Why do people have a fever? See how Academician Zhuang Xiaowei uses MERFISH to answer this question

After the pathogen invades the human body, it will produce symptoms such as fever, what are the neuronal cells that control the fever symptoms? What is the mechanism by which these neuronal cells control fever symptoms? In June 2022, Harvard's team published an article titled A preoptic neuronal population controls fever and appetite during illness in Nature, answering these two questions
with the help of MERFISH technology, immunohistochemistry, fluorescence in situ hybridization, and reverse verification of cell ablation 。 It was revealed that during pathogen infection in mice, the blood-brain barrier activates neurons in the ventral ventral ventral side of the mouse to control the production
of fever symptoms through a paracrine signaling mechanism (non-neuronal cells near neurons secreting immune signaling molecules).

Immunohistochemistry determines the specific location of the hypothalamic preoptic region to control febrile symptoms—VMPO (ventral medial preoptic region)

Injection of LPS (the main component of the cell wall of gram-negative bacteria) into mice mimics the phenomenon of pathogen infection of organisms, monitoring changes in the body temperature of mice, and detecting activated neuronal cells after a rise in body temperature (Figure 1).

After the mice had elevated body temperature, the location of activation in the brain region was determined by the number of Fos-positive cells in the various regions of the brain enriched to the mice and a total of 12 regions showed significant enrichment of Fos-positive cells (Figure 2-c), and cells in the VMPO region were also highly activated (Figure 2-f).

MERFISH technology characterizes VMPO^LPS neuronal cell activation

After determining the VMPO location associated with fever symptoms, the expression of genes was detected by MERFISH super-resolution imaging, the distribution of VMPO neurons was characterized by two specific gene markers of Gal/Amigo2, and the distribution of AVPe (periventricular nucleus anterior ventricular) temperature sensitive neurons was characterized by two specific gene markers of Adcyap1/Sncg
.

MERFISH technology characterizes the spatial distribution and activation of a variety of neuronal and non-neuronal cells associated with neurons, blood-brain barriers, and periventricular organs

In order to further explore the mechanism of activation of VMPO LPS neurons, with the characterization of various types of cells by MERFISH technology, the distribution and activation of microglial cells/inhibitory neurons/activated neurons after^LPS induction can be observed through the 'original' image results (Figure 4), astrocytes/endothelial cells/pericytes that make up the blood-brain barrier, and ependymal cells that make up periventricular organs
。

MERFISH technology and ISH technology combine to explore the mechanism by which neuronal cells in the VMPO region are activated—VMPO^LPS neuronal cells are activated by immune signals secreted by local non-neuronal cells

Further analysis of the spatial distribution of the two non-neuronal cells—ependymal and astrocytes—from a spatial biological point of view, visually observes the distribution of activated ependymal membranes and astrocytes (purple regions) near^{VMPO LPS} (Figure 5).

Determine the function of VMPO neuronal cells by selectively ablation

To verify the function of VMPO^{LPS neurons} in controlling fever symptoms, the purpose of VMPO^LPS neuronal ablation was achieved by transfection of the AAV-DTA (diphtheria toxin subunit A) system, and the fluorescence map (Figure e) showed that the cells were successfully
ablated 。 By injecting physiological saline and LPS into the positive control, negative control and three groups of mice in the experimental group (transfected AAV-GFP system, untransfected AAV-DTA system, and transfected AAV-DTA system), respectively, it was observed that after LPS induction, no fever symptoms appeared in the experimental group mice, which further verified the function of
VMPO^LPS neurons.

Figure 6.
e is a fluorescence detection plot for selective removal of VMPO^LPS neurons; The f-figure shows that the VMPO^LPS neuron is selectively removed and then injected with LPS, which cannot cause fever symptoms
.

This study revealed that during pathogen infection, the blood-brain barrier activates VMPO^LPS neurons through paracrine signaling mechanisms to control the production
of febrile symptoms.
MERFISH technology detects gene expression by means of super-resolution fluorescence in situ imaging with single-molecule detection sensitivity, defines different cell types, retains spatial location information, and more intuitively displays that the distribution of VMPO LPS neuronal cells in the tissue with the ependymal membrane and the cells that make up the blood-brain barrier has spatial proximity, as a strong evidence to find that VMPO^LPS neuronal cells are activated by paracrine cells.
It fully demonstrates the charm
of space biology.

References: Osterhout JA, Kapoor V, Eichhorn SW, Vaughn E, Moore JD, Liu D, Lee D, DeNardo LA, Luo L, Zhuang X, Dulac C.
A preoptic neuronal population controls fever appetite and appetite during sickness.
Nature.
2022 Jun; 606(7916):937-944.
doi: 10.
1038/s41586-022-04793-z.
Epub 2022 Jun 8.
PMID: 35676482.
DOI: 10.
1038/s41586-022-04793-z

In 2021, MERSCOPE, the world's first commercialized multi-FISH super-resolution imaging analysis system,™ was released in the
United States.
Based on the core technology MERFISH technology, MERSCOPE™ can perform super-resolution imaging of 1cm² tissues in 1 day, with a resolution of ≤ 100 nanometers, localizing the spatial distribution of RNA in single cells and quantifying gene expression
.
Achieve true in situ single-cell spatial genome analysis, visualize gene expression and localization, and promote genomics research into the next generation
.

In March 2022, Gene Co.
, Ltd.
officially signed a contract to become the general agent
of MERSCOPE™ MERFISH super-resolution fluorescence microscopic imaging analysis system of Vizgen in China.
Responsible for the system's pre-sales technical consultation, after-sales installation training, application support and other work
.
At the same time, our company also provides MERFISH technical services
.
If you are interested, you can directly add the product manager enterprise WeChat for one-on-one communication, or you can contact the gene people
around you.