Imaging regulatory T cell dynamics and CTLA4-mediated suppression of T cell priming

Foxp3(+) regulatory T cells (Tregs) maintain immune homoeostasis through mechanisms that remain incompletely defined. Here by two-photon (2P) imaging, we examine the cellular dynamics of endogenous Tregs. Tregs are identified as two non-overlapping populations in the T-zone and follicular regions of the lymph node (LN). In the T-zone, Tregs migrate more rapidly than conventional T cells (Tconv), extend longer processes and interact with resident dendritic cells (DC) and Tconv. Tregs intercept immigrant DCs and interact with antigen-induced DC: Tconv clusters, while continuing to form contacts with activated Tconv. During antigen-specific responses, blocking CTLA4-B7 interactions reduces Treg-Tconv interaction times, increases the volume of DC: Tconv clusters and enhances subsequent Tconv proliferation in vivo. Our results demonstrate a role for altered cellular choreography of Tregs through CTLA4-based interactions to limit T-cell priming

Protocol to quantify the activation dynamics of tumor-associated T cells in mice by functional intravital microscopy.

Tumor-associated T cells orchestrate cancer rejection after checkpoint blockade immunotherapy. T cell function depends on dynamic antigen recognition through the T cell receptor (TCR) resulting in T cell activation. Here, we present an approach to quantify the dynamics and magnitude of tumor-associated T cell activation at multiple time points in living mice using the genetically encoded calcium reporter Salsa6f and functional intravital microscopy (F-IVM). Our protocol allows researchers to measure the activation dynamics of various immune cells in vivo. For complete details on the use and execution of this protocol, please refer to Geels et al.1

Immune checkpoint inhibition perturbs neuro-immune homeostasis and impairs cognitive function

BackgroundBlockade of Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and Programmed Cell Death Protein 1 (PD-1) significantly improves progression-free survival in patients with cancers, including melanoma. In addition to unleashing antitumor immunity, immune checkpoint inhibition (ICI) therapies disrupt immune regulatory networks critical for maintaining homeostasis in various tissues, including the central nervous system (CNS). Despite growing reports of cancer- and ICI-related cognitive impairments among survivors, our understanding of the pathophysiology of ICI-related neurodegenerative effects is limited.MethodsIn this study, we used a murine model of melanoma, cognitive function tests, and neuroimmunological assays to investigate the cellular mechanisms and impact of combinatorial blockade of CTLA-4 and PD-1 on brain function. Syngeneic melanoma was induced in C57Bl6 mice via intradermal injection of D4M-3A.UV2 melanoma cells. After confirmation of tumor growth, cancer-bearing and non-cancer mice received combinatorial treatment of anti-CTLA-4 (1 mg per dose, twice per week) and anti-PD-1 (200 µg per dose, thrice per week) for three weeks. One month after completing ICI treatment, mice were evaluated for learning, memory, and memory consolidation cognitive function tasks. Neuroinflammation, synaptic and myelin integrity, and immune cell status in the brain were analyzed to examine neuro-immunological changes post-ICI treatment.ResultsWhile tumor-related alterations in brain function were evident, combined ICI treatment specifically disrupted synaptic integrity and reduced myelin levels independent of neurogenesis and neuronal plasticity in both cancer-bearing and non-cancer mice brains. Combined ICI selectively impaired hippocampal-dependent cognitive function. This was associated with a two-fold increase in T cell numbers within the brain along with immune activation of myeloid cells, especially microglia. Furthermore, an experimental autoimmune encephalomyelitis model revealed that combination ICI predisposes the CNS to exacerbated autoimmunity, highlighting neuroinflammation-related, and tumor-independent, neurodegenerative sequelae of combination ICI.ConclusionOur results demonstrate that combinatorial blockade of CTLA-4 and PD-1 destabilizes neuroimmune-regulatory networks and activates microglia, contributing to long-term neurodegeneration and cognitive impairments. Therefore, selectively limiting microglial activation could be a potential avenue to preserve CNS functions while maintaining the therapeutic benefits of rapidly evolving ICIs and their combinations

Human neural stem cells induce central nervous system specific regulatory T cells from the ex Treg pool and promote repair in models of multiple sclerosis

Abstract: Multiple Sclerosis (MS) is a chronic inflammatory autoimmune disease affecting the central nervous system (CNS) and for which there is no cure. Current treatments focus on suppression of the immune system but fail to repair the resulting damage to the CNS. Neural stem cell (NSC) transplantation is a promising therapeutic strategy for treating neurodegenerative diseases through cell replacement and repair however it is unclear how these cells would mediate repair in MS. We report that human NSCs promote CNS specific T regulatory cells (Tregs) which activate endogenous repair pathways and promote remyelination in a murine model of MS. We observed remyelination, decreased inflammation and an increase in (CNS)-infiltrating CD4+CD25+FoxP3+ Tregs in EAE mice receiving an intra-spinal transplant of NSCs. Recovery was not a result of cell replacement, as NSCs underwent xenograft rejection, and was Treg dependent, as ablation of Tregs abrogated histopathological improvement. RAG2−/−2D2 (R2D2) mice, which bear a TCR repertoire restricted to myelin oligodendrocyte glycoprotein (MOG) and neurofilament, lack CD25+FoxP3+ Tregs under homeostatic conditions; however, upon exposure to MOG, R2D2 mice developed CD25+FoxP3+ Tregs in cervical lymph nodes and the spinal cord. hNSCs also promoted Tregs in vitro in co-cultures with wild type B6 and R2D2 splenocytes, but not with RAG2−/− OT-II+ splenocytes. Additionally, hNSC-Tregs also appear to derive from the exTreg pool suggesting both antigen specific expansion and antigen dependent maintenance of FOXP3 in CNS-specific Tregs. hNSC Tregs also have a unique expression profile and express transglutimase-2 which is implicated in oligodendrocyte dependent repair in the CNS

Incidence and predictors of immune checkpoint inhibitor treatment–related cognitive impairment in a racial and ethnic diverse population

IntroductionImmune checkpoint inhibitors (ICI) have revolutionized cancer therapy in recent years. In addition to rejuvenating anti-cancer immunity, ICI may cause immune dysregulation, impacting homeostasis, including brain functions. Thus, the association of ICI with cognitive function needs further investigation. Using NIH’s PROMIS system, this study investigates self-reported cognitive impairment within a diverse cohort of ICI-treated patients. Additionally, we explore risk factors influencing self-reported cognitive function, including concurrent symptoms and racial/ethnic background.MethodsThis was a prospective, longitudinal study conducted between July 2021 and June 2023. Included patients were ≥ 18 years old, newly diagnosed with cancer, and scheduled to receive ICI therapy. Serial patient-reported outcomes (PROs) were collected from self-reported patient surveys at therapy initiation and while receiving treatment. Clinically significant cognitive impairment was defined as mild to severe symptoms measured on computer adaptive tests using the PROMIS Bank v2.0 — Cognitive Function. Multi-step analysis utilizing generalized estimating equations (GEE) was implemented to evaluate characteristics associated with cognitive function T-scores.ResultsOur study included 51 ICI patients, with 51% being of Asian or Hispanic descent. Of 126 PROMIS symptom survey sets collected, 16.7% reported clinically significant cognitive impairment, with incidence peaking in survey sets collected 1–2 months removed from therapy initiation at 26.1%. All concurrent PROMIS symptom scores significantly correlated with cognitive function, including physical function (r = 0.33, p < 0.001), fatigue (r = − 0.61, p < 0.001), depression (r = − 0.56, p < 0.001), and anxiety (r = − 0.56, p < 0.001). Multi-variable regression demonstrated impaired physical function (Coef = − 4.01, p = 0.007), fatigue (Coef = − 5.15, p = 0.005), and anxiety (Coef = − 4.45, p < 0.001) are associated with decreased cognitive function scores, after adjusting for other patient characteristics.ConclusionPatients receiving ICI therapy experience significant cognitive impairment with therapy initiation and in subsequent weeks and months during their therapy course. Managing and monitoring concurrent symptoms and inflammatory biomarkers may help identify at risk patients and alleviate cognitive impairments

Immune Checkpoint Inhibition Perturbs Neuro-immune Homeostasis and Impairs Cognitive Function.

BACKGROUND: Blockade of Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and Programmed Cell Death Protein 1 (PD-1) significantly improves progression-free survival of individuals with cancers, including melanoma. In addition to unleashing antitumor immunity, immune checkpoint inhibition (ICI) therapies disrupt immune regulatory networks critical for maintaining homeostasis in various tissues, including the central nervous system (CNS). Despite growing reports of cancer- and ICI-related cognitive impairments among survivors, our understanding of the pathophysiology of ICI-related neurodegenerative effects is limited. METHODS: In this study, using a murine model of melanoma, cognitive function tests, and neuroimmunological assays, we investigate the cellular mechanisms and impact of combinatorial blockade of CTLA-4 and PD-1 on brain function. Syngeneic melanoma was induced in a C57Bl6 mouse model using D4M-3A.UV2 melanoma cells. After confirmation of tumor growth, cancer-bearing and non-cancer mice received combinatorial treatment of anti-CTLA-4 (two doses per week) and anti-PD-1 (three doses per week) for three weeks. One month after completing ICI treatment, mice were administered learning, memory, and memory consolidation cognitive function tasks. Neuroinflammation, synaptic, and myelin integrity analyses and immune cell status in the brain were conducted to analyze neuroimmunological changes post-ICI treatment. RESULTS: While tumor-related alterations in brain function were evident, combination ICI specifically disrupted synaptic integrity and reduced myelin levels independent of neurogenesis and neuronal plasticity in both cancer-bearing and non-cancer mice brains. Combination ICI selectively impaired hippocampal-dependent cognitive function. This is associated with two-fold increase in T cell numbers within the brain along with immune activation of myeloid cells, especially microglia. Furthermore, an experimental autoimmune encephalomyelitis model revealed that combination ICI predisposes the CNS to exacerbated autoimmunity, highlighting neuroinflammation-related, and tumor-independent, neurodegenerative sequelae of combination ICI. CONCLUSION: Our results demonstrate that combinatorial blockade of CTLA-4 and PD-1 destabilizes neuroimmune-regulatory networks and activates microglia, contributing to long-term neurodegeneration and cognitive impairments. Therefore, selectively limiting microglial activation could be a potential avenue to preserve CNS functions while maintaining the therapeutic benefits of rapidly evolving ICIs and their combinations

Polymodal K+ channel modulation contributes to dual analgesic and anti-inflammatory actions of traditional botanical medicines.

Pain and inflammation contribute immeasurably to reduced quality of life, yet modern analgesic and anti-inflammatory therapeutics can cause dependence and side effects. Here, we screened 1444 plant extracts, prepared primarily from native species in California and the United States Virgin Islands, against two voltage-gated K+ channels - T-cell expressed Kv1.3 and nociceptive-neuron expressed Kv7.2/7.3. A subset of extracts both inhibits Kv1.3 and activates Kv7.2/7.3 at hyperpolarized potentials, effects predicted to be anti-inflammatory and analgesic, respectively. Among the top dual hits are witch hazel and fireweed; polymodal modulation of multiple K+ channel types by hydrolysable tannins contributes to their dual anti-inflammatory, analgesic actions. In silico docking and mutagenesis data suggest pore-proximal extracellular linker sequence divergence underlies opposite effects of hydrolysable tannins on different Kv1 isoforms. The findings provide molecular insights into the enduring, widespread medicinal use of witch hazel and fireweed and demonstrate a screening strategy for discovering dual anti-inflammatory, analgesic small molecules

Interruption of the intratumor CD8+ T cell:Treg crosstalk improves the efficacy of PD-1 immunotherapy

PD-1 blockade unleashes potent antitumor activity in CD8+ T cells but can also promote immunosuppressive T regulatory (Treg) cells, which may worsen the response to immunotherapy. Tumor-Treg inhibition is a promising strategy to improve the efficacy of checkpoint blockade immunotherapy; however, our understanding of the mechanisms supporting tumor-Tregs during PD-1 immunotherapy is incomplete. Here, we show that PD-1 blockade increases tumor-Tregs in mouse models of melanoma and metastatic melanoma patients. Mechanistically, Treg accumulation is not caused by Treg-intrinsic inhibition of PD-1 signaling but depends on an indirect effect of activated CD8+ T cells. CD8+ T cells produce IL-2 and colocalize with Tregs in mouse and human melanomas. IL-2 upregulates the anti-apoptotic protein ICOS on tumor-Tregs, promoting their accumulation. Inhibition of ICOS signaling before PD-1 immunotherapy improves control over immunogenic melanoma. Thus, interrupting the intratumor CD8+ T cell:Treg crosstalk represents a strategy to enhance the therapeutic efficacy of PD-1 immunotherapy

Modulation de la réponse immunitaire par les immunoglobulines intraveineuses : effets sur la polarisation, la pathogénicité et le trafic des lymphocytes T

Dysregulated activation of T cells leads to pathogenic immune response to self-antigens. Despite an increasing use of high dose therapy of intravenous gammaglobulin (IVIg) in the treatment of T-cell and autoantibody-mediated inflammatory and autoimmune diseases, comprehension of the mechanisms underlying its therapeutic benefit has remained a major challenge. Particularly, the effect of IVIg in T cell mediated autoimmune conditions remains unexplored. I have investigated the effect of high dose IVIg on T cell polarization using actively induced experimental autoimmune encephalomyelitis (EAE), a T cell-mediated autoimmune condition. IVIg inhibits the differentiation of naïve CD4 T cells into effector subsets (Th1 and Th17 cells) and concomitantly induces an expansion of Foxp3+ regulatory cells. IVIg decreases the tissue damaging potential of pathogenic T cells by down regulating GM-CSF and podoplanin. Additionally, IVIg circumvents the neuronal damage by inhibiting the infiltration of CD4 T lymphocytes to the central nervous system by restraining their egress from the DLN through S1P-S1P1-mTOR pathway. Intriguingly and contrary to the current arguments, the inhibitory FcγRIIB and sialylation of IgG are dispensable for IVIg-mediated reciprocal modulation of effector and regulatory CD4 subsets. Altogether, therapeutic benefit of IVIg in EAE involves shifting the balance from Th17/Th1 towards Treg, down-regulating encephalitogenic mediators and inhibition of T cell trafficking to the target organ.L'activation dérégulée de lymphocytes T conduit à une réponse immune délétère envers les antigènes du soi. Malgré une utilisation croissante de doses élevées d'IVIg pour traiter les maladies auto-immunes, la compréhension des mécanismes sous-jacents aux bénéfices thérapeutiques demeure un enjeu majeur. En effet, les effets des IVIg restent inexplorés dans le cadre des maladies auto-immunes associées aux lymphocytes T. J'ai recherché les effets de doses élevées d'IVIg dans la polarisation des lymphocytes T en utilisant le modèle de l'encéphalomyélite auto-immune expérimentale (EAE), une maladie auto-immune associée aux lymphocytes T. Les IVIg inhibent la différenciation des lymphocytes T CD4+ naïfs en sous-populations effectrices (lymphocytes Th1 et Th17) et induisent, de manière concomitante, une prolifération des lymphocytes T Foxp3+. Les IVIg diminuent les effets délétères des lymphocytes T sur les tissus en diminuant l'expression du GM-CSF et de la podoplanine. En outre, les IVIg empêchent la dégénérescence neuronale en inhibant l'infiltrat en lymphocytes T CD4+ dans le système nerveux central (SNC). Ce mécanisme passe par une séquestration de ces lymphocytes dans les ganglions lymphatiques drainants à travers la voie de signalisation S1P-S1P1-mTor. De manière intéressante, et contrairement aux données actuelles, le récepteur inhibiteur FcγRIIB et la sialylation des IVIg ne sont pas indispensables pour la modulation des sous-populations de lymphocytes T CD4+ effecteurs et régulateurs induite par les IVIg. Ainsi, le bénéfice thérapeutique des IVIg dans le modèle de l'EAE implique un déséquilibre de la balance entre les lymphocytes Th17/Th1 et les lymphocytes Trég, au profit des lymphocytes Trég. Ces cellules diminuent l'expression de médiateurs favorisant l'apparition de l'encéphalomyélite et inhibent la migration des lymphocytes T vers l'organe cible

Modulation de la réponse immunitaire par les immunoglobulines intraveineuses : effets sur la polarisation, la pathogénicité et le trafic des lymphocytes T

Dysregulated activation of T cells leads to pathogenic immune response to self-antigens. Despite an increasing use of high dose therapy of intravenous gammaglobulin (IVIg) in the treatment of T-cell and autoantibody-mediated inflammatory and autoimmune diseases, comprehension of the mechanisms underlying its therapeutic benefit has remained a major challenge. Particularly, the effect of IVIg in T cell mediated autoimmune conditions remains unexplored. I have investigated the effect of high dose IVIg on T cell polarization using actively induced experimental autoimmune encephalomyelitis (EAE), a T cell-mediated autoimmune condition. IVIg inhibits the differentiation of naïve CD4 T cells into effector subsets (Th1 and Th17 cells) and concomitantly induces an expansion of Foxp3+ regulatory cells. IVIg decreases the tissue damaging potential of pathogenic T cells by down regulating GM-CSF and podoplanin. Additionally, IVIg circumvents the neuronal damage by inhibiting the infiltration of CD4 T lymphocytes to the central nervous system by restraining their egress from the DLN through S1P-S1P1-mTOR pathway. Intriguingly and contrary to the current arguments, the inhibitory FcγRIIB and sialylation of IgG are dispensable for IVIg-mediated reciprocal modulation of effector and regulatory CD4 subsets. Altogether, therapeutic benefit of IVIg in EAE involves shifting the balance from Th17/Th1 towards Treg, down-regulating encephalitogenic mediators and inhibition of T cell trafficking to the target organ.L'activation dérégulée de lymphocytes T conduit à une réponse immune délétère envers les antigènes du soi. Malgré une utilisation croissante de doses élevées d'IVIg pour traiter les maladies auto-immunes, la compréhension des mécanismes sous-jacents aux bénéfices thérapeutiques demeure un enjeu majeur. En effet, les effets des IVIg restent inexplorés dans le cadre des maladies auto-immunes associées aux lymphocytes T. J'ai recherché les effets de doses élevées d'IVIg dans la polarisation des lymphocytes T en utilisant le modèle de l'encéphalomyélite auto-immune expérimentale (EAE), une maladie auto-immune associée aux lymphocytes T. Les IVIg inhibent la différenciation des lymphocytes T CD4+ naïfs en sous-populations effectrices (lymphocytes Th1 et Th17) et induisent, de manière concomitante, une prolifération des lymphocytes T Foxp3+. Les IVIg diminuent les effets délétères des lymphocytes T sur les tissus en diminuant l'expression du GM-CSF et de la podoplanine. En outre, les IVIg empêchent la dégénérescence neuronale en inhibant l'infiltrat en lymphocytes T CD4+ dans le système nerveux central (SNC). Ce mécanisme passe par une séquestration de ces lymphocytes dans les ganglions lymphatiques drainants à travers la voie de signalisation S1P-S1P1-mTor. De manière intéressante, et contrairement aux données actuelles, le récepteur inhibiteur FcγRIIB et la sialylation des IVIg ne sont pas indispensables pour la modulation des sous-populations de lymphocytes T CD4+ effecteurs et régulateurs induite par les IVIg. Ainsi, le bénéfice thérapeutique des IVIg dans le modèle de l'EAE implique un déséquilibre de la balance entre les lymphocytes Th17/Th1 et les lymphocytes Trég, au profit des lymphocytes Trég. Ces cellules diminuent l'expression de médiateurs favorisant l'apparition de l'encéphalomyélite et inhibent la migration des lymphocytes T vers l'organe cible