Granzyme B May Act as an Effector Molecule to Control the Inflammatory Process in COPD

Chronic obstructive pulmonary disease (COPD) is caused by smoking, but only a small proportion of smokers have disease severe enough to develop COPD. COPD is not always progressive. The question then arises as to what explains the different trajectories of COPD. The role of autoimmunity and regulatory T (Treg) cells in the pathogenesis of COPD is increasingly being recognized. Nine published studies on Treg cells in the lung tissue or bronchoalveolar lavage fluid have shown that smokers with COPD have fewer Treg cells than smokers without COPD or nonsmokers. Three studies showed a positive correlation between Treg cell count and FEV1%, suggesting an important role for Treg cells in COPD progression. Treg cells can regulate immunological responses via the granzyme B (GzmB) pathway. Immunohistochemical staining for GzmB in surgically resected lungs with centrilobular emphysema showed that the relationship between the amount of GzmB+ cells and FEV1% was comparable to that between Treg cell count and FEV1% in the COPD lung, suggesting that GzmB could be a functional marker for Treg cells. The volume fraction of GzmB+  cells in the small airways, the number of alveolar GzmB+ cells, and GzmB expression measured by enzyme-linked immunosorbent assay in the lung tissue of smokers were significantly correlated with FEV1%. These results suggest that the GzmB content in lung tissue may determine the progression of COPD by acting as an effector molecule to control inflammatory process. Interventions to augment GzmB-producing immunosuppressive cells in the early stages of COPD could help prevent or delay COPD progression.

Enhanced cytotoxic activity of natural killer cells from increased calcium influx induced by electrical stimulation

Natural killer (NK) cells play a crucial role in immunosurveillance independent of antigen presentation, which is regulated by signal balance via activating and inhibitory receptors. The anti-tumor activity of NK cells is largely dependent on signaling from target recognition to cytolytic degranulation; however, the underlying mechanism remains unclear, and NK cell cytotoxicity is readily impaired by tumor cells. Understanding the activation mechanism is necessary to overcome the immune evasion mechanism, which remains an obstacle in immunotherapy. Because calcium ions are important activators of NK cells, we hypothesized that electrical stimulation could induce changes in intracellular Ca2+ levels, thereby improving the functional potential of NK cells. In this study, we designed an electrical stimulation system and observed a correlation between elevated Ca2+ flux induced by electrical stimulation and NK cell activation. Breast cancer MCF-7 cells co-cultured with electrically stimulated KHYG-1 cells showed a 1.27-fold (0.5 V/cm) and 1.55-fold (1.0 V/cm) higher cytotoxicity, respectively. Electrically stimulated KHYG-1 cells exhibited a minor increase in Ca2+ level (1.31-fold (0.5 V/cm) and 1.11-fold (1.0 V/cm) higher), which also led to increased gene expression of granzyme B (GZMB) by 1.36-fold (0.5 V/cm) and 1.58-fold (1.0 V/cm) by activating Ca2+-dependent nuclear factor of activated T cell 1 (NFAT1). In addition, chelating Ca2+ influx with 5 μM BAPTA-AM suppressed the gene expression of Ca2+ signaling and lytic granule (granzyme B) proteins by neutralizing the effects of electrical stimulation. This study suggests a promising immunotherapeutic approach without genetic modifications and elucidates the correlation between cytolytic effector function and intracellular Ca2+ levels in electrically stimulated NK cells.

Granzymes in health and diseases: the good, the bad and the ugly

Granzymes are a family of serine proteases, composed of five human members: GA, B, H, M and K. They were first discovered in the 1980s within cytotoxic granules released during NK cell- and T cell-mediated killing. Through their various proteolytic activities, granzymes can trigger different pathways within cells, all of which ultimately lead to the same result, cell death. Over the years, the initial consideration of granzymes as mere cytotoxic mediators has changed due to surprising findings demonstrating their expression in cells other than immune effectors as well as new intracellular and extracellular activities. Additional roles have been identified in the extracellular milieu, following granzyme escape from the immunological synapse or their release by specific cell types. Outside the cell, granzyme activities mediate extracellular matrix alteration via the degradation of matrix proteins or surface receptors. In certain contexts, these processes are essential for tissue homeostasis; in others, excessive matrix degradation and extensive cell death contribute to the onset of chronic diseases, inflammation, and autoimmunity. Here, we provide an overview of both the physiological and pathological roles of granzymes, highlighting their utility while also recognizing how their unregulated presence can trigger the development and/or worsening of diseases.

Homodimeric Granzyme A Opsonizes Mycobacterium tuberculosis and Inhibits Its Intracellular Growth in Human Monocytes via Toll-Like Receptor 4 and CD14

Mycobacterium tuberculosis (Mtb)-specific γ9δ2 T cells secrete granzyme A (GzmA) protective against intracellular Mtb growth. However, GzmA-enzymatic activity is unnecessary for pathogen inhibition, and the mechanisms of GzmA-mediated protection remain unknown. We show that GzmA homodimerization is essential for opsonization of mycobacteria, altered uptake into human monocytes, and subsequent pathogen clearance within the phagolysosome. Although monomeric and homodimeric GzmA bind mycobacteria, only homodimers also bind cluster of differentiation 14 (CD14) and Toll-like receptor 4 (TLR4). Without access to surface-expressed CD14 and TLR4, GzmA fails to inhibit intracellular Mtb. Upregulation of Rab11FIP1 was associated with inhibitory activity. Furthermore, GzmA colocalized with and was regulated by protein disulfide isomerase AI (PDIA1), which cleaves GzmA homodimers into monomers and prevents Mtb inhibitory activity. These studies identify a previously unrecognized role for homodimeric GzmA structure in opsonization, phagocytosis, and elimination of Mtb in human monocytes, and they highlight PDIA1 as a potential host-directed therapy for prevention and treatment of tuberculosis, a major human disease.

Detection of Granzyme B-associated Binding Targets in Peripheral Blood Samples of Hosts in Sickness and in Health Using a Granzyme B-like Peptide Fluorescent Conjugate (GP1R)

Granzyme B, mostly expressed by cytotoxic T lymphocytes in the fight against cancer and infection, is known to induce cell death based on its active enzymatic activity as a serine protease. Recent studies showed cytotoxicity of a non-enzymatic granzyme B-like peptide (also referred to as granzyme B-associated peptide or GP1 in this report) in tumor cells and presence of binding targets for GP1R (i.e., GP1 conjugated with rhodamine fluorochrome) in tumor cells, bacteria, and circulating platelets/neutrophils of healthy hosts. But there were no data on "sick" hosts to help substantiate any potential GP1 based medical applications. Thus, we adopted similar GP1R binding protocols to further study binding of GP1 in different biological samples (including different blood samples of hosts in sickness and in health, cancer cell lines, and trigeminal ganglia culture of infected hosts treated with and without GP1) and determine if any binding patterns might have any associations with different health conditions. The overall preliminary results appear to show certain GP1R + binding patterns in certain blood components (especially neutrophils) have potential correlations with certain health conditions of hosts at sampling times, indicating potential GP1R applications for diagnostic purposes. Findings of different GP1R binding patterns in different cancer cell lines, whole blood samples and trigeminal ganglia culture of experimental mice infected with HSV-1 virus (might cause neuropathy) within a week post-infection, and blood samples of GP1-treated mouse survivors on day 21 post-infection provided preliminary evidence of potential GP1-led tumor cell-specific cell death and treatment efficacy for greater survival.

A Noncanonical CD56dimCD16dim/- NK Cell Subset Indicative of Prior Cytotoxic Activity Is Elevated in Patients with Autoantibody-Mediated Neurologic Diseases

Neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein Ab disease, and autoimmune myasthenia gravis (MG) are autoantibody-mediated neurologic conditions where autoantibodies can induce Ab-dependent cellular cytotoxicity (ADCC), a NK cell-mediated effector function. However, whether ADCC is a pathogenic mechanism in patients with these conditions has not been confirmed. We sought to characterize circulatory NK cells using functional assays, phenotyping, and transcriptomics to elucidate their role in pathology. NK cells from NMOSD patients and MG patients with elevated disease burden exhibited reduced ADCC and CD56dimCD16hi NK cells, along with an elevated frequency of CD56dimCD16dim/- NK cells. We determined that ADCC induces a similar phenotypic shift in vitro. Bulk RNA sequencing distinguished the CD56dimCD16dim/- population from the canonical CD56dimCD16hi cytotoxic and CD56hiCD16- immunomodulatory subsets, as well as CD56hiCD16+ NK cells. Multiparameter immunophenotyping of NK cell markers, functional proteins, and receptors similarly showed that the CD56dimCD16dim/- subset exhibits a unique profile while still maintaining expression of characteristic NK markers CD56, CD94, and NKp44. Notably, expression of perforin and granzyme is reduced in comparison with CD56dimCD16hi NK cells. Moreover, they exhibit elevated trogocytosis capability, HLA-DR expression, and many chemokine receptors, including CCR7. In contrast with NMOSD and MG, myelin oligodendrocyte glycoprotein Ab disease NK cells did not exhibit functional, phenotypic, or transcriptomic perturbations. In summary, CD56dimCD16dim/- NK cells are a distinct peripheral blood immune cell population in humans elevated upon prior cytotoxic activity by the CD56dimCD16hi NK cell subset. The elevation of this subset in NMOSD and MG patients suggests prior ADCC activity.

Development of novel HPV therapeutic vaccine constructs based on engineered exosomes and tumor cell lysates

AIMS

Human papillomavirus (HPV) infections are highly prevalent globally. While preventive HPV vaccines exist, therapeutic vaccines are needed to treat existing HPV lesions and malignancies. This study evaluated the immunostimulatory and anti-tumor effects of three therapeutic vaccine candidates based on the recombinant protein, tumor cell lysate (TCL), and engineered exosome (Exo) harboring the heat shock protein 27 (Hsp27)-E7 fusion construct in mouse model.

MAIN METHODS

At first, the recombinant Hsp27-E7 protein was generated in E. coli expression system. Then, tumor cell lysates-based and engineered exosomes-based vaccine constructs harboring green fluorescent protein (GFP) and Hsp27-E7 were produced using lentiviral system. Finally, their immunological and antitumor effects were investigated in both prophylactic and therapeutic experiments.

KEY FINDINGS

Our data showed that the recombinant Hsp27-E7 protein, TCL-Hsp27-E7 and Exo-Hsp27-E7 regimens can induce the highest level of IFN-γ, TNF-α and Granzyme B, respectively. The percentage of tumor-free mice was identical for three vaccine strategies (survival rate: 75 %) in both prophylactic and therapeutic experiments. Generally, the TCL-Hsp27-E7, Exo-Hsp27-E7 and recombinant Hsp27-E7 protein regimens induced effective immune responses toward Th1 and CTL activity, and subsequently antitumor effects in mouse model.

SIGNIFICANCE

Regarding to higher Granzyme B secretion, lower tumor growth and more safety, the Exo-Hsp27-E7 regimen can be considered as the most promising HPV vaccination strategy.

Leptin/lipopolysaccharide-treated dendritic cell vaccine improved cellular immune responses in an animal model of breast cancer

PURPOSE

In dendritic cells (DCs), leptin as an immune-regulating hormone, increases the IL-12 generation whereas it reduces the IL-10 production, thus contributing to TH1 cell differentiation. Using a murine model of breast cancer (BC), we evaluated the impacts of the Leptin and/or lipopolysaccharide (LPS)-treated DC vaccine on various T-cell-related immunological markers.

MATERIALS AND METHODS

Tumors were established in mice by subcutaneously injecting 7 × 105 4T1 cells into the right flank. Mice received the DC vaccines pretreated with Leptin, LPS, and both Leptin/LPS, on days 12 and 19 following tumor induction. The animals were sacrificed on day 26 and after that the frequency of the splenic cytotoxic T lymphocytes (CTLs) and TH1 cells; interferon gamma (IFN-γ), interleukin 12 (IL-12) and tumor growth factor beta (TGF-β) generation by tumor lysate-stimulated spleen cells, and the mRNA expression of T-bet, FOXP3 and Granzyme B in the tumors were measured with flow cytometry, ELISA and real-time PCR methods, respectively.

RESULTS

Leptin/LPS-treated mDC group was more efficient in blunting tumor growth (p = .0002), increasing survival rate (p = .001), and preventing metastasis in comparison with the untreated tumor-bearing mice (UT-control). In comparison to the UT-control group, treatment with Leptin/LPS-treated mDC also significantly increased the splenic frequencies of CTLs (p < .001) and TH1 cells (p < .01); promoted the production of IFN-γ (p < .0001) and IL-12 (p < .001) by splenocytes; enhanced the T-bet (p < .05) and Granzyme B (p < .001) expression, whereas decreased the TGF-β and FOXP3 expression (p < .05).

CONCLUSION

Compared to the Leptin-treated mDC and LPS-treated mDC vaccines, the Leptin/LPS-treated mDC vaccine was more effective in inhibiting BC development and boosting immune responses against tumor.

Differential Runx3, Eomes, and T-bet expression subdivides MS-associated CD4+ T cells with brain-homing capacity

Multiple sclerosis (MS) is a common and devastating chronic inflammatory disease of the CNS. CD4+ T cells are assumed to be the first to cross the blood-central nervous system (CNS) barrier and trigger local inflammation. Here, we explored how pathogenicity-associated effector programs define CD4+ T cell subsets with brain-homing ability in MS. Runx3- and Eomes-, but not T-bet-expressing CD4+ memory cells were diminished in the blood of MS patients. This decline reversed following natalizumab treatment and was supported by a Runx3+ Eomes+ T-bet- enrichment in cerebrospinal fluid samples of treatment-naïve MS patients. This transcription factor profile was associated with high granzyme K (GZMK) and CCR5 levels and was most prominent in Th17.1 cells (CCR6+ CXCR3+ CCR4-/dim ). Previously published CD28- CD4 T cells were characterized by a Runx3+ Eomes- T-bet+ phenotype that coincided with intermediate CCR5 and a higher granzyme B (GZMB) and perforin expression, indicating the presence of two separate subsets. Under steady-state conditions, granzyme Khigh Th17.1 cells spontaneously passed the blood-brain barrier in vitro. This was only found for other subsets including CD28- cells when using inflamed barriers. Altogether, CD4+ T cells contain small fractions with separate pathogenic features, of which Th17.1 seems to breach the blood-brain barrier as a possible early event in MS.

Granzyme B is elevated in esophageal biopsies from children with eosinophilic esophagitis

OBJECTIVES

Eosinophilic esophagitis (EoE) is an immune-mediated antigen-triggered inflammatory disease of the esophagus. Our aim was to investigate inflammatory responses by an ex vivo biopsy provocation-based method, stimulating biopsies with milk, wheat, and egg extracts.

METHODS

An experimental study was conducted on esophageal biopsies from children who underwent esophagogastroduodenoscopy. Supernatants were collected before and after stimulation of the biopsies with food extracts and analyzed for 45 different inflammatory markers. Biopsies were also stained for histological analyzes.

RESULTS

Study subjects included 13 controls, 9 active EoE, and 4 EoE in remission, median age 12 years. Of the 45 markers analyzed, three had significant differences between controls and patients with active EoE, Granzyme B, (GzmB), IL-1ra, and CXCL8 (p < .05). Levels of GzmB were higher, and levels of IL-1ra were lower in patients with active EoE compared with controls and EoE in remission both at baseline and after food extract stimulation. CXCL8 increased in active EoE compared with controls only after stimulation. The number of histologically detected GzmB-positive cells were significantly higher in patients with active EoE in contrast to control and EoE remission (p < .05).

CONCLUSIONS

The levels of the barrier-damaging protease GzmB were higher in the supernatant both before and after stimulation with food extract ex vivo in patients with active EoE. GzmB was also observed histologically in biopsies from patients with active EoE. The presence of elevated serine protease GzmB in esophageal mucosa of children with active EoE suggests a role in the pathogenesis of this disorder.

The Qi Yin San Liang San decoction enhances anti-CD19 CAR-T cell function in the treatment of B-cell lymphomas

ETHNOPHARMACOLOGICAL RELEVANCE

Adoptive T-cell therapy with anti-CD19 chimeric antigen receptor (CAR)-expressing T cells is a new approach for treating advanced B-cell malignancies. However, CAR-Tcell therapies for tumors are challenging due to tumor heterogeneity, cytokine release syndrome (CRS), and CAR-T cell exhaustion. The Qi Yin San Liang San (SLS) decoction has a significant curative effect in treating tumors and can improve clinical efficacy when combined with tumor immunotherapy. However, there has been no in vitro or in vivo pharmacodynamic evaluation of SLS in combination with immunotherapy, and the underlying immunological mechanism remains unclear.

AIM OF THE REVIEW

The study objective was to determine the auxiliary effect and potential mechanism of SLS as an adjuvant treatment with anti-CD19 CAR-T cells for B-cell lymphomas.

MATERIALS AND METHODS

Network pharmacology analyses, in vitro and in vivo studies, and transcriptome sequencing analyses were performed.

RESULTS

Forty-two components were detected in SLS by HPLC. Sixteen pharmacologically active ingredients were analyzed by searching the TCMSP database. The predicted targets included IL-2, IL-6, IL-10, TNF-α, CASP7, and CASP9. In vitro studies revealed that SLS can dose-dependently promote the killing effect of unmodified T and anti-CD19 CAR-T cells against Raji cell lines. Meanwhile, SLS inhibited unmodified T and anti-CD19 CAR-T cell exhaustion, promoted anti-CD19 CAR-T cell proliferation, reduced the levels of IL-6, IL-10, and TNF-α, and increased granzyme B levels. In vivo studies, SLS effectively improved the anti-tumor function of anti-CD19 CAR-T cells, prolonged the survival of the mice, and reduced the levels of IL-6, GM-CSF, and IL-17. Subsequently, the transcriptomic analysis showed that SLS inhibited the IL-17 signaling pathway and the apoptosis signaling pathway of T cells. In addition, SLS downregulated the expression of IL-17A, IL-6, TNF-α, GM-CSF, S100A8, CASP 7, CASP 9, and CASP 10 in anti-CD19 CAR-T cells. SLS regulated the IL-17 signaling pathway and apoptosis signaling pathway in anti-CD19 CAR-T cells.

CONCLUSION

SLS plays a potential auxiliary role in enhancing the function of anti-CD19 CAR T cells in the treatment of B-cell lymphoma, improving the killing ability of these cells, reducing the potential risk associated with inflammation, and providing synergistic and attenuating effects. The mechanism of SLS is partially mediated by the apoptosis and IL-17 signaling pathways (such as IL-17A, IL-6, TNF-α, GM-CSF, and Granzyme B).

Intraepithelial lymphocytes are associated with epithelial injury in feline intestinal T-cell lymphoma

Our previous study indicated that cytotoxicity of intraepithelial lymphocytes is a poor prognostic factor in feline intestinal T-cell lymphoma (FITL), but the effect of cytotoxic lymphocytes on mucosal epithelium is still unknown. Thus, we investigated the association between cytotoxic lymphocytes and mucosal epithelium in 71 cases of feline intestinal T-cell lymphoma (FITL): epithelial injury, basement membrane injury, cleaved-caspase-3 positivity of epithelial cells, and the number and Ki67 positivity of intraepithelial lymphocytes in granzyme B (GRB)+ and GRB- FITLs were evaluated. Epithelial injury score and the number of intraepithelial lymphocytes in granzyme B (GRB)+ FITL were significantly higher than those of GRB- FITL (P<0.05, P<0.05), but no significant differences were found in the basement membrane injury score, the percentage of cleaved-caspase-3+ epithelial cells, and the percentage of Ki67+ intraepithelial lymphocytes. There was a significant correlation between the epithelial injury score and the number of intraepithelial lymphocytes (P<0.05), but no significant correlation was observed between the epithelial injury score and Ki67+ percentage of intraepithelial lymphocytes. Because epithelial cell cleaved-caspase-3 positivity was observed in FITL, regardless of GRB expression in lymphocytes, GRB-mediated apoptosis may not contribute to epithelial injury in FITL. The association between increased number of intraepithelial lymphocytes and epithelial injury suggests that intraepithelial lymphocytes infiltration may contribute to epithelial injury in FITL.

NADPH Oxidase 2-Derived Reactive Oxygen Species Promote CD8+ T Cell Effector Function

Oxidants participate in lymphocyte activation and function. We previously demonstrated that eliminating the activity of NADPH oxidase 2 (NOX2) significantly impaired the effectiveness of autoreactive CD8+ CTLs. However, the molecular mechanisms impacting CD8+ T cell function remain unknown. In the present study, we examined the role of NOX2 in both NOD mouse and human CD8+ T cell function. Genetic ablation or chemical inhibition of NOX2 in CD8+ T cells significantly suppressed activation-induced expression of the transcription factor T-bet, the master transcription factor of the Tc1 cell lineage, and T-bet target effector genes such as IFN-γ and granzyme B. Inhibition of NOX2 in both human and mouse CD8+ T cells prevented target cell lysis. We identified that superoxide generated by NOX2 must be converted into hydrogen peroxide to transduce the redox signal in CD8+ T cells. Furthermore, we show that NOX2-generated oxidants deactivate the tumor suppressor complex leading to activation of RheB and subsequently mTOR complex 1. These results indicate that NOX2 plays a nonredundant role in TCR-mediated CD8+ T cell effector function.

Compromised melanocyte survival due to decreased suppression of CD4+ & CD8+ resident memory T cells by impaired TRM-regulatory T cells in generalized vitiligo patients

Regulatory T cells (Tregs) are involved in the suppression of activated T cells in generalized vitiligo (GV). The study was aimed to investigate resident memory (TRM)-Tregs and antigen-specific Tregs' numbers and functional defects in 25 GV patients and 20 controls. CD4+ & CD8+ TRM cell proliferation was assessed by BrDU assay; production of IL-10, TGF-β, IFN-γ, perforin and granzyme B were assessed by ELISA and enumeration of TRM cells was done by flowcytometry. GV patients showed significantly increased frequency and absolute count of CD4+ & CD8+ TRM cells in lesional (L), perilesional (PL) and non-lesional (NL) skin compared to controls (p = 0.0003, p = 0.0029 & p = 0.0115, respectively & p = 0.0003, p = 0.003 & p = 0.086, respectively). Whereas, TRM-Treg (p < 0.0001 & p = 0.0015) and antigen-specific Tregs (p = 0.0014 & p = 0.003) exhibited significantly decreased frequency and absolute counts in L & PL skin. GV patients showed reduced suppression of CD8+ & CD4+ TRM cells (with increased IFN-γ, perforin & granzyme B) and decreased TRM-Tregs and antigen-specific Tregs (with decreased IL-10 & TGF-β production) and reduced proliferation of SK-Mel-28 cells in co-culture systems. Immunohistochemistry revealed increased expression of TRM stimulating cytokines: IL-15 & IL-17A and reduced expression of TGF-β & IL-10 in L, PL, NL skins compared to controls. These results for the first time suggest that decreased and impaired TRM-Tregs and antigen-specific Tregs are unable to suppress CD4+ & CD8+ TRMs' cytotoxic function and their proliferation due to decrease production of immunosuppressive cytokines (IL-10 & TGF-β) and increased production of TRM based IFN-γ, perforin and granzyme B production, thus compromising the melanocyte survival in GV.

High-free Fatty Acid Treatment Induced Anti-inflammatory Changes in a Natural Killer (NK) Cell Line

Background

Natural killer (NK) cells play a role in the pathogenesis of various metabolic diseases related to obesity. While our initial findings have indicated a potential involvement of NK cells in the pathogenesis of type 2 diabetes mellitus, the precise mechanism underlying NK cell-mediated development of this form of diabetes remains inadequately comprehended.

Objective

To investigate the impact and the underlying mechanism of high glucose and elevated levels of free fatty acids (FFAs) on immune and inflammatory responses and oxidative stress in NK92 cells.

Methods

In this experiment, the CCK8 cytotoxicity assay was used to select the 44.4 mM and 1.5 mM concentrations of high glucose and high FFAs, respectively, to treat NK92 cells for 4 days. The concentrations of superoxide dismutase (SOD) and glutathione (GSH) were determined using a biochemical analyzer. Intracellular reactive oxygen species (ROS) levels, cytokines concentrations (TNF-α, IFN-γ, IL-6, and IL-10), and the expression levels of intracellular molecules (perforin and granzyme B) were assessed by flow cytometry.

Results

The number of NK92 cell clumps was significantly reduced in the high-FFA (HF) group. In addition, the production of ROS and levels of cytokines (TNF-α, IFN-γ, IL-6, and IL-10) significantly decreased in the HF group but showed no significant change in the high-glucose (HG) group. This observation was consistent with the expression levels of perforin and granzyme B that decreased in the HF group.

Conclusion

High FFAs induced morphological changes and serious damage to oxidative stress and inflammatory response in NK92 cells.

Harnessing the Power of CAR-NK Cells: A Promising Off-the-Shelf Therapeutic Strategy for CD38-Positive Malignancies

Background

CD38 is highly expressed on multiple myeloma (MM) cells and has been successfully targeted by different target therapy methods. This molecule is a critical prognostic marker in both diffuse large B-cell lymphoma and chronic lymphocytic leukemia.

Objective

We have designed and generated an anti-CD38 CAR-NK cell applying NK 92 cell line. The approach has potential application as an off-the-shelf strategy for treatment of CD38 positive malignancies.

Methods

A second generation of anti-CD38 CAR-NK cell was designed and generated, and their efficacy against CD38-positive cell lines was assessed in vitro. The PE-Annexin V and 7-AAD methods were used to determine the percentage of apoptotic target cells. Flow cytometry was used to measure IFN-γ, Perforin, and Granzyme-B production following intracellular staining. Using in silico analyses, the binding capacity and interaction interface were evaluated.

Results

Using Lentivirus, cells were transduced with anti-CD38 construct and were expanded. The expression of anti-CD38 CAR on the surface of NK 92 cells was approximately 25%. As we expected from in silico analysis, our designed CD38-chimeric antigen receptor was bound appropriately to the CD38 protein. NK 92 cells that transduced with the CD38 chimeric antigen receptor, generated significantly more IFN-γ, perforin, and granzyme than Mock cells, and successfully lysed Daudi and Jurkat malignant cells in a CD38-dependent manner.

Conclusion

The in vitro findings indicated that the anti-CD38 CAR-NK cells have the potential to be used as an off-the-shelf therapeutic strategy against CD38-positive malignancies. It is recommended that the present engineered NK cells undergo additional preclinical investigations before they can be considered for subsequent clinical trial studies.

Single-cell atlas of healthy human blood unveils age-related loss of NKG2C+GZMB-CD8+ memory T cells and accumulation of type 2 memory T cells

Extensive, large-scale single-cell profiling of healthy human blood at different ages is one of the critical pending tasks required to establish a framework for the systematic understanding of human aging. Here, using single-cell RNA/T cell receptor (TCR)/BCR-seq with protein feature barcoding, we profiled 317 samples from 166 healthy individuals aged 25-85 years old. From this, we generated a dataset from ∼2 million cells that described 55 subpopulations of blood immune cells. Twelve subpopulations changed with age, including the accumulation of GZMK+CD8+ T cells and HLA-DR+CD4+ T cells. In contrast to other T cell memory subsets, transcriptionally distinct NKG2C+GZMB-CD8+ T cells counterintuitively decreased with age. Furthermore, we found a concerted age-associated increase in type 2/interleukin (IL)4-expressing memory subpopulations across CD4+ and CD8+ T cell compartments (CCR4+CD8+ Tcm and Th2 CD4+ Tmem), suggesting a systematic functional shift in immune homeostasis with age. Our work provides novel insights into healthy human aging and a comprehensive annotated resource.

The USP7-STAT3-granzyme-Par-1 axis regulates allergic inflammation by promoting differentiation of IL-5-producing Th2 cells

Uncontrolled type 2 immunity by type 2 helper T (Th2) cells causes intractable allergic diseases; however, whether the interaction of CD4+ T cells shapes the pathophysiology of allergic diseases remains unclear. We identified a subset of Th2 cells that produced the serine proteases granzyme A and B early in differentiation. Granzymes cleave protease-activated receptor (Par)-1 and induce phosphorylation of p38 mitogen-activated protein kinase (MAPK), resulting in the enhanced production of IL-5 and IL-13 in both mouse and human Th2 cells. Ubiquitin-specific protease 7 (USP7) regulates IL-4-induced phosphorylation of STAT3, resulting in granzyme production during Th2 cell differentiation. Genetic deletion of Usp7 or Gzma and pharmacological blockade of granzyme B ameliorated allergic airway inflammation. Furthermore, PAR-1+ and granzyme+ Th2 cells were colocalized in nasal polyps from patients with eosinophilic chronic rhinosinusitis. Thus, the USP7-STAT3-granzymes-Par-1 pathway is a potential therapeutic target for intractable allergic diseases.

The cytotoxicity of γδT cells in non-small cell lung cancer mediated via coordination of the BCL-2 and AKT pathways

The effectiveness and mechanisms of γδT-cell immunotherapy in lung cancer remain unclear. In this study, we assessed the effects of continuous, low-dose γδT-cell intervention on lung cancer cells. We cultured γδT cells with a lung cancer cell line (A549) and replaced the γδT-cell population every 48 hours. The killing effect of γδTcells on A549 cells and the Half-maximal inhibitory concentration (IC50) value were detected by the cholecystokinin octapeptide (CCK-8) method. The levels of perforin, granzyme B and the inflammatory factors interleukin-6 (IL-6), interferon (IFN)-γ, and tumor necrosis factor-alpha (TNF-a), in the supernatants of cocultured cells were measured by ELISA. The protein expression of Bcl-2, Bax, PI3K and Akt was detected by western blotting. Our results indicated that γδT-cell treatment decreased the protein expression of Bcl-2, PI3K, and AKT but upregulated that of Bax. Moreover, γδT-cell treatment increased perforin and granzyme B release related to the Bax/Bcl-2 signaling pathway. In addition, γδT-cell-mediated cytolysis for A549 cells involved the PI3K/AKT pathway. In vivo results were consistent with the in vitro results. γδT-cell immunotherapy integrated regulation of a signaling pathway network involving the mutual regulation of apoptosis and proliferation. γδT-cell immunotherapy could be used to enhance the cytotoxic killing of lung cancer cells.

Perforin and granzyme A release as novel tool to measure NK cell activation in chickens

Natural killer (NK) cells are cytotoxic lymphocytes that are present in the circulation but also in many organs including spleen and gut, where they play an important role in the defense against infections. Interaction of NK cells with target cells leads to degranulation, which results in the release of perforin and granzymes in the direct vicinity of the target cell. Chicken NK cells have many characteristics similar to their mammalian counterparts and based on similarities with studies on human NK cells, surface expression of CD107 was always presumed to correlate with granule release. However, proof of this degranulation or in fact the actual presence of perforin (PFN) and granzyme A (GrA) in chicken NK cells and their release upon activation is lacking. Therefore, the purpose of the present study was to determine the presence of perforin and granzyme A in primary chicken NK cells and to measure their release upon degranulation, as an additional tool to study the function of chicken NK cells. Using human specific antibodies against PFN and GrA in fluorescent and confocal microscopy resulted in staining in chicken NK cells. The presence of PFN and GrA was also confirmed by Western blot analyses and its gene expression by PCR. Stimulation of NK cells with the pectin SPE6 followed by flow cytometry resulted in reduced levels of intracellular PFN and GrA, suggesting release of PFN and GrA. Expression of PFN and GrA reversely correlated with increased surface expression of the lysosomal marker CD107. Finally it was shown that the supernatant of activated NK cells, containing the NK cell granule content including PFN and GrA, was able to kill Escherichia coli. This study correlates PFN and GrA release to activation of chicken NK cells and establishes an additional tool to study activity of cytotoxic lymphocytes in chickens.

Administration of a glypican-3 peptide increases the infiltration and cytotoxicity of CD8+ T cells against testicular yolk sac tumor, associated with enhancing the intratumoral cGAS/STING signaling

BACKGROUND

Glypican-3 (GPC3) is highly expressed in testicular yolk sac tumor (TYST). GPC3 has been evaluated as a cancer vaccine for some types of tumors, but little is known on the effects of GPC3 peptide-based therapy on TYST. Here, we evaluated the antitumor effect of GPC3144-152 on TYST and its potential mechanisms.

METHODS

GPC3144-152 -specific CD8+ T cells were induced by vaccine immunization and examined by ELISPOT. The CD8+ T cells were purified for testing their cytotoxicity in vitro against TYST cells by CCK-8 and TUNEL assays and in vivo against tumor growth. The influence of GPC3144-152 loading and/or cGAS silencing on the tumor growth, apoptosis and cGAS/STING signaling was tested by immunohistochemistry, immunofluorescence, flow cytometry, and Western blot.

RESULTS

Vaccination with GPC3144-152 induced tumor-specific CD8+ T cells that secreted high levels of IFN-γ and granzyme B, and had potent cytotoxicity against TYST in a dose-dependent manner. Adoptive transfer of CD8+ T cells and treatment with GPC3144-152 significantly inhibited the growth of TYST tumors, but less effective for cGAS-silenced TYST tumors in vivo. Treatment with GPC3144-152 enhanced the infiltration of CD8+ T cells into the tumor environment and their cytotoxicity against TYST tumors in vivo by up-regulating granzyme B and IFN-β expression, but down-regulating GPC3 expression in the tumors. Co-culture of CD8+ T cells with TYST in the presence of exogenous GPC3144-152 enhanced peptide-specific CD8+ T-cell cytotoxicity in vitro, accompanied by enhancing cGAS, γH2AX, TBK1, and IRF3 phosphorylation in TYST cells, but less effective in cGAS-silenced TYST cells.

CONCLUSIONS

These data indicated that GPC3 peptide-specific CD8+ T cells had potent antitumor activity against TYST tumor, particularly for combined treatment with the peptide, which was partially dependent on the intratumoral cGAS/STNG signaling. GPC3 peptide vaccine may be valuable for the combination treatment of TYST.

Mucosal-associated invariant T cells from Clostridioides difficile-infected patients exhibit a distinct proinflammatory phenotype and enhanced cytotoxic activity

Mucosal-associated invariant T (MAIT) cells are innate-like T cells mainly found in the mucosa and peripheral blood. We have recently demonstrated that Clostridioides difficile activates MAIT cells in vitro. However, their role in the pathogenesis of C. difficile infection (CDI) in human patients remains elusive to date. In this study, we performed comprehensive immunophenotyping of MAIT cells derived from CDI patients and compared their phenotype to that of patients with inflammatory bowel diseases (IBD) and healthy controls. Our study revealed that blood MAIT cells from CDI patients exhibit an interleukin 17a (IL-17a)-dominated proinflammatory phenotype and an increased readiness to synthesize the proinflammatory cytokine interferon γ (IFN-γ) following in vitro re-stimulation. Moreover, the cytotoxic activity of MAIT cells, as measured by surface CD107a and intracellular granzyme B expression, was strongly increased in CDI. Multi epitope ligand cartography (MELC) analysis of intestinal biopsies from CDI patients revealed that MAIT cells exhibit an increased production of granzyme B and increased cytotoxicity compared to the control group. Together with previously published in vitro data from our group, our findings suggest that MAIT cells are functionally involved in the immune response against C. difficile and contribute to the pathogenesis of CDI.

Monensin induces secretory granule-mediated cell death in eosinophils

BACKGROUND

Eosinophils contribute to the pathology of several types of disorders, in particular of allergic nature, and strategies to limit their actions are therefore warranted.

OBJECTIVE

We sought to evaluate the possibility of targeting the acidic, lysosome-like eosinophil granules as a potential means of inducing eosinophil cell death.

METHODS

To this end, we used monensin, an ionophoric drug that has previously been shown to permeabilize the secretory granules of mast cells, thereby inducing cell death.

RESULTS

Our findings reveal that monensin induces cell death in human eosinophils, whereas neutrophils were less affected. Blockade of granule acidification reduced the effect of monensin on the eosinophils, demonstrating that granule acidity is an important factor in the mechanism of cell death. Furthermore, monensin caused an elevation of the granule pH, which was accompanied by a decrease of the cytosolic pH, hence indicating that monensin caused leakage of acidic contents from the granules into the cytosol. In agreement with a granule-targeting mechanism, transmission electron microscopy analysis revealed that monensin caused extensive morphological alterations of the eosinophil granules, as manifested by a marked loss of electron density. Eosinophil cell death in response to monensin was caspase-independent, but dependent on granzyme B, a pro-apoptotic serine protease known to be expressed by eosinophils.

CONCLUSIONS

We conclude that monensin causes cell death of human eosinophils through a granule-mediated mechanism dependent on granzyme B.

Expression of Tim-3/Galectin-9 pathway and CD8+T cells and related factors in patients with cystic echinococcosis

OBJECTIVE

One of the primary reasons for the successful patriotization of Echinococcus multilocularis in patients is its ability to induce host immune tolerance. This study examined the expression of the immunosuppressive Tim-3/Galectin-9 pathway, CD8+T cells, and related factors in AE patients. The aim was to analyze the relationship between the Tim-3/Galectin-9 pathway and CD8+T cells in this disease and further understand the mechanism of immune tolerance induced by cystic echinococcosis.

METHODS

Using flow cytometry, we evaluated the expression of CTL, CD8+CD28-T cells, CD8+CD28 + IFN-γ + T cells, CD8+CD28+perforin + T cells, CD8+CD28+granzyme B + T cells, CD8+CD28-IL-10 + T cells, CD8+CD28-TGF-β+T cells, and Tim-3 expression on CD8+T cells in the peripheral blood of control (n = 30) and AE patients (n = 33). qRT-PCR was used to measure CD107a and Tim-3/Galectin-9 mRNA levels in PBMCs from the control and AE groups. Immunohistochemistry was employed to detect IL-10, TGF-β, and Tim-3/Galectin-9 expressions in the infected livers of AE patients.

RESULTS

AE patients exhibited a significant decrease in peripheral blood CTL ratio (P < 0.001) and an increase in CD8+CD28+IFN-γ+T cell ratio (P < 0.001). No significant changes were observed in the ratios of CD8+CD28+perforin + T cells (P = 0.720) and CD8+CD28+granzyme B + T cells (P = 0.051). The proportions of CD8+CD28-T cells (P < 0.001), CD8+CD28-IL-10 + T cells (P < 0.001), and CD8+CD28-TGF-β+T cells (P < 0.001) were notably higher than in the control group. The expression of Tim-3 on CTL and CD8+CD28-T cells in AE patients was significantly upregulated (P < 0.001, P < 0.001). AE patients displayed a substantial decrease in peripheral blood PBMC CD107a mRNA levels (P < 0.001) and significant elevations in Tim-3/Galectin-9 mRNA levels (P < 0.001, P < 0.001). A negative correlation was observed between CD107a mRNA levels and both Tim-3 (r^2 = 0.411, P < 0.001) and Galectin-9 (r2 = 0.180, P = 0.019) mRNA levels. Expressions of IL-10 (P < 0.001), TGF-β (P < 0.001), and Tim-3/Galectin-9 (P < 0.001, P < 0.001) in AE patient-infected livers were significantly higher than in uninfected regions. IL-10 and TGF-β expressions showed a positive correlation with Tim-3/Galectin-9.

CONCLUSION

This study suggests that the high expression of Tim-3 on CD8+T cell surfaces in AE patients might promote an increase in CD8+CD28-T cells and related factors, while suppressing CTL and related factor expressions. This potentially induces the onset of immune tolerance, which is unfavorable for the clearance of Echinococcus multilocularis in patients, leading to the exacerbation of persistent infections.

Heterogeneity of T cells in periapical lesions and in vitro validation of the proangiogenic effect of GZMA on HUVECs

AIM

T cells are key immunomodulatory cells in periapical lesions. This study aimed to explore the roles of T cells in chronic apical periodontitis (CAP) using single-cell RNA sequencing and to further investigate Granzyme A (GZMA) in angiogenesis regulation.

METHODOLOGY

A total of five CAP samples were collected for single-cell RNA sequencing. We performed subcluster and lineage-tracing analyses for T cells. According to differential gene expression, distinct biological functions enriched in T cells of CAP were presented by gene set enrichment analysis (GSEA) and compared with healthy gingiva (data obtained from the GEO database). CellChat was used to explore potential ligand-receptor interactions between T cells and endothelial cells in CAP. The coculture of primary human umbilical vein endothelial cells (HUVECs) and Jurkat T cells, as well as the addition of GZMA recombinant protein, was used to validate the predicted pair of GZMA and coagulation factor II thrombin receptor (F2R) by RT-PCR, angiogenesis and migration assays.

RESULTS

A transcriptomic atlas of 44 746 individual cells was constructed from the periapical lesions of five patients with CAP by single-cell RNA-seq, and eight cell types were identified. We identified nine subsets of T cells and deciphered the cellular heterogeneity of T cells in CAP at the functional level by subclustering and GSEA. Lineage tracing revealed a distinct lineage of T cells in CAP and predicted the transition of the T cellular state upon CAP. GSEA revealed multiple biological processes and relevant angiogenesis genes upregulated in CAP T cells. GZMA-F2R pairs were predicted by cell-cell interactions in CAP. High expression of GZMA and F2R was observed in the coculture of HUVECs and Jurkat T cells, and the proangiogenic capacity of the GZMA recombinant protein was emphasized by in vitro experiments.

CONCLUSIONS

Our study provides novel insights into the heterogeneity of T cells in periapical lesions and reveals the potential role of GZMA in T cells in regulating angiogenesis in HUVECs.

Pyruvate dehydrogenase kinase 1 regulates the function of human decidual natural killer cells

PROBLEM

Pyruvate dehydrogenase kinase 1 (PDK1) is an important enzyme for immune cell development. However, PDK1's role in human decidual natural killer (dNK) cells remains largely unknown.

METHODS OF STUDY

PDK1 expression in dNK cells from patients with recurrent spontaneous abortions (RSA) and age-matched healthy controls was analyzed by qRT-PCR, western bolt and flow cytometry. Moreover, dNK cells were treated with PDK1 inhibitor or the PDK1 siRNA followed by functional assays.

RESULTS

The dNK cells from patients who underwent RSAs had higher mRNA expression and increased protein of PDK1, perforin (PRF1), Granzyme B (GZMB), IFN-γ (IFNG), and CD107a expression compared to dNK cells from age-matched healthy controls. Perforin, Granzyme B, IFN-γ and CD107a expression levels in dNK cells were down-regulated when dNK cells were treated with a PDK1 inhibitor. As measured by the 51 Cr release assay, the killing activity of dNK cells was found to be decreased. We also demonstrated that PDK1 blockade could up-regulate the migration and adhesion of dNK cells. Furthermore, PDK1 inhibition reduced the glycolysis of dNK cells.

CONCLUSION

This study suggested that PDK1 plays an important role in regulating dNK cell functions and human RSA.

Widespread and dynamic expression of granzyme C by skin-resident antiviral T cells

After recognition of cognate antigen (Ag), effector CD8+ T cells secrete serine proteases called granzymes in conjunction with perforin, allowing granzymes to enter and kill target cells. While the roles for some granzymes during antiviral immune responses are well characterized, the function of others, such as granzyme C and its human ortholog granzyme H, is still unclear. Granzyme C is constitutively expressed by mature, cytolytic innate lymphoid 1 cells (ILC1s). Whether other antiviral effector cells also produce granzyme C and whether it is continually expressed or responsive to the environment is unknown. To explore this, we analyzed granzyme C expression in different murine skin-resident antiviral lymphocytes. At steady-state, dendritic epidermal T cells (DETCs) expressed granzyme C while dermal γδ T cells did not. CD8+ tissue-resident memory T cells (TRM) generated in response to cutaneous viral infection with the poxvirus vaccinia virus (VACV) also expressed granzyme C. Both DETCs and virus-specific CD8+ TRM upregulated granzyme C upon local VACV infection. Continual Ag exposure was not required for maintained TRM expression of granzyme C, although re-encounter with cognate Ag boosted expression. Additionally, IL-15 treatment increased granzyme C expression in both DETCs and TRM. Together, our data demonstrate that granzyme C is widely expressed by antiviral T cells in the skin and that expression is responsive to both environmental stimuli and TCR engagement. These data suggest that granzyme C may have functions other than killing in tissue-resident lymphocytes.

Exploring the molecular mechanisms of the involvement of GZMB-Caspase-3-GSDME pathway in the progression of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease with an unclear pathogenesis. Granzyme B (GZMB) has been reported as a potential therapeutic target for RA treatment, but its mechanism remains unclear. This study aimed to explore the molecular mechanism of the GZMB-Caspase-3-GSDME pathway in the progression of RA. An SD rat model of RA was constructed, and Western blot analysis was used to verify the high expression of the GZMB gene in RA rats. Functional validation was then performed on two common RA cells, HFLS-RA cells and MH7A cells, by inhibiting the GZMB gene with the GZMB siRNA virus. Cell proliferation function was measured by CCK8 and EDU assays; cell pyroptosis markers were detected by the LDH assay; inflammation factor levels were measured by ELISA; and the expression of GZMB and pathway-related genes and proteins was measured by Western blot. After GZMB silencing, cell proliferation was decreased compared to the control group, and the inflammation factors IL-1b and IL-18, as well as the pyroptosis markers LDH, IL-1b, and IL-18, were all reduced. The GZMB-related proteins GZMB, caspase-3, and Gasdermin E (GSDME) were also decreased. Therefore, GZMB silencing reduces pyroptosis by inhibiting caspase-3 and Gasdermin E decomposition. In summary, GZMB silencing inhibits the activation of caspase-3 and Gasdermin E, thereby delaying inflammation in RA. The GZMB gene may be a potential therapeutic target for RA.

Spatial predictors of immunotherapy response in triple-negative breast cancer

Immune checkpoint blockade (ICB) benefits some patients with triple-negative breast cancer, but what distinguishes responders from non-responders is unclear1. Because ICB targets cell-cell interactions2, we investigated the impact of multicellular spatial organization on response, and explored how ICB remodels the tumour microenvironment. We show that cell phenotype, activation state and spatial location are intimately linked, influence ICB effect and differ in sensitive versus resistant tumours early on-treatment. We used imaging mass cytometry3 to profile the in situ expression of 43 proteins in tumours from patients in a randomized trial of neoadjuvant ICB, sampled at three timepoints (baseline, n = 243; early on-treatment, n = 207; post-treatment, n = 210). Multivariate modelling showed that the fractions of proliferating CD8+TCF1+T cells and MHCII+ cancer cells were dominant predictors of response, followed by cancer-immune interactions with B cells and granzyme B+ T cells. On-treatment, responsive tumours contained abundant granzyme B+ T cells, whereas resistant tumours were characterized by CD15+ cancer cells. Response was best predicted by combining tissue features before and on-treatment, pointing to a role for early biopsies in guiding adaptive therapy. Our findings show that multicellular spatial organization is a major determinant of ICB effect and suggest that its systematic enumeration in situ could help realize precision immuno-oncology.

Murine regulatory T cells utilize granzyme B to promote tumor metastasis

Regulatory T cells (Tregs) possess a wide range of mechanisms for immune suppression. Among them, Granzyme B (GzmB) and perforin expressed by Tregs were shown to inhibit tumor clearance in previous reports, which contradicted the canonical roles of these cytotoxic molecules expressed by cytotoxic T cells and NK cells in antitumor immune responses. Given the ability of the tumor to manipulate the microenvironment, Treg-derived GzmB function may represent an important approach to aid in tumor growth as well as facilitating tumor metastasis. In this study, we utilized Treg-specific GzmB knockout (Foxp3creGzmBfl/fl) mice to test whether Treg-derived GzmB can aid in tumor progression and metastasis. Using an IL-2 complex to activate GzmB expression in the non-immunogenic B16-F10 tumor model, we provide evidence to show that GzmB produced by Tregs is important for spontaneous metastasis to the lungs. In addition, we depleted CD8 + T cells to selectively measure the impact of Treg-derived GzmB in an experimental lung metastasis model by intravenous injection of B16-F10 tumor cells; our results demonstrate that Treg-derived GzmB plays an important role in increasing the metastatic burden to the lungs.

Granzyme K contributes to endothelial microvascular damage and leakage during skin inflammation

BACKGROUND

Granzyme K (GzmK) is a serine protease with minimal presence in healthy tissues while abundant in inflamed tissues. Initially thought to play an exclusive role in immune-mediated cell death, extracellular GzmK can also promote inflammation.

OBJECTIVES

To evaluate the role of GzmK in the pathogenesis of atopic dermatitis (AD), the most common inflammatory skin disease.

METHODS

A panel of human AD and control samples was analysed to determine if GzmK is elevated. Next, to determine a pathological role for GzmK in AD-like skin inflammation, oxazolone-induced dermatitis was induced in GzmK-/- and wild-type (WT) mice.

RESULTS

In human lesional AD samples, there was an increase in the number of GzmK+ cells compared with healthy controls. GzmK-/- mice exhibited reduced overall disease severity characterized by reductions in scaling, erosions and erythema. Surprisingly, the presence of GzmK did not notably increase the overall pro-inflammatory response or epidermal barrier permeability in WT mice; rather, GzmK impaired angiogenesis, increased microvascular damage and microhaemorrhage. Mechanistically, GzmK contributed to vessel damage through cleavage of syndecan-1, a key structural component of the glycocalyx, which coats the luminal surface of vascular endothelia.

CONCLUSIONS

GzmK may provide a potential therapeutic target for skin conditions associated with persistent inflammation, vasculitis and pathological angiogenesis.

Allelic variation of KIR and HLA tunes the cytolytic payload and determines functional hierarchy of NK cell repertoires

The functionality of natural killer (NK) cells is tuned during education and is associated with remodeling of the lysosomal compartment. We hypothesized that genetic variation in killer cell immunoglobulin-like receptor (KIR) and HLA, which is known to influence the functional strength of NK cells, fine-tunes the payload of effector molecules stored in secretory lysosomes. To address this possibility, we performed a high-resolution analysis of KIR and HLA class I genes in 365 blood donors and linked genotypes to granzyme B loading and functional phenotypes. We found that granzyme B levels varied across individuals but were stable over time in each individual and genetically determined by allelic variation in HLA class I genes. A broad mapping of surface receptors and lysosomal effector molecules revealed that DNAM-1 and granzyme B levels served as robust metric of the functional state in NK cells. Variation in granzyme B levels at rest was tightly linked to the lytic hit and downstream killing of major histocompatibility complex-deficient target cells. Together, these data provide insights into how variation in genetically hardwired receptor pairs tunes the releasable granzyme B pool in NK cells, resulting in predictable hierarchies in global NK cell function.

G Protein-Coupled Receptor 56 Characterizes CTLs and Reflects the Progression of Lung Cancer Patients

CTLs play important roles in host immune responses to tumors. CD4 CTLs are characterized by their ability to secrete cytotoxic effector molecules, such as granzyme B and perforin, and kill target cells in a MHC class II-restricted manner. However, the cell surface markers of CD4 CTLs remain unknown, which hinders their separation and research on their function. In this study, we performed a bioinformatics analysis and experimental validation that revealed that G protein-coupled receptor 56 (GPR56) is a cell surface marker that can be used to characterize CD4 CTLs. We found that GPR56 and granzyme B were coexpressed in extremely high levels in human peripheral blood T cells, and that anti-GPR56 stimulation significantly upregulated the expression of granzyme B in both CD4+GPR56+ and CD8+GPR56+ T cells. These findings suggest that GPR56 expression and the GPR56 signaling pathway could contribute directly to the toxic function of either CD4+ or CD8+ T cells. We also used GPR56 as a biomarker to investigate the clinical significance of CD4 CTLs. GPR56+ T cell levels were increased in patients with lung cancer, and GPR56 expression was significantly correlated with lung cancer progression. A further analysis revealed an increase in exhausted cell states in lung cancer patients because of upregulation of programmed cell death protein 1 expression in GPR56+ T cells. The findings of this study suggest that GPR56 characterizes the cytotoxic states of either CD4+ or CD8+ T cells.

Human Granzyme K Is a Feature of Innate T Cells in Blood, Tissues, and Tumors, Responding to Cytokines Rather than TCR Stimulation

NK cells and CD8 T cells use cytotoxic molecules to kill virally infected and tumor cell targets. While perforin and granzyme B (GzmB) are the most commonly studied lytic molecules, less is known about granzyme K (GzmK). However, this granzyme has been recently associated with improved prognosis in solid tumors. In this study, we show that, in humans, GzmK is predominantly expressed by innate-like lymphocytes, as well as a newly identified population of GzmK+CD8+ non- mucosal-associated invariant T cells with innate-like characteristics. We found that GzmK+ T cells are KLRG1+EOMES+IL-7R+CD62L-Tcf7int, suggesting that they are central memory T and effector memory T cells. Furthermore, GzmK+ cells are absent/low in cord blood, suggesting that GzmK is upregulated with immune experience. Surprisingly, GzmK+ cells respond to cytokine stimuli alone, whereas TCR stimulation downregulates GzmK expression, coinciding with GzmB upregulation. GzmK+ cells have reduced IFN-γ production compared with GzmB+ cells in each T cell lineage. Collectively, this suggests that GzmK+ cells are not naive, and they may be an intermediate memory-like or preterminally differentiated population. GzmK+ cells are enriched in nonlymphoid tissues such as the liver and adipose. In colorectal cancer, GzmK+ cells are enriched in the tumor and can produce IFN-γ, but GzmK+ expression is mutually exclusive with IL-17a production. Thus, in humans, GzmK+ cells are innate memory-like cells that respond to cytokine stimulation alone and may be important effector cells in the tumor.

GSK-3 Inhibitor Elraglusib Enhances Tumor-Infiltrating Immune Cell Activation in Tumor Biopsies and Synergizes with Anti-PD-L1 in a Murine Model of Colorectal Cancer

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase that has been implicated in numerous oncogenic processes. GSK-3 inhibitor elraglusib (9-ING-41) has shown promising preclinical and clinical antitumor activity across multiple tumor types. Despite promising early-phase clinical trial results, there have been limited efforts to characterize the potential immunomodulatory properties of elraglusib. We report that elraglusib promotes immune cell-mediated tumor cell killing of microsatellite stable colorectal cancer (CRC) cells. Mechanistically, elraglusib sensitized CRC cells to immune-mediated cytotoxicity and enhanced immune cell effector function. Using western blots, we found that elraglusib decreased CRC cell expression of NF-κB p65 and several survival proteins. Using microarrays, we discovered that elraglusib upregulated the expression of proapoptotic and antiproliferative genes and downregulated the expression of cell proliferation, cell cycle progression, metastasis, TGFβ signaling, and anti-apoptotic genes in CRC cells. Elraglusib reduced CRC cell production of immunosuppressive molecules such as VEGF, GDF-15, and sPD-L1. Elraglusib increased immune cell IFN-γ secretion, which upregulated CRC cell gasdermin B expression to potentially enhance pyroptosis. Elraglusib enhanced immune effector function resulting in augmented granzyme B, IFN-γ, TNF-α, and TRAIL production. Using a syngeneic, immunocompetent murine model of microsatellite stable CRC, we evaluated elraglusib as a single agent or combined with immune checkpoint blockade (anti-PD-1/L1) and observed improved survival in the elraglusib and anti-PD-L1 group. Murine responders had increased tumor-infiltrating T cells, augmented granzyme B expression, and fewer regulatory T cells. Murine responders had reduced immunosuppressive (VEGF, VEGFR2) and elevated immunostimulatory (GM-CSF, IL-12p70) cytokine plasma concentrations. To determine the clinical significance, we then utilized elraglusib-treated patient plasma samples and found that reduced VEGF and BAFF and elevated IL-1 beta, CCL22, and CCL4 concentrations correlated with improved survival. Using paired tumor biopsies, we found that tumor-infiltrating immune cells had a reduced expression of inhibitory immune checkpoints (VISTA, PD-1, PD-L2) and an elevated expression of T-cell activation markers (CTLA-4, OX40L) after elraglusib treatment. These results address a significant gap in knowledge concerning the immunomodulatory mechanisms of GSK-3 inhibitor elraglusib, provide a rationale for the clinical evaluation of elraglusib in combination with immune checkpoint blockade, and are expected to have an impact on additional tumor types, besides CRC.

Granzyme B Contributes to Choroidal Neovascularization and Age-Related Macular Degeneration Through Proteolysis of Thrombospondin-1

Age-related macular degeneration (AMD) is a leading cause of irreversible central vision loss in the elderly. The pathology of neovascular age-related macular degeneration (nAMD), also known as wet AMD, is associated with an abnormal blood vessel growth in the eye and involves an imbalance of proangiogenic and antiangiogenic factors. Thrombospondin (TSP)-1 and TSP-2 are endogenous matricellular proteins that inhibit angiogenesis. TSP-1 is significantly diminished in eyes with AMD, although the mechanisms involved in its reduction are unknown. Granzyme B (GzmB) is a serine protease with an increased extracellular activity in the outer retina and choroid of human eyes with nAMD-related choroidal neovascularization (CNV). This study investigated whether TSP-1 and TSP-2 are GzmB substrates using in silico and cell-free cleavage assays and explored the relationship between GzmB and TSP-1 in human eyes with nAMD-related CNV and the effect of GzmB on TSP-1 in retinal pigment epithelial culture and an explant choroid sprouting assay (CSA). In this study, TSP-1 and TSP-2 were identified as GzmB substrates. Cell-free cleavage assays substantiated the GzmB proteolysis of TSP-1 and TSP-2 by showing dose-dependent and time-dependent cleavage products. TSP-1 and TSP-2 proteolysis were hindered by the inhibition of GzmB. In the retinal pigment epithelium and choroid of human eyes with CNV, we observed a significant inverse correlation between TSP-1 and GzmB, as indicated by lower TSP-1 and higher GzmB immunoreactivity. In CSA, the vascular sprouting area increased significantly with GzmB treatment and reduced significantly with TSP-1 treatment. Western blot showed significantly reduced expression of TSP-1 in GzmB-treated retinal pigment epithelial cell culture and CSA supernatant compared with that in controls. Together, our findings suggest that the proteolysis of antiangiogenic factors such as TSP-1 by extracellular GzmB might represent a mechanism through which GzmB may contribute to nAMD-related CNV. Future studies are needed to investigate whether pharmacologic inhibition of extracellular GzmB can mitigate nAMD-related CNV by preserving intact TSP-1.

Human granzyme B binds Plasmodium falciparum Hsp70-x and mediates antiplasmodial activity in vitro

Cell surface-bound human Hsp70 (hHsp70) sensitises tumour cells to the cytolytic attack of natural killer (NK) cells through the mediation of apoptosis-inducing serine protease, granzyme B (GrB). hHsp70 is thought to recruit NK cells to the immunological synapse via the extracellularly exposed 14 amino acid sequence, TKDNNLLGRFELSG, known as the TKD motif of Hsp70. Plasmodium falciparum-infected red blood cells (RBCs) habour both hHsp70 and an exported parasite Hsp70 termed PfHsp70-x. Both PfHsp70-x and hHsp70 share conserved TKD motifs. The role of PfHsp70-x in facilitating GrB uptake in malaria parasite-infected RBCs remains unknown, but hHsp70 enables a perforin-independent uptake of GrB into tumour cells. In the current study, we comparatively investigated the direct binding of GrB to either PfHsp70-x or hHsp70 in vitro. Using ELISA, slot blot assay and surface plasmon resonance (SPR) analysis, we demonstrated a direct interaction of GrB with hHsp70 and PfHsp70-x. SPR analysis revealed a higher affinity of GrB for PfHsp70-x than hHsp70. In addition, we established that the TKD motif of PfHsp70-x directly interacts with GrB. The data further suggest that the C-terminal EEVN motif of PfHsp70-x augments the affinity of PfHsp70-x for GrB but is not a prerequisite for the binding. A potent antiplasmodial activity (IC50 of 0.5 µM) of GrB could be demonstrated. These findings suggest that the uptake of GrB by parasite-infected RBCs might be mediated by both hHsp70 and PfHsp70-x. The combined activity of both proteins could account for the antiplasmodial activity of GrB at the blood stage.

NK cell-derived extracellular granzyme B drives epithelial ulceration during HSV-2 genital infection

Genital herpes is characterized by recurrent episodes of epithelial blistering. The mechanisms causing this pathology are ill defined. Using a mouse model of vaginal herpes simplex virus 2 (HSV-2) infection, we show that interleukin-18 (IL-18) acts upon natural killer (NK) cells to promote accumulation of the serine protease granzyme B in the vagina, coinciding with vaginal epithelial ulceration. Genetic loss of granzyme B or therapeutic inhibition by a specific protease inhibitor reduces disease and restores epithelial integrity without altering viral control. Distinct effects of granzyme B and perforin deficiency on pathology indicates that granzyme B acts independent of its classic cytotoxic role. IL-18 and granzyme B are markedly elevated in human herpetic ulcers compared with non-herpetic ulcers, suggesting engagement of these pathways in HSV-infected patients. Our study reveals a role for granzyme B in destructing mucosal epithelium during HSV-2 infection, identifying a therapeutic target to augment treatment of genital herpes.

High TOX expression on CD8+ T cells in pure red cell aplasia

Thymocyte selection-associated high-mobility group box protein (TOX) is an important molecule regulating the development and exhaustion of T lymphocytes. Our aim is to investigate the role of TOX in the immune pathogenesis of pure red cell aplasia (PRCA). TOX expression of CD8⁺ lymphocytes from the peripheral blood of patients with PRCA was detected by flow cytometry. Additionally, the expression of immune checkpoint molecules PD1 and LAG3 and cytotoxic molecules perforin and granzyme B of CD8⁺ lymphocytes was measured. The quantity of CD4⁺CD25⁺CD127^low T cells was analyzed. TOX expression on CD8⁺ T lymphocytes in PRCA patients was significantly increased (40.73 [Formula: see text] 16.03 vs. 28.38 [Formula: see text] 12.20). The expression levels of PD1 and LAG3 on CD8⁺ T lymphocytes in PCRA patients were significantly higher than those in the control group (34.18 [Formula: see text] 13.26 vs. 21.76 [Formula: see text] 9.22 and 14.17 [Formula: see text] 13.74 vs. 7.24 [Formula: see text] 5.44, respectively). The levels of perforin and granzyme in CD8⁺ T lymphocytes of PRCA patients were 48.60 [Formula: see text] 19.02 and 46.66 [Formula: see text] 25.49, respectively, which were significantly higher than those of the control group (31.46 [Formula: see text] 7.82 and 16.17 [Formula: see text] 4.84, respectively). The number of CD4⁺CD25⁺CD127^low Treg cells in PRCA patients was significantly decreased (4.30 [Formula: see text] 1.27 vs. 1.75 [Formula: see text] 1.22). In PRCA patients, CD8⁺ T cells were activated and exhibited overexpression of TOX, PD1, LAG3, perforin, and granzyme B, while regulatory T cells decreased. These findings suggest that T cell abnormality plays a critical role in the pathogenesis of PRCA.

A flow-cytometry-based assay to assess granule exocytosis and GZB delivery by human CD8 T cells and NK cells

CD8 T and NK cells mediate killing by delivery of perforin and granzyme B (GZB) stored in lysosome-like granules. We present a flow-cytometry-based protocol combined with a redirected killing assay to evaluate granule exocytosis and the cytotoxic potential of human CD8 T cells and NK cells. We describe the assessment of the delivered GZB inside the target cells. We then detail the detection of lysosome membrane protein CD107a exposed on the cell surface of the effector cells upon degranulation. For complete details on the use and execution of this protocol, please refer to Chen et al. (2021).1.

Differential regulatory T cell signature after recovery from mild COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is characterized by a range of symptoms in which host immune response have been associated with disease progression. However, the putative role of regulatory T cells (Tregs) in determining COVID-19 outcomes has not been thoroughly investigated. Here, we compared peripheral Tregs between volunteers not previously infected with SARS-CoV-2 (healthy control [HC]) and volunteers who recovered from mild (Mild Recovered) and severe (Severe Recovered) COVID-19. Peripheral blood mononuclear cells (PBMC) were stimulated with SARS-CoV-2 synthetic peptides (Pool Spike CoV-2 and Pool CoV-2) or staphylococcal enterotoxin B (SEB). Results of a multicolor flow cytometric assay showed higher Treg frequency and expression of IL-10, IL-17, perforin, granzyme B, PD-1, and CD39/CD73 co-expression in Treg among the PBMC from the Mild Recovered group than in the Severe Recovered or HC groups for certain SARS-CoV-2 related stimulus. Moreover, Mild Recovered unstimulated samples presented a higher Tregs frequency and expression of IL-10 and granzyme B than did that of HC. Compared with Pool CoV-2 stimuli, Pool Spike CoV-2 reduced IL-10 expression and improved PD-1 expression in Tregs from volunteers in the Mild Recovered group. Interestingly, Pool Spike CoV-2 elicited a decrease in Treg IL-17+ frequency in the Severe Recovered group. In HC, the expression of latency-associated peptide (LAP) and cytotoxic granule co-expression by Tregs was higher in Pool CoV-2 stimulated samples. While Pool Spike CoV-2 stimulation reduced the frequency of IL-10+ and CTLA-4+ Tregs in PBMC from volunteers in the Mild Recovered group who had not experienced certain symptoms, higher levels of perforin and perforin+granzyme B+ co-expression by Tregs were found in the Mild Recovered group in volunteers who had experienced dyspnea. Finally, we found differential expression of CD39 and CD73 among volunteers in the Mild Recovered group between those who had and had not experienced musculoskeletal pain. Collectively, our study suggests that changes in the immunosuppressive repertoire of Tregs can influence the development of a distinct COVID-19 clinical profile, revealing that a possible modulation of Tregs exists among volunteers of the Mild Recovered group between those who did and did not develop certain symptoms, leading to mild disease.

[Experimental Study on the Characteristic Changes of the Immunological Microenvironment at the Maternal-Fetal Interface in IVF-ET Pregnancy]

Objective

To investigate the characteristic functional changes of the decidual natural killer (NK) cells and γδ T cells, two immunocytes in the decidua, at the maternal-fetal interface in in vitro fertilization-embryo transfer (IVF-ET) pregnancy.

Methods

Decidual samples were collected from 12 women of natural pregnancy (NP) and 32 women of IVF-ET pregnancy, who were enrolled in the NP group and the IVF-ET group, respectively. Then part of the decidual samples were paraffin-embedded for HE staining and immunofluorescence staining, while the rest of the samples were digested and Percoll was used for isolating decidual immunocytes (DICs) by gradient centrifugation. Flow cytometry was used to determine the cell counts of decidual NK cells and γδ T cells and the expression levels of their surface activation markers, CD69 and NKG2D in the NP and the IVF-ET groups. In addition, the expression levels of IFN-γ, TNF-α, IL-17A, and IL-10, the intracellular cytokines, and granzyme B, perforin, and granulysin, the cytolytic granules, were measured. The characteristic changes in the relevant immunological indicators were compared and analyzed.

Results

HE staining of the tissue specimens showed that the typical structure of decidua was observed, and that lymphocytes were enriched in the decidua. Immunofluorescence staining showed that the percentage of decidual NK (dNK) cells in nucleated cells of the IVF-ET group was significantly lower than that of the NP group ( P<0.05). Flow cytometry analysis of DICs showed that, compared with those of the NP group, the percentage of dNK cells of the IVF-ET group was decreased ( P<0.05) and the expression levels of IL-10 and perforin were significantly decreased in the IVF-ET group ( P<0.05). However, there was no significant difference in the decidual γδ T (dγδT) cell count between the two groups. The expression of IL-10, IL-17A, and perforin was downregulated in the IVF-ET group ( P<0.05). There was no significant difference in the expression of IFN-γ, TNF-α, granzyme B, and granulysin, the cellular function indicators ( P>0.05).

Conclusion

The dNK cell count and the secretion of some intracellular cytokines of dNK and dγδT cells of women of IVF-ET pregnancy decreased to some degree, which suggests that certain changes may have taken place in the immunological microenvironment at the maternal-fetal interface. The specific effect of these changes on pregnancy outcomes needs further investigation.

Cadmium impairs the development of natural killer cells and bidirectionally modifies their capacity for cytotoxicity

Cadmium (Cd) is a highly toxic heavy metal in the environment. The aim of this study was to investigate the impact of Cd on natural killer (NK) cells. C57BL/6 mice were treated with 10 ppm Cd via drinking water for 3 months, and the development of NK cells in the bone marrow (BM) and the cytotoxicity of mature NK (mNK) cells in the peripheral immune organs were evaluated thereafter; the impact of Cd on the cytotoxicity of mNK cells from human peripheral blood mononuclear cells (PBMC) was also investigated. Whereas Cd treatment impaired the differentiation of NK progenitors in the BM, Cd treatment activated the JAK3/STAT5 signaling to drive the proliferation of mNK cells and thereby lead to a compensation increase of mNK cells in the peripheral immune organs of mice. Additionally, Cd treatment bidirectionally regulated the cytotoxicity of mouse mNK cells to differential tumor cells, dependent on the levels of Fas expression in the tumor cells; mechanically, Cd treatment activated the JAK3/STAT5 signaling to promote the expression of FasL in mNK cells to increase their cytotoxicity, while Cd treatment reduced the expression of granzyme B in mNK cells to impair their cytotoxicity in the peripheral immune organs of mice. Likewise, in vitro assays indicated that Cd treatment also activated the JAK3/STAT5 signaling to increase the expression of FasL, whereas Cd treatment reduced the expression of granzyme B in human mNK cells. Thus Cd treatment impaired the development of NK cells in the BM and bidirectionally regulated the cytotoxicity of mNK cells in the peripheral immune organs, which may extend our current understanding for the immunotoxicity of Cd.

IL-33 induces granzyme C expression in murine mast cells via an MSK1/2-CREB-dependent pathway

Granzymes comprise a group of proteases involved in the killing of infected or cancerous cells by the immune system. Although best studied in T cells and natural killer (NK) cells, they are also expressed in some innate immune cells. Granzymes B and C are encoded in the mouse chymase locus that also encodes a number of mast cell-specific proteases. In line with this, mast cells can express granzyme B, although how this is regulated and their ability to express other granzymes is less well studied. We therefore examined how IL-33, a cytokine able to activate mast cells but not induce degranulation, regulated granzyme B and C levels in mast cells. Granzyme C, but not B, mRNA was strongly up-regulated in bone marrow-derived mast cells following IL-33 stimulation and there was a corresponding increase in granzyme C protein. These increases in both granzyme C mRNA and protein were blocked by a combination of the p38α/β MAPK inhibitor VX745 and the MEK1/2 inhibitor PD184352, which blocks the activation of ERK1/2. ERK1/2 and p38α activate the downstream kinases, mitogen and stress-activated kinases (MSK) 1 and 2, and IL-33 stimulated the phosphorylation of MSK1 and its substrate CREB in an ERK1/2 and p38-dependent manner. The promoter for granzyme C contains a potential CREB-binding site. Bone marrow-derived mast cells from either MSK1/2 double knockout or CREB Ser133Ala knockin mice were unable to up-regulate granzyme C. Together these results indicate that IL-33-induced granzyme C expression in mast cells is regulated by an MSK1/2-CREB-dependent pathway.

The BCL-2 Inhibitor Venetoclax Augments Immune Effector Function Mediated by Fas Ligand, TRAIL, and Perforin/Granzyme B, Resulting in Reduced Plasma Viremia and Decreased HIV Reservoir Size during Acute HIV Infection in a Humanized Mouse Model

The BCL-2 prosurvival protein is implicated in HIV persistence and is a potential therapeutic target for HIV eradication efforts. We now know that cells harboring HIV are preferentially enriched for high BCL-2 expression, enabling their survival, and that the BCL-2 inhibitor venetoclax promotes the death of actively replicating HIV-infected cells in vitro and ex vivo. Herein, we assess the effect of venetoclax on immune clearance of infected cells and show that BCL-2 inhibition significantly enhances target cell killing induced by Fas ligand, TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), and perforin/granzyme B and synergistically enhances autologous NK (natural killer) and CD8 cells' killing of target cells. In a humanized mouse model of acute HIV infection, venetoclax monotherapy significantly decreases plasma viremia and normalizes CD4:CD8 ratios, and results in more mice with undetectable provirus levels than control. In this model, treatment was associated with leukopenia, as has been described clinically in patients receiving venetoclax for other indications. These data confirm meaningful anti-HIV effects of venetoclax during HIV infection but suggest that venetoclax use should be combined with ART (antiretroviral therapy) to reduce toxicity. IMPORTANCE This study is the first to examine the applicability of BCL-2 inhibition in the setting of active HIV infection in vivo. Furthermore, this study demonstrates that venetoclax significantly enhances target cell killing induced by Fas ligand, TRAIL, and perforin/granzyme B and synergistically enhances autologous NK and CD8 cells' killing of target cells.

Graphene oxide modulates dendritic cell ability to promote T cell activation and cytokine production

An important aspect of immunotherapy is the ability of dendritic cells (DCs) to prime T cell immunity, an approach that has yielded promising results in some early phase clinical trials. However, novel approaches are required to improve DC therapeutic efficacy by enhancing their uptake of, and activation by, disease relevant antigens. The carbon nano-material graphene oxide (GO) may provide a unique way to deliver antigen to innate immune cells and modify their ability to initiate effective adaptive immune responses. We have assessed whether GO of various lateral sizes affects DC activation and function in vitro and in vivo, including their ability to take up, process and present the well-defined model antigen ovalbumin (OVA). We have found that GO flakes are internalised by DCs, while having minimal effect on their viability, activation phenotype or cytokine production. Although adsorption of OVA protein to either small or large GO flakes promoted its uptake into DCs, large GO interfered with OVA processing. In terms of modulation of DC function, delivery of OVA via small GO flakes significantly enhanced DC ability to induce proliferation of OVA-specific CD4⁺ T cells, promoting granzyme B secretion in vitro. On the other hand, delivery of OVA via large GO flakes augmented DC ability to induce proliferation of OVA-specific CD8⁺ T cells, and their production of IFN-γ and granzyme B. Together, these data demonstrate the capacity of GO of different lateral dimensions to act as a promising delivery platform for DC modulation of distinct facets of the adaptive immune response, information that could be exploited for future development of targeted immunotherapies.

The low-density lipoprotein receptor-mTORC1 axis coordinates CD8+ T cell activation

Activation of T cells relies on the availability of intracellular cholesterol for an effective response after stimulation. We investigated the contribution of cholesterol derived from extracellular uptake by the low-density lipoprotein (LDL) receptor in the immunometabolic response of T cells. By combining proteomics, gene expression profiling, and immunophenotyping, we described a unique role for cholesterol provided by the LDLR pathway in CD8+ T cell activation. mRNA and protein expression of LDLR was significantly increased in activated CD8+ compared to CD4+ WT T cells, and this resulted in a significant reduction of proliferation and cytokine production (IFNγ, Granzyme B, and Perforin) of CD8+ but not CD4+ T cells from Ldlr -/- mice after in vitro and in vivo stimulation. This effect was the consequence of altered cholesterol routing to the lysosome resulting in a lower mTORC1 activation. Similarly, CD8+ T cells from humans affected by familial hypercholesterolemia (FH) carrying a mutation on the LDLR gene showed reduced activation after an immune challenge.

Hemizygous Granzyme A Mice Expressing the hSOD1G93A Transgene Show Slightly Extended Lifespan

Granzyme A (gzmA), a serine protease involved in the modulation of the inflammatory immune response, is found at an elevated level in the serum from ALS patients. However, the influence of gzmA on the progression of ALS remains unclear. The aim of our work was to assess whether the absence of gzmA in an ALS murine model could help slow down the progression of the disease. Homozygous and hemizygous gzmA-deficient mice expressing the hSOD1G93A transgene were generated, and survival of these mice was monitored. Subsequently, gene and protein expression of inflammatory and oxidative stress markers was measured in the spinal cord and quadriceps of these mice. We observed the longest lifespan in gzmA+/- mice. GzmA gene and protein expression was downregulated in the spinal cord and serum from gmzA+/- mice, confirming that the increased survival of hemizygous mice is correlated with lower levels of gzmA. In addition, mRNA and protein levels of glutathione reductase (GSR), involved in oxidative stress, were found downregulated in the spinal cord and quadriceps of gmzA+/- mice, together with lower IL-1β and IL-6 mRNA levels in hemyzigous mice. In summary, our findings indicate for the first time that reduced levels, but not the absence, of gzmA could slightly ameliorate the disease progression in this animal model.

A hydrogel platform for co-delivery of immunomodulatory proteins for pancreatic islet allografts

Type 1 diabetes (T1D), an autoimmune disorder in which the insulin-producing β-cells in the islets of Langerhans in the pancreas are destroyed, afflicts over 1.6 million Americans. Although pancreatic islet transplantation has shown promise in treating T1D, continuous use of required immunosuppression regimens limits clinical islet transplantation as it poses significant adverse effects on graft recipients and does not achieve consistent long-term graft survival with 50%-70% of recipients maintaining insulin independence at 5 years. T cells play a key role in graft rejection, and rebalancing pathogenic T effector and protective T regulatory cells can regulate autoimmune disorders and transplant rejection. The synergy of the interleukin-2 (IL-2) and Fas immunomodulatory pathways presents an avenue for eliminating the need for systemic immune suppression by exploiting IL-2's role in expanding regulatory T cells and leveraging Fas ligand (FasL) activity on antigen-induced cell death of effector T cells. Herein, we developed a hydrogel platform for co-delivering an analog of IL-2, IL-2D, and FasL-presenting microgels to achieve localized immunotolerance to pancreatic islets by targeting the upregulation of regulatory T cells and effector T cells simultaneously. Although this hydrogel provided for sustained, local delivery of active immunomodulatory proteins, indefinite allograft survival was not achieved. Immune profiling analysis revealed upregulation of target regulatory T cells but also increases in Granzyme B-expressing CD8+ T cells at the graft site. We attribute the failed establishment of allograft survival to these Granzyme B-expressing T cells. This study underscores the delicate balance of immunomodulatory components important for allograft survival - whose outcome can be dependent on timing, duration, modality of delivery, and disease model.