A new COVID-19 drug breakthrough study led by researchers from the Department of Infectious Diseases, Konkuk University-Gwangjin-gu-South Korea along with help from Chung-Ang University- Gyeonggi-South Korea has demonstrated that the pharmaceutical product called Hemin can be used to treat COVID-19 via heme oxygenase-1 Induction.
The antiviral effects of heme oxygenase-1 (HO-1), a cytoprotective enzyme that inhibits the inflammatory response and reduces oxidative stress, have been investigated in several viral infections.
To confirm whether HO-1 suppresses SARS-CoV-2 infection, the study team assessed the antiviral activity of hemin, an effective and safe HO-1 inducer, in SARS-CoV-2 infection.
The study findings showed that treatment with hemin efficiently suppressed SARS-CoV-2 replication (selectivity index: 249.7012).
Besides, the transient expression of HO-1 using an expression vector also suppressed the growth of the virus in cells.
Free iron and biliverdin, which are metabolic byproducts of heme catalysis by HO-1, also suppressed the viral infection. Additionally, hemin indirectly increased the expression of interferon-stimulated proteins known to restrict SARS-CoV-2 replication.
The study findings were published in the peer reviewed journal: Scientific Reports (Nature)
Heme oxygenase-1 (HO-1), encoded by Hmox1, is a cytoprotective enzyme that inhibits the inflammatory response and reduces oxidative stress4. HO-1 expression can be induced by hemin, CoPP-9, and andrographolide5,6,7. HO-1 catalyzes heme into carbon monoxide, biliverdin, and iron, which are also known to inhibit the proliferation of various viruses8.
HO-1 was also shown to interact with interferon (IFN) regulatory factor 3, independent of its enzyme activity, which activated the type I IFN response to inhibit infection by influenza A virus9. Hemin, which is the representative HO-1 inducer, has antiviral effects against several viruses including hepatitis A virus5,10,11,12.
Induction of HO-1 with other chemicals demonstrates the antiviral activity against hepatitis B and C viruses, Ebola virus, HIV, dengue virus, Zika virus, and human respiratory syncytial virus13,14. The suitability of HO-1 as an antiviral candidate for SARS-CoV-2 has been discussed in recent studies15,16.
In this study, we primarily used hemin to induce HO-1 expression, which led to a reduction in SARS-CoV-2 replication in vitro. We also attempted to identify the basic mechanisms underlying the antiviral effects of HO-1, with respect to its enzymatic as well as non-enzymatic functions.
To date there is no licensed antiviral drug in the market that specifically treats the SARS-CoV-2 infection. Considering the devastating effects caused by the COVID-19 pandemic, identifying antiviral drugs that are effective against SARS-CoV-2 is of the utmost importance.
To date, more than more than a quarter billion individuals globally have been infected with the SARS-CoV-2 virus and more than 5.06 million people have died from the COVId-19 disease.
Some of the proposed overpriced antiviral drugs to treat COVID-19 that are being promoted by the Western pharmaceutical giants and the elites controlling the COVId-19 narratives are extremely toxic and mutagenic.
Hemin is a pharmaceutical preparation available under the trade names Panhematin® and Normosang®, and has a well-established safety profile. There are also many cheap generic versions of it available across the globe.
Hemin (haemin; ferric chloride heme) is an iron-containing porphyrin with chlorine that can be formed from a heme group, such as heme B found in the hemoglobin of human blood.
Hemin is endogenously produced in the human body, for example during the turnover of old red blood cells. It can form inappropriately as a result of hemolysis or vascular injury. Several proteins in human blood bind to hemin, such as hemopexin and serum albumin.
A lyophilised form of hemin is used as a pharmacological agent in certain cases for the treatment of porphyria attacks, particularly in acute intermittent porphyria. Administration of hemin can reduce heme deficits in suchpatients, thereby suppressing the activity of delta-amino-levulinic acid synthase (a key enzyme in the synthesis of the porphyrins) by biochemical feedback, which in turn reduces the production of porphyrins and of the toxic precursors of heme.
In such pharmacological contexts, hemin is typically formulated with human albumin prior to administration by a medical professional, to reduce the risk of phlebitis and to stabilize the compound, which is potentially reactive if allowed to circulate in free-form.
The enzyme heme oxygenase-1 (HO-1) is a cytoprotective enzyme that can be induced by hemin, Cobalt protoporphyrin-9 (CoPP-9), and andrographolide. HO-1 acts by attenuating the inflammatory response and oxidative stress inside cells.
More importantly, heme oxygenase-1 (HO-1), encoded by Hmox1, is also a cytoprotective enzyme that inhibits the inflammatory response and reduces oxidative stress. https://portlandpress.com/clinsci/article-abstract/122/3/93/68996/Haem-oxygenase-1-non-canonical-roles-in-physiology?redirectedFrom=fulltext
HO-1 catalyzes heme degradation to carbon monoxide, biliverdin, and iron, all of which have been reported to exert antiviral effects. https://www.sciencedirect.com/science/article/pii/S0002944016305326
The non-enzymatic action of HO-1 has been reported, wherein it inhibits influenza A infection through its interactions with interferon (IFN) regulatory factor 3, which results in the activation of the type I IFN response. https://www.sciencedirect.com/science/article/abs/pii/S0891584916300363
Importantly hemin which an iron-containing porphyrin compound, is also a known HO-1 inducer whose antiviral effects against viruses such as the hepatitis A virus and many other viruses have been already reported. https://www.jimmunol.org/content/176/7/4252.short
Also, HO-1 has been reported to exhibit an immunomodulatory and antiviral effect against viruses affecting the respiratory system, such as the influenza virus and respiratory syncytial virus.
Despite the fact that an earlier publication has hypothesized that hemin-induced HO-1 may exert anti-viral activity against SARS-CoV-2, no evidence was presented. https://www.preprints.org/manuscript/202004.0075/v1
The study team explored the antiviral activity of HO-1 induced by hemin against SARS-CoV-2 and attempted to describe the mechanism of its anti-viral action.
For the study, induction of HO-1 by hemin and the consequent antiviral effect against SARS-CoV-2 was assessed using in vitro assays on Vero 76 cells. Cells were infected with SARS-CoV-2 after pre-treatment with hemin.
Importantly a dose-dependent increase in HO-1 messenger ribonucleic acid (mRNA) and protein levels, accompanied by a dose-dependent decrease in SARS-CoV-2 RNA and viral nucleoprotein content, was subsequently observed, thereby indicating the antiviral activity exerted by hemin.
The COVID-19 Drugs study team also performed time of addition experiments to determine at what stage of the viral infection hemin exerts its action. Suppression of viral protein expression was evident when cells were exposed to hemin, even after viral entry. This suggests that hemin may inhibit the SARS-CoV-2 intracellular replication phase of its life cycle.
In addition, immunofluorescence assays showed that there was a decrease in the number of Vero 76 cells containing the SARS-CoV-2 spike protein as the concentration of hemin increased at 24 hours post-infection.
Interestingly transient overexpression of monkey HO-1 in Vero-76 cells using expression vectors was found to inhibit SARS-CoV-2 replication in these cells.
Hence this indicates that HO-1 contributes to the observed antiviral effect and porphyrin in hemin may not be solely responsible as earlier reports suggest in the case of the human immunodeficiency virus (HIV).
Utilizing detailed cytotoxicity assays, it was found that hemin exhibited a 50% cytotoxicity concentration (CC50 ) of 169.9217 micromolar (μM), whereas its 50% effective concentration EC50 was found to be 0.6805 μM. Selectivity index (SI), which is the ratio of CC50 and EC50, gives the measure of the window between cytotoxicity and antiviral activity. The SI for hemin was found to be 249.7, thereby suggesting that CC50 was approximately 249 times higher than EC50 confirming that hemin is an effective and safe therapeutic agent.
It was also observed that HO-1 catalyzes the breakdown of heme to metabolites like free iron, biliverdin, and carbon monoxide (CO). The induction of HO-1 expression by hemin may lead to an increase in metabolite byproducts due to heme breakdown.
The study team also evaluated the antiviral activity of CO-releasing molecule (CORM), which induces CO production, iron III chloride (FeCl3), and biliverdin against SARS-CoV-2. The findings suggested that FeCl3 and biliverdin significantly inhibited SARS-CoV-2 replication, while CORM did not have an effect. This finding confirms the antiviral effect of the enzymatic action of HO-1.
The study team further explored if the enzymatic activity of HO-1 played a role in its antiviral effect against SARS-CoV-2. Assays were performed, wherein Vero 76 cells were treated with both hemin and zinc protoporphyrin-9 (ZnPP-9), which is a known inhibitor of HO-1 enzymatic activity.
Significantly when compared to cells treated with hemin alone, there was a higher reduction of SARS-CoV-2 RNA and protein in the cells that received both ZnPP-9 and hemin.
However, when HO-1 expression was knocked down using short interfering RNA against HO-1, the antiviral activity was significantly inhibited. The findings indicate an additional antiviral effect of HO-1, which may be attributed to activities that are distinct from its enzymatic actions.
Also interesting was the fact that the study team also observed that in cells treated with just ZnPP-9, there was a low level of HO-1 expression and inhibition of SARS-CoV-2 replication.
Past studies suggest that though ZnPP-9 inhibits HO-1 enzymatic activity, it increases the expression of HO-1 proteins. The elevated levels of HO-1 may exert their antiviral effect indirectly through the IFN regulatory factor-3 (IRF3)-mediated pathway.
The research team explored if the hemin-induced expression of HO-1 results in an increase in levels of IFN-stimulated gene (ISG) proteins such as OAS1, Mx1, and ISG15.
The study findings showed that the expression of ISG proteins was increased in Vero 76 cells, irrespective of whether they were infected with SARS-CoV-2 in the presence or absence of hemin pre-treatment.
Importantly cells that were pre-treated with hemin and subsequently infected with SARS-CoV-2 showed elevated expression of ISG proteins, while the viral nucleocapsid protein was not detected in these cells. This indicates the antiviral activity of ISG proteins.
It should be noted that ISG proteins induced by the viral infection alone in the absence of hemin did not exert an inhibitory effect on viral replication, which was evident by the detection of viral nucleocapsid protein in these cells.
This study finding suggests that ISG proteins induced by SARS-CoV-2 infection do not effectively inhibit viral replication.
According to the study team, a possible explanation for this effect is that SARS-CoV-2 induces ISG proteins at a later stage when the viral replication is complete, while HO-1 induces ISG protein expression through the IRF3-mediated pathway at an earlier stage, effectively inhibiting viral replication.
It should be noted that the hemin product that was used in this study to induce HO-1 is commercially available in the market as Panhematin® and has a well-established safety profile.
The study findings from this present research demonstrate that hemin exhibits significant in vitro antiviral activity against SARS-CoV-2 by inducing the expression of HO-1.
Corresponding author, Dr In-Soo Choi from the Department of Infectious Diseases, College of Veterinary Medicine, Konkuk University told, “Hemin may prove to be a safe and effective antiviral drug therapy for SARS-CoV-2 infection. The findings from this study may pave the way for developing effective therapeutics that can combat COVID-19.”
The study team will next be liaising with 3 other medical facilities to initiate clinical trials using Hemin to treat COVID-19.