Nikhil Prasad Fact checked by:Thailand Medical News Team Jul 04, 2024 4 months, 2 weeks, 3 days, 13 hours, 19 minutes ago
COVID-19 News: In an exciting new discovery, scientists have found that histamine receptor H1 (HRH1), commonly targeted by allergy medications, can also act as an entry point for the SARS-CoV-2 virus, the culprit behind COVID-19. This finding opens up potential new treatment options using antihistamines, drugs that are widely available and generally safe.
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Antihistamine drugs prevented SARS-CoV-2 infection in transgenic hACE2 mice.. (C) Schematic of the animal infection assay. Four transgenic hACE2 mice (C57BL/6) were intravenously administrated with acrivastine at a dosage of 10 mg/kg of body weight. Mice in the control group were administrated with an equal volume of saline. Six hours later, all mice were intranasally challenged with 1 × 105 focus-forming units of the SARS-CoV-2 D614G virus. On Day 5 post-infection, the mice were euthanized. Lung tissues were harvested and subjected to HE, immunohistochemistry (IHC), and viral quantification assays. (D) Lung tissues from both saline- and acrivastine-treated mice (challenged with authentic SARS-CoV-2) were analyzed by HE staining as well as IHC with antibodies against the SARS-CoV-2 N protein. (E) SARS-CoV-2 RNA copies in lung tissues were quantified via RT-PCR and are presented as log10 copies per milliliter (mL). (F) Schematic of ACE2- or HRH1-dependent SARS-CoV-2 entry. In ACE2high/HRHlow cells, SARS-CoV-2 viruses enter susceptible cells mainly by binding to ACE2 receptors through S proteins, while in cells with low ACE2 expression and high HRH1 expression (ACE2low/HRH1high cells), SARS-CoV-2 viruses can utilize HRH1 as alternative receptors to enter target cells. In cells expressing both ACE2 and HRH1 (ACE2medium/HRH1medium cells), SARS-CoV-2 can use both receptors to enter target cells. In addition, the presence of HRH1 could enhance ACE2-dependent viral entry. represent the mean ± SEM of biological quadruplicate samples.
How The Study Started
The study, led by Dr Fei Yu and a team of researchers from Guangdong Provincial People’s Hospital-China, Guangzhou National Laboratory-China, Sun Yat-sen University-China, South China University of Technology-China, The Second Affiliated Hospital of Guangzhou Medical University-China, the First Affiliated Hospital of Guangzhou Medical University-China and Shenyang Medical College-China that is covered in this
COVID-19 News, started by examining various FDA-approved drugs to see if any could block the entry of SARS-CoV-2 into human cells. What they found was remarkable: several antihistamines, which are usually used to combat allergic reactions, were effective in stopping the virus.
What Are Antihistamines?
Antihistamines are drugs that block the effects of histamine, a substance in the body that causes allergy symptoms like itching, sneezing, and runny nose. These drugs work by binding to histamine receptors, which prevents histamine from attaching and causing allergic reactions. Some well-known antihistamines include clemastine, astemizole, azelastin
e, brompheniramine, and ebastine.
The Role of HRH1 in COVID-19
The research revealed that the SARS-CoV-2 virus can use HRH1 as an alternative to the better-known ACE2 receptor to enter cells. By binding to the HRH1 receptor, the virus can effectively hijack the cell, leading to infection. However, when antihistamines bind to HRH1, they block the virus from gaining entry, thereby preventing infection.
Testing the Hypothesis
To confirm their findings, the researchers conducted a series of experiments. They used different strains of the virus and tested various antihistamines to see if they could prevent the virus from entering cells. The results were promising: antihistamines showed strong efficacy against multiple strains of SARS-CoV-2, including the original strain and several mutants.
The Mechanism Explained
HRH1 facilitates the entry of SARS-CoV-2 by directly interacting with the virus's spike protein, a key part of the virus that allows it to attach to and enter human cells. Antihistamines block this process by binding to HRH1 themselves, thus preventing the spike protein from attaching to the receptor. This discovery means that antihistamines could potentially be repurposed to treat COVID-19.
Real-World Implications
To see if these findings held up in real-world scenarios, the researchers tested the effects of antihistamines on actual SARS-CoV-2 infections using humanized mouse models. The results were encouraging: mice treated with antihistamines had significantly lower levels of the virus in their lungs compared to untreated mice. This suggests that antihistamines could be effective in preventing and treating COVID-19 in humans.
Why This Matters
The discovery that HRH1 can act as an alternative receptor for SARS-CoV-2 and that antihistamines can block this interaction is significant for several reasons. First, antihistamines are already widely available and have a well-documented safety profile, making them an attractive option for repurposing as COVID-19 treatments. Second, this finding could lead to new strategies for preventing and treating COVID-19, especially in cases where other treatments are not available or effective.
Next Steps
While the findings are promising, more research is needed to confirm the efficacy and safety of using antihistamines to treat COVID-19 in humans. Clinical trials will be essential to determine the appropriate dosages and to ensure that these drugs do not cause adverse effects when used for this new purpose.
Conclusion
The discovery that antihistamines can prevent SARS-CoV-2 from entering human cells by blocking the HRH1 receptor is a groundbreaking development in the fight against COVID-19. This new understanding of how the virus can enter cells opens up exciting possibilities for using existing drugs to combat the pandemic. As researchers continue to explore this potential, there is hope that antihistamines could become a valuable tool in the global effort to control and eventually overcome COVID-19.
The study findings were published in the peer reviewed journal: mBio.
https://journals.asm.org/doi/10.1128/mbio.01088-24
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COVID-19 News, keep on logging to Thailand Medical News.
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