Darcy Gill - Academia.edu (original) (raw)

Papers by Darcy Gill

ABSTRACTImportanceDespite widespread use of clinical diagnostic tests to assess prior exposure to... more ABSTRACTImportanceDespite widespread use of clinical diagnostic tests to assess prior exposure to SARS-CoV-2, limited evidence exists regarding how test results affect patient behaviors and decision-making.ObjectiveTo understand the rationale behind ordering diagnostic T-cell receptor (TCR) immunosequencing for assessment of prior SARS-CoV-2 infection and evaluate how test results affect patient behaviors, including day-to-day activities and decisions about vaccination.DesignMandatory demographic information and clinical characteristics were collected for all individuals ordering T-Detect™ COVID. Study participants completed a one-time survey that included additional questions about demographics and clinical characteristics, relevant interactions with healthcare providers, reasons for ordering diagnostic TCR immunosequencing, and the utility of test results.SettingUS participants ordering T-Detect COVID between February 2021 and March 2022.ParticipantsOf the 806 individuals who unde...

Trends in Molecular Medicine, 2004

Cellular Microbiology, 2001

Pili of Neisseria gonorrhoeae mediate binding of the bacteria to human host cells. Membrane cofac... more Pili of Neisseria gonorrhoeae mediate binding of the bacteria to human host cells. Membrane cofactor protein (MCP or CD46), a human cell-surface protein involved in regulation of complement activation, acts as a cellular pilus receptor. In this work, we examined which domains of CD46 mediate bacterial adherence. The CD46 expression was quantified and characterized in human epithelial cell lines. N. gonorrhoeae showed the highest adherence to ME180 cells, which have BC1 as the dominant phenotype. The BC isoforms of CD46 were expressed in all cell lines tested. The adherence was not enhanced by high expression of other isoforms, showing that the BC domain of CD46 is important in adherence of N. gonorrhoeae to human cells. To characterize the pilus-binding site within the CD46 molecule, a set of CD46-BC1 deletion constructs were transfected into COS-7 cells. Piliated N. gonorrhoeae attached well to CD46-BC1-expressing COS-7 cells. We show that the complement control protein repeat 3 (CCP-3) and the serine-threonine-proline (STP)-rich domain of CD46 are important for efficient adherence to host cells. Further, partial deletion of the cytoplasmic tail of CD46 results in low bacterial binding, indicating that the cytoplasmic tail takes part in the process of establishing a stable interaction between N. gonorrhoeae and host cells.

Cellular Microbiology, 2005

Following attachment of Neisseria gonorrhoeae to human epithelial cell lines, the cellular pilus ... more Following attachment of Neisseria gonorrhoeae to human epithelial cell lines, the cellular pilus receptor CD46 is shed from the cell and accumulates in the media. In this report, we assess Neisseria-induced alterations in CD46 surface distribution and characterize this complement regulatory protein following its release from the infected cell. Within 3 h of attachment of gonococci to human epithelial cell lines, CD46 is enriched beneath sites of microcolony adhesion. By 6 h post infection, differential ultracentrifugation of culture media from ME-180 monolayers resulted in sedimentation of structurally and functionally intact CD46. Electron microscopy of these 100,000 g pellets revealed 30-200 nm vesicles. These vesicles likely originated from the host cell as they contained additional host cell surface proteins including CD55 and the epidermal growth factor receptor. Further, these vesicles were visualized by quick-freeze, deep-etch electron microscopy in association with the surface of infected ME-180 cells and with pili of adherent gonococci. Like CD46 shedding, CD46 redistribution and vesicle release were insensitive to colchicine and cytochalasin-D but dependent on expression of the pilus retraction protein PilT. This vesiculation may represent a host cell defence response in which surface proteins that are commonly exploited by pathogens, such as CD46, are removed from the cell.

Transplantation and Cellular Therapy

Transplantation and Cellular Therapy, 2022

s / Transplant Cell Ther 28 3S (2021) S1–S509 S475 baseline bone marrow disease burden (54 vs 3.1... more s / Transplant Cell Ther 28 3S (2021) S1–S509 S475 baseline bone marrow disease burden (54 vs 3.1%, p<0.0001), ferritin (median 3406 vs 1330 ng/mL, p=0.0008), and C-reactive protein (CRP) (4.9 vs 0.9 mg/dL, p=0.001), and lower platelets (36 vs 121×109/L, p <0.0001) and absolute neutrophil count (10 vs 500 cells/uL, p<0.0001). They had higher risk of non-response at day 28 (OR 4.36, p=0.03), relapse (OR 3.49, p=0.004), and death (OR 10.77, p<0.0001). Death was due to B-ALL in 63% in CAR-HLH and 81.3% in no CAR-HLH groups. Median survival was 85 days in CAR-HLH with ferritin >100k, 127 days with CAR-HLH and ferritin >10k, and not reached for those without CAR-HLH. Only 3 of 26 (11.5%) with CAR HLH survived without relapse, and 0 of 13 patients with CAR-HLH and ferritin >100k survived without relapse. 15 of 20 (75%) patients with grade 4 CRS met criteria for CAR-HLH but survival was significantly worse for patients with grade 4 CRS+CAR-HLH (p=0.021). In Cox regression survival analysis, CAR-HLH status had a hazard ratio of 3.08 with p=0.002, controlling for pre-CAR T disease burden, age, and CRS treatments. CAR-HLH was associated with poor OS and RFS, with especially dismal outcomes for those with CAR-HLH and ferritin >100K. These findings suggest the need for early recognition of CAR-HLH and further investigations on mitigation strategies including pre-emptive tailored immunomodulation, relapse prevention and disease burden reduction to circumvent CAR-HLH and improve outcomes for this group of high-risk patients.

Toxoplasma gondii strains defective in oral transmission are also defective in developmental stag... more Toxoplasma gondii strains defective in oral transmission are also defective in developmental stage differentiation

Neisseria gonorrhoeae to the cellular pilus receptor CD46: identification of domains importan...

Human membrane cofactor protein (CD46) protects host cells against complement attack and may func... more Human membrane cofactor protein (CD46) protects host cells against complement attack and may function as a receptor for pathogenic Neisseriae. We assessed CD46 expression in the human cervical cell line ME-180 after exposure to Neisseria gonorrhoeae. Piliated but not nonpiliated gonococci adhered to cells and produced up to an 80 % reduction in CD46 surface expression by 6 h that persisted for at least 24 h. This response required a minimum multiplicity of infection of 10 and was not prevented by antibodies to CD46. CD46 down-regulation was not attributable to intracellular retention or a global or specific shutdown of mRNA or protein synthesis. Substantial quantities of CD46 were found in the supernatants, indicating a specific shedding of this protein. Adherent gonococci lacking the pilus retraction protein PilT did not down-regulate CD46 but de-repression of pilT expression restored CD46 down-regulation. After experimental infection of human volunteers with a gonococcal variant i...

This article cites 42 articles, 17 of which can be accessed free

The Journal of Rheumatology, 2019

Objective.To assess differences in joint damage and inflammation using magnetic resonance imaging... more Objective.To assess differences in joint damage and inflammation using magnetic resonance imaging (MRI) between patients with rheumatoid arthritis (RA) who achieved low disease activity with tocilizumab (TCZ) + methotrexate (MTX) and subsequently continued or discontinued MTX.Methods.In the COMP-ACT trial, US patients with RA received subcutaneous TCZ 162 mg + MTX. Those who achieved 28-joint count Disease Activity Score calculated with erythrocyte sedimentation rate (DAS28-ESR) ≤ 3.2 at Week 24 were randomized 1:1 (double-blind) to discontinue MTX (TCZ monotherapy; mono) or continue TCZ + MTX until Week 52. In a subset of patients, 1.5-Tesla MRI was used to obtain images of bilateral hands and wrists at weeks 24 and 40. Outcomes included changes in MRI-assessed synovitis, osteitis, erosion, and cartilage loss from Week 24 to Week 40, and in the proportion of patients with progression of each score.Results.Of 296 patients who achieved DAS28-ESR ≤ 3.2 at Week 24, 79 were enrolled in ...

Arthritis & rheumatology (Hoboken, N.J.), Jan 25, 2018

To evaluate whether tocilizumab (TCZ) monotherapy is non-inferior to TCZ + methotrexate (MTX) in ... more To evaluate whether tocilizumab (TCZ) monotherapy is non-inferior to TCZ + methotrexate (MTX) in maintaining clinical response in patients with rheumatoid arthritis (RA) who achieve low disease activity with TCZ+MTX. Patients with RA who experienced an inadequate response to MTX received MTX plus TCZ 162 mg subcutaneous. At 24 weeks, patients who achieved Disease Activity Score 28-erythrocyte sedimentation rate (DAS28-ESR) ≤3.2 were randomized to receive TCZ monotherapy or continue TCZ+MTX until week 52. The primary outcome was the comparison of mean change in DAS28-ESR from weeks 24 to 40 between the TCZ monotherapy and TCZ+MTX arms (non-inferiority margin of 0.6). Secondary outcomes included DAS28-ESR worsening ≥1.2, achievement of DAS28-ESR <2.6 and ≤3.2 and safety and immunogenicity. Of 718 patients enrolled, 294 were randomized at week 24 (TCZ monotherapy, n = 147; TCZ+MTX, n = 147). The mean changes in DAS28-ESR from weeks 24 to 40 were 0.46 and 0.14 in the TCZ monotherapy ...

Trends in Immunology, 2004

Journal of Experimental Medicine, 2003

Human membrane cofactor protein (CD46) protects host cells against complement attack and may func... more Human membrane cofactor protein (CD46) protects host cells against complement attack and may function as a receptor for pathogenic Neisseriae. We assessed CD46 expression in the human cervical cell line ME-180 after exposure to Neisseria gonorrhoeae. Piliated but not nonpiliated gonococci adhered to cells and produced up to an 80% reduction in CD46 surface expression by 6 h that persisted for at least 24 h. This response required a minimum multiplicity of infection of 10 and was not prevented by antibodies to CD46. CD46 down-regulation was not attributable to intracellular retention or a global or specific shutdown of mRNA or protein synthesis. Substantial quantities of CD46 were found in the supernatants, indicating a specific shedding of this protein. Adherent gonococci lacking the pilus retraction protein PilT did not down-regulate CD46 but de-repression of pilT expression restored CD46 down-regulation. After experimental infection of human volunteers with a gonococcal variant in...

Infection and Immunity, 2007

Toxoplasma gondii undergoes differentiation from rapidly growing tachyzoites to slowly growing br... more Toxoplasma gondii undergoes differentiation from rapidly growing tachyzoites to slowly growing bradyzoites during its life cycle in the intermediate host, and conversion can be induced in vitro by stress. Representative strains of the three clonal lineages showed equal capacity to differentiate into bradyzoites in vitro, as evidenced by induction of bradyzoite antigen 1, staining with Dolichos biflorus lectin (DBL), pepsin resistance, and oral infectivity in mice. We also examined several recently described exotic strains of T. gondii , which are genetically diverse and have a different ancestry from the clonal lineages. The exotic strain COUG was essentially like the clonal lineages and showed a high capacity to induce bradyzoites in vitro and in vivo, consistent with its ability to be efficiently transmitted by the oral route. In contrast, exotic strains MAS and FOU, which are defective in oral transmission, showed a decreased potential to develop into bradyzoites in vitro. This d...

Cellular Microbiology, 2005

Membrane cofactor protein (MCP or CD46), a widely distributed complement regulatory human protein... more Membrane cofactor protein (MCP or CD46), a widely distributed complement regulatory human protein, is a cell surface receptor for many pathogens including group A streptococci (GAS). The surface M protein of GAS binds CD46 and mediates GAS adherence to keratinocytes. In the present study, we studied the role of CD46 in GAS invasion of human lung epithelial cells, A549. Anti-CD46 antibody which specifically blocks the domain to which M protein binds inhibited adherence to and invasion of A549 cells by GAS. Moreover, downregulation of CD46 expression on A549 by RNA interference resulted in reduced invasion of these cells by GAS. A mutant form of CD46 with a deletion in the cytoplasmic domain was overexpressed in A549 cells, which resulted in partial inhibition of invasion. This indicates that the cytoplasmic tail is required for CD46 to promote invasion by GAS. Invasion assays with Lactococcus lactis that express M protein demonstrated the dependence of CD46-promoted invasion on interaction with M protein. In addition, CD46-mediated invasion was also found to be dependent on the extracellular matrix protein fibronectin.

ABSTRACTImportanceDespite widespread use of clinical diagnostic tests to assess prior exposure to... more ABSTRACTImportanceDespite widespread use of clinical diagnostic tests to assess prior exposure to SARS-CoV-2, limited evidence exists regarding how test results affect patient behaviors and decision-making.ObjectiveTo understand the rationale behind ordering diagnostic T-cell receptor (TCR) immunosequencing for assessment of prior SARS-CoV-2 infection and evaluate how test results affect patient behaviors, including day-to-day activities and decisions about vaccination.DesignMandatory demographic information and clinical characteristics were collected for all individuals ordering T-Detect™ COVID. Study participants completed a one-time survey that included additional questions about demographics and clinical characteristics, relevant interactions with healthcare providers, reasons for ordering diagnostic TCR immunosequencing, and the utility of test results.SettingUS participants ordering T-Detect COVID between February 2021 and March 2022.ParticipantsOf the 806 individuals who unde...

Trends in Molecular Medicine, 2004

Cellular Microbiology, 2001

Pili of Neisseria gonorrhoeae mediate binding of the bacteria to human host cells. Membrane cofac... more Pili of Neisseria gonorrhoeae mediate binding of the bacteria to human host cells. Membrane cofactor protein (MCP or CD46), a human cell-surface protein involved in regulation of complement activation, acts as a cellular pilus receptor. In this work, we examined which domains of CD46 mediate bacterial adherence. The CD46 expression was quantified and characterized in human epithelial cell lines. N. gonorrhoeae showed the highest adherence to ME180 cells, which have BC1 as the dominant phenotype. The BC isoforms of CD46 were expressed in all cell lines tested. The adherence was not enhanced by high expression of other isoforms, showing that the BC domain of CD46 is important in adherence of N. gonorrhoeae to human cells. To characterize the pilus-binding site within the CD46 molecule, a set of CD46-BC1 deletion constructs were transfected into COS-7 cells. Piliated N. gonorrhoeae attached well to CD46-BC1-expressing COS-7 cells. We show that the complement control protein repeat 3 (CCP-3) and the serine-threonine-proline (STP)-rich domain of CD46 are important for efficient adherence to host cells. Further, partial deletion of the cytoplasmic tail of CD46 results in low bacterial binding, indicating that the cytoplasmic tail takes part in the process of establishing a stable interaction between N. gonorrhoeae and host cells.

Cellular Microbiology, 2005

Following attachment of Neisseria gonorrhoeae to human epithelial cell lines, the cellular pilus ... more Following attachment of Neisseria gonorrhoeae to human epithelial cell lines, the cellular pilus receptor CD46 is shed from the cell and accumulates in the media. In this report, we assess Neisseria-induced alterations in CD46 surface distribution and characterize this complement regulatory protein following its release from the infected cell. Within 3 h of attachment of gonococci to human epithelial cell lines, CD46 is enriched beneath sites of microcolony adhesion. By 6 h post infection, differential ultracentrifugation of culture media from ME-180 monolayers resulted in sedimentation of structurally and functionally intact CD46. Electron microscopy of these 100,000 g pellets revealed 30-200 nm vesicles. These vesicles likely originated from the host cell as they contained additional host cell surface proteins including CD55 and the epidermal growth factor receptor. Further, these vesicles were visualized by quick-freeze, deep-etch electron microscopy in association with the surface of infected ME-180 cells and with pili of adherent gonococci. Like CD46 shedding, CD46 redistribution and vesicle release were insensitive to colchicine and cytochalasin-D but dependent on expression of the pilus retraction protein PilT. This vesiculation may represent a host cell defence response in which surface proteins that are commonly exploited by pathogens, such as CD46, are removed from the cell.

Transplantation and Cellular Therapy

Transplantation and Cellular Therapy, 2022

s / Transplant Cell Ther 28 3S (2021) S1–S509 S475 baseline bone marrow disease burden (54 vs 3.1... more s / Transplant Cell Ther 28 3S (2021) S1–S509 S475 baseline bone marrow disease burden (54 vs 3.1%, p<0.0001), ferritin (median 3406 vs 1330 ng/mL, p=0.0008), and C-reactive protein (CRP) (4.9 vs 0.9 mg/dL, p=0.001), and lower platelets (36 vs 121×109/L, p <0.0001) and absolute neutrophil count (10 vs 500 cells/uL, p<0.0001). They had higher risk of non-response at day 28 (OR 4.36, p=0.03), relapse (OR 3.49, p=0.004), and death (OR 10.77, p<0.0001). Death was due to B-ALL in 63% in CAR-HLH and 81.3% in no CAR-HLH groups. Median survival was 85 days in CAR-HLH with ferritin >100k, 127 days with CAR-HLH and ferritin >10k, and not reached for those without CAR-HLH. Only 3 of 26 (11.5%) with CAR HLH survived without relapse, and 0 of 13 patients with CAR-HLH and ferritin >100k survived without relapse. 15 of 20 (75%) patients with grade 4 CRS met criteria for CAR-HLH but survival was significantly worse for patients with grade 4 CRS+CAR-HLH (p=0.021). In Cox regression survival analysis, CAR-HLH status had a hazard ratio of 3.08 with p=0.002, controlling for pre-CAR T disease burden, age, and CRS treatments. CAR-HLH was associated with poor OS and RFS, with especially dismal outcomes for those with CAR-HLH and ferritin >100K. These findings suggest the need for early recognition of CAR-HLH and further investigations on mitigation strategies including pre-emptive tailored immunomodulation, relapse prevention and disease burden reduction to circumvent CAR-HLH and improve outcomes for this group of high-risk patients.

Toxoplasma gondii strains defective in oral transmission are also defective in developmental stag... more Toxoplasma gondii strains defective in oral transmission are also defective in developmental stage differentiation

Neisseria gonorrhoeae to the cellular pilus receptor CD46: identification of domains importan...

Human membrane cofactor protein (CD46) protects host cells against complement attack and may func... more Human membrane cofactor protein (CD46) protects host cells against complement attack and may function as a receptor for pathogenic Neisseriae. We assessed CD46 expression in the human cervical cell line ME-180 after exposure to Neisseria gonorrhoeae. Piliated but not nonpiliated gonococci adhered to cells and produced up to an 80 % reduction in CD46 surface expression by 6 h that persisted for at least 24 h. This response required a minimum multiplicity of infection of 10 and was not prevented by antibodies to CD46. CD46 down-regulation was not attributable to intracellular retention or a global or specific shutdown of mRNA or protein synthesis. Substantial quantities of CD46 were found in the supernatants, indicating a specific shedding of this protein. Adherent gonococci lacking the pilus retraction protein PilT did not down-regulate CD46 but de-repression of pilT expression restored CD46 down-regulation. After experimental infection of human volunteers with a gonococcal variant i...

This article cites 42 articles, 17 of which can be accessed free

The Journal of Rheumatology, 2019

Objective.To assess differences in joint damage and inflammation using magnetic resonance imaging... more Objective.To assess differences in joint damage and inflammation using magnetic resonance imaging (MRI) between patients with rheumatoid arthritis (RA) who achieved low disease activity with tocilizumab (TCZ) + methotrexate (MTX) and subsequently continued or discontinued MTX.Methods.In the COMP-ACT trial, US patients with RA received subcutaneous TCZ 162 mg + MTX. Those who achieved 28-joint count Disease Activity Score calculated with erythrocyte sedimentation rate (DAS28-ESR) ≤ 3.2 at Week 24 were randomized 1:1 (double-blind) to discontinue MTX (TCZ monotherapy; mono) or continue TCZ + MTX until Week 52. In a subset of patients, 1.5-Tesla MRI was used to obtain images of bilateral hands and wrists at weeks 24 and 40. Outcomes included changes in MRI-assessed synovitis, osteitis, erosion, and cartilage loss from Week 24 to Week 40, and in the proportion of patients with progression of each score.Results.Of 296 patients who achieved DAS28-ESR ≤ 3.2 at Week 24, 79 were enrolled in ...

Arthritis & rheumatology (Hoboken, N.J.), Jan 25, 2018

To evaluate whether tocilizumab (TCZ) monotherapy is non-inferior to TCZ + methotrexate (MTX) in ... more To evaluate whether tocilizumab (TCZ) monotherapy is non-inferior to TCZ + methotrexate (MTX) in maintaining clinical response in patients with rheumatoid arthritis (RA) who achieve low disease activity with TCZ+MTX. Patients with RA who experienced an inadequate response to MTX received MTX plus TCZ 162 mg subcutaneous. At 24 weeks, patients who achieved Disease Activity Score 28-erythrocyte sedimentation rate (DAS28-ESR) ≤3.2 were randomized to receive TCZ monotherapy or continue TCZ+MTX until week 52. The primary outcome was the comparison of mean change in DAS28-ESR from weeks 24 to 40 between the TCZ monotherapy and TCZ+MTX arms (non-inferiority margin of 0.6). Secondary outcomes included DAS28-ESR worsening ≥1.2, achievement of DAS28-ESR <2.6 and ≤3.2 and safety and immunogenicity. Of 718 patients enrolled, 294 were randomized at week 24 (TCZ monotherapy, n = 147; TCZ+MTX, n = 147). The mean changes in DAS28-ESR from weeks 24 to 40 were 0.46 and 0.14 in the TCZ monotherapy ...

Trends in Immunology, 2004

Journal of Experimental Medicine, 2003

Human membrane cofactor protein (CD46) protects host cells against complement attack and may func... more Human membrane cofactor protein (CD46) protects host cells against complement attack and may function as a receptor for pathogenic Neisseriae. We assessed CD46 expression in the human cervical cell line ME-180 after exposure to Neisseria gonorrhoeae. Piliated but not nonpiliated gonococci adhered to cells and produced up to an 80% reduction in CD46 surface expression by 6 h that persisted for at least 24 h. This response required a minimum multiplicity of infection of 10 and was not prevented by antibodies to CD46. CD46 down-regulation was not attributable to intracellular retention or a global or specific shutdown of mRNA or protein synthesis. Substantial quantities of CD46 were found in the supernatants, indicating a specific shedding of this protein. Adherent gonococci lacking the pilus retraction protein PilT did not down-regulate CD46 but de-repression of pilT expression restored CD46 down-regulation. After experimental infection of human volunteers with a gonococcal variant in...

Infection and Immunity, 2007

Toxoplasma gondii undergoes differentiation from rapidly growing tachyzoites to slowly growing br... more Toxoplasma gondii undergoes differentiation from rapidly growing tachyzoites to slowly growing bradyzoites during its life cycle in the intermediate host, and conversion can be induced in vitro by stress. Representative strains of the three clonal lineages showed equal capacity to differentiate into bradyzoites in vitro, as evidenced by induction of bradyzoite antigen 1, staining with Dolichos biflorus lectin (DBL), pepsin resistance, and oral infectivity in mice. We also examined several recently described exotic strains of T. gondii , which are genetically diverse and have a different ancestry from the clonal lineages. The exotic strain COUG was essentially like the clonal lineages and showed a high capacity to induce bradyzoites in vitro and in vivo, consistent with its ability to be efficiently transmitted by the oral route. In contrast, exotic strains MAS and FOU, which are defective in oral transmission, showed a decreased potential to develop into bradyzoites in vitro. This d...

Cellular Microbiology, 2005

Membrane cofactor protein (MCP or CD46), a widely distributed complement regulatory human protein... more Membrane cofactor protein (MCP or CD46), a widely distributed complement regulatory human protein, is a cell surface receptor for many pathogens including group A streptococci (GAS). The surface M protein of GAS binds CD46 and mediates GAS adherence to keratinocytes. In the present study, we studied the role of CD46 in GAS invasion of human lung epithelial cells, A549. Anti-CD46 antibody which specifically blocks the domain to which M protein binds inhibited adherence to and invasion of A549 cells by GAS. Moreover, downregulation of CD46 expression on A549 by RNA interference resulted in reduced invasion of these cells by GAS. A mutant form of CD46 with a deletion in the cytoplasmic domain was overexpressed in A549 cells, which resulted in partial inhibition of invasion. This indicates that the cytoplasmic tail is required for CD46 to promote invasion by GAS. Invasion assays with Lactococcus lactis that express M protein demonstrated the dependence of CD46-promoted invasion on interaction with M protein. In addition, CD46-mediated invasion was also found to be dependent on the extracellular matrix protein fibronectin.