The molecular characterization of antibody binding to a superantigen-like protein from a commensal microbe

2021 ◽  
Vol 118 (39) ◽  
pp. e2023898118
Author(s):  
Marta T. Borowska ◽  
Christoph Drees ◽  
Alexander E. Yarawsky ◽  
Mayuri Viswanathan ◽  
Sean M. Ryan ◽  
...  
Keyword(s):  
Heavy Chain ◽  
Immune Cell ◽  
Targeted Mutagenesis ◽  
Functional Studies ◽  
Immunoglobulin Binding Protein ◽  
Contact Residues ◽  
Stimulation Experiments ◽  
Immunoglobulin Binding

Microorganisms have coevolved diverse mechanisms to impair host defenses. A major one, superantigens, can result in devastating effects on the immune system. While all known superantigens induce vast immune cell proliferation and come from opportunistic pathogens, recently, proteins with similar broad specificity to antibody variable (V) domain families were identified in a commensal microbiota. These proteins, identified in the human commensal Ruminococcus gnavus, are called immunoglobulin-binding protein (Ibp) A and B and have been shown to activate B cells in vitro expressing either human VH3 or murine VH5/6/7. Here, we provide molecular and functional studies revealing the basis of this Ibp/immunoglobulin (Ig) interaction. The crystal structure and biochemical assays of a truncated IbpA construct in complex with mouse VH5 antigen-binding fragment (Fab) shows a binding of Ig heavy chain framework residues to the Ibp Domain D and the C-terminal heavy chain binding domain (HCBD). We used targeted mutagenesis of contact residues and affinity measurements and performed studies of the Fab-IbpA complex to determine the stoichiometry between Ibp and VH domains, suggesting Ibp may serve to cluster full-length IgA antibodies in vivo. Furthermore, in vitro stimulation experiments indicate that binding of the Ibp HCBD alone is sufficient to activate responsive murine B cell receptors. The presence of these proteins in a commensal microbe suggest that binding a broad repertoire of immunoglobulins, particularly in the gut/microbiome environment, may provide an important function in the maintenance of host/microbiome homeostasis contrasting with the pathogenic role of structurally homologous superantigens expressed by pathogens.

scholarly journals Dickkopf-1: A Promising Target for Cancer Immunotherapy

2021 ◽  
Vol 12 ◽  
Author(s):  
Hang Yin Chu ◽  
Zihao Chen ◽  
Luyao Wang ◽  
Zong-Kang Zhang ◽  
Xinhuan Tan ◽  
...  
Keyword(s):  
Cancer Immunotherapy ◽  
Immune Cell ◽  
Immune Surveillance ◽  
Suppressor Cells ◽  
Functional Studies ◽  
Promising Target ◽  
Using Data ◽  
Dickkopf 1

Clinical studies in a range of cancers have detected elevated levels of the Wnt antagonist Dickkopf-1 (DKK1) in the serum or tumors of patients, and this was frequently associated with a poor prognosis. Our analysis of DKK1 gene profile using data from TCGA also proves the high expression of DKK1 in 14 types of cancers. Numerous preclinical studies have demonstrated the cancer-promoting effects of DKK1 in both in vitro cell models and in vivo animal models. Furthermore, DKK1 showed the ability to modulate immune cell activities as well as the immunosuppressive cancer microenvironment. Expression level of DKK1 is positively correlated with infiltrating levels of myeloid-derived suppressor cells (MDSCs) in 20 types of cancers, while negatively associated with CD8+ T cells in 4 of these 20 cancer types. Emerging experimental evidence indicates that DKK1 has been involved in T cell differentiation and induction of cancer evasion of immune surveillance by accumulating MDSCs. Consequently, DKK1 has become a promising target for cancer immunotherapy, and the mechanisms of DKK1 affecting cancers and immune cells have received great attention. This review introduces the rapidly growing body of literature revealing the cancer-promoting and immune regulatory activities of DKK1. In addition, this review also predicts that by understanding the interaction between different domains of DKK1 through computational modeling and functional studies, the underlying functional mechanism of DKK1 could be further elucidated, thus facilitating the development of anti-DKK1 drugs with more promising efficacy in cancer immunotherapy.

scholarly journals Glioblastoma epigenome profiling identifies SOX10 as a master regulator of molecular tumour subtype

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Yonghe Wu ◽  
Michael Fletcher ◽  
Zuguang Gu ◽  
Qi Wang ◽  
Barbara Costa ◽  
...  
Keyword(s):  
Regulatory Networks ◽  
Immune Cell ◽  
Sequencing Data ◽  
Master Regulator ◽  
Mesenchymal Transition ◽  
Functional Studies ◽  
Bona Fide ◽  
Oligodendrocyte Precursor

AbstractGlioblastoma frequently exhibits therapy-associated subtype transitions to mesenchymal phenotypes with adverse prognosis. Here, we perform multi-omic profiling of 60 glioblastoma primary tumours and use orthogonal analysis of chromatin and RNA-derived gene regulatory networks to identify 38 subtype master regulators, whose cell population-specific activities we further map in published single-cell RNA sequencing data. These analyses identify the oligodendrocyte precursor marker and chromatin modifier SOX10 as a master regulator in RTK I-subtype tumours. In vitro functional studies demonstrate that SOX10 loss causes a subtype switch analogous to the proneural–mesenchymal transition observed in patients at the transcriptomic, epigenetic and phenotypic levels. SOX10 repression in an in vivo syngeneic graft glioblastoma mouse model results in increased tumour invasion, immune cell infiltration and significantly reduced survival, reminiscent of progressive human glioblastoma. These results identify SOX10 as a bona fide master regulator of the RTK I subtype, with both tumour cell-intrinsic and microenvironmental effects.

Functional Studies on the C-Type Lectin Receptor CD302 Present on Dendritic Cells and Macrophages

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2198-2198
Author(s):  
Derek NJ Hart ◽  
Pablo Silveira ◽  
Tsun Ho Lo ◽  
Nirupama Verma ◽  
Ai Vu ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Dendritic Cells ◽  
Immune Cell ◽  
Blood Monocytes ◽  
Lectin Receptors ◽  
Functional Studies ◽  
Cell Functions ◽  
Equity Ownership

Abstract Introduction: C-type lectin receptors (CLR) play an important role in the immune system by recognising molecular patterns expressed by exogenous and endogenous threats. They have been shown to capture and internalise antigens and to mediate other important immune cell functions. DEC205 and CLEC9A are being actively investigated as targets for clinical therapeutic cancer vaccines. We discovered CD302 as a new CLR expressed on human dendritic cells (DC), monocytes and macrophages (J Immunol 2007;179:6052). Our initial studies suggested the molecule could play a role in cell adhesion or migration due to its co-localisation with migratory structures on macrophages. Our study set out to investigate the potential immunological function of CD302 using mouse models and to define its wider tissue expression in man. Methods: We generated CD302 knockout (KO) mice lacking exon 1 of its gene, abrogating transcription, for functional studies. We characterised the transcriptional expression of CD302 in mouse immune cells using real-time PCR. We developed monoclonal mAb to mCD302. Human studies utilized the anti-CD302 mAbs, MMRI-20 & 21 in flow cytometry and confocal microscopy studies of human immune cell populations. Results: CD302 was primarily expressed in mouse liver, lungs, lymph nodes (LN) and spleen. In spleen, macrophages, granulocytes and dendritic cells (DC) expressed CD302. Analysis of LN DC subsets revealed 2.5-fold higher CD302 mRNA expression in migratory compared to resident DC populations. Enumeration of various immune populations in lymphoid organs by flow cytometry uncovered a modest deficiency in migratory DC number and proportion within LN of CD302 KO mice compared to wild-type (WT) mice. In vitro studies showed CD302 KO and WT DC had an equivalent capacity to be activated by various stimuli, prime T cells and migrate towards the lymphoid-homing chemokines CCL19/CCL21. CD302 KO migratory DC exhibited a reduced in vivo migratory capacity to LN after FITC skin-painting. However, CD302 KO macrophages migrated similarly to WT macrophages in vivo in response to thioglycollate. In man, CD302 was present in high density in liver and peripheral blood monocytes and myeloid but not plasmacytoid DC. Current studies are aimed at clarifying its distribution on tissue DC and macrophage subsets. Anti-CD302 coated microbeads were taken up by human monocyte derived macrophages and anti-CD302 mAb was also internalized by DC. Confocal studies showed that CD302 co-localized with F-actin structures at the near basal surface such as filopodia and lamellipodia and podosomes of human macrophages and EGFP tagged CD302 expressed in COS-1 cells associated with F-actin. Conclusion: Our data suggests that CD302 may play a specialist role in DC and macrophage membrane functions. This appears to relate to its ability to associate with F-actin and may contribute to the membrane interactions required for DC to migrate towards the draining LN. Disclosures Hart: DendroCyte BioTech Pty Ltd: Equity Ownership. Clark:DendroCyte BioTech Pty Ltd: Equity Ownership.

scholarly journals POLRMT mutations impair mitochondrial transcription causing neurological disease

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Monika Oláhová ◽  
Bradley Peter ◽  
Zsolt Szilagyi ◽  
Hector Diaz-Maldonado ◽  
Meenakshi Singh ◽  
...  
Keyword(s):  
Progressive External Ophthalmoplegia ◽  
Global Developmental Delay ◽  
Disease Mechanism ◽  
Mitochondrial Transcription ◽  
Functional Studies ◽  
Mtdna Deletions ◽  
Molecular Nature ◽  
Important Disease

AbstractWhile >300 disease-causing variants have been identified in the mitochondrial DNA (mtDNA) polymerase γ, no mitochondrial phenotypes have been associated with POLRMT, the RNA polymerase responsible for transcription of the mitochondrial genome. Here, we characterise the clinical and molecular nature of POLRMT variants in eight individuals from seven unrelated families. Patients present with global developmental delay, hypotonia, short stature, and speech/intellectual disability in childhood; one subject displayed an indolent progressive external ophthalmoplegia phenotype. Massive parallel sequencing of all subjects identifies recessive and dominant variants in the POLRMT gene. Patient fibroblasts have a defect in mitochondrial mRNA synthesis, but no mtDNA deletions or copy number abnormalities. The in vitro characterisation of the recombinant POLRMT mutants reveals variable, but deleterious effects on mitochondrial transcription. Together, our in vivo and in vitro functional studies of POLRMT variants establish defective mitochondrial transcription as an important disease mechanism.

scholarly journals An integrated framework for quantifying immune-tumour interactions in a 3D co-culture model

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Gheed Al-Hity ◽  
FengWei Yang ◽  
Eduard Campillo-Funollet ◽  
Andrew E. Greenstein ◽  
Hazel Hunt ◽  
...  
Keyword(s):  
Immune System ◽  
Immune Cell ◽  
In Vitro Models ◽  
Proof Of Concept ◽  
Culture Model ◽  
Spheroid Growth ◽  
Confocal Images ◽  
Cancer Spheroids

AbstractInvestigational in vitro models that reflect the complexity of the interaction between the immune system and tumours are limited and difficult to establish. Herein, we present a platform to study the tumour-immune interaction using a co-culture between cancer spheroids and activated immune cells. An algorithm was developed for analysis of confocal images of the co-culture to evaluate the following quantitatively; immune cell infiltration, spheroid roundness and spheroid growth. As a proof of concept, the effect of the glucocorticoid stress hormone, cortisol was tested on 66CL4 co-culture model. Results were comparable to 66CL4 syngeneic in vivo mouse model undergoing psychological stress. Furthermore, administration of glucocorticoid receptor antagonists demonstrated the use of this model to determine the effect of treatments on the immune-tumour interplay. In conclusion, we provide a method of quantifying the interaction between the immune system and cancer, which can become a screening tool in immunotherapy design.

scholarly journals Halofuginone functions as a therapeutic drug for chronic periodontitis in a mouse model

2020 ◽  
Vol 34 ◽  
pp. 205873842097489
Author(s):  
Jiang Wang ◽  
Bo Wang ◽  
Xin Lv ◽  
Yingjie Wang
Keyword(s):  
Alveolar Bone ◽  
Immune Cell ◽  
Critical Role ◽  
Therapeutic Drug ◽  
Mice Model ◽  
T Helper 17 ◽  
Th17 Cell Differentiation ◽  
Tnf Α

Periodontitis is an inflammatory disease caused by host immune response, resulting in a loss of periodontium and alveolar bone. Immune cells, such as T cells and macrophages, play a critical role in the periodontitis onset. Halofuginone, a natural quinazolinone alkaloid, has been shown to possess anti-fibrosis, anti-cancer, and immunomodulatory properties. However, the effect of halofuginone on periodontitis has never been reported. In this study, a ligature-induced mice model of periodontitis was applied to investigate the potential beneficial effect of halofuginone on periodontitis. We demonstrated that the administration of halofuginone significantly reduced the expression levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) in vivo, and markedly suppressed immune cell infiltration into the infected sites. Furthermore, we also observed that halofuginone treatment blocked the T-helper 17 (Th17) cell differentiation in vivo and in vitro. We demonstrated for the first time that halofuginone alleviated the onset of periodontitis through reducing immune responses.

scholarly journals 114 Preclinical development of a novel iPSC-derived CAR-MICA/B NK cell immunotherapy to overcome solid tumor escape from NKG2D-mediated mechanisms of recognition and killing

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A126-A126
Author(s):  
John Goulding ◽  
Mochtar Pribadi ◽  
Robert Blum ◽  
Wen-I Yeh ◽  
Yijia Pan ◽  
...  
Keyword(s):  
T Cells ◽  
Cancer Immunotherapy ◽  
Tumor Immunity ◽  
Immune Cell ◽  
Nk Cell ◽  
Tumor Escape ◽  
Car T Cells ◽  
Car T

BackgroundMHC class I related proteins A (MICA) and B (MICB) are induced by cellular stress and transformation, and their expression has been reported for many cancer types. NKG2D, an activating receptor expressed on natural killer (NK) and T cells, targets the membrane-distal domains of MICA/B, activating a potent cytotoxic response. However, advanced cancer cells frequently evade immune cell recognition by proteolytic shedding of the α1 and α2 domains of MICA/B, which can significantly reduce NKG2D function and the cytolytic activity.MethodsRecent publications have shown that therapeutic antibodies targeting the membrane-proximal α3 domain inhibited MICA/B shedding, resulting in a substantial increase in the cell surface density of MICA/B and restoration of immune cell-mediated tumor immunity.1 We have developed a novel chimeric antigen receptor (CAR) targeting the conserved α3 domain of MICA/B (CAR-MICA/B). Additionally, utilizing our proprietary induced pluripotent stem cell (iPSC) product platform, we have developed multiplexed engineered, iPSC-derived CAR-MICA/B NK (iNK) cells for off-the-shelf cancer immunotherapy.ResultsA screen of CAR spacer and ScFv orientations in primary T cells delineated MICA-specific in vitro activation and cytotoxicity as well as in vivo tumor control against MICA+ cancer cells. The novel CAR-MICA/B design was used to compare efficacy against NKG2D CAR T cells, an alternative MICA/B targeting strategy. CAR-MICA/B T cells showed superior cytotoxicity against melanoma, breast cancer, renal cell carcinoma, and lung cancer lines in vitro compared to primary NKG2D CAR T cells (p<0.01). Additionally, using an in vivo xenograft metastasis model, CAR-MICA/B T cells eliminated A2058 human melanoma metastases in the majority of the mice treated. In contrast, NKG2D CAR T cells were unable to control tumor growth or metastases. To translate CAR-MICA/B functionality into an off-the-shelf cancer immunotherapy, CAR-MICA/B was introduced into a clonal master engineered iPSC line to derive a multiplexed engineered, CAR-MICA/B iNK cell product candidate. Using a panel of tumor cell lines expressing MICA/B, CAR-MICA/B iNK cells displayed MICA specificity, resulting in enhanced cytokine production, degranulation, and cytotoxicity. Furthermore, in vivo NK cell cytotoxicity was evaluated using the B16-F10 melanoma cell line, engineered to express MICA. In this model, CAR-MICA/B iNK cells significantly reduced liver and lung metastases, compared to untreated controls, by 93% and 87% respectively.ConclusionsOngoing work is focused on extending these preclinical studies to further support the clinical translation of an off-the-shelf, CAR-MICA/B iNK cell cancer immunotherapy with the potential to overcome solid tumor escape from NKG2D-mediated mechanisms of recognition and killing.ReferenceFerrari de Andrade L, Tay RE, Pan D, Luoma AM, Ito Y, Badrinath S, Tsoucas D, Franz B, May KF Jr, Harvey CJ, Kobold S, Pyrdol JW, Yoon C, Yuan GC, Hodi FS, Dranoff G, Wucherpfennig KW. Antibody-mediated inhibition of MICA and MICB shedding promotes NK cell-driven tumor immunity. Science 2018 Mar 30;359(6383):1537–1542.

scholarly journals Use of an Endogenous Plasmid Locus for Stable intransComplementation in Borrelia burgdorferi

2014 ◽  
Vol 81 (3) ◽  
pp. 1038-1046 ◽  
Author(s):  
Irene N. Kasumba ◽  
Aaron Bestor ◽  
Kit Tilly ◽  
Patricia A. Rosa
Keyword(s):  
Borrelia Burgdorferi ◽  
Shuttle Vector ◽  
Targeted Mutagenesis ◽  
Multiple Cloning Site ◽  
Stable Gene ◽  
Content Type ◽  
Shuttle Vectors ◽  
Stable Maintenance

ABSTRACTTargeted mutagenesis and complementation are important tools for studying genes of unknown function in the Lyme disease spirocheteBorrelia burgdorferi. A standard method of complementation is reintroduction of a wild-type copy of the targeted gene on a shuttle vector. However, shuttle vectors are present at higher copy numbers thanB. burgdorferiplasmids and are potentially unstable in the absence of selection, thereby complicating analyses in the mouse-tick infectious cycle.B. burgdorferihas over 20 plasmids, with some, such as linear plasmid 25 (lp25), carrying genes required by the spirochetein vivobut relatively unstable duringin vitrocultivation. We propose that complementation on an endogenous plasmid such as lp25 would overcome the copy number andin vivostability issues of shuttle vectors. In addition, insertion of a selectable marker on lp25 could ensure its stable maintenance by spirochetes in culture. Here, we describe the construction of a multipurpose allelic-exchange vector containing a multiple-cloning site and either of two selectable markers. This suicide vector directs insertion of the complementing gene into thebbe02locus, a site on lp25 that was previously shown to be nonessential during bothin vitroandin vivogrowth. We demonstrate the functional utility of this strategy by restoring infectivity to anospCmutant through complementation at this site on lp25 and stable maintenance of theospCgene throughout mouse infection. We conclude that this represents a convenient and widely applicable method for stable gene complementation inB. burgdorferi.

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