Can CBD help boost the immune system?
The immune system plays a vital role in keeping the body healthy, modulating a range of actions such as inflammatory responses in reaction to injury. However, its most important function is as the body’s built-in defence system. And, as such, it is the body’s first line of defence again pathogens like bacteria, viruses and other microbial organisms intent on invading the body, preventing these pathogens from wreaking havoc on biological and physiological systems in the body.
Cannabinoids can modulate these immune reactions, with some studies suggesting that they can act as either an immunosuppressant, but also immune-boosting effects. In other words, on the one hand, cannabinoids have the potential to relieve symptoms of patients with over-active immune systems, suffering from autoimmune diseases and chronic inflammation. On the other hand, they also can help people suffering from immunodeficiency disorders such as HIV, through its ability to boost white blood counts.
This makes for a complicated and dichotomous relationship between cannabinoids and the immune system that is still poorly understood. In addition, the actions of cannabinoids like cannabidiol (CBD) and tetrahydrocannabinol (THC) are mediated primarily by the endocannabinoid system (ECS), meaning that they also interact with and all biological activity - including that of the immune system.
It is clear that there is much that remains to be discovered about how cannabinoids affect the immune system. However, as research into this field continues, a picture is emerging of cannabinoids like CBD and THC acting as immune system modulator that continually fine tunes and maintains immune function and response. Let’s take a look.
The Immune System and How it Works
Before detailing the effects of cannabinoids on the immune system, it is useful to recap its components and the function of each.
As mentioned, the immune system is the body’s built-in defence mechanisms that fights of microbial invaders in addition to activating and coordinating the signalling pathways that regulate inflammatory responses in injured tissue cells.
White blood cells, in particular, play a vital role in both of these two primary roles of the immune system. They are responsible for defending the body against infection by detecting and destroying foreign bodies and organisms. They are also responsible for a process called phagocytosis in which they “eat” dead and damaged cells after injury.
White blood cells, also called leukocytes, come in two distinct groups;
- Lymphocytes, of which there are two types: B lymphocytes and T lymphocytes. Lymphocytes destroy pathogens and modulate immunity by creating antibodies that will trigger future immune responses against future infections, and;
- Phagocytes come in several types including neutrophils, monocytes, macrophages and mast cells. Phagocytes ingest and digest foreign particles, pathogens, and dead or dying cells, thus fighting off infections.
Other components of the immune system include:
- Other types of immune cells including dendritic cells, granulocytes and lymphoid cells
- Organs such as the spleen and thymus
- A range of biological and physiological systems like the lymphatic system and the endocannabinoid system
Together, these cells, organs, biological and physiological systems that make up the immune system keeps the body healthy by recognising and destroying microbes, antigens, and dead cells and tissues.
The Role of the Endocannabinoid System in the Immune System
You might have noticed that the endocannabinoid system (ECS) is one of the physiological systems that is in intricately intertwined with, and plays a vital role in the functioning of the immune system.
The primary components of the ECS are its endogenous ligands (endocannabinoids) and protein receptors (cannabinoid receptors) in addition to proteins and metabolic enzymes responsible for signalling and metabolic synthesis.
The two main endocannabinoids are anandamide and 2-AG that act as a retrograde neurotransmitter that has the ability to travel backwards across the synapses of receptors. This means they can modulate cell activity that allows them to regulate homeostasis besides controlling various physiological processes.
The ECS also contains CB1 and CB2 cannabinoid receptors that are the two primary receptor proteins for cannabinoids. Although CB-1 receptors are mainly in the brain and central nervous system, they have also been found in immune cells. Several studies have now shown that the activation of CB1 receptors may be linked to alterations of immune cell reactivity.
However, when it comes to the immune system, CB-2 receptors are the stars. In fact, they are most extensively found in the immune system, the spleen, tonsils, and thymus glands. CB2 receptors are also found in abundance in immune cells including macrophages and leucocytes.
The Role of Endocannabinoids and the Immune System
Because cannabinoid receptors are found at localised sites throughout the body, but also in the peripheral (PNS) and central nervous systems (CNS), it may explain the immediate and effective actions of endocannabinoids on immune functions.
Scientists have found that endocannabinoids are actually present in various immune cells, including monocytes, macrophages, basophils, lymphocytes, and dendritic cells. So, for instance, 2-AG is thought to be the functionally relevant endocannabinoid linked to CB2 immune function. Similarly, anandamide has been linked to the modulation of immune function with both endocannabinoids acting in a biphasic manner. In other words, the endocannabinoids anandamide and 2-AG have both immunosuppressant as well as immunopotentiating effects through the modulation of immune system function.
CB2 receptors also seem to be involved with immune function and response, with scientist hypothesising that they are the primary therapeutic target for immune system disorders. In addition to regulating inflammatory responses, cell death and cell migration, several studies have also shown that CB2 receptors affect immune responses by activating immune cells like T-cells, B-cells, macrophages and dendritic cells that are responsible for recognising, destroying and processing of antigen material.
What this ultimately means is that, when endocannabinoids activate CB2 receptors, it creates an immunomodulatory effect that can either result in either immunosuppressant or immunopotentiating effect. It is also highly suggestive of a complex and adaptable relationship between the various components of the ECS and those of the immune system. One in which endocannabinoids and cannabinoid receptors play a key role in “fine tuning” immune function and response to maintain its overall homeostasis.
Plant Cannabinoids and the Immune System
Although the research is limited, scientists know that plant cannabinoids like THC and CBD can impact disease resistance by interacting with the endocannabinoid system.
For instance, because THC binds to the CB2 receptor and activates it, it has a strong anti-inflammatory and immunosuppressant effect. Similarly, CBD is also considered being an immunosuppressant because of its ability to reduce cytokine production and inhibiting T-cell function - this despite its low cannabinoid receptor binding affinity.
So what is going on?
Cannabidiol and the Immune System
CBD’s interaction with the ECS is thought to be through a variety of indirect actions, including the inhibition of FAAH. FAAH is the enzyme that breaks down endocannabinoids, meaning that this inhibition results in higher levels of anandamide and 2-AG, both of which we have shown are implicated in maintaining homeostasis and healthy immune system function and response. Basically, CBD supports the homeostatic regulatory function of the ECS, helping it to mediate the appropriate immune response (i.e., either suppressing or boosting it when needed).
Likewise, because TRPV1 receptors are found in abundance in the neuro-immune axis, especially in the central immune cells, it has lead scientists to believe that, when CBD activates these TRPV1 receptors, it enhances immune response via the cytokines and chemokines in the CNS. This means that CBD when activates TRPV1 receptors it enhances immune responses to pathophysiological attacks.
What this means is that, because CBD doesn’t bind directly to receptors, it seems to play a modulatory role in immune system function. This means CBD has the potential to treat autoimmune diseases such as Crohn’s and multiple sclerosis by down-regulating an overactive immune system that has turned on itself and reduce inflammation. But, it also means that CBD has immune-stimulating effects that can support patients with HIV by up-regulating the immune system.
Tetrahydrocannabinol and the Immune System
In contrast to CBD, THC is thought to affect immune responses and resistance due to its strong binding affinity on both CB1 and CB2 receptors. This is because when THC binds to these receptors, it potentially diminishes immune responses by disturbing the balance of T helper (Th)1 pro-inflammatory versus Th2 anti-inflammatory cytokines.
In addition, THC has also been shown to be associated with reduced resistance to tumours and viral infection, inhibit the development of immunity to the bacterial and suppress the function of T-cells and natural killer cells (NK cells). This suggests that THC can, in certain circumstances, and in particular in certain viral infections, do more harm than good.
However, more recent research suggests that THC can actually up-regulate the immune system, potentially improving patient outcomes, especially for those with HIV. A 2011 study revealed that THC appeared to have some kind of protective effect and reducing viral load in monkeys infected with HIV.
In the end, the immune system is complex, comprising a variety of organs, cells, tissues and soluble factors that work together to produce a plethora of immune functions. This complexity provides many avenues for cannabinoids to modulate and alter immune function, primarily through their interaction with cannabinoid and other immune system related receptors. And it is when these are activated, that an immunomodulatory that, in effect, continually tweaks and maintains immune function and response.