Biology subjects

McMullan, P.

Publications and source records attributed to McMullan, P..

3 recordsLinked to original sources

bioRxiv2026

High-Throughput, Multiplex Immunofluorescence for the Computer-automated Immunophenotyping of Mycosis Fungoides

The diagnosis of Mycosis Fungoides (MF) is difficult and often delayed, exacerbated by the constraint of conventional immunohistochemistry (IHC) to analyze only one antigen per tissue section, often necessitating repeat biopsies and extensive workups. We sought to validate a high-throughput Multiplex Immunofluorescence (MIF) method, coupled with computer-automated image analysis, to generate comprehensive immunophenotyping data from a single formalin-fixed, paraffin-embedded (FFPE) biopsy. We applied an 11-biomarker MIF panel across 18 archived skin specimens (9 MF/TCR clonality positive and 9 control/TCR clonality negative). Initial validation confirmed that MIF antigen expression and spatial localization were concordant with sequential IHC-stained sections. Whole slide image stacks were analyzed using both computer-assisted and fully computer-automated pipelines. Both methods successfully delineated immunophenotypic differences. MF specimens showed a significant expansion of hematopoietic cells and proliferative T-lymphocytes compared to controls. Crucially, MF tissues also exhibited a significant increase in the percentage of atypical T-lymphocytes. Our results validate the potential of MIF to obtain comprehensive, high-dimensional diagnostic information from a single tissue section. Integration with computer-automated analysis offers a scalable, high-throughput platform that can significantly aid in the timely and accurate diagnosis of cutaneous lymphomas.

pathology↗

bioRxiv2024

Hair follicle-resident progenitor cells are a major cellular contributor to heterotopic subcutaneous ossifications in a mouse model of Albright hereditary osteodystrophy

Heterotopic ossifications (HOs) are the pathologic process by which bone inappropriately forms outside of the skeletal system. Despite HOs being a persistent clinical problem in the general population, there are no definitive strategies for their prevention and treatment due to a limited understanding of the cellular and molecular mechanisms contributing to lesion development. One disease in which the development of heterotopic subcutaneous ossifications (SCOs) leads to morbidity is Albright hereditary osteodystrophy (AHO). AHO is caused by heterozygous inactivation of GNAS, the gene that encodes the -stimulatory subunit (Gs) of G proteins. Previously, we had shown using our laboratorys AHO mouse model that SCOs develop around hair follicles (HFs). Here we show that SCO formation occurs due to inappropriate expansion and differentiation of HF-resident stem cells into osteoblasts. We also show in AHO patients and mice that Secreted Frizzled Related Protein 2 (SFRP2) expression is upregulated in regions of SCO formation and that elimination of Sfrp2 in male AHO mice exacerbates SCO development. These studies provide key insights into the cellular and molecular mechanisms contributing to SCO development and have implications for potential therapeutic modalities not only for AHO patients but also for patients suffering from HOs with other etiologies.

cell biology↗

bioRxiv2021

Parental origin of Gsα inactivation differentially affects bone remodeling in a mouse model of Albright hereditary osteodystrophy

Albright hereditary osteodystrophy (AHO) is caused by heterozygous inactivation of GNAS, a complex locus that encodes the alpha-stimulatory subunit of GPCRs (Gs) in addition to NESP55 and XLs due to alternative first exons. AHO skeletal manifestations include brachydactyly, brachymetacarpia, compromised adult stature, and subcutaneous ossifications. AHO patients with maternally-inherited GNAS mutations develop pseudohypoparathyroidism type 1A (PHP1A) with resistance to multiple hormones that mediate their actions through GPCRs requiring Gs (eg., PTH, TSH, GHRH, calcitonin) and severe obesity. Paternally-inherited GNAS mutations cause pseudopseudohypoparathyroidism (PPHP), in which patients have AHO skeletal features but do not develop hormonal resistance or marked obesity. These differences between PHP1A and PPHP are caused by tissue-specific reduction of paternal Gs expression. Previous reports in mice have shown loss of Gs causes osteopenia due to impaired osteoblast number and function and suggest AHO patients could display evidence of reduced bone mineral density (BMD). However, we previously demonstrated PHP1A patients display normal-increased BMD measurements without any correlation to body mass index or serum PTH. Due to these observed differences between PHP1A and PPHP, we utilized our laboratorys AHO mouse model to address whether Gs heterozygous inactivation by the targeted disruption of exon 1 of Gnas differentially affects bone remodeling based on the parental inheritance of the mutation. Mice with paternally-inherited (GnasE1+/-p) and maternally-inherited (GnasE1+/-m) mutations displayed reductions in osteoblasts along the bone surface compared to wildtype. GnasE1+/-p mice displayed reduced cortical and trabecular bone parameters due to impaired bone formation and excessive bone resorption. GnasE1+/-m mice however displayed enhanced bone parameters due to increased osteoblast activity and normal bone resorption. These distinctions in bone remodeling between GnasE1+/-p and GnasE1+/-m mice appear to be secondary to changes in the bone microenvironment driven by calcitonin-resistance within GnasE1+/-m osteoclasts and therefore warrant further studies into understanding how Gs influences osteoblast-osteoclast coupling interactions.

cell biology↗