CD127 Expression in Naive and Memory T Cells in HIV Patients Who Have Undergone Long-Term HAART

Enhancing cross-protection against influenza by heterologous sequential immunization with mRNA LNP and protein nanoparticle vaccines

Enhancing influenza vaccine cross-protection is imperative to alleviate the significant public health burden of influenza. Heterologous sequential immunization may synergize diverse vaccine formulations and routes to improve vaccine potency and breadth. Here we investigate the effects of immunization strategies on the generation of cross-protective immune responses in female Balb/c mice, utilizing mRNA lipid nanoparticle (LNP) and protein-based PHC nanoparticle vaccines targeting influenza hemagglutinin. Our findings emphasize the crucial role of priming vaccination in shaping Th bias and immunodominance hierarchies. mRNA LNP prime favors Th1-leaning responses, while PHC prime elicits Th2-skewing responses. We demonstrate that cellular and mucosal immune responses are pivotal correlates of cross-protection against influenza. Notably, intranasal PHC immunization outperforms its intramuscular counterpart in inducing mucosal immunity and conferring cross-protection. Sequential mRNA LNP prime and intranasal PHC boost demonstrate optimal cross-protection against antigenically drifted and shifted influenza strains. Our study offers valuable insights into tailoring immunization strategies to optimize influenza vaccine effectiveness.

Many Faces of Regulatory T Cells: Heterogeneity or Plasticity?

Regulatory T cells (Tregs) are essential for maintaining the immune balance in normal and pathological conditions. In autoimmune diseases and transplantation, they restrain the loss of self-tolerance and promote engraftment, whereas in cancer, an increase in Treg numbers is mostly associated with tumor growth and poor prognosis. Numerous markers and their combinations have been used to identify Treg subsets, demonstrating the phenotypic diversity of Tregs. The complexity of Treg identification can be hampered by the unstable expression of some markers, the decrease in the expression of a specific marker over time or the emergence of a new marker. It remains unclear whether such phenotypic shifts are due to new conditions or whether the observed changes are due to initially different populations. In the first case, cellular plasticity is observed, whereas in the second, cellular heterogeneity is observed. The difference between these terms in relation to Tregs is rather blurred. Considering the promising perspectives of Tregs in regenerative cell-based therapy, the existing confusing data on Treg phenotypes require further investigation and analysis. In our review, we introduce criteria that allow us to distinguish between the heterogeneity and plasticity of Tregs normally and pathologically, taking a closer look at their diversity and drawing the line between two terms.

Down-regulation of zinc finger protein 335 undermines natural killer cell function in mouse colitis-associated colorectal carcinoma

Natural killer (NK) cells constitute an active and potent anti-tumor effector population against multiple malignancies. NK cells exploit tumoricidal machinery to restrain colorectal carcinoma (CRC) expansion and invasion. Nonetheless, it is becoming increasingly evident that functional exhaustion considerably compromises the potency of NK cells in patients with CRC. To elucidate the factors that impair NK cell function in the context of CRC, we determined the role of zinc finger protein 335 (ZFP335) in modulating NK cell activity in mouse CRC induced by azoxymethane and dextran sulfate sodium. ZFP335 was profoundly decreased in NK cells in mesenteric lymph nodes of CRC-bearing mice. ZFP335 was especially diminished in NK cells that were both phenotypically and functionally exhausted. Besides, effective ZFP335 knockdown markedly undermined NK cell proliferation, tumoricidal protein production, degranulation, and cytotoxic efficacy on malignant cells, strongly suggesting that ZFP335 reinforces NK cell function. Importantly, ZFP335 knockdown lowered the expression of Janus kinase 1 (JAK1) and Janus kinase 3 (JAK3), both of which play crucial roles in NK cell homeostasis and activation. Collectively, ZFP335 down-regulation is essential for NK cell exhaustion in mesenteric lymph nodes of mice with CRC. We discovered a new ZFP335-JAK1/3 signaling pathway that modulates NK cell exhaustion.

Influence of bariatric surgery on the peripheral blood immune system of female patients with morbid obesity revealed by high-dimensional mass cytometry

Introduction

Obesity is associated with low-grade chronic inflammation, altered levels of adipocytokines, and impaired regulation of gastrointestinal hormones. Secreted, these factors exert immunostimulatory functions directly influencing peripheral immune cells.

Methods

In the realm of this study, we aimed to investigate the composition and activation status of peripheral blood immune cells in female patients with morbid obesity compared to lean controls using high-dimensional mass cytometry. Besides, we also assessed the influence of bariatric surgery with respect to its ability to reverse obesity-associated alterations within the first-year post-surgery.

Results

Patients with morbid obesity showed typical signs of chronic inflammation characterized by increased levels of CRP and fibrinogen. Apart from that, metabolic alterations were characterized by increased levels of leptin and resistin as well as decreased levels of adiponectin and ghrelin compared to the healthy control population. All these however, except for ghrelin levels, rapidly normalized after surgery with regard to control levels. Furthermore, we found an increased population of monocytic CD14⁺, HLA-DR^-, CD11b⁺, CXCR3⁺ cells in patients with morbid obesity and an overall reduction of the HLA-DR monocytic expression compared to the control population. Although CD14⁺, HLA-DR^-, CD11b⁺, CXCR3⁺ decreased after surgery, HLA-DR expression did not recover within 9 - 11 months post-surgery. Moreover, compared to the control population, patients with morbid obesity showed a perturbed CD4+ T cell compartment, characterized by a strongly elevated CD127⁺ memory T cell subset and decreased naïve T cells, which was not recovered within 9 - 11 months post-surgery. Although NK cells showed an activated phenotype, they were numerically lower in patients with morbid obesity when compared to healthy controls. The NK cell population further decreased after surgery and did not recover quantitatively within the study period.

Conclusions

Our results clearly demonstrate that the rapid adaptions in inflammatory parameters and adipocytokine levels that occur within the first year post-surgery do not translate to the peripheral immune cells. Apart from that, we described highly affected, distinct immune cell subsets, defined as CD127⁺ memory T cells and monocytic CD14⁺, HLA-DR, CD11b⁺, CXCR3⁺ cells, that might play a significant role in understanding and further decoding the etiopathogenesis of morbid obesity.

Immunosenescence evaluation of peripheral blood lymphocyte subsets in 957 healthy adults from 20 to 95 years old

Immunosenescence is characterized by an age-related decline in immune system function. Major efforts have been made to identify changes in peripheral blood lymphocyte subsets accompanying immunosenescence in elderly adults. However, the change trends of some lymphocyte subsets with age are still controversial, and populations of advanced ages, such as people in their 80s or 90s, have not yet been thoroughly investigated. To provide further insight, we recruited 957 healthy donors without certain diseases with ages ranging from 20 to 95 years. Peripheral lymphocyte subsets, including T cells, CD4 T cells, CD8 T cells, B cells and NK cells, and the CD4/CD8 ratio were measured by flow cytometry. Additionally, regulatory CD4 T cells with inhibitory functions marked by CD3⁺CD4⁺CD25^hi and the expression of the costimulatory molecule CD28 on CD8 T cells were evaluated. Sex was considered at the same time. The data indicated that in elderly people, peripheral T (p < 0.001), CD4 T (p < 0.001) and B (p < 0.001) lymphocyte subsets decreased, but the NK cell population (p < 0.001) increased. More regulatory CD4 T cells may imply stronger inhibition in the elderly population. The decreased CD28 expression with age in females verified CD28 to be an immunosenescence marker and the sharply decreased CD28 expression after 75 years in males indicated a rapid immunosenescence at the late life span of the male populations. In addition, our study established reference values for peripheral lymphocyte subsets at different age stages in males and females, which are urgently needed for the clinical management and treatment of geriatric diseases.

Plasmacytoid dendritic cells have divergent effects on HIV infection of initial target cells and induce a pro-retention phenotype

Although HIV infection inhibits interferon responses in its target cells in vitro, interferon signatures can be detected in vivo soon after sexual transmission, mainly attributed to plasmacytoid dendritic cells (pDCs). In this study, we examined the physiological contributions of pDCs to early HIV acquisition using coculture models of pDCs with myeloid DCs, macrophages and the resting central, transitional and effector memory CD4 T cell subsets. pDCs impacted infection in a cell-specific manner. In myeloid cells, HIV infection was decreased via antiviral effects, cell maturation and downregulation of CCR5 expression. In contrast, in resting memory CD4 T cells, pDCs induced a subset-specific increase in intracellular HIV p24 protein expression without any activation or increase in CCR5 expression, as measured by flow cytometry. This increase was due to reactivation rather than enhanced viral spread, as blocking HIV entry via CCR5 did not alter the increased intracellular p24 expression. Furthermore, the load and proportion of cells expressing HIV DNA were restricted in the presence of pDCs while reverse transcriptase and p24 ELISA assays showed no increase in particle associated reverse transcriptase or extracellular p24 production. In addition, pDCs also markedly induced the expression of CD69 on infected CD4 T cells and other markers of CD4 T cell tissue retention. These phenotypic changes showed marked parallels with resident memory CD4 T cells isolated from anogenital tissue using enzymatic digestion. Production of IFNα by pDCs was the main driving factor for all these results. Thus, pDCs may reduce HIV spread during initial mucosal acquisition by inhibiting replication in myeloid cells while reactivating latent virus in resting memory CD4 T cells and retaining them for immune clearance.

IFNs constitute one of the first and most important innate immune controls to restrict initial viral replication and spread. As HIV has evolved mechanisms to block IFN-I induction in its target cells, but not in infiltrating pDCs, understanding how pDCs influence HIV infection of target cells upon initial transmission is critical to prevent or control initial infection. Therefore, we modelled the early events occurring immediately as HIV enters the human genital mucosa. We showed that IFNα secreting pDC compensated for HIV inhibition of IFN-I production in its target cells in two different ways: i) reduced infection in DCs and macrophages which would limit viral spread to resident or newly infiltrating memory CD4 T cells; ii) reactivation of latent HIV in all subsets of resting memory CD4 T cell subsets, accompanied by limited viral spread, upregulation of MHC-I and induction of a tissue retention phenotype. The increased HIV protein, MHC-I expression and retention may enhance exposure to CD8 T cell surveillance. This model suggests that IFNα reactivation of latent HIV combined with adoptive immunotherapy using CD8 T cells or those expressing chimeric antigen receptors (CAR) could provide a novel ‘kick and kill’ approach to eradicate HIV reservoirs.

PLA2G1B is involved in CD4 anergy and CD4 lymphopenia in HIV-infected patients

The precise mechanism leading to profound immunodeficiency of HIV-infected patients is still only partially understood. Here, we show that more than 80% of CD4+ T cells from HIV-infected patients have morphological abnormalities. Their membranes exhibited numerous large abnormal membrane microdomains (aMMDs), which trap and inactivate physiological receptors, such as that for IL-7. In patient plasma, we identified phospholipase A2 group IB (PLA2G1B) as the key molecule responsible for the formation of aMMDs. At physiological concentrations, PLA2G1B synergized with the HIV gp41 envelope protein, which appears to be a driver that targets PLA2G1B to the CD4+ T cell surface. The PLA2G1B/gp41 pair induced CD4+ T cell unresponsiveness (anergy). At high concentrations in vitro, PLA2G1B acted alone, independently of gp41, and inhibited the IL-2, IL-4, and IL-7 responses, as well as TCR-mediated activation and proliferation, of CD4+ T cells. PLA2G1B also decreased CD4+ T cell survival in vitro, likely playing a role in CD4 lymphopenia in conjunction with its induced IL-7 receptor defects. The effects on CD4+ T cell anergy could be blocked by a PLA2G1B-specific neutralizing mAb in vitro and in vivo. The PLA2G1B/gp41 pair constitutes what we believe is a new mechanism of immune dysfunction and a compelling target for boosting immune responses in HIV-infected patients.

The replication-competent HIV-1 latent reservoir is primarily established near the time of therapy initiation

Although antiretroviral therapy (ART) is highly effective at suppressing HIV-1 replication, the virus persists as a latent reservoir in resting CD4⁺ T cells during therapy. This reservoir forms even when ART is initiated early after infection, but the dynamics of its formation are largely unknown. The viral reservoirs of individuals who initiate ART during chronic infection are generally larger and genetically more diverse than those of individuals who initiate therapy during acute infection, consistent with the hypothesis that the reservoir is formed continuously throughout untreated infection. To determine when viruses enter the latent reservoir, we compared sequences of replication-competent viruses from resting peripheral CD4⁺ T cells from nine HIV-positive women on therapy to viral sequences circulating in blood collected longitudinally before therapy. We found that, on average, 71% of the unique viruses induced from the post-therapy latent reservoir were most genetically similar to viruses replicating just before ART initiation. This proportion is far greater than would be expected if the reservoir formed continuously and was always long lived. We conclude that ART alters the host environment in a way that allows the formation or stabilization of most of the long-lived latent HIV-1 reservoir, which points to new strategies targeted at limiting the formation of the reservoir around the time of therapy initiation.

Blocking Formation of the Stable HIV Reservoir: A New Perspective for HIV-1 Cure

Recent studies demonstrate that the stable HIV-1 reservoir in resting CD4+ T cells is mostly formed from viruses circulating when combination antiretroviral therapy (ART) is initiated. Here we explore the immunological basis for these observations. Untreated HIV-1 infection is characterized by a progressive depletion of memory CD4+ T cells which mostly express CD127, the α chain of the IL-7 receptor (IL-7R). Depletion results from both direct infection and bystander loss of memory CD4+ T cells in part attributed to dysregulated IL-7/IL-7R signaling. While IL-7/IL7R signaling is not essential for the generation of effector CD4+ T cells from naïve cells, it is essential for the further transition of effectors to memory CD4+ T cells and their subsequent homeostatic maintenance. HIV-1 infection therefore limits the transition of CD4+ T cells from an effector to long-lived memory state. With the onset of ART, virus load (VL) levels rapidly decrease and the frequency of CD127+ CD4+ memory T cells increases, indicating restoration of effector to memory transition in CD4+ T cells. Collectively these data suggest that following ART initiation, HIV-1 infected effector CD4+ T cells transition to long-lived, CD127+ CD4+ T cells forming the majority of the stable HIV-1 reservoir. We propose that combining ART initiation with inhibition of IL-7/IL-7R signaling to block CD4+ T cell memory formation will limit the generation of long-lived HIV-infected CD4+ T cells and reduce the overall size of the stable HIV-1 reservoir.

CD8+T-bet+ cells as a predominant biomarker for inclusion body myositis

BACKGROUND

Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.

OBJECTIVES

Our aim was to deepen our understanding of the immune mechanisms involved in inclusion body myositis and identify specific biomarkers.

METHODS

Using a panel of thirty-six markers and mass cytometry, we performed deep immune profiling of peripheral blood cells from inclusion body myositis patients and healthy donors, divided into two cohorts: test and validation cohorts. Potential biomarkers were compared to myositis controls (anti-Jo1-, anti-3-hydroxyl-3-methylglutaryl CoA reductase-, and anti-signal recognition particle-positive patients).

RESULTS

Unsupervised analyses revealed substantial changes only within CD8+ cells. We observed an increase in the frequency of CD8+ cells that expressed high levels of T-bet, and containing mainly both effector and terminally differentiated memory cells. The senescent marker CD57 was overexpressed in CD8+_T-bet+ cells of inclusion body myositis patients. As expected, senescent CD8+_{T-bet+ CD57+} cells of both patients and healthy donors were CD28_nullCD27_nullCD127_null. Surprisingly, non-senescent CD8+_{T-bet+ CD57-} cells in inclusion body myositis patients expressed lower levels of CD28, CD27, and CD127, and expressed higher levels of CD38 and HLA-DR compared to healthy donors. Using classification and regression trees alongside receiver operating characteristics curves, we identified and validated a frequency of CD8+_T-bet+ cells >51.5% as a diagnostic biomarker specific to inclusion body myositis, compared to myositis control patients, with a sensitivity of 94.4%, a specificity of 88.5%, and an area under the curve of 0.97.

CONCLUSION

Using a panel of thirty-six markers by mass cytometry, we identify an activated cell population (CD8+_{T-bet+ CD57-} CD28_lowCD27_lowCD127_low CD38+ HLA-DR+) which could play a role in the physiopathology of inclusion body myositis, and identify CD8+_T-bet+ cells as a predominant biomarker of this disease.

Reduced expression of the IL7Ra signaling pathway in Neuromyelitis optica

Neuromyelitis optica (NMO) is a chronic inflammatory demyelinating autoimmune disease of the central nervous system that most commonly affects the optic nerves and spinal cord. To characterize the immunological pathways involved in NMO, whole blood RNA expression array was performed using Nanostring nCounter technology. Two major clusters of genes were found associated with NMO: T cell-associated genes and the TNF/NF-kB signaling pathway. Analysis of the genes within the first cluster confirmed significantly reduced expression of IL7Ra (CD127) in the peripheral blood of NMO patients vs that in healthy controls. IL7Ra upstream transcription factors and its downstream survival signaling pathway were also markedly reduced. In line with the essential role of IL7Ra in T cell maturation and survival, a significantly lower number of naïve T cells, and reduced T cell survival signaling mediated by increased BID (BH3-interacting domain death agonist) expression and increased apoptosis was observed. Cumulatively, these findings indicate that the IL7Ra signaling pathway may play a role in the autoimmune process in NMO.