Key Takeaways

• Cortisol is a glucocorticoid hormone central to the stress response, immune regulation and homeostasis.
• It is released by the adrenal gland under control of the hypothalamic-pituitary-adrenal (HPA) axis.
• Cortisol acts through the glucocorticoid receptor (GR/NR3C1) via canonical and non-canonical pathways.
• It suppresses inflammation, dampening cytokines such as IL-6 and TNF-alpha.
• Dysregulated cortisol is linked to autoimmune disorders, chronic stress and cancer.
• Its role in cancer therapy is complex and depends on the tumour type.

Contents

• What is Cortisol?
• The HPA Axis
• Cortisol and the Glucocorticoid Receptor
• Cortisol and the Inflammatory Response
• Stress, Cortisol and Disease
• Cortisol in Cancer Therapy
• Frequently Asked Questions

Cortisol, HPA-Axis & Cytokine ELISA Kits

From the HPA-axis hormones that drive cortisol release to the inflammatory cytokines it suppresses, these validated ELISA kits cover the whole pathway.

CRH

CRH ELISA Kit

HPA HormoneHuman

Corticotropin-releasing hormone starts the cascade from the hypothalamus.

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ACTH

ACTH ELISA Kit

HPA HormoneHuman

Pituitary ACTH signals the adrenal gland to release cortisol.

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Cortisol

Cortisol ELISA Kit

GlucocorticoidMulti-species

The stress hormone itself — the end-product of the HPA axis.

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NR3C1

Glucocorticoid Receptor (NR3C1) ELISA Kit

ReceptorHuman

The intracellular receptor through which cortisol acts.

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IL-6

IL-6 ELISA Kit

CytokineHuman

A pro-inflammatory cytokine that cortisol strongly suppresses.

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TNF-α

TNF-alpha ELISA Kit

CytokineHuman

A key inflammatory mediator dampened by glucocorticoid signalling.

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What is Cortisol?

Cortisol is a steroid hormone and a member of the glucocorticoid family. It is involved in a wide range of physiological processes that maintain homeostasis, from metabolism to immune regulation. Cortisol is produced by the adrenal gland in response to stress and to falling blood-sugar levels, but it is also released in a circadian rhythm under normal conditions, peaking in the early morning and falling through the day.

Because it touches so many systems, cortisol sits at the intersection of endocrinology and immunology. Its best-known role is as the body’s master anti-inflammatory hormone — the reason synthetic glucocorticoids are among the most widely prescribed drugs for inflammatory and autoimmune conditions.

The HPA Axis

Cortisol release is governed by the hypothalamic-pituitary-adrenal (HPA) axis. In response to stress, the hypothalamus secretes corticotropin-releasing hormone (CRH), which signals the pituitary gland to release adrenocorticotropic hormone (ACTH). ACTH in turn stimulates the adrenal cortex to synthesise and release cortisol into the bloodstream.

Cortisol then feeds back to the hypothalamus and pituitary to switch off its own production — a classic negative-feedback loop. When this feedback is disrupted by chronic stress, cortisol levels remain persistently elevated, with wide-ranging effects on immunity and health.

Cortisol and the Glucocorticoid Receptor

Once inside a cell, cortisol binds the glucocorticoid receptor (GR or GCR), encoded by the gene NR3C1. The receptor is an intracellular protein expressed by almost every cell type, regulating immune responses, metabolism and development. It contains three domains: an N-terminal transactivation domain, a DNA-binding domain, and a C-terminal ligand-binding domain. The active isoform, GRα, is most highly expressed in the central nervous system and macrophages.

Canonical signalling

In the classical pathway, the cortisol-bound receptor translocates to the nucleus, binds glucocorticoid-response elements in DNA, and directly switches target genes on or off — including many involved in inflammation.

Non-canonical signalling

Beyond direct DNA binding, the activated receptor also interferes with other transcription factors such as NF-κB and AP-1, rapidly repressing pro-inflammatory gene programmes without binding DNA itself.

Cortisol and the Inflammatory Response

Cortisol is a potent immunosuppressant. Through the glucocorticoid receptor it dampens the production of pro-inflammatory cytokines such as IL-6 and TNF-alpha, reduces the recruitment and activity of immune cells, and promotes an overall anti-inflammatory state. This is the mechanism that makes glucocorticoid drugs so effective at controlling inflammation.

The same power, however, comes with a cost: sustained high cortisol suppresses immune defence, which is why chronic stress can leave the body more vulnerable to infection and slower to heal.

Stress, Cortisol and Disease

Dysregulated cortisol signalling is linked to a range of diseases. Chronically elevated cortisol, as seen in prolonged stress or Cushing’s syndrome, impairs immunity and metabolism, while impaired cortisol signalling is associated with autoimmune and inflammatory disorders where the anti-inflammatory brake fails. Because the glucocorticoid receptor is expressed almost everywhere, disturbances in this pathway ripple across many organ systems.

Cortisol in Cancer Therapy

Cortisol and synthetic glucocorticoids play a complex role in oncology. They are widely used to manage inflammation, nausea and immune side-effects during cancer treatment, and can directly trigger apoptosis in certain blood cancers such as leukaemia and lymphoma. In other tumour types, however, glucocorticoid signalling can promote resistance to therapy — so the effect depends heavily on the specific cancer.