Search Results (45)

Background/Objective: Francisella tularensis is a highly infectious intracellular pathogen that causes severe pulmonary tularemia following aerosol exposure, yet no licensed vaccine exists. Because infection initiates at the respiratory mucosa, understanding mechanisms of protective pulmonary immunity is critical for mucosal vaccine development. This study investigated the role of lung-resident γδ T cells following intranasal immunization with inactivated F. tularensis (iFt) and subsequent lethal challenge with live vaccine strain (LVS). Methods: Mice were intranasally immunized with iFt and later challenged with lethal LVS. Pulmonary immune responses were evaluated using flow cytometry and cytokine analysis. Recruitment of γδ and αβ T cells, production of IL-17 and IFN-γ, neutrophil infiltration, and γδ T cell memory phenotypes were assessed in naïve and immunized mice following infection. Results: Primary LVS infection induced rapid recruitment of γδ T cells to the lung beginning on Day 2 post-infection, preceding significant αβ T cell accumulation. Increased pulmonary IL-17 and IFN-γ correlated with expansion of IL-17– and IFN-γ–associated γδ T cell populations. Following iFt immunization, mice demonstrated enhanced survival after lethal LVS challenge, accompanied by early increases in pulmonary IL-17 and IL-17 producing γδ T cells. Immunized mice also exhibited expansion of effector memory and central memory γδ T cell populations associated with IL-17 production. Conclusions: These findings identify IL-17 producing γδ T cells as contributors to early mucosal immunity following intranasal vaccination against F. tularensis and suggest that targeting lung-resident γδ T cells may support the development of next-generation mucosal vaccines against respiratory pathogens. Full article

Background: Pancreatic ductal adenocarcinoma (PDAC) has a profoundly immunosuppressive tumour microenvironment (TME) that limits anti-tumour immunity and contributes to resistance to immunotherapy. Although γδ T-cells can integrate innate and adaptive immune signals, their abundance, transcriptional states and regulatory pathways in PDAC remain incompletely defined. Methods: We performed integrated single-cell RNA sequencing analysis of 39 pancreatic tissue samples, comprising 33 PDAC tumours and 6 adjacent normal tissues. After dataset integration, immune cell annotation, and stringent per-cell gating, γδ T-cells were quantified and profiled for checkpoint-, ligand-, and chemokine-related programmes. Results: γδ T-cells were detectable across PDAC samples but showed substantial inter-sample heterogeneity in abundance. Among candidate inhibitory pathways, PDCD1, CD274, and HAVCR2 expression in γδ T-cells did not differ significantly between tumour and adjacent tissues, whereas KLRC1 (encoding NKG2A) showed a tumour-associated difference at the single-cell level, with a consistent directional pattern in sample-level summaries. NKG2A expression was comparable between γδ T-cells and NK cells, suggesting a shared inhibitory programme. HLA-E, the ligand for NKG2A, showed higher epithelial-cell expression in tumour than adjacent tissue in sample-level summaries (median 1.06 vs. 0.57; BH-q = 0.035). Chemokine analysis identified enrichment of CCL2, CCL4, CCL5, CXCL8 and CXCL12, with limited CXCL9/10/11 signalling within the PDAC TME. Within γδ T-cells, CXCR4 was the trafficking receptor, followed by CCR6, CCR7 and CXCR6. Conclusions: PDAC-infiltrating γδ T-cells show marked inter-sample heterogeneity and variable inhibitory and trafficking-related programmes. Integrated transcriptomic analysis nominates HLA-E–NKG2A as a candidate regulatory axis, with NK cells included as a biologically relevant comparator. Chemokine receptor patterns, particularly CXCR4, CCR6, CCR7 and CXCR6, suggest candidate trafficking features. These findings are hypothesis-generating and require spatial, protein-level and functional validation. Full article

Immunoglobulin G (IgG) is a central component of humoral immunity in coronavirus disease 2019 (COVID-19); however, increasing evidence suggests that infection-induced IgG repertoires exert immunomodulatory effects beyond classical antiviral functions. In this study, we investigated whether IgG from patients with moderate or severe COVID-19 directly modulates human peripheral γδ T cells and whether these effects are associated with disease severity-dependent IgG idiotype profiles. Purified IgG from non-exposed healthy controls, moderate COVID-19 patients, or severe COVID-19 patients was incubat-ed with peripheral blood mononuclear cells from healthy donors. γδ T cell phenotype, subset distribution, homing markers, and cytokine production were assessed by flow cytometry, while direct IgG–cell interactions were evaluated using fluorescent IgG binding assays. In parallel, proteomic profiling using human proteome microarrays was performed to identify γδ T cell-expressed protein targets recognized by COVID-19-induced IgG. IgG from SARS-CoV-2-infected individuals selectively reduced Vγ9⁺Vδ2⁺ γδ T cells, altered memory differentiation, downregulated CCR5, CCR6, and CD161 expression, and reshaped cytokine production in a severity-dependent manner. COVID-19 IgG bound directly to the γδ T cell membrane without inducing apoptosis, indicating a non-cytotoxic mechanism of modulation. Proteomic analysis revealed a marked expansion and diversification of γδ T cell-associated IgG targets in COVID-19, particularly in severe disease, with enrichment of pathways related to immune signaling and inflammation. Collectively, these findings identify γδ T cells as direct functional targets of SARS-CoV-2-induced IgG repertoires and demonstrate that disease severity shapes IgG idiotype networks with distinct immunomodulatory capacities. This work highlights a previously underappreciated antibody-mediated mechanism contributing to immune dysregulation in COVID-19. Full article

Autoinflammatory diseases are characterized by inappropriate activation of innate immunity resulting in excessive or persistent inflammation in the absence of infection. γδ T cells possess innate-like properties, including rapid responsiveness to stress-induced self-molecules, phosphoantigens, and inflammasome-derived cytokines, while retaining adaptive effector functions. Neutrophils and macrophages are well-established drivers of autoinflammatory disease, but increasing evidence implicates γδ T cells as key intermediaries by linking innate immune activation to tissue-specific inflammatory pathology. Here, we review evidence that in both monogenic and multifactorial autoinflammatory diseases—including, for example, familial Mediterranean fever, hyper-immunoglobulin (Ig) D syndrome, gout, Behçet’s disease, Still’s disease, atherosclerosis, and neurodegenerative disorders—γδ T cells display altered frequencies, activation states, cytokine polarization, and tissue recruitment. In inflammasome-driven diseases, skewing of γδ T cells toward interleukin (IL)-17 production has been observed, often accompanied by reduced interferon (IFN)γ secretion, thereby amplifying neutrophilic inflammation and tissue damage. In other diseases, e.g., Behcet’s disease, IFNγ and tumor necrosis factor (TNF)α producton predominate. Transcriptomic and tissue-based analyses support the accumulation and functional specialization of γδ T cells at sites of sterile inflammation. Collectively, these findings position γδ T cells as central amplifiers and modulators of inappropriate innate immune activation in the context of autoinflammatory diseases. Improved understanding of γδ T cell subset-specific regulation may inform novel therapeutic strategies targeting autoinflammatory diseases. Full article

Understanding the mechanisms of immune activation and deactivation is paramount. A host must initiate effective immunity against pathogenic infections while avoiding triggering immunity against self-antigens, which can lead to detrimental autoimmune disorders. Host immunological pathways can be categorized as Immunoglobulin (Ig)G-dominant eradicable immune reactions and IgA-dominant tolerable immune reactions. Eradicable immune reactions include Th1, Th2, Th22, and Thαβ immune responses against four different types of pathogens. Tolerable immune reactions include Th1-like, Th9, Th17, and Th3 immune responses against four different types of pathogens. Here, we try to determine the mechanisms of activation and deactivation of host immune reactions. The spleen and liver play contrasting roles in mediating immune responses: the spleen is primarily involved in immune activation, whereas the liver is responsible for immune deactivation. Similarly, the sympathetic and parasympathetic nervous systems have opposing functions in immune modulation, with the sympathetic system promoting pro-inflammatory responses and the parasympathetic system facilitating anti-inflammatory processes. Furthermore, adrenocorticotropic hormone (ACTH) and glucocorticosteroids exhibit contrasting effects on immune regulation: ACTH is involved in activating adaptive immunity while inhibiting innate immunity, whereas glucocorticosteroids activate natural IgM antibody associated with innate immunity while inhibiting adaptive immunity. Heat shock proteins, particularly molecular chaperones induced by fever, play pivotal roles in immune activation. Conversely, IgD B cells and gamma/delta T cells contribute to immune deactivation through mechanisms such as clonal anergy. Understanding these mechanisms provides insights into immunological pathways, aiding in the better management of infectious diseases and autoimmune disorders. Full article

Background: In the adaptive immune response of the dromedary (Camelus dromedarius, Camdro), the T cell receptor (TR) repertoire of the gamma–delta (γδ) T cells is unusually diversified both by somatic hypermutation in rearranged TR gamma (TRG) and delta (TRD) genes and by the diversity in sequence and length of the third complementarity-determining region (CDR3) of the TRD chain. Methods: The purpose was to investigate, in the absence of 3D structures, the role of Camdro γδ T cells, focusing on the binding interactions at the interface between the V-gamma and V-delta domains, and in complex with the CD1D, a major histocompatibily class I (MH1)-like glycoprotein presenting lipid antigen in association with B2M. A combination of hypermutated TRG dromedary cDNA clones was paired with TRD clones bearing very long, long, or short CDR3s, all isolated from the spleen of a single animal. Results: The 3D models of the Camdro TRG_TRD/CD1D_B2M complexes were inferred using the Homo sapiens 3D structure and the ImMunoGeneTics (IMGT) numbering for V, C, and G domains, and investigated for binding interactions at the interface of the paired V-gamma_V-delta and at the interface with CD1D. Our results suggest that transcripts with long CDR3s may derive from a population of CD1D-restricted γδ T cells. Both the CD1D G-alpha1-like and G-alpha-2 like domain helices were contacted by both the V-gamma and V-delta CDR-IMGT loops. Conclusions: Our findings further emphasize the similarity between the γδ T cells population we analyzed in Camelus dromedarius and the CD1D-restricted γδ NKT cells in Homo sapiens. Full article

Dendritic epidermal T cells (DETCs) are a γδ T cell subset residing in the skin epidermis. Although they have been known for decades, the fate of DETCs has largely remained enigmatic. Recent studies have highlighted the relationship between the gut microbiome and γδ T cells in various epithelial and non-epithelial tissues, such as the small intestine, lung, liver, gingiva, and testis. While the skin microbiota has been shown to impact skin γδ T cells, a direct relationship between the gut microbiota and DETCs remains unexplored. In this study, we investigated whether DETCs are regulated by the gut microbiota in the steady-state skin epidermis. We examined the occurrence of DETCs in Balb/c mice, which have a skin epidermis barely populated with DETCs, compared to C57BL/6 mice, under different housing conditions. Our findings reveal that local skin inflammation markedly increases DETC numbers in the ear epidermis of Balb/c mice and that DETCs are activated by environmental factors. Furthermore, an investigation of the gut microbiota under different housing conditions revealed distinct microbial compositions and functional profiles. Taken together, these results suggest a strong connection between DETCs and gut microbiota. Full article

Epstein–Barr virus is highly associated with nasopharyngeal carcinoma (NPC) with genes expressed for tumor transformation or maintenance of viral latency, but there are certain genes that can modulate immune molecules. Butyrophilin 2A1 (BTN2A1) is an important activating protein for presenting phosphoantigens for recognition by Vγ9Vδ2 T cells to achieve antitumor activities. We have previously shown that Vγ9Vδ2 T cells achieve efficacy against NPC when BTN2A1 and BTN3A1 are upregulated by stimulating EBV gene expression, particularly LMP1. While BTN3A1 can be induced by the LMP1-mediated IFN-γ/JNK/NLRC5 pathway, the viral gene that can regulate BTN2A1 remains elusive. We showed that BTN2A1 expression is directly mediated by EBV BRRF1, which can trigger the BTN2A1 promoter and downstream JAK3-STAT3 pathway in NPC43 cells, as shown by RNA-seq data and verified via inhibitor experiments. Furthermore, BRRF1 downregulated IL-22 binding protein (IL-22RA2) to complement the EBNA1-targeting probe (P₄)-induced IL-22 expression. Therefore, this study elucidated a new mechanism of stimulating BTN2A1 expression in NPC cells via the EBV gene BRRF1. The JAK3-STAT3 pathway could act in concordance with IL-22 to enhance the expression of BTN2A1, which likely leads to increased tumor cell killing by Vγ9Vδ2 T cells for enhanced potential as immunotherapy against the cancer. Full article

Cryptococcus neoformans is an environmental pathogen that causes life-threatening disease in immunocompromised persons. The majority of immunological studies have centered on CD4⁺ T-cell dysfunction and associated cytokine signaling pathways, optimization of phagocytic cell function against fungal cells, and identification of robust antigens for vaccine development. However, a growing body of literature exists regarding cytotoxic cells, specifically CD8⁺ T-cells, Natural Killer cells, gamma/delta T-cells, NK T-cells, and Cytotoxic CD4⁺ T-cells, and their role in the innate and adaptive immune response during C. neoformans and C. deneoformans infection. In this review, we (1) provide a comprehensive report of data gathered from mouse and human studies on cytotoxic cell function and phenotype, (2) discuss harmonious and conflicting results on cellular responses in mice models and human infection, (3) identify gaps of knowledge in the field ripe for exploration, and (4) highlight how innovative immunological tools could enhance the study of cytotoxic cells and their potential immunomodulation during cryptococcosis. Full article

Although the vast majority of CTCL subtypes are of the CD4+ T-helper cell differentiation phenotype, there is a spectrum of CD8+ variants that manifest wide-ranging clinical, histologic, and phenotypic features that inform the classification of the disease. CD8, like CD4, and cytotoxic molecules (including TIA and granzyme) are readily detectable via IHC staining of tissue and, when expressed on the phenotypically abnormal T-cell population, can help distinguish specific CTCL subtypes. Nonetheless, given that the histopathologic differential for CD8+ lymphoproliferative disorders and lymphomas may range from very indolent lymphomatoid papulosis (LyP) to aggressive entities like CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma (AECTCL), CD8 and/or cytotoxic molecule expression alone is insufficient for diagnosis and is not in itself an indicator of prognosis. We present a review of CTCL subtypes that can demonstrate CD8 positivity: CD8+ mycosis fungoides (MF), LyP type D, subcutaneous panniculitis-like T-cell lymphoma (SPTCL), primary cutaneous gamma/delta T-cell lymphoma (PCGDTL), CD8+ AECTCL, and acral CD8+ T-cell lymphoproliferative disorder (acral CD8+ TCLPD). These diseases may have different clinical manifestations and distinctive treatment algorithms. Due to the rare nature of these diseases, it is imperative to integrate clinical, histologic, and immunohistochemical findings to determine an accurate diagnosis and an appropriate treatment plan. Full article

Glioblastoma (GBM) is an immunologically cold tumor, but several immunotherapy-based strategies show promise, including the administration of ex vivo expanded and activated cytotoxic gamma delta T cells. Cytotoxicity is partially mediated through interactions with natural killer group 2D ligands (NKG2DL) on tumor cells. We sought to determine whether the addition of the blood–brain barrier penetrant PARP inhibitor niraparib to the standard of care DNA alkylator temozolomide (TMZ) could upregulate NKG2DL, thereby improving immune cell recognition. Changes in viability were consistent with prior publications as there was a growth inhibitory effect of the combination of TMZ and niraparib. However, decreases in viability did not always correlate with changes in NKG2DL mRNA. ULBP1/Mult-1 mRNA was increased with the combination therapy in comparison to either drug alone in two of the three cell types tested, even though viability was consistently decreased. mRNA expression correlated with protein levels and ULBP1/MULT-1 cell surface protein was significantly increased with TMZ and niraparib treatment in four of the five cell types tested. Gamma delta T cell-mediated cytotoxicity at a 10:1 effector-to-target ratio was significantly increased upon pretreatment of cells derived from a GBM PDX with TMZ and niraparib in comparison to the control or either drug alone. Together, these data demonstrate that the combination of PARP inhibition, DNA alkylation, and gamma delta T cell therapy has the potential for the treatment of GBM. Full article

Chimeric antigen receptor-T cells have spearheaded the field of adoptive cell therapy and have shown remarkable results in treating hematological neoplasia. Because of the different biology of solid tumors compared to hematological tumors, response rates of CAR-T cells could not be transferred to solid entities yet. CAR engineering has added co-stimulatory domains, transgenic cytokines and switch receptors to improve performance and persistence in a hostile tumor microenvironment, but because of the inherent cell type limitations of CAR-T cells, including HLA incompatibility, toxicities (cytokine release syndrome, neurotoxicity) and high costs due to the logistically challenging preparation process for autologous cells, the use of alternative immune cells is gaining traction. NK cells and γδ T cells that do not need HLA compatibility or macrophages and dendritic cells with additional properties such as phagocytosis or antigen presentation are increasingly seen as cellular vehicles with potential for application. As these cells possess distinct properties, clinicians and researchers need a thorough understanding of their peculiarities and commonalities. This review will compare these different cell types and their specific modes of action seen upon CAR activation. Full article

Encapsulation of Doxorubicin (Dox), a potent cytotoxic agent and immunogenic cell death inducer, in pegylated (Stealth) liposomes, is well known to have major pharmacologic advantages over treatment with free Dox. Reformulation of alendronate (Ald), a potent amino-bisphosphonate, by encapsulation in pegylated liposomes, results in significant immune modulatory effects through interaction with tumor-associated macrophages and activation of a subset of gamma-delta T lymphocytes. We present here recent findings of our research work with a formulation of Dox and Ald co-encapsulated in pegylated liposomes (PLAD) and discuss its pharmacological properties vis-à-vis free Dox and the current clinical formulation of pegylated liposomal Dox. PLAD is a robust formulation with high and reproducible remote loading of Dox and high stability in plasma. Results of biodistribution studies, imaging with radionuclide-labeled liposomes, and therapeutic studies as a single agent and in combination with immune checkpoint inhibitors or gamma-delta T lymphocytes suggest that PLAD is a unique product with distinct tumor microenvironmental interactions and distinct pharmacologic properties when compared with free Dox and the clinical formulation of pegylated liposomal Dox. These results underscore the potential added value of PLAD for chemo-immunotherapy of cancer and the relevance of the co-encapsulation approach in nanomedicine. Full article

(1) Background: The role of rare immune cell subtypes in many solid tumors, chief among them head and neck squamous cell carcinoma (HNSCC), has not been well defined. The objective of this study was to assess the association between proportions of common and rare immune cell subtypes and survival outcomes in HNSCC. (2) Methods: In this cohort study, we utilized a deconvolution approach based on the CIBERSORT algorithm and the LM22 signature matrix to infer proportions of immune cell subtypes from 517 patients with untreated HPV-negative HNSCC from The Cancer Genome Atlas. We performed univariate and multivariable survival analysis, integrating immune cell proportions with clinical, pathologic, and genomic data. (3) Results: We reliably deconvolved 22 immune cell subtypes in most patients and found that the most common immune cell types were M0 macrophages, M2 macrophages, and memory resting CD4 T cells. In the multivariable analysis, we identified advanced N stage and the presence of γδ T cells as independently predictive of poorer survival. (4) Conclusions: We uncovered that γδ T cells in the tumor microenvironment were a negative predictor of survival among patients with untreated HNSCC. Our findings underscore the need to better understand the role of γδ T cells in HNSCC, including potential pro-tumorigenic mechanisms, and whether their presence may predict the need for alternative therapy approaches. Full article

Basal cell carcinoma (BCC) is the most common form of skin cancer, contributing to nearly a third of new cancer cases in Western countries. Most BCCs are considered low risk “routine” lesions that can either be excised through surgery or treated with chemotherapeutic agents. However, around 1–2% of BCC cases are locally aggressive, present a high risk of metastasis, and often develop chemoresistance, termed advanced BCC. There currently exists no animal model or cell line that can recapitulate advanced BCC, let alone intermediate-risk and high-risk early BCC. We previously found that aggressive BCC tumours presented a Th2 cytokine inflammation profile, mesenchymal stem cell properties, and macrophage-induced tumoral inflammation. In this study, we aimed to identify potential BCC “relatives” among solid-organ malignancies who present similar immune cell proportions in their microenvironment compositions. Using immune cell type deconvolution by CIBERSORTx, and cell type enrichment by xCell, we determined three cancers with the most similar tumour microenvironments as compared to BCC. Specifically, chromophobe renal cell carcinoma, sarcoma, and skin cutaneous melanoma presented significance in multiple cell types, namely in CD4+ T lymphocytes, gammadelta T lymphocytes, and NK cell populations. Consequently, further literature analysis was conducted to understand similarities between BCC and its “relatives”, as well as investigating novel treatment targets. By identifying cancers most like BCC, we hope to propose prospective druggable pathways, as well as to gain insight on developing a reliable animal or cell line model to represent advanced BCC. Full article