Study Links Gonadal Sex to TB Susceptibility Through Immune Response Differences
A mouse study using a genetic model that separates gonadal sex from chromosomal sex found that gonadal males develop more severe tuberculosis due to dysfunctional myeloid immune responses, while gonadal females — especially XX females — showed greater resistance. Researchers used Four Core Genotype mice to isolate the effects of testes and ovaries from X and Y chromosome influences. The findings help explain why human males experience TB at roughly 1.7 times the rate of females and suffer higher mortality.
Tuberculosis kills more people globally than any other single infectious disease, and males are disproportionately affected, with a male-to-female incidence ratio exceeding 1.7. To investigate whether this disparity is driven by gonadal hormones or sex chromosomes, researchers employed Four Core Genotype (FCG) mice, which allow gonadal sex and chromosomal sex to be experimentally decoupled. Both XX and XY gonadal males showed increased mortality, higher bacterial burden, and more severe lung pathology compared to gonadal females, pointing to the testes — and likely androgens — as key drivers of susceptibility. Mechanistically, gonadal males exhibited early myeloid priming, excessive neutrophil recruitment, accumulation of CCR2+ monocytes, hyperinflammation, enhanced neutrophil extracellular trap (NET) formation, and disorganized granulomas. By contrast, gonadal females, particularly those with XX chromosomes, mounted coordinated T- and B-cell responses and enhanced B-cell follicle formation, correlating with the greatest resistance to infection. XY gonadal females were less susceptible than males but showed somewhat reduced resistance compared to XX gonadal females, suggesting a modest additional protective role for XX chromosomes. The study identifies gonad-driven myeloid dysregulation as a central mechanism underlying male TB susceptibility, with potential implications for sex-informed therapeutic strategies.
What's missing
The study is conducted entirely in mice, and it remains unclear how directly these gonadal mechanisms translate to human TB immunology. The specific androgenic hormones responsible (e.g., testosterone vs. other androgens) are implicated but not fully characterized. The study does not address whether androgen-blocking interventions could reduce TB severity in males, nor does it examine how age-related hormonal changes (e.g., post-menopausal females or aging males) might affect these dynamics.
What different sources said
- bioRxivCenter
Gonadal regulation of sex-specific immunity in tuberculosis: enhanced lymphocyte function in females and dysfunctional myeloid responses in males
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.