Regulatory T cells in the peripheral blood of women with gestational diabetes: a systematic review and meta-analysis

Background

Gestational diabetes (GDM) affects approximately 14% of pregnancies globally and is associated with short- and long-term complications for both the mother and child. In addition, GDM has been linked to chronic low-grade inflammation with recent research indicating a potential immune dysregulation in pathophysiology and a disparity in regulatory T cells.

Objective

This systematic review and meta-analysis aimed to determine whether there is an association between GDM and the level of Tregs in the peripheral blood.

Methods

Literature searches were conducted in PubMed, Embase, and Ovid between the 7th and 14th of February 2022. The inclusion criteria were any original studies published in the English language, measuring differentiated Tregs in women with GDM compared with glucose-tolerant pregnant women. Meta-analysis was performed between comparable Treg markers. Statistical tests were used to quantify heterogeneity: τ 2, χ 2, and I 2. Study quality was assessed using a modified version of the Newcastle-Ottawa scale.

Results

The search yielded 223 results: eight studies were included in the review and seven in the meta-analysis (GDM = 228, control = 286). Analysis of Tregs across all trimesters showed significantly lower Treg numbers in women with GDM (SMD, -0.76; 95% CI, -1.37, -0.15; I 2 = 90%). This was reflected in the analysis by specific Treg markers (SMD -0.55; 95% CI, -1.04, -0.07; I 2 = 83%; third trimester, five studies). Non-significant differences were found within subgroups (differentiated by CD4+FoxP3+, CD4+CD127-, and CD4+CD127-FoxP3) of both analyses.

Conclusion

GDM is associated with lower Treg numbers in the peripheral maternal blood. In early pregnancy, there is clinical potential to use Treg levels as a predictive tool for the subsequent development of GDM. There is also a potential therapeutic intervention to prevent the development of GDM by increasing Treg populations. However, the precise mechanism by which Tregs mediate GDM remains unclear.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42022309796.

Acquisition of Immune Privilege in GBM Tumors: Role of Prostaglandins and Bile Salts

Based on the postulate that glioblastoma (GBM) tumors generate anti-inflammatory prostaglandins and bile salts to gain immune privilege, we analyzed 712 tumors in-silico from three GBM transcriptome databases for prostaglandin and bile synthesis/signaling enzyme-transcript markers. A pan-database correlation analysis was performed to identify cell-specific signal generation and downstream effects. The tumors were stratified by their ability to generate prostaglandins, their competency in bile salt synthesis, and the presence of bile acid receptors nuclear receptor subfamily 1, group H, member 4 (NR1H4) and G protein-coupled bile acid receptor 1 (GPBAR1). The survival analysis indicates that tumors capable of prostaglandin and/or bile salt synthesis are linked to poor outcomes. Tumor prostaglandin D₂ and F₂ syntheses are derived from infiltrating microglia, whereas prostaglandin E₂ synthesis is derived from neutrophils. GBMs drive the microglial synthesis of PGD₂/F₂ by releasing/activating complement system component C3a. GBM expression of sperm-associated heat-shock proteins appears to stimulate neutrophilic PGE₂ synthesis. The tumors that generate bile and express high levels of bile receptor NR1H4 have a fetal liver phenotype and a RORC-Treg infiltration signature. The bile-generating tumors that express high levels of GPBAR1 are infiltrated with immunosuppressive microglia/macrophage/myeloid-derived suppressor cells. These findings provide insight into how GBMs generate immune privilege and may explain the failure of checkpoint inhibitor therapy and provide novel targets for treatment.

Dynamics and epigenetic signature of regulatory T-cells following antiretroviral therapy initiation in acute HIV infection

BACKGROUND

HIV infection promotes the expansion of immunosuppressive regulatory T-cells (Tregs), contributing to immune dysfunction, tissue fibrosis and disease progression. Early antiretroviral treatment (ART) upon HIV infection improves CD4 count and decreases immune activation. However, Treg dynamics and their epigenetic regulation following early ART initiation remain understudied.

METHODS

Treg subsets were characterized by flow cytometry in 103 individuals, including untreated HIV-infected participants in acute and chronic phases, ART-treated in early infection, elite controllers (ECs), immunological controllers (ICs), and HIV-uninfected controls. The methylation status of six regulatory regions of the foxp3 gene was assessed using MiSeq technology.

FINDINGS

Total Treg frequency increased overtime during HIV infection, which was normalized in early ART recipients. Tregs in untreated individuals expressed higher levels of activation and immunosuppressive markers (CD39, and LAP(TGF-β1)), which remained unchanged following early ART. Expression of gut migration markers (CCR9, Integrin-β7) by Tregs was elevated during untreated HIV infection, while they declined with the duration of ART but not upon early ART initiation. Notably, gut-homing Tregs expressing LAP(TGF-β1) and CD39 remained higher despite early treatment. Additionally, the increase in LAP(TGF-β1)⁺ Tregs overtime were consistent with higher demethylation of conserved non-coding sequence (CNS)-1 in the foxp3 gene. Remarkably, LAP(TGF-β1)-expressing Tregs in ECs were significantly higher than in uninfected subjects, while the markers of Treg activation and gut migration were not different.

INTERPRETATION

Early ART initiation was unable to control the levels of immunosuppressive Treg subsets and their gut migration potential, which could ultimately contribute to gut tissue fibrosis and HIV disease progression.

FUNDING

This study was funded by the Canadian Institutes of Health Research (CIHR, grant MOP 142294) and in part by the AIDS and Infectious Diseases Network of the Réseau SIDA et maladies infectieuses du Fonds de recherche du Québec-Santé (FRQ-S).

Impaired Differentiation of Highly Proliferative ICOS+-Tregs Is Involved in the Transition from Low to High Disease Activity in Systemic Lupus Erythematosus (SLE) Patients

Dysregulations in the differentiation of CD4⁺-regulatory-T-cells (Tregs) and CD4⁺-responder-T-cells (Tresps) are involved in the development of active systemic lupus erythematosus (SLE). Three differentiation pathways of highly proliferative inducible costimulatory molecule (ICOS)⁺- and less proliferative ICOS^--CD45RA⁺CD31⁺-recent-thymic-emigrant (RTE)-Tregs/Tresps via CD45RA^-CD31⁺-memory-Tregs/Tresps (CD31⁺-memory-Tregs/Tresps), their direct proliferation via CD45RA⁺CD31^--mature naïve (MN)-Tregs/Tresps, and the production and differentiation of resting MN-Tregs/Tresp into CD45RA^-CD31^--memory-Tregs/Tresps (CD31^--memory-Tregs/Tresps) were examined in 115 healthy controls, 96 SLE remission patients, and 20 active disease patients using six color flow cytometric analysis. In healthy controls an appropriate sequence of these pathways ensured regular age-dependent differentiation. In SLE patients, an age-independently exaggerated differentiation was observed for all Treg/Tresp subsets, where the increased conversion of resting MN-Tregs/Tresps particularly guaranteed the significantly increased ratios of ICOS⁺-Tregs/ICOS⁺-Tresps and ICOS^--Tregs/ICOS^--Tresps during remission. Changes in the differentiation of resting ICOS⁺-MN-Tresps and ICOS^--MN-Tregs from conversion to proliferation caused a significant shift in the ratio of ICOS⁺-Tregs/ICOS⁺-Tresps in favor of ICOS⁺-Tresps and a further increase in the ratio of ICOS^--Tregs/ICOS^--Tresps with active disease. The differentiation of ICOS⁺-RTE-Tregs/Tresps seems to be crucial for keeping patients in remission, where their limited production of proliferating resting MN-Tregs may be responsible for the occurrence of active disease flares.

Heterogeneous Tumor-Immune Microenvironments between Primary and Metastatic Tumors in a Patient with ALK Rearrangement-Positive Large Cell Neuroendocrine Carcinoma

Evolution of tumor-immune microenviroments (TIMEs) occurs during tumor growth and dissemination. Understanding inter-site tumor-immune heterogeneity is essential to harness the immune system for cancer therapy. While the development of immunotherapy against lung cancer with driver mutations and neuroendocrine tumors is ongoing, little is known about the TIME of large cell neuroendocrine carcinoma (LCNEC) or anaplastic lymphoma kinase (ALK) rearrangement-positive lung cancer. We present a case study of a 32-year-old female patient with ALK-rearrangement-positive LCNEC, who had multiple distant metastases including mediastinal lymph-node, bilateral breasts, multiple bones, liver and brain. Multiple biopsy samples obtained from primary lung and three metastatic tumors were analyzed by fluorescent multiplex immunohistochemistry. Tissue localizations of tumor-infiltrating lymphocytes in the tumor nest and surrounding stroma were evaluated. T cell and B cell infiltrations were decreased with distance from primary lung lesion. Although each tumor displayed a unique TIME, all tumors exhibited concomitant regression after treatment with an ALK-inhibitor. This study provides the first evidence of the coexistence of distinct TIME within a single individual with ALK-rearrangement-positive LCNEC. The present study contributes to our understanding of heterogeneous TIMEs between primary and metastatic lesions and provides new insights into the complex interplay between host-immunity and cancer cells in primary and metastatic lesions.

T-Cell Hyperactivation and Paralysis in Severe COVID-19 Infection Revealed by Single-Cell Analysis

Severe COVID-19 patients show various immunological abnormalities including T-cell reduction and cytokine release syndrome, which can be fatal and is a major concern of the pandemic. However, it is poorly understood how T-cell dysregulation can contribute to the pathogenesis of severe COVID-19. Here we show single cell-level mechanisms for T-cell dysregulation in severe COVID-19, demonstrating new pathogenetic mechanisms of T-cell activation and differentiation underlying severe COVID-19. By in silico sorting CD4+ T-cells from a single cell RNA-seq dataset, we found that CD4+ T-cells were highly activated and showed unique differentiation pathways in the lung of severe COVID-19 patients. Notably, those T-cells in severe COVID-19 patients highly expressed immunoregulatory receptors and CD25, whilst repressing the expression of FOXP3. Furthermore, we show that CD25⁺ hyperactivated T-cells differentiate into multiple helper T-cell lineages, showing multifaceted effector T-cells with Th1 and Th2 characteristics. Lastly, we show that CD25-expressing hyperactivated T-cells produce the protease Furin, which facilitates the viral entry of SARS-CoV-2. Collectively, CD4⁺ T-cells from severe COVID-19 patients are hyperactivated and FOXP3-mediated negative feedback mechanisms are impaired in the lung, which may promote immunopathology. Therefore, our study proposes a new model of T-cell hyperactivation and paralysis that drives immunopathology in severe COVID-19.

Higher infiltration of intratumoral CD25+ FOXP3+ lymphocytes correlates with a favorable prognosis in patients with diffuse large B-cell lymphoma

Regulatory T-cells (Tregs) play an important role in cancer immunity but their prognostic impact is controversial in diffuse large B-cell lymphoma (DLBCL). Intratumoral Tregs in DLBCL (n = 70) were evaluated by double-stained CD25 and FOXP3 lymphocytes in formalin-fixed paraffin-embedded tissues, and correlated with clinicopathologic features. We found that increased numbers of intratumoral FOXP3+ lymphocytes (>2.4/HPF) and CD25 + FOXP3+ lymphocytes (>0.8/HPF) are favorable prognosticators (p = .004 and p < .001, respectively) in DLBCL patients, along with age <70 years, stage I-II disease, normal serum LDH level and low IPI scores (p < .001, .002, .002, and <.001, respectively). On multivariate analyses, a higher number of CD25 + FOXP3+ lymphocytes retained prognostic significance (p = .040). Interestingly, higher Treg infiltration correlated with increased infiltration by cytotoxic T-lymphocytes (γ = 0.294, p = .038) and nodal location (γ = 0.390, p = .004), but not with infiltration by CD123+ plasmacytoid dendritic cells, which were reported to induce Tregs with immune tolerance. Therefore, congruent with literature meta-analyses, higher intratumoral CD25 + FOXP3+ lymphocytes have a beneficial impact on DLBCL.

Akt3-Mediated Protection Against Inflammatory Demyelinating Disease

Akt is a serine/threonine protein kinase that plays a major role in regulating multiple cellular processes. While the isoforms Akt1 and Akt2 are involved in apoptosis and insulin signaling, respectively, the role for Akt3 remains uncertain. Akt3 is predominantly expressed in the brain, and total deletion of Akt3 in mice results in a reduction in brain size and neurodegeneration following injury. Previously, we found that Akt3-/- mice have a significantly worse clinical course during myelin-oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), an animal model in which autoreactive immune cells enter the CNS, resulting in inflammation, demyelination, and axonal injury. Spinal cords of Akt3-/- mice are severely demyelinated and have increased inflammation compared to WT, suggesting a neuroprotective role for Akt3 during EAE. To specifically address the role of Akt3 in neuroinflammation and maintaining neuronal integrity, we used several mouse strains with different manipulations to Akt3. During EAE, Akt3 Nmf350 mice (with enhanced Akt3 kinase activity) had lower clinical scores, a lag in disease onset, a delay in the influx of inflammatory cells into the CNS, and less axonal damage compared to WT mice. A significant increased efficiency of differentiation toward FOXP3 expressing iTregs was also observed in Akt3 Nmf350 mice relative to WT. Mice with a conditional deletion of Akt3 in CD4+ T-cells had an earlier onset of EAE symptoms, increased inflammation in the spinal cord and brain, and had fewer FOXP3+ cells and FOXP3 mRNA expression. No difference in EAE outcome was observed when Akt3 expression was deleted in neurons (Syn1-CKO). These results indicate that Akt3 signaling in T-cells and not neurons is necessary for maintaining CNS integrity during an inflammatory demyelinating disease.

Control of Germinal Center Responses by T-Follicular Regulatory Cells

Regulatory T-cells (Treg cells), expressing the transcription factor Foxp3, have an essential role in the control of immune homeostasis. In order to control diverse types of immune responses Treg cells must themselves show functional heterogeneity to control different types of immune responses. Recent advances have made it clear that Treg cells are able to mirror the homing capabilities of known T-helper subtypes such as Th1, Th2, Th17, and T-follicular helper cells (Tfh), allowing them to travel to the sites of inflammation and deliver suppression in situ. One of the more recent discoveries in this category is the description of T-follicular regulatory (Tfr) cells, a specialized subset of Treg cells that control Tfh and resulting antibody responses. In this review we will discuss recent advances in our understanding of Tfr biology and the role of both Tfr and activated extra-follicular Tregs (eTreg) in the control of humoral immunity.

Evaluation of T-lymphocyte subpopulations in actinic keratosis, in situ and invasive squamous cell carcinoma of the skin

BACKGROUND

Tumor infiltrating lymphocytes (TILs) represent important regulators of carcinogenesis. Cutaneous invasive squamous cell carcinoma (inSCC) develops through precursor lesions, namely in situ squamous cell carcinoma (isSCC) and actinic keratosis (AK), representing a natural model of carcinogenesis. The study evaluates TIL subpopulations in inSCC and its precursors by comparing 2 semiquantitative scoring systems, and assesses the presence of regulatory T-cells (Tregs) in these lesions.

METHODS

Paraffin sections from 33 cases of AK, 19 isSCCs and 34 inSCCs with adjacent precursor lesions or normal skin (NS) were immunostained for CD3, CD4, CD8 and Foxp3. TIL subgroups were evaluated by the semiquantitative Klintrup-Mäkinen (K-M) score, and by a more detailed modification of this system. Treg counts were assessed by image analysis quantification.

RESULTS

An increase of all TIL subpolulations from precursor lesions toward inSCC was shown by both scoring systems. Treg counts progressively increased from NS to AK and isSCC, but decreased in inSCC. Tregs were more numerous in pT2 and around indolent inSCCs compared to T1 and aggressive subtypes.

CONCLUSIONS

T-cells and cytotoxic T-cells progressively increase in cutaneous squamous cell carcinogenesis, while Treg counts diminish in inSCC. The K-M score is an appropriate, easily applicable TIL scoring system in cutaneous inSCC.

Immunosuppressive Tryptophan Catabolism and Gut Mucosal Dysfunction Following Early HIV Infection

BACKGROUND

Tryptophan (Trp) catabolism into kynurenine (Kyn) contributes to immune dysfunction in chronic human immunodeficiency virus (HIV) infection. To better define the relationship between Trp catabolism, inflammation, gut mucosal dysfunction, and the role of early antiretroviral therapy (ART), we prospectively assessed patients early after they acquired HIV.

METHODS

Forty patients in the early phase of infection were longitudinally followed for 12 months after receiving a diagnosis of HIV infection; 24 were untreated, and 16 were receiving ART. Kyn/Trp ratio, regulatory T-cells (Tregs) frequency, T-cell activation, dendritic cell counts, and plasma levels of gut mucosal dysfunction markers intestinal-type fatty acid-binding protein, soluble suppression of tumorigenicity 2, and lipopolysaccharide were assessed.

RESULTS

Compared with healthy subjects, patients in the early phase of infection presented with elevated Kyn/Trp ratios, which further increased in untreated patients but normalized in ART recipients. Accordingly, in untreated subjects, the elevated Treg frequency observed at baseline continued to increase over time. The highest CD8(+) T-cell activation was observed during the early phase of infection and decreased in untreated patients, whereas activation normalized in ART recipients. The Kyn/Trp ratio was positively associated with CD8(+) T-cell activation and levels of inflammatory cytokines (interleukin 6, interferon γ-inducible protein 10, interleukin 18, and tumor necrosis factor α) and negatively associated with dendritic cell frequencies at baseline and in untreated patients. However, ART did not normalize plasma levels of gut mucosal dysfunction markers.

CONCLUSIONS

Early initiation of ART normalized enhanced Trp catabolism and immune activation but did not improve plasma levels of gut mucosal dysfunction markers.