased mRNA expression of inflammatory cytokines in the chorio-decidua but not in the uterus, suggesting that inhibition of TNF-signaling decreased the inflammation in a tissue-specific manner within the uterine compartment. Taken together, our results demonstrate a predominant role for TNF-signaling in modulating the neutrophilic infiltration at the feto-maternal interface during IUI and suggest that blockade of TNF-signaling could be considered as a therapeutic approach for IUI, the major leading cause of preterm birth