Biology subjects

Nehring, M.

Publications and source records attributed to Nehring, M..

6 recordsLinked to original sources

bioRxiv2025

Contractility governs cardiomyocyte cell cycle activity

The hearts rhythmic contractions keep blood flowing to deliver the oxygen and nutrients that sustain life, but this very strength may also explain why the heart has so little capacity to regenerate. Whereas embryonic and neonatal hearts can repair themselves, this ability is rapidly lost after birth as heart muscle cells (cardiomyocytes) exit the cell cycle. We tested whether the force-generating machinery of the heart acts as a barrier to regeneration. Across human cardiomyocytes, engineered heart tissue, and myocardial slices, we found that active force generation suppresses proliferation, whereas its inhibition, through chemogenetic or pharmacological modulation, enabled cell cycle re-entry. These findings identify contractility as a central regulator of regenerative potential, highlighting new directions for strategies to restore repair in the diseased heart.

cell biology↗

bioRxiv2024

Impacts of Antiretroviral Therapy on the Oral Microbiome and Periodontal Health of Feline Immunodeficiency Virus Positive Cats

Feline immunodeficiency virus (FIV) is the domestic cat analogue of HIV infection in humans. Both viruses induce oral disease in untreated individuals, with clinical signs that include gingivitis and periodontal lesions. Oral disease manifestations in HIV patients are abated by highly effective combination antiretroviral therapy (cART), though certain oral manifestations persist despite therapy. Microorganisms associated with oral cavity opportunistic infections in patients with HIV cause similar pathologies in cats. To further develop this model, we evaluated characteristics of feline oral health and oral microbiome during experimental FIV infection over an 8-month period following cART. Using 16S metagenomics sequencing, we evaluated gingival bacterial communities at four timepoints in uninfected and FIV-infected cats treated with cART or placebo. Comprehensive oral examinations were also conducted by a veterinary dental specialist over the experimental period. Gingival inflammation was higher in FIV-infected cats treated with placebo compared to cART-treated cats and controls at study endpoint. Oral microbiome alpha diversity increased in all groups, while beta diversity differed among treatment groups, documenting a significant effect of cART therapy on microbiome community composition. This finding has not previously been reported and indicates cART ameliorates immunodeficiency virus-associated oral disease via preservation of oral mucosal microbiota. Further, this study illustrates the value of the FIV animal model for investigations of mechanistic associations and therapeutic interventions for HIV oral manifestations. IMPORTANCEFeline Immunodeficiency Virus (FIV) is the viral analogue to HIV in humans, and both infections are associated with oral disease. Our study explored how antiretroviral treatment affects the oral health and microbiome of domestic cats infected with FIV. Cats treated with antiretroviral therapy had less gum inflammation and a different community of oral bacteria compared to untreated FIV-positive cats. This suggests that antiretroviral therapy not only helps in controlling FIV infection but also benefits feline oral health. These findings advance our understanding of antiretroviral treatment for lentiviral-associated oral disease and highlight FIV as a valuable experimental model for the similar condition in humans.

microbiology↗

bioRxiv2023

Impulse initiation in engrafted pluripotent stem cell-derived cardiomyocytes can stimulate the recipient heart.

Transplantation of pluripotent stem cell-derived cardiomyocytes is a novel promising cell-based therapeutic approach for patients with heart failure. However, engraftment arrhythmias are a predictable life-threatening complication and represent a major hurdle for clinical translation. Catheter-based electrophysiological analysis suggested that the ventricular arrhythmias were caused by an automaticity of the transplanted cells, but whether impulse generation by transplanted cardiomyocytes can propagate to the host myocardium and override the recipient rhythm has not been directly assessed experimentally. We used optogenetics to specifically activate engrafted cardiomyocytes, which resulted in impulse generation in the engrafted cardiomyocytes and stimulated the recipient heart (4/9 hearts). Thus, our study shows that transplanted cardiomyocytes can electrically couple to the host myocardium and stimulate the recipient heart, providing experimental evidence that cardiomyocyte automaticity can serve as a trigger for ventricular arrhythmias.

pharmacology and toxicology↗

bioRxiv2022

Impact of prior infection on SARS-CoV-2 antibody responses in vaccinated long-term care facility staff

SARS-CoV-2 emerged in 2019 and has resulted in millions of deaths worldwide. Certain populations are at higher risk for infection, especially staff and residents at long term care facilities (LTCF), due to the congregant living setting, and residents with many comorbidities. Prior to vaccine availability, these populations represented a large fraction of total COVID-19 cases and deaths in the U.S. Due to the high-risk setting and outbreak potential, staff and residents were among the first groups to be vaccinated. To define the impact of prior infection on response to vaccination, we measured antibody responses in a cohort of staff members at a LTCF, many of whom were previously infected by SARS-CoV-2. We found that neutralizing, receptor-binding-domain (RBD) and nucleoprotein (NP) binding antibody levels were significantly higher post-full vaccination course in individuals that were previously infected, and NP antibody levels could discriminate individuals with prior infection from vaccinated individuals. While an anticipated antibody titer increase was observed after vaccine booster dose in naive individuals, boost response was not observed in individuals with previous COVID-19 infection. We observed a strong relationship between neutralizing antibodies and RBD-binding antibodies post-vaccination across all groups, suggesting RBD-binding antibodies may be used as a correlate of neutralization. One individual with high levels of neutralizing and binding antibodies experienced a breakthrough infection (prior to the introduction of Omicron), demonstrating that the presence of antibodies is not always sufficient for complete protection against infection. These results highlight that history of COVID-19 exposure significantly increases SARS-CoV-2 antibody responses following vaccination. ImportanceLong-term care facilities (LTCFs) have been disproportionately impacted by COVID-19, due to their communal nature, high-risk profile of residents and vulnerability to respiratory pathogens. In this study, we analyzed the role of prior natural immunity to SARS-CoV-2 on post-vaccination antibody responses. The LTCF in our cohort experienced a large outbreak with almost 40% of staff becoming infected. We found that individuals that were infected prior to vaccination, had higher levels of neutralizing and binding antibodies post-vaccination. Importantly, the second vaccine dose significantly boosted antibody levels in those that were immunologically naive prior to vaccination, but not those that had prior immunity. Regardless of pre-vaccination immune status, levels of binding and neutralizing antibodies were highly correlated. The presence of NP-binding antibodies can be used to identify individuals that were previously infected when pre-vaccination immune status is not known. Our results reveal that vaccination antibody responses differ depending on prior natural immunity.

immunology↗

bioRxiv2021

Durable antibody responses in staff at two long-term care facilities, during and post SARS-CoV-2 outbreaks

SARS-CoV-2 has had a disproportionate impact on non-hospital healthcare settings such as long-term care facilities (LTCFs). The communal nature of these facilities, paired with the high-risk profile of residents, has resulted in thousands of infections and deaths and a high case fatality rate. To detect pre-symptomatic infections and identify infected workers, we performed weekly surveillance testing of staff at two LTCFs which revealed a large outbreak at one of the sites. We collected serum from staff members throughout the study and evaluated it for binding and neutralization to measure seroprevalence, seroconversion, and type and functionality of antibodies. At the site with very few incident infections, we detected that over 40% of the staff had preexisting SARS-CoV-2 neutralizing antibodies, suggesting prior exposure. At the outbreak site, we saw rapid seroconversion following infection. Neutralizing antibody levels were stable for many weeks following infection, suggesting a durable, long-lived response. Receptor-binding domain antibodies and neutralizing antibodies were strongly correlated. The site with high seroprevalence among staff had two unique introductions of SARS-CoV-2 into the facility through seronegative infected staff during the period of study but these did not result in workplace spread or outbreaks. Together our results reveal that high seroprevalence rate among staff can contribute to herd immunity within a workplace and protect against subsequent infection and spread within a facility.

immunology↗

bioRxiv2020

Pathogenesis, transmission and response to re-exposure of SARS-CoV-2 in domestic cats

The pandemic caused by SARS-CoV-2 has reached nearly every country in the world with extraordinary person-to-person transmission. The most likely original source of the virus was spillover from an animal reservoir and subsequent adaptation to humans sometime during the winter of 2019 in Wuhan Province, China. Because of its genetic similarity to SARS-CoV-1, it is likely that this novel virus has a similar host range and receptor specificity. Due to concern for human-pet transmission, we investigated the susceptibility of domestic cats and dogs to infection and potential for infected cats to transmit to naive cats. We report that cats are highly susceptible to subclinical infection, with a prolonged period of oral and nasal viral shedding that is not accompanied by clinical signs, and are capable of direct contact transmission to other cats. These studies confirm that cats are susceptible to productive SARS-CoV-2 infection, but are unlikely to develop clinical disease. Further, we document that cats develop a robust neutralizing antibody response that prevented re-infection to a second viral challenge. Conversely, we found that dogs do not shed virus following infection, but do mount an anti-viral neutralizing antibody response. There is currently no evidence that cats or dogs play a significant role in human exposure; however, reverse zoonosis is possible if infected owners expose their domestic pets during acute infection. Resistance to re-exposure holds promise that a vaccine strategy may protect cats, and by extension humans, to disease susceptibility.

microbiology↗