Neutrophils in antiretroviral therapy-controlled HIV demonstrate hyperactivation associated with a specific IL-17/IL-22 environment

Circulating levels of inflammatory mediators in pregnant people living with HIV according to antiretroviral therapy regimen

Introduction

The use of antiretroviral therapy (ART) during pregnancy, particularly protease-inhibitor-based regimens (PI), has been linked to adverse outcomes including preterm delivery. As this outcome may be related to systemic inflammation, we sought to characterize inflammatory profiles of pregnant people living with HIV (PLWH) by comparing their levels of inflammatory mediators at two timepoints during pregnancy according to ART regimen, and to HIV-negative controls.

Methods

Second and third trimester samples from 144 pregnant PLWH treated with ART and 24 HIV-uninfected controls were retrieved from the CARMA-PREG cohort. Peripheral plasma levels of 12 inflammatory mediators previously linked to HIV infection and/or poor pregnancy outcomes were quantified by multiplex assay: HMGB1, GM-CSF, IFNα, IFNβ, IFNγ, IL-10, IL-17, IL-1β, IL-6, TNFα, AGP, and CRP. Levels were compared by ART regimen and HIV status.

Results

Adjusted analyses showed that PLWH have higher levels of AGP throughout pregnancy and lower levels of IFNγ and IL-1β during the second trimester. PI-based regimens are associated with significantly higher levels of IFNα and IL-17 during the second trimester and IFNα, CRP, HMGB1, and IFNβ during the third trimester compared to InSTI-based regimens. The PI-subgroup was associated with preterm delivery and higher HIV-1 viral load.

Discussion

Our results suggest that PI-based regimens are associated with a pro-inflammatory and antiviral immunological response and a high viral load, which may be a mechanism through which PI-based regimens increase the risk of preterm delivery. Further investigations into cellular mechanisms and pro-inflammatory cascades leading to preterm delivery are necessary to support this association.

Low-density granulocytes display immature cells with enhanced NET formation in people living with HIV

While the protective role of neutrophil extracellular traps (NETs) in limiting human immunodeficiency virus (HIV) spread to susceptible cells has been documented, there is comparatively little insight into whether NET formation is harmful in people living with HIV (PLWH). To gain insight into neutrophil dysregulation and the pathological role of NETs in HIV, we examined expressions of NET-associated markers [cell-free DNA (cfDNA) and citrullinated histone H3 (CitH3)] in the plasmas from a cohort of the Hawaii Aging with HIV-cardiovascular and HIV-seronegative (HIV-) individuals. In a subset of participants, circulating low-density granulocyte (LDG) levels and their maturation and activation status were analyzed via flow cytometry. We demonstrated higher plasma levels of CitH3 in PLWH compared to HIV- individuals. LDGs from PLWH had heightened CD66b, but reduced CD16 expression. The percentages and counts of CD10+ LDGs were significantly decreased in PLWH. In addition, the CD16Lo LDG subsets were enriched in PLWH, compared to HIV- group, indicating that immature LDGs are increased in PLWH. Moreover, LDGs from PLWH exhibited significantly higher NET forming capacity. In summary, our study presents evidence that LDGs from PLWH on ART display an immature and altered phenotype with increased NET formation. Among PLWH, plasma NET levels as well as LDG parameters correlated with blood markers for inflammation and coagulation, suggesting that neutrophil activation and NETs may exert proinflammatory and coagulation effects. Our data provide insights into the pathologic role of LDGs at least in part mediated through NET formation in PLWH.

Current Knowledge of Th22 Cell and IL-22 Functions in Infectious Diseases

T helper 22 (Th22) cells, a newly defined CD4+ T-cell lineage, are characterized by their distinct cytokine profile, which primarily consists of IL-13, IL-22 and TNF-α. Th22 cells express a wide spectrum of chemokine receptors, such as CCR4, CCR6 and CCR10. The main effector molecule secreted by Th22 cells is IL-22, a member of the IL-10 family, which acts by binding to IL-22R and triggering a complex downstream signaling system. Th22 cells and IL-22 have been found to play variable roles in human immunity. In preventing the progression of infections such as HIV and influenza, Th22/IL-22 exhibited protective anti-inflammatory characteristics, and their deleterious proinflammatory activities have been demonstrated to exacerbate other illnesses, including hepatitis B and Helicobacter pylori infection. Herein, we review the current understanding of Th22 cells, including their definition, differentiation and mechanisms, and the effect of Th22/IL-22 on human infectious diseases. According to studies on Th22 cells, Th22/IL-22 may be a promising therapeutic target and an effective treatment strategy for various infections.

Chitinase-3-like Protein 1 Is Associated with Poor Virologic Control and Immune Activation in Children Living with HIV

Perinatally infected children living with HIV (CLWH) face lifelong infection and associated inflammatory injury. Chitinase-like 3 protein-1 (CHI3L1) is expressed by activated neutrophils and may be a clinically informative marker of systemic inflammation in CLWH. We conducted a multi-centre, cross-sectional study of CLWH, enrolled in the Early Pediatric Initiation Canadian Child Cure Cohort Study (EPIC⁴). Plasma levels of CHI3L1, pro-inflammatory cytokines, and markers of microbial translocation were measured by enzyme-linked immunosorbent assays. Longitudinal clinical characteristics (viral load, neutrophil count, CD4+ and CD8+ T-lymphocyte counts, and antiretroviral (ARV) regimen) were abstracted from patient medical records. One-hundred-and-five (105) CLWH (median age 13 years, 62% female) were included in the study. Seventy-seven (81%) had viral suppression on combination antiviral therapy (cART). The median CHI3L1 level was 25 μg/L (IQR 19-39). CHI3L1 was directly correlated with neutrophil count (ρ = 0.22, p = 0.023) and inversely correlated with CD4/CD8 lymphocyte ratio (ρ = -0.35, p = 0.00040). Children with detectable viral load had higher levels of CHI3L1 (40 μg/L (interquartile range, IQR 33-44) versus 24 μg/L (IQR 19-35), p = 0.0047). CHI3L1 levels were also correlated with markers of microbial translocation soluble CD14 (ρ = 0.26, p = 0.010) and lipopolysaccharide-binding protein (ρ = 0.23, p = 0.023). We did not detect differences in CHI3L1 between different cART regimens. High levels of neutrophil activation marker CHI3L1 are associated with poor virologic control, immune dysregulation, and microbial translocation in CLWH on cART.

S100A8-mediated metabolic adaptation controls HIV-1 persistence in macrophages in vivo

HIV-1 eradication is hindered by viral persistence in cell reservoirs, established not only in circulatory CD4⁺T-cells but also in tissue-resident macrophages. The nature of macrophage reservoirs and mechanisms of persistence despite combined anti-retroviral therapy (cART) remain unclear. Using genital mucosa from cART-suppressed HIV-1-infected individuals, we evaluated the implication of macrophage immunometabolic pathways in HIV-1 persistence. We demonstrate that ex vivo, macrophage tissue reservoirs contain transcriptionally active HIV-1 and viral particles accumulated in virus-containing compartments, and harbor an inflammatory IL-1R⁺S100A8⁺MMP7⁺M4-phenotype prone to glycolysis. Reactivation of infectious virus production and release from these reservoirs in vitro are induced by the alarmin S100A8, an endogenous factor produced by M4-macrophages and implicated in “sterile” inflammation. This process metabolically depends on glycolysis. Altogether, inflammatory M4-macrophages form a major tissue reservoir of replication-competent HIV-1, which reactivate viral production upon autocrine/paracrine S100A8-mediated glycolytic stimulation. This HIV-1 persistence pathway needs to be targeted in future HIV eradication strategies.

HIV-1 eradication is hindered by viral persistence in different cell reservoirs, including circulatory CD4+ T-cells and tissue-resident macrophages. Here, by analyzing male genital mucosa from cART-suppressed HIV1-infected individuals, Real et al. show that M4 macrophages represent the major macrophage HIV-1 reservoir in this tissue. These macrophages have an inflammatory IL1R⁺S100A8⁺MMP7⁺M4-phenotype, and contain transcriptionally active HIV-1, which reactivate infectious virus production from viral latency in response to autocrine/paracrine S100A8-mediated glycolysis.

Effect of Antiretroviral Therapy on Neutrophil Oxidative Burst in Children

OBJECTIVE

To ascertain the effect of human immunodeficiency virus (HIV) infection, as well as, antiretroviral therapy (ART) on neutrophil oxidative burst in children.

METHODS

Fifty-five children living with HIV infection (30 receiving ART for ≥ 2 y, 25 treatment-naïve) and 30 healthy controls, aged 18 mo-18 y, were assessed for hemogram and neutrophil oxidative burst. The treatment-naïve children were followed up and the above tests were repeated after 6 mo of ART.

RESULTS

Mean (SD) serum MPO activity at 6 mo after ART [32.1 (± 19.9) U/L] was comparable to that at disease onset [17.2 (± 23.0) U/L], although it was significantly higher compared to that in children on ART ≥ 2 y [13.3 (± 15.8) U/L] and controls [12.1 (± 11.9) U/L]. Median fluorescence intensity (MFI) of unstimulated DHR was highest at 6 mo after ART and in the treatment-naïve group, which was significantly higher than in the controls, as well as, children receiving ART ≥ 2 y. Stimulation index was highest in the control group [442.4 (341.9-562.9)], which was comparable to that in children on ART ≥ 2 y [304.2 (153.2-664.8)], but was significantly higher than the treatment-naïve cohort [266.1 (148.2-339.4)] and children on ART for 6 mo [318.8 (154.9-395.6)].

CONCLUSION

A hyperinflammatory state caused by an increased serum myeloperoxidase enzyme activity and increased basal neutrophil oxidative burst was seen in untreated HIV infection and during initial 6 mo of ART. ART given for ≥ 2 y normalized the impaired neutrophilic phagocytic functions.

Expansion of Immature Neutrophils During SIV Infection Is Associated With Their Capacity to Modulate T-Cell Function

In spite of the efficacy of combinational antiretroviral treatment (cART), HIV-1 persists in the host and infection is associated with chronic inflammation, leading to an increased risk of comorbidities, such as cardiovascular diseases, neurocognitive disorders, and cancer. Myeloid cells, mainly monocytes and macrophages, have been shown to be involved in the immune activation observed in HIV-1 infection. However, less attention has been paid to neutrophils, the most abundant circulating myeloid cell, even though neutrophils are strongly involved in tissue damage and inflammation in several chronic diseases, in particular, autoimmune diseases. Herein, we performed a longitudinal characterization of neutrophil phenotype and we evaluated the interplay between neutrophils and T cells in the model of pathogenic SIVmac251 experimental infection of cynomolgus macaques. We report that circulating granulocytes consists mainly of immature CD10- neutrophils exhibiting a prime phenotype during primary and chronic infection. We found that neutrophil priming correlates with CD8⁺ T cell activation. Moreover, we provide the evidence that neutrophils are capable of modulating CD4⁺ and CD8⁺ T-cell proliferation and IFN-γ production in different ways depending on the time of infection. Thus, our study emphasizes the role of primed immature neutrophils in the modulation of T-cell responses in SIV infection.

Neutrophils promote T-cell activation through the regulated release of CD44-bound Galectin-9 from the cell surface during HIV infection

The interaction of neutrophils with T cells has been the subject of debate and controversies. Previous studies have suggested that neutrophils may suppress or activate T cells. Despite these studies, the interaction between neutrophils and T cells has remained a largely unexplored field. Here, based on our RNA sequencing (RNA-seq) analysis, we found that neutrophils have differential transcriptional and functional profiling depending on the CD4 T-cell count of the HIV-infected individual. In particular, we identified that neutrophils in healthy individuals express surface Galectin-9 (Gal-9), which is down-regulated upon activation, and is consistently down-regulated in HIV-infected individuals. However, down-regulation of Gal-9 was associated with CD4 T-cell count of patients. Unstimulated neutrophils express high levels of surface Gal-9 that is bound to CD44, and, upon stimulation, neutrophils depalmitoylate CD44 and induce its movement out of the lipid raft. This process causes the release of Gal-9 from the surface of neutrophils. In addition, we found that neutrophil-derived exogenous Gal-9 binds to cell surface CD44 on T cells, which promotes LCK activation and subsequently enhances T-cell activation. Furthermore, this process was regulated by glycolysis and can be inhibited by interleukin (IL)-10. Together, our data reveal a novel mechanism of Gal-9 shedding from the surface of neutrophils. This could explain elevated plasma Gal-9 levels in HIV-infected individuals as an underlying mechanism of the well-characterized chronic immune activation in HIV infection. This study provides a novel role for the Gal-9 shedding from neutrophils. We anticipate that our results will spark renewed investigation into the role of neutrophils in T-cell activation in other acute and chronic conditions, as well as improved strategies for modulating Gal-9 shedding.

This study shows that HIV-infected individuals have different neutrophil profiles depending on their CD4 T cell count. In particular, neutrophils express high levels of surface Gal-9 but this is shed upon stimulation; this exogenous Gal-9 binds to CD44 on T cells, which promotes LCK activation and subsequently enhances T cell activation.

H3K4me3 Histone ChIP-Seq Analysis Reveals Molecular Mechanisms Responsible for Neutrophil Dysfunction in HIV-Infected Individuals

Peripheral neutrophils in HIV-infected individuals are characterized by impairment of chemotaxis, phagocytosis, bactericidal activity, and oxidative burst ability regardless of whether patients are receiving antiretroviral therapy or not. Neutrophil dysfunction leads not only to increased susceptibility to opportunistic infections but also to tissue damage through the release of reactive oxygen species (ROS), proteases, and other potentially harmful effector molecules contributing to AIDS progression. In this study, we demonstrated high levels of histone H3 lysine K4 trimethylated (H3K4me3) and dysregulation of DNA transcription in circulating neutrophils of HIV-infected subjects. This dysregulation was accompanied by a deficient response of neutrophils to LPS, impaired cytokine/chemokine/growth factor synthesis, and increased apoptosis. Chromatin immunoprecipitation sequencing (ChIPseq) H3K4me3 histone analysis revealed that the most spectacular abnormalities were observed in the exons, introns, and promoter-TSS regions. Bioinformatic analysis of Gene Ontology, including biological processes, molecular function, and cellular components, demonstrated that the main changes were related to the genes responsible for cell activation, cytokine production, adhesive molecule expression, histone remodeling via upregulation of methyltransferase process, and downregulation of NF-κB transcription factor in canonical pathways. Abnormalities within H3K4me3 implicated LPS-mediated NF-κB canonical activation pathway that was a result of low amounts of κB DNA sites within histone H3K4me3, low NF-κB (p65 RelA) and TLR4 mRNA expression, and reduced free NF-κB (p65 RelA) accumulation in the nucleus. Genome-wide survey of H3K4me3 provided evidence that chromatin modifications lead to an impairment within the canonical NF-κB cell activation pathway causing the neutrophil dysfunction observed in HIV-infected individuals.

Neutrophil-T cell crosstalk in inflammatory bowel disease

Neutrophils are the most abundant leucocytes in human blood, promptly recruited to the site of tissue injury, where they orchestrate inflammation and tissue repair. The multifaceted functions of neutrophils have been more appreciated during the recent decade, and these cells are now recognized as sophisticated and essential players in infection, cancer and chronic inflammatory diseases. Consequently, our understanding of the role of neutrophils in inflammatory bowel disease (IBD), their immune responses and their ability to shape adaptive immunity in the gut have been recognized. Here, current knowledge on neutrophil responses in IBD and their capacity to influence T cells are summarized with an emphasis on the role of these cells in human disease.

Interactions of HIV and Antiretroviral Therapy With Neutrophils and Platelets

Neutrophils are important components of the innate immune system that mediate pathogen defense by multiple processes including phagocytosis, release of proteolytic enzymes, production of reactive oxygen species, and neutrophil extracellular trap formation. Abnormalities of neutrophil count and function have been described in the setting of HIV infection, with the majority of antiretroviral agents (ARVs), excluding zidovudine, having been reported to correct neutropenia. Questions still remain, however, about their impact on neutrophil function, particularly the possibility of persistent neutrophil activation, which could predispose people living with HIV to chronic inflammatory disorders, even in the presence of virally-suppressive treatment. In this context, the effects of protease inhibitors and integrase strand transfer inhibitors, in particular, on neutrophil function remain poorly understood and deserve further study. Besides mediating hemostatic functions, platelets are increasingly recognized as critical role players in the immune response against infection. In the setting of HIV, these cells have been found to harbor the virus, even in the presence of antiretroviral therapy (ART) potentially promoting viral dissemination. While HIV-infected individuals often present with thrombocytopenia, they have also been reported to have increased platelet activation, as measured by an upregulation of expression of CD62P (P-selectin), CD40 ligand, glycoprotein IV, and RANTES. Despite ART-mediated viral suppression, HIV-infected individuals reportedly have sustained platelet activation and dysfunction. This, in turn, contributes to persistent immune activation and an inflammatory vascular environment, seemingly involving neutrophil-platelet-endothelium interactions that increase the risk for development of comorbidities such as cardiovascular disease (CVD) that has become the leading cause of morbidity and mortality in HIV-infected individuals on treatment, clearly underscoring the importance of unraveling the possible etiologic roles of ARVs. In this context, abacavir and ritonavir-boosted lopinavir and darunavir have all been linked to an increased risk of CVD. This narrative review is therefore focused primarily on the role of neutrophils and platelets in HIV transmission and disease, as well as on the effect of HIV and the most common ARVs on the numbers and functions of these cells, including neutrophil-platelet-endothelial interactions.

Residual immune dysfunction under antiretroviral therapy

The usage of combination antiretroviral therapy in people with HIV (PWH) has incited profound improvement in morbidity and mortality. Yet, PWH may not experience full restoration of immune function which can manifest with non-AIDS comorbidities that frequently associate with residual inflammation and can imperil quality of life or longevity. In this review, we discuss the pathogenesis underlying chronic inflammation and residual immune dysfunction in PWH, as well as potential therapeutic interventions to ameliorate them and prevent incidence or progression of non-AIDS comorbidities. Current evidence advocates that early diagnosis and prompt initiation of therapy at high CD4 counts may represent the best available approach for an improved immune recovery in PWH.

Samsum ant venom modulates the immune response and redox status at the acute toxic dose in vivo

Background:

Ant venoms express surface molecules that participate in antigen presentation involving pro- and anti-inflammatory cytokines. This work aims to investigate the expression of MHC-II, CD80 and CD86 on the polymorphonuclear cells (PMNs) in rats injected with samsum ant venom (SAV).

Methods:

Rats were divided into three groups - control, SAV-treated (intraperitoneal route, 600 μg/kg), and SAV-treated (subcutaneous route, 600 μg/kg). After five doses, animals were euthanized and samples collected for analysis.

Results:

The subcutaneous SAV-trated rats presented decreased levels of glutathione with increased cholesterol and triglyceride levels. Intraperitoneal SAV-treated animals displayed significantly reduced concentrations of both IFN-γ and IL-17 in comparison with the control group. However, intraperitoneal and subcutaneous SAV-treated rats were able to upregulate the expressions of MHC-II, CD80 and CD86 on PMNs in comparison with the control respectively. The histological examination showed severe lymphocyte depletion in the splenic white pulp of the intraperitoneal SAV-injected rats.

Conclusion:

Stimulation of PMNs by SAV leads to upregulation of MHC-II, CD 80, and CD 86, which plays critical roles in antigen presentation and consequently proliferation of T-cells. Subcutaneous route was more efficient than intraperitoneal by elevating MHC-II, CD80 and CD86 expression, disturbing oxidative stability and increasing lipogram concentration.

Interleukin 17 (IL-17) manipulates mouse bone marrow- derived neutrophils in response to acute lung inflammation

Interleukin 17 (IL-17) mediates neutrophil migration to the lungs during acute inflammation, potentially leading to lung tissue damage. In the present study, we evaluated whether IL-17 could facilitate certain neutrophil functions in a mouse model. Mice were divided into four groups and intranasally challenged with PBS (1 = Control), Influenza A (H1N1) and Klebsiella pneumoniae (2 = Mix), Influenza A alone (3 = Flu), or K. pneumoniae (4 = KP) alone. Bone marrow, BAL cells, and lung specimens were collected seven days post-challenge for analysis. Mice in the Flu group showed the highest mortality rate. Neutrophils were the prominent cell type in BAL from Mix and KP, whereas lymphocytes were most numerous in Flu. Lesions in the lungs revealed considerably damage in the Mix, Flu, and KP groups. Isolated bone marrow-derived neutrophils were in vitro primed with mouse recombinant IL-17A protein (rIL-17A) followed by various functional assays. The reactive oxygen species (ROS) levels in rIL-17A primed cells showed significant elevations in all groups. Phagocytosis and bacterial destruction showed no significant difference between (+) or (-) rIL-17A groups. The formation of neutrophil extracellular traps (NETs) in rIL-17A-primed neutrophils showed elevated NET production. We next monitored expressions of genes in neutrophils. IL-17A mRNA expression was significantly increased in Mix and Flu; IL-1β mRNA only significantly increased in Flu, and IL-17RA showed constitutive expressions in all groups. In summary, neutrophils may cause tissue damage during lung inflammation through specific functions influenced by IL-17.

The protective and pathogenic roles of IL-17 in viral infections: friend or foe?

Viral infections cause substantial human morbidity and mortality, and are a significant health burden worldwide. Following a viral infection, the host may initiate complex antiviral immune responses to antagonize viral invasion and replication. However, proinflammatory antiviral immune responses pose a great threat to the host if not properly held in check. Interleukin (IL)-17 is a pleiotropic cytokine participating in a variety of physiological and pathophysiological conditions, including tissue integrity maintenance, cancer progression, autoimmune disease development and, more intriguingly, infectious diseases. Abundant evidence suggests that while IL-17 plays a crucial role in enhancing effective antiviral immune responses, it may also promote and exacerbate virus-induced illnesses. Accumulated experimental and clinical evidence has broadened our understanding of the seemingly paradoxical role of IL-17 in viral infections and suggests that IL-17-targeted immunotherapy may be a promising therapeutic option. Herein, we summarize current knowledge regarding the protective and pathogenic roles of IL-17 in viral infections, with emphasis on underlying mechanisms. The various and critical roles of IL-17 in viral infections necessitate the development of therapeutic strategies that are uniquely tailored to both the infectious agent and the infection environment.

Mass Cytometry Reveals the Immaturity of Circulating Neutrophils during SIV Infection

The infected host fails to eradicate HIV-1, despite significant control of viral replication by combinational antiretroviral therapy. Here, we assessed the impact of HIV infection on immune-cell compartments in a SIVmac251 nonhuman primate infection model, which allowed the choice of contamination route, time of infection, and treatment follow-up. We performed high-throughput multiparameter single-cell phenotyping by mass cytometry to obtain a global vision of the immune system in blood and bone marrow. Circulating polymorphonuclear neutrophils (PMNs) with impaired phagocytosis had altered surface expression of CD62L and CD11b during early chronic infection. The initiation of combinational antiretroviral treatment during primary infection did not restore PMN function. The maturation state of PMNs was highly altered during late chronic SIV infection, showing a primarily immature phenotype. Our results provide new insights into PMN involvement in the pathogenesis of HIV infection and may play a role in the establishment and maintenance of chronic immune activation.

The Dual Role of Neutrophils in HIV Infection

PURPOSE OF REVIEW

We summarize what is known about neutrophils in HIV infection, focusing on their potential roles in HIV protection, acquisition, and pathogenesis.

RECENT FINDINGS

Recent studies have demonstrated that neutrophil-associated proteins and cytokines in genital tissue pre-infection associate with HIV acquisition. However, recent in vivo assessment of highly exposed seronegative individuals and in vitro studies of anti-HIV functions of neutrophils add to older literature evidence that neutrophils may be important in a protective response to HIV infection. Neutrophils are important for containment of pathogens but can also contribute to tissue damage due to their release of reactive oxygen species, proteases, and other potentially harmful effector molecules. Overall, there is a clear evidence for both helpful and harmful roles of neutrophils in HIV acquisition and pathogenesis. Further study, particularly of tissue neutrophils, is needed to elucidate the kinetics, phenotype, and functionality of neutrophils in HIV infection to better understand this dichotomy.

Harmful neutrophil subsets in patients with ischemic stroke: Association with disease severity

Objective

To better understand the functional state of circulating neutrophils in patients with ischemic stroke (IS) for planning future clinical trials.

Methods

We analyzed by flow cytometry activation state of circulating neutrophils and the distribution of neutrophil peripheral subsets in 41 patients with acute IS less than 6 hours before admission and compared them with 22 age-matched healthy controls.

Results

Our results demonstrated continuous basal hyperactivation of circulating neutrophils during acute IS, characterized by lower l-selectin expression and higher CD11b expression at the cell surface, increased ROS production by neutrophils, and greater circulating levels of neutrophil elastase. Neutrophil hyperactivation was associated with deregulation of the equilibrium between apoptotic and necrotic. Patients also had higher percentages than controls of the overactive senescent (CXCR4^bright/CD62L^dim) neutrophil subset and increased percentage of neutrophils with a reverse transendothelial migration (CD54^highCXCR1^low) phenotype. Importantly, neutrophil alterations were associated with the clinical severity of the stroke, evaluated by its NIH Stroke Scale score.

Conclusion

Altogether, our results indicate that during acute IS, the inflammatory properties of circulating neutrophils rise, associated with the expansion of harmful neutrophil subsets. These changes in neutrophil homeostasis, associated with disease severity, may play an instrumental role by contributing to systemic inflammation and to the blood-brain barrier breakdown. Our findings highlight new potential therapeutic approaches of stroke by rebalancing the ratio of senescent to immunosuppressive neutrophils or decreasing reverse neutrophil transmigration or both.

Neutrophil hyperactivation correlates with Alzheimer's disease progression

OBJECTIVE

Recent studies have underlined the effect of systemic inflammation on the pathophysiology of Alzheimer's disease (AD). Neutrophils are key components of early innate immunity and contribute to uncontrolled systemic inflammation if not tightly regulated. The aim of our study was to fully characterize human circulating neutrophils at different disease stages in AD.

METHODS

We analyzed neutrophil phenotypes and functions in 42 patients with AD (16 with mild cognitive impairment and 26 with dementia), and compared them to 22 age-matched healthy subjects. This study was performed directly in whole blood to avoid issues with data interpretation related to cell isolation procedures.

RESULTS

Blood samples from AD patients with dementia revealed neutrophil hyperactivation associated with increased reactive oxygen species production and increased levels of intravascular neutrophil extravascular traps. The homeostasis of circulating neutrophils in these patients also changed: The ratio between the harmful hyperreactive CXCR4^high /CD62L^low senescent and the CD16^bright /CD62L^dim immunosuppressive neutrophil subsets rose in the later stage of the disease. These abnormalities were greater in fast-decliner than in slow-decliner patients.

INTERPRETATION

Our results indicate that the inflammatory properties of circulating neutrophils shift as the percentage of aged neutrophils expands in patients with AD-changes that may play an instrumental role in establishing systemic chronic inflammation. Most important, our data strongly suggest that the neutrophil phenotype may be associated with the rate of cognitive decline and may thus constitute an innovative and prognostic blood biomarker in patients with AD. Ann Neurol 2018;83:387-405.

The role of polymorphonuclear neutrophils during HIV-1 infection

It is well-recognized that human immunodeficiency virus type-1 (HIV-1) mainly targets CD4⁺ T cells and macrophages. Nonetheless, during the past three decades, a huge number of studies have reported that HIV-1 can directly or indirectly target other cellular components of the immune system including CD8⁺ T cells, B cells, dendritic cells, natural killer cells, and polymorphonuclear neutrophils (PMNs), among others. PMNs are the most abundant leukocytes in the human circulation, and are known to play principal roles in the elimination of invading pathogens, regulating different immune responses, healing of injured tissues, and maintaining mucosal homeostasis. Until recently, little was known about the impact of HIV-1 infection on PMNs as well as the impact of PMNs on HIV-1 disease progression. This is because early studies focused on neutropenia and recurrent microbial infections, particularly, during advanced disease. However, recent studies have extended the investigation area to cover new aspects of the interactions between HIV-1 and PMNs. This review aims to summarize these advances and address the impact of HIV-1 infection on PMNs as well as the impact of PMNs on HIV-1 disease progression to better understand the pathophysiology of HIV-1 infection.

First Report of CD4 Lymphopenia and Defective Neutrophil Functions in a Patient with Amebiasis Associated with CMV Reactivation and Severe Bacterial and Fungal Infections

We report the case of a patient with acute necrotizing colitis due to invasive amebiasis associated with CD4 lymphopenia and impaired neutrophil responses. The course of the disease was characterized by CMV reactivation and severe and recurrent bacterial and fungal infections, which might be related to the decreased CD4 T cell count and the impaired functional capacities of neutrophils, respectively. The clinical outcome was positive with normalization of both CD4 cell count and neutrophil functions.

Immune activation and immune aging in HIV infection

PURPOSE OF REVIEW

The development of serious non-AIDS-related pathologies typically associated with aging, and the premature immune aging that characterizes HIV-1-infected patients, even with suppressive antiretroviral therapy, have raised increasing concerns in recent years. Deciphering the causes of these phenomena is key for our understanding of HIV pathogenesis and for the clinical care of patients living with the virus.

RECENT FINDINGS

An important basis for the immune parallels between HIV infection and aging lies in the exhaustion of the lymphopoietic capacity of infected individuals, which eventually affects all compartments of the immune system. The alleged cause for these immune alterations, and the onset of age-related comorbidities, is the systemic chronic immune activation that is established in patients. However, there is a multiplicity of contributors to this immune activation.

SUMMARY

Our understanding of the precise link between immune activation and aging in HIV infection is complicated by the influence of coinfections and life style factors. Developing rational interventions to reduce the hyper-inflammatory status of HIV-1-infected patients requires a clearer delineation of the factors contributing to the increased levels of systemic immune activation.

Review of functional MRI in HIV: effects of aging and medication

HIV-associated neurocognitive disorder (HAND) is a frequently occurring comorbidity of HIV infection. Evidence suggests this condition starts subclinical before a progression to a symptomatic stage. Blood oxygenated level dependent (BOLD) fMRI has shown to be a sensitive tool to detect abnormal brain function in an early stage and might therefore be useful to evaluate the effect of HIV infection on brain function. An extensive literature search was performed in June 2015. Eligibility criteria for included studies were as follows: (1) conducting with HIV-positive patients, (2) using BOLD fMRI, and (3) including a HIV-negative control group. A total of 19 studies were included in the review including 931 participants. Differences in activation between HIV-positive and -negative participants were found when testing multiple domains, i.e., attention, (working) memory, and especially executive functioning. Overall, HIV-positive patients showed hyperactivation in task-related brain regions despite equal performances as controls. Task performance was degraded only for the most complex tasks. A few studies investigated the effect of aging on fMRI, and most of them found no interaction with HIV infection. Only three studies evaluated the effect of combination antiretroviral therapy (cART) on functional data suggesting an increase in activation with the use of cART. fMRI is a sensitive instrument to detect subtle cognitive changes in HIV patients. Open questions remain regarding the effects of cART on fMRI and the effects of aging on fMRI.

Differential Diagnosis of Autoimmune Pancreatitis From Pancreatic Cancer by Analysis of Serum Gelatinase Levels

OBJECTIVES

The aim of this study was to analyze serum gelatinases as part of the clinical strategy for the preoperative differentiation between autoimmune pancreatitis (AIP) and pancreatic ductal adenocarcinoma (PDAC). The finding of differential markers will prevent unnecessary surgical resection and allow optimal treatment of these diseases.

METHODS

Quantitative gelatin zymography was applied to analyze all individual gelatinase forms in serum and to define proteinase alterations associated with AIP and PDAC. For this purpose, sera of 130 patients, being 29 with AIP, 33 with chronic pancreatitis, 32 with PDAC, and 36 healthy controls, were first assayed for gelatinase levels by quantitative zymography before further validation by the analysis with commercial sandwich enzyme linked immunosorbent assays.

RESULTS

Serum profiling data obtained by zymography analysis revealed that gelatinase B/matrix metalloproteinase 9 (MMP-9), the neutrophil gelatinase B-associated lipocalin/MMP-9 complex, and gelatinase A/MMP-2 levels were significantly increased in patients with AIP. These proteins are promising markers to discriminate between AIP and PDAC. The best composite parameter, being the ratio of total MMP-9 over MMP-2 levels, can predict 93% of the AIP and 75% of the PDAC correctly. With enzyme linked immunosorbent assay, we confirmed the zymography results.

CONCLUSIONS

Differential gelatinase serum profiles as AIP markers, together with other clinical tests, help to assure the diagnosis of PDAC or AIP.

Effect of Chocolate and Yerba Mate Phenolic Compounds on Inflammatory and Oxidative Biomarkers in HIV/AIDS Individuals

Flavonoids in cocoa and yerba mate have a beneficial role on inflammation and oxidative disorders. Their effect on HIV individuals has not been studied yet, despite the high cardiovascular risk of this population. This study investigated the role of cocoa and yerba mate consumption on oxidative and inflammatory biomarkers in HIV+ individuals. A cross-over, placebo-controlled, double-blind, randomized clinical trial was conducted in 92 individuals on antiretroviral therapy for at least six months and at viral suppression. Participants were randomized to receive either 65 g of chocolate or chocolate-placebo or 3 g of yerba mate or mate-placebo for 15 days each, alternating by a washout period of 15 days. At baseline, and at the end of each intervention regimen, data regarding anthropometry, inflammatory, oxidative and immunological parameters were collected. High-sensitivity C-reactive protein, fibrinogen, lipid profile, white blood cell profile and thiobarbituric acid reactive substances were assessed. There was a difference between mean concentrations of HDL-c (ANOVA; p ≤ 0.05) among the different regimens: dark chocolate, chocolate-placebo, yerba mate and mate-placebo. When a paired Student t-test was used for comparisons between mean HDL-c at baseline and after each regimen, the mean concentration of HDL-c was higher after supplementation with dark chocolate (p = 0.008).

mTOR Mediates IL-23 Induction of Neutrophil IL-17 and IL-22 Production

It has been shown recently that neutrophils are able to produce IL-22 and IL-17, which differentially regulate the pathogenesis of inflammatory bowel disease. However, it is still largely unknown how the neutrophil production of IL-22 and IL-17 is regulated, and their role in the pathogenesis of inflammatory bowel disease. In this study, we found that IL-23 promoted neutrophil production of IL-17 and IL-22. IL-23 stimulated the neutrophil expression of IL-23R as well as rorc and ahr. Retinoid acid receptor-related orphan receptor γ t and aryl-hydrocarbon receptor differentially regulated IL-23 induction of neutrophil IL-17 and IL-22. In addition, IL-23 induced the activation of mTOR in neutrophils. Blockade of the mTOR pathway inhibited IL-23-induced expression of rorc and ahr, as well as IL-17 and IL-22 production. By using a microbiota Ag-specific T cell-mediated colitis model, we demonstrated that depletion of neutrophils, as well as blockade of IL-22, resulted in a significant increase in the severity of colitis, thereby indicating a protective role of neutrophils and IL-22 in chronic colitis. Collectively, our data revealed that neutrophils negatively regulate microbiota Ag-specific T cell induction of colitis, and IL-23 induces neutrophil production of IL-22 and IL-17 through induction of rorc and ahr, which is mediated by the mTOR pathway.

Platelet microparticles inhibit IL-17 production by regulatory T cells through P-selectin

Self-tolerance and immune homeostasis are orchestrated by FOXP3(+)regulatory T cells (Tregs). Recent data have revealed that upon stimulation, Tregs may exhibit plasticity toward a proinflammatory phenotype, producing interleukin 17 (IL-17) and/or interferon γ (IFN-γ). Such deregulation of Tregs may contribute to the perpetuation of inflammatory processes, including graft-versus-host disease. Thus, it is important to identify immunomodulatory factors influencing Treg stability. Platelet-derived microparticles (PMPs) are involved in hemostasis and vascular health and have recently been shown to be intimately involved in (pathogenic) immune responses. Therefore, we investigated whether PMPs have the ability to affect Treg plasticity. PMPs were cocultured with healthy donor peripheral blood-derived Tregs that were stimulated with anti-CD3/CD28 monoclonal antibodies in the presence of IL-2, IL-15, and IL-1β. PMPs prevented the differentiation of peripheral blood-derived Tregs into IL-17- and IFN-γ-producing cells, even in the presence of the IL-17-driving proinflammatory cytokine IL-1β. The mechanism of action by which PMPs prevent Treg plasticity consisted of rapid and selective P-selectin-dependent binding of PMPs to a CCR6(+)HLA-DR(+)memory-like Treg subset and their ability to inhibit Treg proliferation, in part through CXCR3 engagement. The findings that ~8% of Tregs in the circulation of healthy individuals are CD41(+)P-selectin(+)and that distinct binding of patient plasma PMPs to Tregs was observed support in vivo relevance. These findings open the exciting possibility that PMPs actively regulate the immune response at sites of (vascular) inflammation, where they are known to accumulate and interact with leukocytes, consolidating the (vascular) healing process.

Histological Evidence of Chronic Mycoplasma genitalium-Induced Cervicitis in HIV-Infected Women: A Retrospective Cohort Study

BACKGROUND

Mycoplasma genitalium is an emerging sexually transmitted pathogen implicated in inflammatory syndromes of the female reproductive tract. The objective of this study was to investigate human immunodeficiency virus (HIV)-infected women for an association between M. genitalium and cervicitis, a putative mechanism for enhanced HIV transmission efficiency to an uninfected partner.

METHODS

Using a longitudinal cohort of antiretroviral therapy-adherent New Orleans women, we retrospectively screened for M. genitalium and quantitatively characterized several markers of cervical inflammation, including secreted cytokines and cytological and histological signs of leukocyte infiltration.

RESULTS

We observed a high prevalence of M. genitalium (7.4%) among HIV-infected New Orleans women. Chronic M. genitalium infection was associated with increased secretion of proinflammatory cytokines, including interleukin 1β, interleukin 6, and interleukin 8, and marked inflammatory cervical infiltrates in the cervix with enrichment of HIV target cells. Cure of M. genitalium infection resulted in ablation of all signs of inflammation.

CONCLUSIONS

These findings implicate M. genitalium as an etiologic agent of cervicitis in HIV-infected women, providing a potential mechanism for enhanced HIV transmission to an uninfected partner. Screening and treatment of M. genitalium among HIV-infected individuals may be warranted to further understand this coinfection scenario, improve cervical health, and reduce the spread of HIV.

Immune activation in the course of HIV-1 infection: Causes, phenotypes and persistence under therapy

Systemic immune activation is a striking consequence of HIV-1 infection. Even in virologically suppressed patients, some hyperactivity of the immune system and even of the endothelium and of the coagulation pathway may persist. Apart from immune deficiency, this chronic activation may contribute to various morbidities including atherothrombosis, neurocognitive disorders, liver steatosis and osteoporosis, which are currently main challenges. It is therefore of major importance to better understand the causes and the phenotypes of immune activation in the course of HIV-1 infection. In this review we will discuss the various causes of immune activation in HIV-1 infected organisms: the presence of the virus together with other microbes, eventually coming from the gut, CD4+ T cell lymphopenia, senescence and dysregulation of the immune system, and/or genetic factors. We will also describe the activation of the immune system: CD4+ and CD8+ T cells, B cells, NKT and NK cells, dendritic cells, monocytes and macrophages, and neutrophils of the inflammation cascade, as well as of the endothelium and the coagulation system. Finally, we will see that antiretroviral therapy reduces the hyperactivity of the immune and coagulation systems and the endothelial dysfunction, but often does not abolish it. A better knowledge of this phenomenon might help us to identify biomarkers predictive of non AIDS-linked comorbidities, and to define new strategies aiming at preventing their emergence.

Impact of HIV infection and smoking on lung immunity and related disorders

HIV-infected persons not only have higher rates of smoking than the general population, but are also unusually vulnerable to the associated adverse health effects, both infective and noninfective in origin. Indeed, in the setting of well-organised care and availability of highly active antiretroviral therapy, HIV-infected smokers lose more life-years to smoking than to HIV infection per se, presenting a major challenge to healthcare providers. Not surprisingly, the respiratory system is particularly susceptible to the damaging interactive chronic inflammatory and immunosuppressive effects of HIV and smoking, intensifying the risk of the development of opportunistic infections, as well as lung cancer and obstructive lung disorders. The impact of smoking on the immunopathogenesis and frequencies of these respiratory conditions in the setting of HIV infection, as well as on the efficacy of antiretroviral therapy, represent the primary focus of this review.

Advances in basic and clinical immunology in 2014

Genetic identification of immunodeficiency syndromes has become more efficient with the availability of whole-exome sequencing, expediting the identification of relevant genes and complementing traditional linkage analysis and homozygosity mapping. New genes defects causing immunodeficiency include phophoglucomutase 3 (PGM3), cytidine 5' triphosphate synthase 1 (CTPS1), nuclear factor κB-inducing kinase (NIK), cytotoxic T lymphocyte-associated antigen 4 (CTLA4), B-cell chronic lymphocytic leukemia/lymphoma 10 (BCL10), phosphoinositide-3 kinase regulatory subunit 1 (PIK3R1), IL21, and Jagunal homolog 1 (JAGN1). New case reports expanded the clinical spectrum of gene defects. For example, a specific recombination-activating gene 1 variant protein with partial recombinant activity might produce Omenn syndrome or a common variable immunodeficiency phenotype. Central and peripheral B-cell tolerance was investigated in patients with several primary immunodeficiencies, including common variable immunodeficiency and Wiskott-Aldrich syndrome, to explain the occurrence of autoimmunity and inflammatory disorders. The role of IL-12 and IL-15 in the enhancement of natural killer cell activity was reported. Newborn screening for T-cell deficiency is being implemented in more states and is achieving its goal of defining the true incidence of severe combined immunodeficiency and providing early treatment that offers the highest survival for these patients. Definitive treatment of severe immunodeficiency with both hematopoietic stem cell transplantation and gene therapy was reported to be successful, with increasing definition of conditions needed for optimal outcomes. Progress in HIV infection is directed toward the development of an effective vaccine and the eradication of hidden latent virus reservoirs.

Transcriptional Regulation of CXCL5 in HIV-1-Infected Macrophages and Its Functional Consequences on CNS Pathology

Human immunodeficiency virus-1 (HIV-1)-infected monocytes/macrophages and microglia release increased levels of proinflammatory cytokines and chemokines, including ELR+ (containing glutamic acid-leucine-arginine motif) chemokines. To investigate the role of HIV-1 infection on chemokine regulation, monocyte-derived macrophages (MDMs) from normal donors were infected with HIV-1 and the expression of chemokines and their downstream biological functions were evaluated. Among the tested chemokines, CXCL5 was upregulated significantly both at the mRNA and protein level in the HIV-1-infected MDMs compared with mock-infected cultures. Upregulation of CXCL5 in the HIV-1-infected MDMs is, in part, regulated by increased interleukin-1β (IL-1β) production and phosphorylation of ERK1/2. Functional analyses indicate that HIV-1-induced overexpression of CXCL5 has enhanced the ability to attract neutrophils, as observed by chemotaxis assay. However, exposure of NT2, SH-SY5Y cells, and primary neurons to HIV-1-infected MDM supernatants resulted in cell death that was not rescued by anti-CXCL5 antibody suggesting that CXCL5 does not have direct effect on neuronal death. Together, these results suggest that the increased level of CXCL5 in tissue compartments, including the central nervous system of HIV-1-infected individuals might alter the inflammatory response through the infiltration of neutrophils into tissue compartment, thus causing secondary effects on resident cells.