Ginger shows promise as a natural defense against autoimmune diseases

By Hugo Francisco de SouzaReviewed by Susha Cheriyedath, M.Sc.Oct 2 2023

In a recent study published in the journal JCI Insight, authors built upon their previous work where they investigated the anti-autoimmune disease effects of 6-gingerol, the most abundant phytochemical produced by the roots of the ginger herb. Since their previous work highlighted that this plant extract could reverse the impacts of neutrophil hyperactivity in mice model systems, the researchers herein evaluated if the oral consumption of whole ginger extracts could have similar effects, both in murine models and pilot human trials. Their results demonstrate that ginger consumption for as few as seven days neutralizes hyperactivity in neutrophils in both in vivo systems. When taken by healthy individuals, it increases their resistance against developing conditions, including lupus and antiphospholipid syndrome (APS).

Study: Ginger intake suppresses neutrophil extracellular trap formation in autoimmune mice and healthy humans. Image Credit: Nataly Studio / Shutterstock

Neutrophil autoimmune conditions and the untapped potential of herbs

Antiphospholipid antibody syndrome (APS) is an autoimmune disease primarily affecting women between ages 30 and 40. APS results in the formation of abnormal proteins that promote clot formation in veins and arteries and is especially harmful to both a mother and her fetus during pregnancy. APS and lupus, a frequent comorbidity characterized by circulating immune complexes that damage organs following their deposition, are life-long, incurable conditions resulting from genetics, environmental exposure, or a combination of these. Both diseases result in significant mortality, morbidity, and healthcare costs.

Prior research has identified that, despite having starkly dissimilar clinical profiles, both APS and lupus are pathologically driven by the exaggerated and abnormal neutrophil extracellular trap formation, medically termed “NETosis.” During NETosis, neutrophils overexpress and secrete their nuclear chromatin in the form of web-like structures with pro-inflammatory properties and potentially harmful granule-derived proteins that, despite in organs and the circulatory system, severely impacting health.

Recent studies have demonstrated that in addition to its standalone negative impacts, excessive NETosis can result in durable autoantibody formation, resulting in other autoimmune conditions that would otherwise have been suppressed by the body’s adaptive immune tolerance. Given that most of these autoimmune conditions do not have a cure, require constant and usually expensive medical intervention, and present significant mortality costs, finding an inexpensive therapeutic for NETosis is imperative.

In recent years, scientific attention has shifted to the potential of herb-derived phytochemicals with anti-inflammatory properties as a treasure trove of safe and natural remedies against autoimmune disorders in general, and NETosis specifically. In a previous study, the authors of the current work demonstrated that a purified ginger extract, 6-gingerol, showed promise in boosting intracellular cyclic adenosine monophosphate (cAMP) and blunting neutrophil phosphodiesterase (PDE) activity, both of which are key mechanistic outcomes of NETosis.

Notably, their research identified that NETs and neutrophils in thrombo-inflammatory disease manifestations affect not only APS, lupus, and similar autoimmune conditions but also promote adverse outcomes in communicable diseases like the coronavirus disease 2019 (COVID-19).

About the study

The present research aimed to verify if whole ginger extracts have similar NETosis-reversing effects as 6-gingerol and have beneficial effects on consumption even for healthy individuals who do not present autoimmune symptoms. This study represents a pilot investigation that may form the basis for future clinical testing of the beneficial proteins of ginger in treating a whole spectrum of NETosis-related autoimmune diseases, including APS, lupus, vasculitis, rheumatoid arthritis, and even COVID-19.

Researchers began by testing the efficacy of powdered whole ginger obtained from Aurea Biolabs (Kerala, India) in in vitro assays. Immunoglobulin G (IgG) was obtained both from APS and lupus patients (cases) and healthy controls and purified using the Protein G Agarose Kit (Pierce). IgG purity and concentration were estimated using Coomassie staining and BCA protein assay, respectively. For human neutrophil NETosis assays, blood was collected from healthy human volunteers, purified via density-gradient centrifugation, and neutrophils were isolated using dextran sedimentation and red blood cell (RBC) lysis. Flow cytometry and nuclear morphology microscopy were used to verify purity.

For NETosis assays, the above-purified neutrophils were mixed with neutrophils derived from APS and lupus patients (3 volunteers, respectively). In vitro assays comprised of immunofluorescence microscopy, phosphodiesterase (PDE) activity measurements, and computations of intracellular cAMP levels.

In vivo APS models comprised venous thrombosis experiments conducted on male C57BL/6 mice (10–13 weeks). Female BALB/c mice (9 weeks old) were used for lupus assays. The venous thrombosis assays were carried out using an electrolytic inferior vena cava (IVC) model. Circulating myeloperoxidase (MPO)-DNA complexes were then quantified, and isolated thrombi were processed via thrombus sectioning and immunohistochemistry.

Finally, the pilot human study was conducted. Participants above the age of 18 and devoid of NETosis-associated autoimmune diseases were recruited. Female participants needed to be of childbearing potential to allow for the evaluation of ginger consumption in tandem with contraception. Women who were pregnant, breastfeeding, or suffering from cardiovascular disease, diabetes, or cancer were excluded to avoid confounds due to their diseases or the medication they consumed. All statistics carried out in this study were 1-way analysis of variance (ANOVA) corrects from multiple corrections.

Study findings

The key findings of this study were that ginger consumption significantly inhibited NETosis in healthy study participants, even after stimulation (mixing) of neutrophils from APS or lupus patients. This was expected given that their previous research reported the same finding on the use of purified 6-gingerol supplementation, and whole ginger extracts comprise approximately 20% 6-gingerol. Similarly, this study presents that whole ginger consumption inhibited cAMP-specific PDE activity, confirming previous findings.

Whole ginger consumption was found to attenuate APS IgG-mediated venous thrombosis and NETosis in in vivo murine models. Notable, whole ginger consumption was shown to blunt lupus-relevant disease activity even in lupus-positive female BALB/c mice.

Human pilot experiments confirm ginger as a key focus of future clinical trials as it was found to boost neutrophil cAMP and reduce NETosis in healthy human volunteers, even after only seven days of ginger diet supplementation. To verify these results and confirm that findings were not a by-product of the small sample size (N = 9; 3 male, 6 female), the study was repeated with a non-related volunteer cohort (N = 8), with study findings consistent between replicates. Additionally, the second cohort study revealed a reduction in plasma NET levels (measured from the MPO-DNA complexes).

Conclusion

The present study highlights the potential of whole ginger consumption as a safe and natural intervention, both to treat existing cases of APS, lupus, and other NETosis-associated diseases and to prevent the development of these conditions in hitherto healthy humans. They combined in vitro assays with in vivo murine and human models and found that whole ginger consumption blunts venous thrombosis (APS) and significantly reduces the clinical characteristics of lupus in murine models.

In healthy human volunteers, ginger consumption for only seven days was associated with a notable reduction in NETosis and cAMP, confirming its anti-autoimmune disorder potential in future clinical trials.

“…we found that the solubilized ginger extract antagonized neutrophil PDE activity. The result was increased neutrophil intracellular cAMP levels, which associated with blunted NETosis by human neutrophils in vitro. Such data extend recent studies that have reported a role for ginger extracts, and specifically 6-gingerol, as inhibitors of cAMP-specific PDE activity. Importantly, the suppressive effects of ginger on NETosis could be mitigated by blocking PKA activity, a key downstream cAMP-dependent kinase. The fact that increasing neutrophil cAMP and activating PKA would be beneficial for disease activity in mice aligns well with our previous work demonstrating the potential therapeutic target of this pathway in APS and lupus models with synthetic PDE4 inhibitors.”