PubMed Health⌕ Search

Biomedical subjects

Daniel Martin

Publications and source records attributed to Daniel Martin.

At least 19 recordsLinked to original sources
PubMed2025

GZMK+CD8+ T cells target a specific acinar cell type in Sjögren's disease.

OBJECTIVES: Sjögren's disease (SjD) is a systemic autoimmune disorder characterized by dysfunction of exocrine glands, particularly the salivary and lacrimal glands, with no clear etiology or effective therapy. This study explores the complex interplay of varied cell types in the salivary glands and their role in the pathology of Sjögren's disease. METHODS: Utilizing single-cell and spatial transcriptomics alongside spatial immunophenotyping to analyze human minor salivary glands, we developed a comprehensive understanding of the cellular landscape of non-SjD salivary glands and how that landscape changes in SjD patients. In vitro cellular assays and novel patient-derived primary epithelial cells were co-cultured with autologous T cells to confirm effector states and the delivery and effect of disease-associated granzymes. RESULTS: We identified previously unrecognized heterogeneity among acinar cells, including a PRR4⁺CST3⁺WFDC2⁻ seromucous acinar population that is selectively lost in Sjögren's disease. Expression and organizational changes were linked to clinical features: (i) T cells in the glands of SSA⁺, high-focus score patients showed increased transcriptional signatures of activation, antigen presentation, and apoptosis resistance compared with patients with mild or moderate disease, and (ii) patients with low immune infiltration exhibited distinct epithelial organization. Notably, GZMK⁺CD8⁺ T cells, which accumulate with disease severity, displayed a cytotoxic transcriptional program, degranulated upon stimulation ex vivo, and localized spatially with immune-engaged epithelial cells. Functional assays demonstrated that GZMK activates interferon signaling in vitro, and autologous co-cultures of patient-derived T cells and epithelial cells validated these findings. CONCLUSIONS: Using single-cell and spatial transcriptomics and proteomics, this study identifies a selective loss of PRR4⁺CST3⁺WFDC2⁻ seromucous acinar cells and a rise in GZMK⁺CD8⁺ T cells in Sjögren's disease, revealing distinct immune-mediated epithelial remodeling and interferon-driven dysfunction across diverse clinical presentations. These findings uncover a novel sub-cytolytic effector mechanism by which GZMK⁺CD8⁺ T cells impair mitochondrial integrity and activate innate immune signaling, linking epithelial injury to type I interferon responses and offering new therapeutic targets.

Humans↗
PubMed2006

Computational prediction of proteotypic peptides for quantitative proteomics.

Mass spectrometry-based quantitative proteomics has become an important component of biological and clinical research. Although such analyses typically assume that a protein's peptide fragments are observed with equal likelihood, only a few so-called 'proteotypic' peptides are repeatedly and consistently identified for any given protein present in a mixture. Using >600,000 peptide identifications generated by four proteomic platforms, we empirically identified >16,000 proteotypic peptides for 4,030 distinct yeast proteins. Characteristic physicochemical properties of these peptides were used to develop a computational tool that can predict proteotypic peptides for any protein from any organism, for a given platform, with >85% cumulative accuracy. Possible applications of proteotypic peptides include validation of protein identifications, absolute quantification of proteins, annotation of coding sequences in genomes, and characterization of the physical principles governing key elements of mass spectrometric workflows (e.g., digestion, chromatography, ionization and fragmentation).

Algorithms↗
PubMed2006

The Galpha13-Rho signaling axis is required for SDF-1-induced migration through CXCR4.

The CXC chemokine stromal cell-derived factor-1alpha (SDF-1) binds to CXCR4, a seven-transmembrane G protein-coupled receptor that plays a critical role in many physiological processes that involve cell migration and cell fate decisions, ranging from stem cell homing, angiogenesis, and neuronal development to immune cell trafficking. CXCR4 is also implicated in various pathological conditions, including metastatic spread and human immunodeficiency virus infection. Although SDF-1-induced cell migration in CXCR4-expressing cells is sensitive to pertussis toxin treatment, hence involving heterotrimeric G proteins of the G(i) family, whether other G proteins participate in the chemotactic response to SDF-1 is still unknown. In this study, we took advantage of the potent chemotactic activity of SDF-1 in Jurkat T-cells to examine the nature of the heterotrimeric G protein subunits contributing to CXCR4-mediated cell migration. We observed that whereas G(i) and Gbetagamma subunits are involved in SDF-1-induced Rac activation and cell migration, CXCR4 can also stimulate Rho potently leading to the phosphorylation of myosin light chain through the Rho effector, Rho kinase, but independently of G(i). Furthermore, we found that Galpha(13) mediates the activation of Rho by CXCR4 and that the functional activity of both Galpha(13) and Rho is required for directional cell migration in response to SDF-1. Collectively, our data indicate that signaling by CXCR4 to Rho through Galpha(13) contributes to cell migration when stimulated by SDF-1, thus identifying the Galpha(13)-Rho signaling axis as a potential pharmacological target in many human diseases that involve the aberrant function of CXCR4.

Cell Line↗
PubMed2006

Fluocinolone acetonide implant (Retisert) for noninfectious posterior uveitis: thirty-four-week results of a multicenter randomized clinical study.

PURPOSE: To report the interim 34-week safety and efficacy results of a 3-year study to evaluate an investigational intravitreal fluocinolone acetonide (FA) implant in patients with noninfectious posterior uveitis. DESIGN: Prospective, dose-masked, dose-randomized, historically controlled, multicenter trial in patients with unilateral or bilateral disease. PARTICIPANTS: A total of 278 patients with recurrent noninfectious posterior uveitis were randomized to receive a 0.59-mg (n = 110) or 2.1-mg (n = 168) implant. In patients with bilateral disease, the more severely affected eye received the implant. METHODS: The implant was inserted surgically into the vitreous cavity through a pars plana incision. Follow-up visits were scheduled on day 2, week 1, and then every 4 to 6 weeks through 34 weeks after implantation. Systemic, periocular, and topical therapies were reduced as allowed by the clinical response. MAIN OUTCOME MEASURES: The primary efficacy outcome was a comparison of the recurrence rate in the implanted eye from the 34 weeks before implantation to the 34 weeks after implantation. Visual acuity (VA), need for adjunctive therapy, and safety also were assessed. RESULTS: Combining both doses, the FA implant reduced the rate of recurrences from 51.4% in the 34 weeks preceding implantation to 6.1% postimplantation (P<0.0001) in the study eyes. Comparatively, there was a significant increase in the recurrence rate in the fellow nonimplanted eyes from 20.3% preimplantation to 42.0% postimplantation (P<0.0001). Visual acuity was stabilized or improved in 87% of implanted eyes and generally was associated with reductions in the area of macular hyperfluorescence. The percentage of eyes that required systemic medications, periocular injections, and topical corticosteroids decreased from 52.9%, 63.0%, and 35.7%, respectively, preimplantation to 12.1%, 2.2%, and 16.5% postimplantation (P< or =0.0001 in all cases). At week 34, 51.1% of implanted eyes required ocular antihypertensive drops, and 5.8% underwent glaucoma filtering surgery. Lens opacity scores increased by > or =2 grades in 19.8% of phakic implanted eyes, and 9.9% required cataract surgery. There were no statistically significant differences in any of the parameters studied for the 0.59-mg implant, compared with the 2.1-mg implant. CONCLUSIONS: The FA implant significantly reduced uveitis recurrences, improved VA, and decreased the need for adjunctive therapy in the studied patient population. The most common side effects included increased intraocular pressure and cataract progression.

Adolescent↗
PubMed2006

The Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor as a therapeutic target for the treatment of Kaposi's sarcoma.

The Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a G protein-coupled receptor (vGPCR) that has been implicated in the initiation of Kaposi's sarcoma, identifying vGPCR as an attractive target for preventing Kaposi's sarcoma. However, as only a fraction of cells in advanced Kaposi's sarcoma lesions express vGPCR, it is unclear whether this unique viral oncogene contributes to Kaposi's sarcoma progression. We therefore set out to determine whether the few cells that express vGPCR in established tumors represent an appropriate therapeutic target for the treatment of patients with preexisting Kaposi's sarcoma. To this end, we generated endothelial cell lines stably expressing vGPCR or key KSHV latently expressed proteins (vCyclin, vFlip, and LANA1). The endothelial cell line expressing vGPCR was rendered sensitive to treatment with the nucleoside analogue ganciclovir by using a bicistronic construct coexpressing the herpes simplex virus 1 thymidine kinase. S.c. injection into nude mice with mixed-cell populations formed tumors that approximate the ratio of vGPCR-expressing and KSHV latent gene-expressing cells. These mice were then treated with ganciclovir to specifically target only the vGPCR-expressing cells. Surprisingly, despite the expression of KSHV latent genes in the vast majority of tumor cells, specifically targeting only the few vGPCR-expressing cells in established tumors resulted in tumor regression. Moreover, we observed an increase in apoptosis of latent gene-expressing cells after the pharmacologic deletion of the vGPCR-expressing cells. These findings indicate that vGPCR may play a key role in Kaposi's sarcoma progression and provide experimental justification for developing molecular-based therapies specifically targeting vGPCR and its effectors for the treatment of Kaposi's sarcoma patients.

Animals↗