The team built its case on single-cell transcriptomics. Using both single-cell and single-nucleus RNA sequencing, the researchers generated a high-resolution cellular map of the mouse and human mediobasal hypothalamus, then integrated the two datasets computationally in a shared latent space to compare tanycytes across species. The integration workflow, based on deep generative models and probabilistic label transfer, allowed them to annotate eight tanycyte subclusters in the human tissue that correspond to subclusters defined in the mouse. Among these, one subcluster stood out. In both species, the T8 tanycyte state was enriched for genes associated with innate immunity, showing robust activation of interferon-α and interferon-γ response pathways and expression of downstream interferon-stimulated genes. In other words, a cell type conventionally classified as glia carries a transcriptional programme that resembles an immune cell state, and this programme is conserved between mouse and human hypothalamus.

What makes the finding striking is its dynamics. In female mice, the abundance and activity of this immune-associated tanycyte state changed across the oestrous cycle. The researchers captured sex-, oestrous cycle- and high-fat diet-dependent transcriptomic shifts in tanycytes, and found a cyclic expression of the gene encoding interferon regulatory factor 7 (Irf7), a master transcription factor of the interferon signalling family, together with downstream interferon-stimulated genes such as Cxcl10, a chemokine that recruits leukocytes. Spatial validation by RNAscope fluorescent in situ hybridization showed that Irf7 mRNA transcripts concentrated in defined ventricular regions of the arcuate nucleus and median eminence, and that regions containing CD45-high infiltrating leukocytes spatially coincided with zones of elevated Irf7 and Cxcl10 expression. In physiological males, by contrast, Irf7 expression in tanycytes remained stable and markedly lower, suggesting that cycling females mount a distinct pattern of immune activation in the brain that is tied to the changing hormonal milieu of the cycle, particularly oestradiol.

The mechanistic thread connecting oestradiol to interferon signalling runs through kinases. Upstream kinase analysis of oestradiol-regulated phosphosites in tanycytes identified TBK1 and IKKε, the canonical kinases that phosphorylate IRF7, as top hits with negative kinase statistics and high specificity scores, indicating that oestradiol treatment suppresses the activity of these IRF7-activating kinases. At the same time, imaging of NF-κB reporter mice revealed that κ-EGFP-positive tanycytes in the arcuate nucleus and median eminence increased at oestrus compared with diestrus, and that vimentin-stained tanycyte processes contacted κ-EGFP-positive microglia and CD45-positive immune cell complexes near vessels. Oestradiol thus appears to engage both the NF-κB and interferon regulatory signalling axes in tanycytes and in the immune cells of the median eminence, positioning these glial cells as integrators of endocrine and inflammatory signals at the brain’s metabolic gateway.

To test whether this cyclic immune programme matters functionally, the team manipulated oestrogen and interferon signalling in tanycytes. Ovariectomy with and without oestradiol replacement altered serum oestradiol levels and changed tanycytic IRF7 activity and leukocyte infiltration into the median eminence. The data support a model in which balanced, cyclic leukocyte infiltration into the median eminence may have a role in maintaining the oestrous cycle itself. This is a provocative idea: rather than viewing immune cell traffic across the permeable median eminence as pathological inflammation, the study suggests that a controlled, hormone-gated influx of leukocytes could be part of the physiological machinery that supports reproductive cycling, with tanycytes orchestrating the timing through interferon-dependent chemokine release.

The reach of tanycytic IRF7 extends beyond the brain. By selectively depleting Irf7 in tanycytes using an adeno-associated viral vector carrying an Irf7 short hairpin RNA, delivered into the lateral ventricle with a Dio2 promoter-driven Cre recombinase that restricts recombination to tanycytes, the researchers generated mice with tanycyte-specific Irf7 knockdown. RNAscope quantification confirmed the reduction of Irf7 mRNA transcripts in the knockdown animals. Flow cytometry of circulating blood then revealed that Irf7 in tanycytes modulates the proportions of circulating monocytes, the classical, intermediate and non-classical subsets that patrol vessels and migrate into tissues. Neutrophils, eosinophils, natural killer cells and T cell populations were unchanged, indicating a selective effect on the monocyte compartment. The finding provides direct evidence of brain-to-immune system communication through tanycytes, echoing earlier work showing that hypothalamic sensing of metabolic state regulates circulating monocytes.

How could glial cells lining a brain ventricle influence the blood immune compartment? The most plausible route lies in the anatomy of the median eminence, where tanycytes form the blood–hypothalamus barrier and contact both the portal vasculature and the cerebrospinal fluid. Tanycytes release chemokines such as CXCL10 in an interferon-dependent manner, and their processes extend toward vessels and immune cell complexes in the arcuate nucleus. Signalling through this interface could alter the cytokine milieu that reaching monocytes encounter, or modify endothelial and perivascular cues that determine monocyte egress from the bone marrow and patrolling behaviour in the bloodstream. The study also documented cyclic cytokine responses, with serum concentrations of inflammatory cytokines measured across the oestrous cycle, and found that interferon-γ pathway components, including Ifng, Tbx21 and the interferon-γ receptor subunits, were expressed in the mediobasal hypothalamus, providing potential ligand–receptor pairs that could drive the tanycytic interferon programme during the cycle.

The cross-species dimension of the work strengthens its relevance to human biology. Human tanycyte subclusters predicted by the computational integration showed the same enrichment of interferon-α and interferon-γ response pathways and interferon-stimulated gene expression in the human T8 state as in the mouse. The human samples came from single-nucleus sequencing of the mediobasal hypothalamus of donors, including donors with Alzheimer’s disease, frontotemporal dementia, type 2 diabetes and chronic myelomonocytic leukemia, and the descriptive analyses showed that the immune-associated tanycyte state was present across sexes and pathological conditions. Because sex-biased differences in metabolic and immune function are shaped by endocrine–immune interactions, the identification of a conserved, hormone-responsive immune programme in tanycytes offers a cellular substrate for understanding why many inflammatory, metabolic and neurodegenerative diseases show sex-biased incidence and progression.

Technically, the study exemplifies the current generation of single-cell neuroscience. The researchers used scVI-based deep generative modelling to integrate mouse and human datasets, scANVI for probabilistic label transfer of tanycyte subclusters, SCENIC for transcription factor regulon inference that identified the Irf7 regulon and its two target subnetworks enriched for innate immune and interferon-related functions and for antigen presentation and leukocyte activation, and scProportionTest with permutation-based cell-level statistics to quantify changes in subcluster abundance between conditions. Spatial transcriptomic validation with published hypothalamic atlases and RNAscope in situ hybridization anchored the cell states to defined anatomical zones along the anteroposterior axis of the third ventricle. Kinome assays with serine–threonine phosphosite analysis connected oestradiol to the IRF7 phosphorylating kinases. The combination of computational and spatial methods, together with physiological follow-up of body weight, fat mass and blood glucose in the sequenced animals, gives the findings a solid technical footing.

The implications reach toward several frontiers. If cyclic interferon signalling in tanycytes gates leukocyte traffic into the median eminence and shapes circulating monocyte proportions, then disruptions of this programme, whether by chronic high-fat diet, by loss of ovarian hormones, or by pathological inflammation, could alter both reproductive function and systemic immune regulation. The study’s observation that high-fat diet feeding changed tanycytic transcriptomic states, and that the immune-associated state responded to diet and cycle in combination, suggests that metabolic disease may reprogramme the brain’s immune interface. Conversely, the tanycyte degeneration linked to impaired tau clearance in recent work hints that these cells also participate in neurodegenerative pathology. By revealing an immune-associated role for tanycytes and a conserved, oestradiol-responsive IRF7 programme that communicates between brain, body and immune system across the ovarian cycle, the study opens a new chapter in neuroendocrine immunology, one in which the glial border of the metabolic brain is not merely a barrier but an active, hormone-gated immune organ.

Subject of Research: IRF7 signalling in tanycytes controls brain–body–immune response across the ovarian cycle

Article Title: IRF7 signalling in tanycytes controls brain–body–immune response across the ovarian cycle

Article References: IRF7 signalling in tanycytes controls brain–body–immune response across the ovarian cycle. (n.d.). https://doi.org/10.1038/s42255-026-01635-4

Image Credits: AI Generated

DOI: 10.1038/s42255-026-01635-4

Keywords: IRF7, signalling, tanycytes, controls, brain, body, immune, response, across, ovarian, cycle, scientific research

The scientific logic behind this drug repositioning effort is elegant. BM212 is a 1,3,5-trisubstituted pyrrole originally identified during a phenotypic screen of azole, imidazole, pyrrole, and toluidine derivatives against Mycobacterium tuberculosis, where it displayed a minimal inhibitory concentration of 5 micromolar against drug-sensitive strains and 8 micromolar against multidrug-resistant strains. Whole-genome sequencing of resistant mutants later revealed that BM212 acts by directly binding MmpL3, an essential inner membrane protein involved in trehalose monomycolate flipping during mycobacterial cell wall biosynthesis. Meanwhile, a structurally related pyrazole compound, MMV1580843, had emerged from a parallel screen of the Medicines for Malaria Venture Pandemic Response Box as a hit with striking stage-specific activity against late-stage gametocytes, showing a half-maximal inhibitory concentration of 0.11 micromolar while being comparatively inactive against asexual blood-stage parasites. Recognizing the considerable structural similarity between the two molecules, the team hypothesized that the BM212 pyrrole scaffold could be systematically optimized to yield antiplasmodial activity across the parasite life cycle.

The medicinal chemistry campaign was deliberately modular. The researchers synthesized a focused library of 33 compounds, keeping the central pyrrole core constant while systematically varying substituents at three positions: N1, C5, and C3. The synthetic strategy relied on a Stetter reaction between methyl vinyl ketone and appropriate benzaldehydes to generate 1,4-diketones, which were then cyclized with corresponding amines to afford 1,5-disubstituted pyrroles. A subsequent Mannich reaction with formaldehyde and amines introduced the C3 cyclic amine substituents. This efficient, step-economical route enabled rapid access to structurally diverse derivatives in good overall yields, providing a sufficiently diverse compound set to support a comprehensive structure-activity relationship investigation. Several compounds had been previously reported as BM212 analogues evaluated for antitubercular activity, but they were deliberately resynthesized and re-evaluated within the present work to enable a coherent SAR analysis in the antiplasmodial context.

Biological profiling was conducted across multiple life cycle stages using rigorous, orthogonal assays. Activity against asexual blood-stage parasites of the drug-sensitive NF54 strain was measured using a SYBR Green I fluorescence assay, detecting parasite proliferation after 96 hours of drug pressure. Compounds with IC50 values below 1 micromolar were additionally profiled against the multidrug-resistant Dd2 strain to assess cross-resistance potential. Late-stage gametocyte activity was evaluated using PrestoBlue fluorescence or flow cytometric readouts with MitoTracker Deep Red staining, while cytotoxicity was assessed against a human hepatocellular carcinoma line, Hep G2. All IC50 values were calculated through nonlinear regression using a four-parameter logistic dose-response model, with all data reported from a minimum of three independent biological replicates performed in technical triplicates. Assay reproducibility was confirmed by Z-factors all exceeding 0.8, ensuring the reliability of the SAR conclusions drawn from the dataset.

The first and most striking SAR trend concerned the C3 cyclic amine, which emerged as the dominant driver of life cycle stage preference. BM212 itself, bearing an N-methylpiperazine at C3, displayed more than 50-fold increased activity against late-stage gametocytes over asexual parasites, with an IC50 of 0.18 micromolar against gametocytes while being inactive above 10 micromolar against both NF54 and Dd2 asexual stages. When the researchers replaced this piperazine with a morpholine or a 4,4-difluoropiperidine, gametocytocidal activity collapsed, but measurable activity against asexual blood stages was retained. In contrast, the dimethyl-azasilinane analogue, compound 1, retained potent gametocytocidal activity with an IC50 of 0.48 micromolar while displaying improved activity against asexual parasites with an IC50 of 1.08 micromolar, suggesting that dual-stage activity can indeed be achieved within the BM212 pyrrole scaffold, in contrast to the structurally related pyrazole MMV’843, which predominantly displays gametocytocidal activity.

Further optimization focused on the electronic properties of the N1 and C5 substituents. Electron-deficient aryl groups such as 4-fluorophenyl and 2-trifluoromethylphenyl consistently enhanced potency and improved physicochemical properties across the series. In the methylpiperazine series, the difluorinated analogue, compound 7, achieved a remarkable IC50 of 0.093 micromolar against late-stage gametocytes, a twofold improvement over BM212 itself, while simultaneously delivering a fourfold improvement in asexual blood-stage activity relative to the parent compound. Aqueous solubility also improved dramatically, reaching 185 micromolar for compound 7 compared with just 10 micromolar for BM212. However, a clear limitation emerged: simultaneously reducing lipophilicity at both N1 and C5, for example by introducing pyridyl rings at both positions, proved detrimental to biological activity, with compound 12 showing a greater than 30-fold reduction in potency against both life cycle stages. This finding underscores the delicate balance between polarity and hydrophobic fit that governs activity in this scaffold.

The morpholine series provided additional SAR insights from a bioisosteric perspective. Morpholine is a privileged heterocycle commonly used in medicinal chemistry to reduce basicity relative to piperazine, improve metabolic stability, and introduce an additional hydrogen-bond acceptor through its ether oxygen. Although the initial morpholine analogue showed limited activity against both asexual parasites and gametocytes, subsequent modifications led to modest improvements in asexual blood-stage activity, with compounds 18 through 20 displaying IC50 values below 2.5 micromolar. Potent gametocytocidal activity was restored by introducing fluorophenyl substituents, with compounds 25, 26, and 32 all retaining sub-micromolar activity against late-stage gametocytes. Notably, exchanging the N1 and C5 substituents between compounds 32 and 33 resulted in a marked change in biological profile, indicating that the positional arrangement of these substituents strongly influences activity. The difluorophenyl analogue, compound 26, exhibited substantially improved aqueous solubility of 180 micromolar compared with less than 5 micromolar for the parent morpholine analogue.

Resistance profiling and transmission-blocking evaluation provided the most compelling translational evidence. Several optimized analogues retained activity against the multidrug-resistant Dd2 strain, with IC50 values ranging from 1.01 to 1.54 micromolar and less than threefold differences in potency relative to the drug-sensitive NF54 strain. This sensitivity profile implies that mutations in the chloroquine resistance transporter PfCRT, antifolate resistance mutations, or copy number variation in the multidrug resistance transporter do not confer resistance to the compounds evaluated here, a critical consideration given the de novo development of artemisinin kelch-13 resistance mutations in African parasite populations. In the standard membrane feeding assay, compound 9 achieved 81 percent transmission-reducing activity, while BM212 itself achieved 62 percent. Interestingly, both compounds showed a markedly stronger effect on female gamete formation than on male gamete exflagellation, a profile that differs from many antimalarial candidates and may suggest a mechanism of action distinct from compounds that primarily interfere with cell division during male gametogenesis.

The molecular target of these compounds in Plasmodium remains unknown, and this represents both a challenge and an opportunity. Plasmodium does not possess an MmpL3 homolog, the primary target of BM212 in mycobacteria, so the antiplasmodial activity must arise through a different mechanism. Interestingly, other well-known MmpL3 inhibitors such as ethambutol and the ethylenediamine SQ109 have previously also shown activity against P. falciparum parasites with a similar preference towards late-stage gametocytes, although the involvement of resistance nodulation-division superfamily proteins has been excluded for these compounds, pointing instead to ionophore activity. The researchers propose that enhanced evolution techniques to select for resistant parasites, thermal protein profiling, or chemical pulldown proteomics using labelled versions of lead compounds could directly identify protein target engagement in the parasites. Determining the minimum inoculum of resistance for this series would also be important to evaluate their potential propensity to resistance.

Overall, this work positions BM212-derived pyrroles as a promising and versatile multistage antiplasmodial chemotype while delineating the key structural determinants required to achieve potency, selectivity, and transmission-blocking efficacy. The scaffold now stands ready for a formal hit-to-lead campaign, where the effects of structural changes on active compounds must be investigated in light of enhanced metabolic stability in microsomes and hepatocytes, leading to pharmacokinetic characterization and in vivo efficacy studies to assess the potential of early lead antimalarial candidates. Given that malaria elimination will require a multipronged approach including recently recommended vaccines such as RTS,S and R21/Matrix-M, together with strategies aimed at blocking parasite transmission, chemotypes that target both asexual blood-stage parasites and mature gametocytes offer genuine promise for reducing transmission rates and preventing the spread of resistance once it has developed in the asexual stages. The BM212 pyrrole scaffold, born from tuberculosis drug discovery and reborn through systematic antiplasmodial optimization, may yet contribute meaningfully to that effort.

Subject of Research: Probing the activity of BM212, an antimycobacterial, and its derivatives against multiple life cycle stages of Plasmodium falciparum

Article Title: Probing the activity of BM212, an antimycobacterial, and its derivatives against multiple life cycle stages of Plasmodium falciparum

Article References: Salvucci, B., van der Watt, M., Tammaro, C., Guida, M., Pantaleo, L., Reader, J., Rabie, T., Tshabalala, S., Naude, M., Venter, N., Welcome, T., Erlank, E., Koekemoer, L. L., Biava, M., Birkholtz, L.-M., & Poce, G. (2026). Probing the activity of BM212, an antimycobacterial, and its derivatives against multiple life cycle stages of Plasmodium falciparum. Frontiers in Drug Discovery, 6, Article 1919483. https://doi.org/10.3389/fddsv.2026.1919483

Image Credits: AI Generated

DOI: 10.3389/fddsv.2026.1919483

Keywords: Probing, activity, BM212, antimycobacterial, derivatives, against, multiple, life, cycle, stages, Plasmodium, falciparum