Beyond Pain: The Neuroendocrine–Immune Axis in Endometriosis

Neuroendocrine–immune crosstalk redefines endometriosis beyond pain

Key Points

Highlights:

• Endometriosis involves a complex interaction between the nervous, endocrine, and immune systems.
• Neuroendocrine–immune imbalance contributes not only to pain but also to lesion progression and infertility.
• Chronic stress amplifies disease activity through HPA axis and immune dysregulation.

Importance:

• Neuroendocrine–immune dysregulation should be recognized as a central mechanism in endometriosis, extending beyond pain perception to disease progression and infertility.

What's Done Here:

• This is a narrative review summarizing current evidence on the neuroendocrine–immune axis in endometriosis.
• It integrates interactions between neural, hormonal, and immune pathways in disease pathogenesis and discusses how these interactions contribute to pain, lesion development, and infertility.
• Study also reviews emerging therapeutic strategies targeting this axis.

Key Results:

• Increased nerve fiber density and neurogenic inflammation are closely linked to pain severity.
• Estrogen-driven immune and neural interactions promote inflammation, angiogenesis, and lesion growth.
• Chronic stress activates the HPA axis and sympathetic system, leading to immune dysfunction and disease progression.
• Macrophage–nerve and mast cell–nerve interactions contribute to neuroinflammation and pain sensitization.
• Neuroendocrine mediators such as CRH, BDNF, and cytokines play central roles in linking stress, immunity, and endometriosis.

Strengths and LImitations:

• Strengths are: comprehensive integration of neural, endocrine, and immune mechanisms; focus on system-level interaction rather than isolated pathways; inclusion of emerging therapeutic targets.
• Limitations are: narrative design without systematic methodology; reliance on heterogeneous preclinical and clinical evidence; limited direct clinical validation of proposed mechanisms.

From the Editor-in-Chief – EndoNews

"This review brings attention to a dimension of endometriosis that is increasingly recognized but still insufficiently integrated into routine clinical thinking: the neuroendocrine–immune interface.

The concept itself is not new. Neural involvement, immune activation, and hormonal regulation have each been described independently for decades. What this work does is to place these components within a single framework, emphasizing their interaction rather than their isolated contributions. In doing so, it aligns with a growing body of evidence suggesting that endometriosis is not adequately explained by a purely anatomical or hormonal model.

The discussion of nerve fiber density, neurogenic inflammation, and immune–neural crosstalk is particularly relevant, as it directly challenges the traditional view of pain as a secondary consequence of lesion burden. Instead, it supports the perspective that pain may be intrinsically embedded within disease biology. This distinction is important, as it may help explain the frequent mismatch between lesion extent and symptom severity observed in clinical practice.

At the same time, the review must be interpreted within the limitations inherent to its design. Much of the evidence remains associative, derived from heterogeneous experimental and clinical studies, and lacks consistent standardization. The integration of these findings into a unified model is conceptually appealing but not yet supported by robust, prospective clinical data.

Importantly, the proposed framework should not be taken as a definitive mechanistic explanation, but rather as a working model that helps organize existing observations. Whether neuroendocrine–immune interactions represent a primary driver of disease, a secondary amplification mechanism, or a parallel pathway remains to be clarified.

From a clinical standpoint, the value of this perspective lies less in immediate therapeutic implications and more in reframing how endometriosis is conceptualized. It encourages a shift from a lesion-centered view toward a systems-based understanding, which may ultimately influence future research directions and, over time, therapeutic strategies.

In summary, this review contributes by consolidating a complex and fragmented field into a more coherent narrative. Its strength lies in integration; its limitation lies in the current level of evidence. The challenge ahead will be to translate this conceptual framework into clinically actionable knowledge."

Lay Summary

Endometriosis is often considered a hormonal and inflammatory disease—but this may be only part of the story.

A recent review published in Biomolecules by Chang et al. from Fudan University, Shanghai, highlights that endometriosis is better understood as a condition involving a complex interaction between the nervous, endocrine, and immune systems.

Rather than acting independently, these systems appear to communicate closely, shaping how the disease develops, progresses, and produces symptoms.

The presence of nerve fibers within endometriotic lesions, together with activated immune cells and estrogen-driven pathways, creates a dynamic environment that contributes not only to chronic pain but also to lesion growth and persistence. In this context, pain is no longer simply a symptom—it becomes part of the disease mechanism itself.

Importantly, stress-related pathways may further amplify this process. Activation of the body’s stress response system can influence immune function and inflammation, potentially worsening both symptoms and disease progression.

Taken together, these insights suggest that endometriosis should not be viewed as a purely local pelvic disorder, but rather as a systemic condition involving multiple interacting pathways.

This broader perspective may help explain why symptoms vary widely between patients and why treatment responses are often inconsistent.

Research Source: https://pubmed.ncbi.nlm.nih.gov/41301454/