A Bodybuilding Supplement Shows Up in an Unexpected Immune Pathway

A new study finds that dendritic cells inside tumors rely on creatine to power their attack on cancer.

Researchers found that intratumoral dendritic cells (DC) markedly upregulate the creatine transporter (CrT) compared to their splenic counterparts. Knock out CrT in mice, and DCs become weaker: less CD86, less MHC-II, fewer inflammatory cytokines, and a reduced ability to prime CD8 T cells against tumor antigens. Supplement with creatine instead, and the reverse happens — better activation markers, better adenosine triphosphate (ATP) levels, stronger antigen-specific T cell responses, and in a B16 melanoma model, smaller tumors.

The mechanism the authors propose: creatine buffers intracellular ATP, and that ATP reserve appears to support NF-κB signaling during pattern recognition receptor activation. Blocking the creatine transporter pharmacologically (with RGX-202) reduced NF-κB pathway activity alongside impaired DC activation. The effect also held in human monocyte-derived DCs, which showed enhanced ability to activate NY-ESO-1-specific T cells after creatine treatment.

The authors describe this as "a previously unrecognized role for creatine metabolism in regulating DC function."

This is one mouse tumor model, and the authors note the mechanism — particularly why cDC1 abundance increased in tumors — remains unclear. Still, for those tracking metabolic approaches to checkpoint therapy resistance, this is a pathway worth watching.

Source: iScience

Fireworks, Not Fentanyl: How the Fourth of July May Mellow Out Psychedelic Trips

Here's a strange one: taking psychedelics on Independence Day seems to track with less support for partisan violence — while tripping during a party convention tracks with more.

A team led by researchers at Karolinska Institutet and the University of Wisconsin–Madison recruited 21,990 US adults in 2023 and 2024. Just over half (12,345) completed the 2-month follow-up survey, and of those, 505 reported using a classic psychedelic — psilocybin, LSD, ayahuasca, and similar compounds. Only 19 people had their most intense trip on July 4th, but that small group showed a larger drop in support for partisan violence than the 486 who tripped on some other date. A similar dip appeared around the Trump assassination attempt, an effect the authors report was limited to Republican respondents.

Here's the sneaky part: the same approach applied to the Democratic and Republican National Conventions, and to dates closer to Election Day, found the reverse — increased support for partisan violence.

The authors don't pin down why, but they point to a concept from prior psychedelic theory called "collective 'set and setting'" — the idea that the surrounding social and political mood, not just individual mindset, might shape how these substances land.

Nineteen people on July 4th is a whisper, not a shout, and the authors themselves urge caution given the small numbers involved. Still, it's a nudge to ask patients not just what they took, but what was happening in the world around them when they took it.

As the authors put it, "the broader sociocultural context could influence outcomes following naturalistic psychedelic use."

Source: Psychedelic Medicine

The Muscle Scare That, Statistically, Almost Never Happens

Nearly 4 million people eligible for statin therapy were tracked for up to a decade, and 99.6% had a predicted 10-year risk of serious muscle disorders — think rhabdomyolysis, not everyday achiness — below 10%. That's a strikingly low number for the side effect most blamed for statin hesitancy.

Researchers built a prediction model from 1.8 million UK primary care patients and validated it in another 3.9 million, landing on 22 predictors. Statins did raise risk (atorvastatin SHR 1.77, rosuvastatin 2.04), but the strongest signals were a prior muscle problem (SHR 6.24) and vitamin D deficiency (2.65). Here's the sneaky part: CVD, hypertension, and diabetes were all associated with lower muscle-disorder risk (SHRs 0.68–0.88) — the authors don't explain why, just that it held up. Separately, among patients with confirmed eligibility for treatment, 62.5% remained untreated, some despite high CVD risk.

The model can't account for genetic predisposition or activity level, and may overestimate risk in the highest-risk sliver of patients — well under 1% of the cohort. As the authors put it, concerns about muscle adverse events are "arguably exaggerated" relative to actual incidence.

Clinical takeaway: pair this personalized muscle-risk calculator with a CVD risk score like QRISK3 to ground statin conversations in individual numbers rather than general fear.

Source: The Lancet Digital Health

Fentanyl's Respiratory Depression Risk Dwarfs Codeine's — And Gabapentin Makes It Worse

Here's a stat worth sitting with: patients on both opioids and gabapentinoids had nearly four times the respiratory depression risk of patients on neither (HR 3.88), a finding that undercuts gabapentinoids' reputation as the "safer," opioid-sparing choice.

A cohort of 32,909 hospitalized patients with noncancer pain in Northwest England tracked respiratory depression using actual vital signs — respiratory rate, oxygen saturation, consciousness — rather than relying on ICD codes after the fact. Fentanyl carried the highest risk versus codeine (HR 3.36), climbing to 5.44 in patients newly starting opioids. Oxycodone (HR 2.10) and combination opioids (HR 2.74) were also significantly elevated. Even doses as low as 31 to 60 MME/day — well under the "high dose" 120 MME/day threshold — showed a statistically significant risk bump.

The twist: benzodiazepine co-prescribing showed a lower observed risk (HR 0.65), which the authors suspect may reflect channelling bias — clinicians already avoiding that combination in higher-risk patients, given years of prior warnings. Gabapentinoids, prescribed under the assumption they're safer, hadn't attracted that same caution yet.

Mechanistically, the authors point to fentanyl's potency (80 to 100x morphine) and high lipophilicity, which speeds brain uptake and can trigger abrupt respiratory suppression.

Takeaway: this supports closer monitoring — and reconsidering non-opioid alternatives — specifically when gabapentinoids are added to an opioid regimen, and extra caution with fentanyl even at doses that don't look alarming on paper.

Source: BMC Medicine