The researchers analyzed three groups totaling 609 women. Group A included 98 women with a history of ectopic pregnancy but no prior intrauterine operation. Group B included 244 women with a history of ectopic pregnancy and at least one intrauterine operation. The control group comprised 267 women with recurrent spontaneous abortion. Endometrial CD38 and/or CD138-positive cells were present in 53 of 98 women in Group A, 177 of 244 in Group B, and 75 of 267 controls. The authors reported that positivity was significantly more frequent in the endometrium of women with a history of ectopic pregnancy than in the recurrent-spontaneous-abortion control group.

CD38 and CD138 were examined as markers associated with chronic endometritis. Within the ectopic-pregnancy groups, positivity was more common among women who had undergone an intrauterine operation: 177 of 244 women in Group B were positive for CD38 and/or CD138, compared with 53 of 98 in Group A. This subgroup difference was observed in the retrospective data, but the study did not establish that intrauterine operations caused the higher positivity rate. Likewise, the analysis identified an association between endometrial marker status and ectopic-pregnancy history rather than proving a causal role for chronic endometritis in ectopic pregnancy.

The findings are consistent with the study authors’ hypothesis that chronic endometritis may be an underlying pathogenic factor contributing to ectopic pregnancy. However, the evidence comes from a retrospective comparison with unequal group sizes, and the control population had recurrent spontaneous abortion rather than no reproductive history. The design also cannot determine whether CD38 and CD138 positivity was present before the ectopic pregnancies, developed afterward, or reflected other differences between the groups. The study therefore supports an association worthy of further investigation, not a demonstrated mechanism, diagnostic tool, preventive measure, or clinical benefit.

Subject of Research: Endometrial CD38 and CD138 positivity, chronic endometritis markers, and ectopic pregnancy history in a retrospective cohort

Article Title: Increased Endometrial CD38 and CD138 Positivity in Women with Ectopic Pregnancy History: A Retrospective Study

Article References: Li, Y., Li, Y., Chen, D., Xie, X., Zhang, C., Zhong, X., & Xie, M. (2026). Increased Endometrial CD38 and CD138 Positivity in Women with Ectopic Pregnancy History: A Retrospective Study. Reproductive Sciences. https://doi.org/10.1007/s43032-026-02246-w

Image Credits: AI Generated

DOI: 10.1007/s43032-026-02246-w

Keywords: ectopic pregnancy, endometrium, CD38, CD138, chronic endometritis, retrospective study, reproductive health, intrauterine procedures, recurrent spontaneous abortion, inflammatory markers, Increased, Endometrial

The research team, led by Olivia M. Shorthouse and Juan F. Quintana, set out to answer a deceptively simple question. Reproductive dysfunction has been reported anecdotally in both human patients and experimental animals infected with T. brucei, but nobody knew whether the parasites actually entered the female reproductive tract or whether the observed problems were merely secondary effects of systemic illness. By tracking parasite localisation during both acute and chronic stages of infection in mice, the investigators demonstrated that the organisms take up residence in the endometrium, the specialised mucosal lining of the uterus. This direct infiltration of reproductive tissue places the parasite in intimate contact with the immune cells and hormone-responsive epithelium that govern fertility.

What the parasites do once they arrive proved to be as important as where they settle. The study revealed a progressive and multi-layered deterioration of reproductive health as infection moved from its acute phase into chronicity. Chronically infected mice lost substantial fat mass, a sign of the metabolic wasting characteristic of trypanosome disease. Their oestrous cycles, the rodent equivalent of the menstrual cycle, became disrupted and eventually arrested. The uterus and ovaries themselves shrank, showing measurable atrophy. Perhaps most strikingly, the researchers documented extensive transcriptional dysregulation across the hypothalamic-pituitary-gonadal axis, the hormonal control circuit that links the brain to the gonads and orchestrates fertility from the top down.

The hypothalamic-pituitary-gonadal axis is a delicate three-tiered system. The hypothalamus, a small region at the base of the brain, releases gonadotropin-releasing hormone in pulses that instruct the pituitary gland to secrete luteinising hormone and follicle-stimulating hormone. These hormones, in turn, act on the ovaries to drive follicle development, ovulation, and the production of oestrogen and progesterone. The new findings show that chronic T. brucei infection distorts gene expression at every level of this hierarchy, implying that the parasite does not merely damage the uterus locally but interferes with the central neuroendocrine commands that regulate it. This systemic rewiring of reproductive control represents a form of pathology that has rarely been characterised in parasitic infection.

Immune remodelling within the uterus emerged as a central feature of the disease process. In both acute and chronic infection, the researchers observed infiltration of T cells into uterine tissue and activation of pro-inflammatory myeloid cells, the innate immune population that includes monocytes, macrophages, and their inflammatory descendants. Beyond the uterus itself, the team detected broader type 1 inflammatory signatures spreading across reproductive tissues and components of the hypothalamic-pituitary-gonadal axis. Type 1 inflammation, typically driven by interferon signalling and associated with defence against intracellular pathogens, is not normally the dominant immune tone of the reproductive tract, which tends to favour tolerance and controlled responses. Its expansion here suggests that the infection fundamentally reprograms the immunological identity of the female reproductive organs.

The ovaries told their own story of damage. Examination of ovarian pathology revealed follicular degeneration, meaning the structures that house and nurture developing eggs were deteriorating. The researchers also counted a reduction in corpora lutea, the transient endocrine structures that form after ovulation and produce the progesterone needed to support early pregnancy. Fewer corpora lutea indicate fewer successful ovulations, a direct readout of impaired fertility. Alongside these structural changes, alterations to steroidogenic pathways were detected, pointing to disruption of the enzymatic machinery that converts cholesterol into the steroid hormones essential for cyclicity and reproduction.

One of the most compelling experiments in the study involved a therapeutic intervention designed to disentangle two competing explanations. If the uterine damage were driven purely by falling oestrogen levels, then restoring oestrogen signalling should rescue the tissue. The researchers treated infected mice with tamoxifen, a selective oestrogen receptor modulator widely known for its use in breast cancer therapy. The results were revealing but partial. Tamoxifen restored uterine morphology and prevented the arrest of the oestrous cycle, demonstrating that endocrine dysfunction is indeed a major driver of the structural collapse of the uterus. However, the hormone treatment did not reverse the infection-induced remodelling of the uterine immune environment. The inflammatory cell populations and their activation states persisted despite hormonal rescue.

This dissociation carries a significant conceptual message: endocrine dysfunction and infection-driven inflammation are two distinct processes, each contributing to reproductive pathology through separate routes. Hormonal collapse explains the loss of normal uterine architecture and cyclicity, but the immune reprogramming is a direct consequence of the infection itself and cannot be corrected simply by fixing the hormonal signal. For patients, this implies that treating the hormonal consequences of chronic parasitic disease may not be sufficient to restore full reproductive health unless the underlying inflammatory drive, and ideally the infection itself, is also addressed. It also raises the possibility that immune-mediated damage to the reproductive tract could outlast or operate independently of the visible endocrine symptoms.

The broader significance of the work lies in what it says about systemic infection as a whole. The female reproductive tract is an immunologically dynamic organ that must balance defence against pathogens with the tolerance required for successful reproduction. The new findings identify it as a major target of T. brucei infection and demonstrate how a chronic parasitic disease can disrupt reproductive physiology through a combination of immune, endocrine, and metabolic pathways acting in parallel. Fat wasting, hypothalamic dysregulation, ovarian degeneration, and uterine inflammation are not isolated phenomena but interconnected consequences of a systemic infection that reaches into every tier of reproductive control. The authors suggest that this interplay between metabolism, immunity, and endocrinology may be relevant well beyond trypanosomiasis.

Indeed, the study closes with a methodological warning for the wider research community. Because the female reproductive tract has been so frequently overlooked in models of systemic inflammation, the effects of other infectious and inflammatory diseases on fertility and reproductive endocrinology may be underappreciated. The researchers argue that future studies of systemic inflammatory conditions should specifically assess the female reproductive tract rather than assuming it is a passive bystander. For sleeping sickness, a disease that affects tens of thousands of people in sub-Saharan Africa, the findings open a new dimension of clinical concern and a new set of questions about how parasitic infection shapes long-term reproductive health in survivors. They also provide a framework for investigating whether other chronic infections quietly inflict similar damage on the reproductive system.

Subject of Research: Trypanosoma brucei infection of the female reproductive tract and its effects on uterine immunity and reproductive hormone regulation

Article Title: Trypanosoma brucei infection remodels the uterine immune environment and drives neuroendocrine dysfunction

Article References: Shorthouse, O. M., Barnes, C., Colombo, S. A. P., Costa, J., Wonsbek, K., Mohon, A., MacDonald, A. S., Mann, E., Costain, A. H., & Quintana, J. F. (2026). Trypanosoma brucei infection remodels the uterine immune environment and drives neuroendocrine dysfunction. PLOS Pathogens, 22(10), e1014667. https://doi.org/10.1371/journal.ppat.1014667

Image Credits: AI Generated

DOI: 10.1371/journal.ppat.1014667

Keywords: Trypanosoma brucei, sleeping sickness, uterus, endometrium, reproductive immunology, hypothalamic-pituitary-gonadal axis, oestrous cycle, ovarian pathology, tamoxifen, inflammation, parasitology, PLOS Pathogens

Autophagy is a highly conserved intracellular quality-control system in which cytoplasmic material is sequestered into double-membrane vesicles called autophagosomes and delivered to lysosomes for degradation and recycling. The process is orchestrated by autophagy-related gene products, with initiation controlled by the ULK1 kinase complex and regulated on one side by the nutrient-sensing kinase mTOR, which suppresses autophagy when resources are abundant, and on the other by AMP-activated protein kinase, which activates it under energy stress. Beyond bulk recycling, selective forms of autophagy use cargo receptors such as p62/SQSTM1 to remove damaged mitochondria, protein aggregates, and invading microbes. In tissues that undergo constant remodeling, including the endometrium, which regenerates and sheds every menstrual cycle, this housekeeping function is not a luxury but a structural requirement.

The review first lays out the general logic of autophagy-mediated fibrosis, drawing on studies of lung, liver, kidney, skin, and heart. Fibrosis is the pathological endpoint of chronic tissue injury: activated fibroblasts differentiate into contractile, collagen-secreting myofibroblasts marked by alpha-smooth muscle actin, and they deposit excessive extracellular matrix rich in collagen type I, collagen type III, and fibronectin. The master profibrotic cytokine is transforming growth factor beta, which drives fibroblast activation, epithelial-to-mesenchymal transition, and fibroblast-to-myofibroblast transition. When autophagy is impaired, damaged mitochondria accumulate, reactive oxygen species rise, and cells slip into senescence, a state of permanent growth arrest accompanied by a senescence-associated secretory phenotype that floods the tissue with inflammatory cytokines such as interleukin-6 and interleukin-8. This oxidative and inflammatory milieu reinforces TGF-beta signaling, creating what the literature describes as a perverse cycle in which TGF-beta and reactive oxygen species amplify one another.

Applied to the endometrium, this framework explains much of what goes wrong in the aging uterus. Evidence from intrauterine adhesions, also known as Asherman’s syndrome, shows that defective autophagy contributes to endometrial epithelial-mesenchymal transition, a process in which epithelial cells lose their identity and acquire motile, matrix-producing characteristics. Overactivated Sonic hedgehog signaling aggravates intrauterine adhesions by inhibiting autophagy in endometrial stromal cells, while reduced expression of the inhibitory SMAD7 diminishes autophagy and promotes the transition of stromal cells into myofibroblasts. Loss of the Wnt antagonist DKK1 promotes fibrosis through autophagy dysregulation and exosome-mediated macrophage-to-myofibroblast transition, showing that immune cells can be recruited into the scarring program. In each case, the failure of cellular quality control appears upstream of matrix accumulation and declining receptivity.

Decidualization, the transformation of endometrial stromal cells that makes the lining receptive to an embryo, adds another layer of vulnerability. Genetic work has shown that the autophagy gene Atg16L1 is necessary for normal decidualization in mice, and endometrial autophagy has been shown to be essential for embryo implantation in early pregnancy. Rapamycin, an mTOR inhibitor that pharmacologically induces autophagy, has been reported to prevent spontaneous abortion in mouse models by triggering autophagy in decidual stromal cells, which in turn influences the residence of uterine natural killer cells. Senescent decidual cells, which accumulate with age and impair implantation in human endometrial assembloid models, are normally cleared by uterine natural killer cells during the menstrual cycle, a surveillance system that itself depends on the plasticity of the tissue. When autophagic flux falters, senescent cells persist, the secretory phenotype spreads, and the delicate decidual microenvironment deteriorates.

Yet the review is emphatic that the story does not end with autophagy as a universal protector. Under specific cellular and microenvironmental conditions, autophagy can facilitate profibrotic remodeling. In hepatic stellate cells, autophagy liberates lipids that fuel the activated, collagen-producing state. In other fibrotic settings, autophagy fosters myofibroblast differentiation through mTORC2 activation and downstream upregulation of connective tissue growth factor, and TGF-beta itself can induce autophagy through epigenetic regulation involving the acetyltransferase MYST1, thereby potentiating fibrosis. Transcription factor EB, a master regulator of lysosomal biogenesis and autophagy, has been shown to promote dermal fibroblast differentiation and collagen production. Mechanosignaling through the YAP/TAZ pathway, which drives fibroblast activation in fibrotic organs, requires autophagic flux to sustain cell phenotypic plasticity. In aging trabecular meshwork cells of the eye, enhanced autophagy activity promotes fibrotic progression via TGF-beta signaling. The direction of the effect, protective or pathological, depends on which cell is autophagying, what it is degrading, and what signals surround it.

This duality has direct consequences for how researchers should interpret endometrial data. Kobayashi’s review explicitly distinguishes mechanisms established in the endometrium from concepts extrapolated from other organs, a caution that matters because the endometrium is unusual: it cycles, sheds, and regenerates, tolerates repeated inflammatory bursts during menstruation, and supports a uniquely immunologically complex interface with the embryo. A pathway that restrains fibrosis in the kidney might accelerate it in a stromal cell responding to TGF-beta, and the review argues that only cell type-specific and age-dependent studies can resolve which regime dominates in the human uterus at a given life stage.

The translational implications are considerable but tempered. If impaired autophagy drives endometrial senescence and scarring, then restoring autophagic flux could, in principle, rejuvenate the lining and improve receptivity in patients of advanced maternal age or those with intrauterine adhesions. Fibroblast growth factor 1 has been reported to ameliorate thin endometrium in rats through activation of the autophagic pathway, and natural products that enhance autophagy are being explored as aids to embryo implantation. But the dual-role problem cuts the other way: indiscriminate autophagy activation could nourish myofibroblast differentiation and worsen fibrosis in the wrong cellular context. Safe therapeutic strategies will therefore require biomarkers that reveal, in a given patient’s endometrium, whether autophagy is deficient, excessive, or misdirected, and at which cell type.

The review also situates endometrial aging within the broader hallmarks of aging. Autophagy declines with age across tissues, and its loss promotes mitochondrial dysfunction, oxidative stress, stem cell exhaustion, and cellular senescence, all recognized drivers of aging. Single-cell transcriptomic studies of endometrium from women of advanced maternal age reveal disturbed decidual microenvironments, accumulation of senescent and multiciliated epithelial cells, and altered signaling landscapes, consistent with a lining that has lost the plasticity associated with successful implantation. Evolutionary framing, including the concept of antagonistic pleiotropy, suggests that pathways beneficial in early reproductive life may become detrimental later, which could explain why a quality-control system as fundamental as autophagy is not simply maximized throughout life.

What emerges is a research agenda rather than a finished therapy. Priority questions include mapping autophagic flux in specific endometrial cell populations across the reproductive lifespan, defining the tipping points at which autophagy switches from antifibrotic to profibrotic, and validating whether markers such as LC3-II, p62/SQSTM1, and Beclin-related activity can serve as clinically useful readouts of endometrial health. The review’s careful separation of endometrium-specific evidence from organ-external extrapolation is itself a methodological contribution, urging the field to test, rather than assume, that lessons from liver and lung apply to the womb. For millions of people pursuing pregnancy at older ages, understanding when to boost and when to restrain this cellular recycling program may prove decisive for keeping the aging endometrium receptive.

Subject of Research: The dual, context-dependent roles of autophagy in endometrial fibrosis and age-related reproductive dysfunction

Article Title: Dual Roles of Autophagy in Endometrial Fibrosis and Its Implications in Age-Related Reproductive Dysfunction

Article References: Kobayashi, H. (2026). Dual Roles of Autophagy in Endometrial Fibrosis and Its Implications in Age-Related Reproductive Dysfunction. Reproductive Sciences. https://doi.org/10.1007/s43032-026-02192-7

Image Credits: AI Generated

DOI: 10.1007/s43032-026-02192-7

Keywords: autophagy, endometrium, fibrosis, reproductive aging, endometrial receptivity, cellular senescence, TGF-beta, decidualization, intrauterine adhesions, mitochondrial dysfunction, epithelial-mesenchymal transition, fertility

The answer, according to the new work, centers on monocytes, a population of white blood cells that circulates in the bloodstream and is best known as an emergency responder dispatched to sites of infection or injury. The research reveals that in the uterus, monocytes play a far more nuanced role than simply arriving to fight threats. They act as a continuous supply line, replenishing distinct subsets of uterine macrophages, the tissue-resident immune cells that orchestrate tissue remodeling, clear cellular debris and calibrate inflammatory responses throughout the reproductive cycle.

Macrophages are not a uniform population. In tissues across the body, they exist as specialized subsets, each tuned to particular functions. Some are heavily phagocytic, engulfing dead cells and remodelled extracellular matrix. Others are regulatory, producing signals that suppress damaging immune reactions and promote tissue tolerance. In the uterus, this specialization is especially pronounced, because the organ must alternately support inflammatory processes, such as the tissue breakdown that accompanies menstruation or the onset of labor, and anti-inflammatory states, such as the immune tolerance required during pregnancy.

One of the central discoveries of the study is that these uterine macrophage subsets are not self-sustaining. Unlike macrophages in some other tissues, which can persist for long periods by dividing locally, many uterine macrophage populations depend on continual replenishment from blood-borne monocytes. As the reproductive cycle progresses and the uterine landscape shifts from proliferative to secretory to menstrual phases, monocytes are recruited into the tissue and differentiate into the specific macrophage subsets required at each stage. This means the composition of the uterine immune system is actively rebuilt across every cycle rather than being fixed at steady state.

That arrangement is elegant in its responsiveness, but it also creates vulnerability. Because the system depends on a constant influx and correct differentiation of monocytes, any disruption to monocyte recruitment, survival or maturation can ripple outward, altering the balance of macrophage subsets and, with it, the integrity of the tissue environment. The researchers found evidence that such disruptions occur in reproductive disease, where the normal homeostatic loop between monocytes and macrophages breaks down, contributing to maladaptive inflammation and impaired tissue repair.

The concept of dual roles is key to interpreting these findings. On one hand, monocytes serve as builders and maintainers, supplying fresh macrophages that support regeneration and keep inflammation in check. On the other hand, monocytes are the raw material of inflammation itself. When recruited in excessive numbers or instructed inappropriately, they can differentiate into macrophage states that amplify inflammatory damage rather than resolve it. The same cellular pathway that sustains health can, when dysregulated, drive pathology. This duality helps explain why the uterus, with its repeated cycles of wounding and repair, is susceptible to inflammatory and remodeling disorders.

Technically, the study relied on a combination of modern single-cell approaches and lineage tracing, tools that allow researchers to follow individual cells and their descendants over time. By profiling the transcriptomes of uterine immune cells across different phases of the reproductive cycle, the team could map which macrophage subsets were present at each stage and infer their origins. Fate-mapping experiments then demonstrated directly that newly arriving monocytes, rather than long-lived resident cells dividing in place, gave rise to the replenished macrophage pools. Functional analyses connected these cellular dynamics to the tissue-level processes of remodeling and inflammation regulation.

The implications extend across a broad range of reproductive health conditions. Abnormal menstrual bleeding, endometriosis, adenomyosis, recurrent pregnancy loss, preterm birth and poor wound healing after childbirth have all been linked, to varying degrees, with altered macrophage activity in the uterus. The new framework provides a unifying explanation: if monocytes fail to replenish the right macrophage subsets at the right time, or if they replenish the wrong ones, the result can be tissue that remodels abnormally, inflammation that lingers when it should resolve, or repair that proceeds incompletely.

There is also a broader significance beyond reproductive biology. The finding that a major tissue macrophage compartment depends on continuous monocyte supply adds to a growing appreciation that tissue-resident macrophages in many organs occupy a spectrum, with some established before birth and self-maintained, and others continually renewed from blood. Where a given tissue sits on that spectrum likely shapes its disease susceptibility, its regenerative capacity and its response to therapy. The uterus, with its naturally recurring cycles of breakdown and rebuilding, offers an unusually accessible window into these dynamics.

For clinicians and drug developers, the work suggests potential avenues for intervention. If reproductive diseases arise from imbalances in the monocyte-to-macrophage pipeline, then strategies that modulate monocyte recruitment, guide their differentiation toward restorative macrophage states, or correct the signals that misdirect them could offer new treatments. Such approaches remain distant, and the researchers caution that the mechanisms linking monocyte-derived macrophages to specific disease processes still require detailed elaboration. But the study provides a clear cellular target and a conceptual map for future investigation into conditions that affect millions of people worldwide.

Subject of Research: The roles of uterine monocytes in replenishing uterine macrophages and maintaining tissue homeostasis across reproductive cycles in health and disease.

Article Title: The dual roles of uterine monocytes in regulation of tissue homeostasis throughout reproductive cycles in health and disease

Article References: Shahzad, A., Moran, O., Alebrahim, Y., Colombo, S., Lacerda Mariano, L., Shorthouse, O., Morgan, H., Bhatt, D., Scott, N., Hunter, F. K., Laverty, C., Ruane, P., Graham, G., Paterson, I., Kaur, N., Amin, Z., Lokman, M., Lin, I.-H., Murtuza-Baker, S., … Mann, E. R. (2026). The dual roles of uterine monocytes in regulation of tissue homeostasis throughout reproductive cycles in health and disease. Nature Immunology. https://doi.org/10.1038/s41590-026-02651-y

Image Credits: AI Generated

DOI: 10.1038/s41590-026-02651-y

Keywords: uterine monocytes, macrophages, tissue homeostasis, reproductive cycle, endometrium, inflammation, tissue remodeling, immunology, monocyte differentiation, reproductive disease, immune cells, uterus