Biology subjects

Francis, K. P.

Publications and source records attributed to Francis, K. P..

3 recordsLinked to original sources

bioRxiv2025

A Mouse Model of SARS-CoV-2-Driven Acute Maladaptive Responses and Chronic Systemic Diseases

Our understanding of SARS-CoV-2 acute and post-acute pathogenesis is hindered by the lack of adequate small animal models. We present RAB/6N, a mouse model prone to severe disease after exposure to SARS-CoV-2 clinical isolates, with lethal cases showing no widespread brain infection typical of the widely used K18-hACE2 mouse model. Lung viral replication in RAB/6N mice remains steady for several days before a decline in viral titers. Delayed initiation of infection clearance is marked by increased lung T-cell extravasation and type-2 immune responses, leading to maladaptive lung consolidation. While systemic antiviral cytokine responses only correlate with SARS-CoV-2 brain infection in K18-hACE2 mice, they are concomitant with pulmonary immune dynamics in infected RAB/6N mice. Convalescent RAB/6N mice display systemic inflammation and decreased antibody titers against SARS-CoV-2 spike RBD, persistent viral RNA and prolonged lymphoid infiltration in the lungs. These animals also exhibit signatures of multi-organ dysfunction, cognitive impairment, cardiac inflammation, hyper- immunoglobulin production, and various autoimmune disorders, illuminating the molecular correlates of various pathologies associated with post-acute sequelae of COVID-19 (PASC). RAB/6N mice pave the way for dissecting the molecular drivers underlying SARS-CoV-2-induced acute maladaptive responses and subsequent post-acute systemic diseases. This preclinical platform also opens opportunities for the exploration of therapeutic interventions against systemic PASC and for anticipating the emergence of PASC-associated comorbidities. One-sentence summaryWe generated a hACE2-transgenic mouse model that develops maladaptive lung immune responses upon acute SARS-CoV-2 infection, leading to fatal outcomes or post-acute systemic disease syndromes in convalescent animals.

microbiology↗

bioRxiv2024

Versatile Cell Penetrating Peptide for Multimodal CRISPR Gene Editing in Primary Stem Cells

CRISPR gene editing offers unprecedented genomic and transcriptomic control for precise regulation of cell function and phenotype. However, delivering the necessary CRISPR components to therapeutically relevant cell types without cytotoxicity or unexpected side effects remains challenging. Viral vectors risk genomic integration and immunogenicity while non-viral delivery systems are challenging to adapt to different CRISPR cargos, and many are highly cytotoxic. The arginine-alanine-leucine-alanine (RALA) cell penetrating peptide is an amphiphilic peptide that self-assembles into nanoparticles through electrostatic interactions with negatively charged molecules before delivering them across the cell membrane. This system has been used to deliver DNAs, RNAs, and small anionic molecules to primary cells with lower cytotoxicity compared to alternative non-viral approaches. Given the low cytotoxicity, versatility, and competitive transfection rates of RALA, we aimed to establish this peptide as a new CRISPR delivery system in a wide range of molecular formats across different editing modalities. We report that RALA was able to effectively encapsulate and deliver CRISPR in DNA, RNA, and ribonucleic protein (RNP) formats to primary mesenchymal stem cells (MSCs). Comparisons between RALA and commercially available reagents revealed superior cell viability leading to higher numbers of transfected cells and the maintenance of cell proliferative capacity. We then used the RALA peptide for the knock-in and knock-out of reporter genes into the MSC genome as well as for the transcriptional activation of therapeutically relevant genes. In summary, we establish RALA as a powerful tool for safer and effective delivery of CRISPR machinery in multiple cargo formats for a wide range of gene editing strategies.

bioengineering↗

bioRxiv2021

Macrophages govern antiviral responses in human lung tissues protected from SARS-CoV-2 infection

The majority of SARS-CoV-2 infections among healthy individuals result in asymptomatic to mild disease. However, the immunological mechanisms defining effective lung tissue protection from SARS-CoV-2 infection remain elusive. Unlike mice solely engrafted with human fetal lung xenograft (fLX), mice co-engrafted with fLX and a myeloid-enhanced human immune system (HNFL mice) are protected against SARS-CoV-2 infection, severe inflammation, and histopathology. Effective control of viral infection in HNFL mice associated with significant macrophage infiltration, and the induction of a potent macrophage-mediated interferon response. The pronounced upregulation of the USP18-ISG15 axis (a negative regulator of IFN responses), by macrophages was unique to HNFL mice and represented a prominent correlate of reduced inflammation and histopathology. Altogether, our work shed light on unique cellular and molecular correlates of lung tissue protection during SARS-CoV-2 infection, and underscores macrophage IFN responses as prime targets for developing immunotherapies against coronavirus respiratory diseases. HIGHLIGHTSO_LIMice engrafted with human fetal lung xenografts (fLX-mice) are highly susceptible to SARS-CoV-2. C_LIO_LICo-engraftment with a human myeloid-enriched immune system protected fLX-mice against infection. C_LIO_LITissue protection was defined by a potent and well-balanced antiviral response mediated by infiltrating macrophages. C_LIO_LIProtective IFN response was dominated by the upregulation of the USP18-ISG15 axis. C_LI

microbiology↗