Tag Archives: #hormone

Metabolic Hormone ‘Leptin’ Linked To Poor Vaccine Response (Medicine)

Reduced levels of a metabolic hormone known as leptin is linked to poor vaccine antibody responses in the general population, a University of Queensland study has found.

Reduced levels of a metabolic hormone known as leptin is linked to poor vaccine antibody responses in the general population, a University of Queensland study has found.

The researchers made the discovery while investigating several cohorts’ responses to the influenza vaccine or hepatitis B vaccine pre-COVID.

UQ’s Professor Di Yu identified a link between the metabolic and immune systems that could be used to develop new strategies for improving vaccine protection in vulnerable populations.

“Using multiple advanced techniques in immunology, genetics and biochemistry, our study found leptin directly promoted the development and function of cells which are vital in triggering an antibody response,” Professor Yu said.

“In collaboration with global teams, we identified the reduction of an essential metabolic hormone called leptin was associated with compromised vaccine responses in both young and older individuals.

“As a result, we can now identify those who are at risk of not generating an antibody response after vaccination.”

Professor Yu said leptin was a metabolic hormone largely produced by fat tissue.

“Vaccines have been known for a very long time to have a different efficacy for individuals,” he said.

“Although our genetics partially contribute to the difference, other factors are also essential.

“When we are fit and healthy, we have a much better vaccine efficacy.

“If we are healthy, we have a good metabolism and a normal level of leptin, but if we have malnutrition or some disease conditions, we may have a low level of leptin, which may limit our vaccine response and immune protection.”

Professor Yu said many people with obesity and high levels of leptin conversely often had leptin resistance which could potentially lead to a poorer vaccine response – an area that should be carefully investigated in the future.

The researchers are keen to test responses to the COVID-19 vaccines to determine biomarkers that could identify those people at risk of not generating a strong vaccine response.

“During the era of the COVID-19 pandemic, the successful vaccination for SARS-CoV-2 is the major hope to bring society back to normalcy,” he said.

“Differing vaccine responses cause a major bottleneck in large-scale vaccination programs.”

The research is published in Nature Communications (DOI: 10.1038/s41467-021-23220-x).

Reference: Deng, J., Chen, Q., Chen, Z. et al. The metabolic hormone leptin promotes the function of TFH cells and supports vaccine responses. Nat Commun 12, 3073 (2021). https://doi.org/10.1038/s41467-021-23220-x

Provided by University of Queensland

The Plant Hormone Auxin May Promote Disease By Regulating Virulence Gene Expression (Botany)

Scientists have long known that the plant hormone auxin controls many aspects of plant growth, development, and responses to the environment. Only more recently have they begun to understand that there is also a link between auxin and leaf spotting diseases.

Auxin: plant growth hormone ©shutterstock

Several years ago scientists, including Barbara Kunkel, discovered an increased concentration of auxin in leaves inoculated by the bacterial pathogen, Pseudomonas syringae, that causes bacterial spot and speck diseases on many plants.

“We previously demonstrated that auxin promotes disease caused by P. syringae on Arabidopsis thaliana plants, which means that auxin is not acting as a classic plant defense hormone,” Kunkel explained. “We were also one group to demonstrate that auxin also suppresses salicylic acid (SA)-mediated plant defense responses.”

However, Kunkel and her colleagues knew there was more work to be done. “It was clear that there was a second role for auxin in P. syringae infection, that appeared to be independent of modulating SA-mediated defenses.” In a new article published in the MPMI journal, Kunkel and colleagues at Washington University in St. Louis and the University of California San Diego present the first investigation of the role of auxin in regulating pathogen gene expression in plant tissue.

This article makes two new contributions to our understanding of the role of auxin during P. syringae infection of Arabidopsis thaliana plants. First, the research demonstrated that the canonical host auxin signaling pathway is required to suppress SA-mediated host defense and normal diseases susceptibility to P. syringae. Second, auxin plays a second role in promoting disease by regulating virulence gene expression in P. syringae.

“Our data led us to propose a working model in which auxin acts as a signal to the pathogen to switch from an early state of infection to a later stage that requires expression of a second set of virulence genes,” Kunkel said. “There have been several reports that bacteria can respond to auxin and auxin has begun to be considered as a potential microbial signaling molecule. However, to the best of our knowledge, this is the first time a biologically relevant example has been demonstrated. This is an exciting breakthrough in plant-microbe interactions.”

This work provides another example of how plant hormones can be used by microbes as an environmental cue, which seems to be emerging as a common strategy as scientists learn more about how pathogens and parasites sense their plant hosts. To learn more about this study, read “Dual Role of Auxin in Regulating Plant Defense and Bacterial Virulence Gene Expression During Pseudomonas syringae PtoDC3000 Pathogenesis” published in the August issue of MPMI.

References: Arnaud T. Djami-Tchatchou, Gregory A. Harrison, Chris P. Harper, Renhou Wang, Michael J. Prigge, Mark Estelle, and Barbara N. Kunkel, “Dual Role of Auxin in Regulating Plant Defense and Bacterial Virulence Gene Expression During Pseudomonas syringae PtoDC3000 Pathogenesis”, Molecular Plant-Microbe Interactions® 2020 33:8, 1059-1071

Provided by American Phytopathological Society

New Dopamine Sensors Could Help Unlock The Mysteries Of Brain Chemistry (Neuroscience)

In 2018, Lin Tian and her team at UC Davis Health developed dLight1, a single fluorescent protein-based biosensor. This family of highly specific sensors detects dopamine, a hormone released by neurons to send signals to other nerve cells. When combined with advanced microscopy, dLight1 provides high resolution, real-time imaging of the spatial and temporal release of dopamine in live animals.

RdLight1 sensors depicting dopamine in neurons. Credit: UC Regents

Recently, Tian and her team succeeded in expanding the color spectrum of the dLight1 sensor. In an article published Sept. 7 in Nature Methods, they introduced two new spectral variants of dLight1: the yellow YdLight1 and the red RdLight1.

The new sensors will help researchers to detect and monitor different information processing activities in the brain. With the different colors, they will be able to see multiple neurochemical release and neural activities at the same time.

The RdLight1 permits the simultaneous assessment of dopamine, pre- or post-synaptic neuronal activity and the glutamate release in specific types of cells and neuronal projections in animals. Its increased light penetration and imaging depth provide enhanced dopamine signal quality. This allows researchers to optically dissect dopamine’s release and model its effects on neural circuits.

As a neurotransmitter, dopamine plays an important role in movement, attention, learning and the brain’s pleasure and reward system.

These exciting new tools opened a new door to developing color-shifted neurochemical indicators. Together with other tools, they have great potential to unlock the mysteries of brain chemistry in health and disease. The knowledge they gained from these sensors will facilitate the development of safer next-generation therapies to neuropsychiatric disorders such as depression, anxiety, schizophrenia and addiction.

References: Patriarchi, T., Mohebi, A., Sun, J. et al. An expanded palette of dopamine sensors for multiplex imaging in vivo. Nat Methods (2020). https://doi.org/10.1038/s41592-020-0936-3 link: https://www.nature.com/articles/s41592-020-0936-3