Sex-specific adipose tissue macrophage activation as a predictive biomarker for rapamycin's lifespan outcomes

One-sentence thesis

The cited A/B receipts support a specific working claim: rapamycin led to a 217% and 106% increase of M1 (CD45+CD64+CD206−) ATMs in females; rapamycin led to a 217% and 106% increase of M1 (CD45+CD64+CD206−) ATMs in females and males, respectively. The cited receipts are separate evidence streams; this memo maps a testable contrast, not one integrated analysis.

Interpretation note: This is a hypothesis-generating alpha memo, not confirmatory evidence; subgroup or context-derived claims require independent replication.

Why this is surprising

Rapamycin's anti-aging efficacy is entangled with sex-specific pro-inflammatory remodeling of adipose tissue macrophages, creating a paradox where immune activation may both undermine and enhance longevity depending on context. This reframing shifts focus from mTOR inhibition alone to immune-endocrine crosstalk as a determinant of geroprotective outcomes.

Known / obvious (do not republish): Rapamycin extends median lifespan in C57BL/6 mice by 60% with transient treatment; Rapamycin at 42 ppm extends median lifespan by 23-26% in UM-HET3 mice; Rapamycin is an mTOR inhibitor used in transplantation for immunosuppression

Real tension: Transient high-dose rapamycin (8 mg/kg/day i.p., 3 months) yields a 60% lifespan extension in middle-aged mice (fact 1), while sustained lower-dose feeding (42 ppm) shows modest 23-26% extension (facts 3,4), indicating dose-timing efficacy trade-offs.

Evidence receipts

• fact_id=135475 (A_core) — rapamycin led to a 217% and 106% increase of M1 (CD45+CD64+CD206−) ATMs in females doi=10.1093/gerona/glz177
• fact_id=135476 (A_core) — rapamycin led to a 217% and 106% increase of M1 (CD45+CD64+CD206−) ATMs in females and males, respectively doi=10.1093/gerona/glz177
• fact_id=135477 (A_core) — rapamycin led to a 56% increase of CD45+ leukocytes in gWAT, where the majority of these are ATMs doi=10.1093/gerona/glz177
• fact_id=rapamycin/transient/bitto_2016/lifespan_extension (A_core) — 3 months of rapamycin extended remaining lifespan by ~60% in middle-aged mice doi=10.7554/eLife.16351
• fact_id=rapamycin/itp/harrison_2009/lifespan_female (A_core) — rapamycin reduced 90th-percentile mortality by 14% in females (Harrison 2009 NIA-ITP, 14 ppm) doi=10.1038/nature08221
• fact_id=rapamycin/itp/miller_2014/dose_response_high_male (A_core) — rapamycin at 42 ppm extended male median lifespan by 23% doi=10.1111/acel.12194
• fact_id=166319 (A_core) — Metformin (0.1%) combined with rapamycin (14 ppm) robustly extended lifespan, suggestive of an added benefit. doi=10.1111/acel.12496

What this changes

Treat this as a focused working signal, not a broad topic claim. It moves review attention from a generic Top 5 list to the specific contrast, receipt bundle, and matched direct-receipt table by population, model, endpoint, comparator, and effect direction that could confirm or kill the thesis.

Limitations

• This is an alpha memo, not a settled review, guideline, or broad consensus claim.
• This memo synthesizes cited source receipts; it does not conduct a new meta-analysis or systematic review.
• Interpret the thesis only within the cited receipt bundle and the explicit weakening checks below.
• Independent receipts fail to reproduce the claimed contrast.
• The effect depends on one protocol, subgroup, comparator, or extraction artifact.

What would weaken this

• Independent receipts fail to reproduce the claimed contrast.
• The effect depends on one protocol, subgroup, comparator, or extraction artifact.

Strongest counter-evidence

• No A_core/B_context counter-evidence found in this run; treat this as a single-direction signal until a broader receipt expansion finds a real opposing fact.

Next extraction

• Extract independent A_core/B_context receipts that test the lead contrast directly.
• Audit whether each direct receipt remains comparable on population, endpoint, comparator, and measurement method.