Key papers ✓ 7~ 2? 1

• ? Inconclusive reviewCurr Pharm Des · 2014

  Physiology and therapeutic potential of the thymic peptide thymulin.

  No new data

  Narrative review

  Review of thymulin physiology: anti-inflammatory and analgesic effects and gene-therapy approaches are supported by animal models; human therapeutic potential is yet to be assessed.

  Study details

  Main outcome

  Physiology, neuroendocrine and anti-inflammatory actions of thymulin and gene therapy approaches

  Authors' conclusion

  Thymulin and its analog show anti-inflammatory and analgesic properties in the CNS, and thymulin gene therapy may restore thymulin levels in thymodeficient animal models and eventually in humans.

  Limitations

  Narrative review; supporting evidence is from animal models.

  DOI 10.2174/1381612820666140130211157PubMed 24588820
• ~ Mixed reviewAnn N Y Acad Sci · 2006

  Role of thymulin or its analogue as a new analgesic molecule.

  No new data

  Narrative review of the authors' rodent studies on thymulin and its analogue PAT

  Review of rodent work: low (nanogram) doses of thymulin increased pain sensitivity via inflammatory mediators, while higher doses or an analogue reduced inflammatory pain and sickness behavior.

  Study details

  Main outcome

  Pain, hyperalgesia and inflammatory cytokines

  Authors' conclusion

  Low-dose thymulin caused hyperalgesia while higher doses of thymulin or the analogue PAT reduced inflammatory pain and cytokines. The authors indicate a possible therapeutic use as analgesic and anti-inflammatory drugs; mechanism not fully elucidated.

  Limitations

  Review; mechanism of action is not fully elucidated.

  DOI 10.1196/annals.1366.006PubMed 17192563
• ✓ Positive animalNat Commun · 2026

  Thymulin restrains age-associated myeloid inflammation and enhances cancer immunotherapy.

  Humans + animals

  Heterochronic parabiosis, bone marrow chimeras, and tumor immunotherapy experiments

  Thymulin declined with age and suppressed inflammatory cytokine production by aged myeloid cells; in older mice it improved tumor control and responses to anti-PD-L1 immunotherapy.

  Study details

  Studied

  Aged and young mice (and humans for myeloid cell frequency); breast tumor models

  Compared with

  Young vs aged hosts

  Main outcome

  Myeloid inflammatory cytokine production; tumor control and survival with anti-PD-L1

  Authors' conclusion

  Thymulin suppresses pro-inflammatory myeloid cytokine production via NF-kB inhibition and enhances antitumor T-cell immunity and anti-PD-L1 response in an age-dependent manner, suggesting a strategy to improve immunotherapy in older individuals.

  Limitations

  Mostly mouse data.

  DOI 10.1038/s41467-026-75383-0PubMed 42481458Free full text
• ✓ Positive animalInt Immunopharmacol · 2019

  Thymulin treatment attenuates inflammatory pain by modulating spinal cellular and molecular signaling pathways.

  Animalssize not reported21 days

  Intraperitoneal thymulin at different doses and timings

  In rats with adjuvant-induced inflammation, thymulin reduced paw swelling and heat hypersensitivity and lowered spinal microglial activation and TNF-alpha/IL-6.

  Study details

  Studied

  Rats with Complete Freund's adjuvant (CFA)-induced inflammation

  Compared with

  CFA without thymulin

  Main outcome

  Thermal hyperalgesia, paw edema, spinal microglial activity, p38 MAPK, cytokines

  Authors' conclusion

  Thymulin notably reduced CFA-induced thermal hyperalgesia and paw edema, probably through inhibition of spinal microglia and reduced p38 MAPK phosphorylation and pro-inflammatory cytokines.

  Limitations

  Rat model of inflammatory pain.

  DOI 10.1016/j.intimp.2019.02.042PubMed 30851702
• ✓ Positive animalPLoS One · 2018

  Thymulin, free or bound to PBCA nanoparticles, protects mice against chronic septic inflammation.

  Animalssize not reported

  Free versus polybutylcyanoacrylate nanoparticle-bound thymulin treatment

  In mice with chronic LPS-induced septic inflammation, thymulin reduced fever, inflammatory cytokines and lymphocyte death; a nanoparticle-bound form worked better in some respects.

  Study details

  Studied

  Mice with chronic inflammation induced by gradually raised lipopolysaccharide doses

  Compared with

  LPS-treated untreated mice

  Main outcome

  Signaling pathway activity, apoptosis, cytokines, melatonin and serotonin

  Authors' conclusion

  Thymulin suppressed the proinflammatory response in LPS-treated mice, indicating potential for thymulin co-therapy in sepsis; nanoparticle-bound thymulin was more effective in several respects.

  Limitations

  Mouse LPS model.

  DOI 10.1371/journal.pone.0197601PubMed 29795607Free full text
  Fig 2
• ✓ Positive animalInt J Immunopathol Pharmacol · 2021

  Thymulin and peroxiredoxin 6 have protective effects against streptozotocin-induced type 1 diabetes in mice.

  Animalssize not reported

  Prolonged treatment with thymulin or peroxiredoxin 6 (PRDX6)

  In mice with streptozotocin-induced type 1 diabetes, prolonged thymulin treatment reduced physiological impairments and inflammatory cytokines.

  Study details

  Studied

  Mice with streptozotocin-induced type 1 diabetes

  Compared with

  Untreated diabetic mice

  Main outcome

  Blood glucose, body weight, organ cell counts, cytokines, NF-kB and JNK activity

  Authors' conclusion

  Both thymulin and PRDX6 reduced physiological impairments in diabetic mice and showed anti-inflammatory functions via different mechanisms; the authors suggest possible supporting use in COVID-19 patients with diabetes.

  Limitations

  Mouse model; the COVID-19 suggestion is speculative.

  DOI 10.1177/20587384211005645PubMed 33779346Free full text
• ✓ Positive animalSci Adv · 2020

  Nanoparticle-based thymulin gene therapy therapeutically reverses key pathology of experimental allergic asthma.

  Animalssize not reportedAssessed 20 days after treatment

  Single intratracheal dose of thymulin-expressing plasmid in mucus-penetrating nanoparticles

  In mice with established allergic asthma, a single inhaled dose of thymulin-expressing gene therapy normalized lung inflammation, fibrosis and mechanics (gene therapy, not the peptide itself).

  Study details

  Studied

  Mice with established experimental allergic asthma

  Main outcome

  Lung inflammation, fibrosis and mechanical dysregulation

  Authors' conclusion

  Inhaled thymulin gene therapy normalized key asthmatic lung pathology in mice through anti-inflammatory and antifibrotic effects, opening a possible avenue for clinical development.

  Limitations

  Mouse model of asthma; gene therapy, not peptide dosing.

  DOI 10.1126/sciadv.aay7973PubMed 32577505Free full text
• ✓ Positive animalInt J Mol Sci · 2019

  Protective Effect of PBCA Nanoparticles Loaded with Thymulin Against the Relapsing-Remitting Form of Experimental Autoimmune Encephalomyelitis in Mice.

  Animalssize not reported

  Animal study comparing free thymulin and PBCA nanoparticle-bound thymulin in rEAE

  In mice with relapsing-remitting experimental autoimmune encephalomyelitis (a multiple-sclerosis model), thymulin, especially bound to PBCA nanoparticles, eased symptoms and lowered plasma cytokines and NF-kB/JNK activation.

  Study details

  Studied

  Mice with relapsing-remitting experimental autoimmune encephalomyelitis (rEAE)

  Compared with

  Untreated rEAE mice (and free vs nanoparticle-bound thymulin)

  Main outcome

  Symptom severity score, plasma cytokines (IFN-gamma, IL-17), NF-kB and SAPK/JNK activation

  Authors' conclusion

  Thymulin significantly alleviated rEAE symptoms and lowered cytokines; the nanoparticle-bound form was more effective, and the authors consider it a prospective treatment for this pathology.

  Limitations

  Mouse model only; group sizes not stated in abstract.

  DOI 10.3390/ijms20215374PubMed 31671728Free full text
  Figure 2
• ✓ Positive animalArch Biochem Biophys · 2023

  Protective effect of exogenous peroxiredoxin 6 and thymic peptide thymulin on BBB conditions in an experimental model of multiple sclerosis.

  Animalssize not reported

  Animal study of thymulin, peroxiredoxin 6, and both together

  In mice with relapsing-remitting EAE, thymulin and peroxiredoxin 6 each improved blood-brain barrier integrity and symptoms, and giving both together produced complete symptomatic restoration.

  Study details

  Studied

  Mice with relapsing-remitting experimental autoimmune encephalomyelitis

  Compared with

  Untreated EAE mice

  Main outcome

  Blood-brain barrier condition (Evans blue, tight junction proteins, lymphocyte infiltration), EAE symptoms, cytokines

  Authors' conclusion

  Thymulin and Prdx6 improved BBB condition and EAE symptoms; together they gave complete symptomatic restoration, which the authors present as a prospective strategy for multiple sclerosis.

  Limitations

  Mouse model only; group sizes not stated in abstract.

  DOI 10.1016/j.abb.2023.109729PubMed 37633587
• ~ Mixed animalRussian-languageВестник Российской академии медицинских наук · 2015

  Влияние тимических пептидов на анальгезию, вызванную острой и подострой иммобилизацией

  Animalssize not reportedAcute (3 h) and subacute (12 h) immobilization

  Animal experiment comparing thymic peptides (thymulin, thymosin fraction 5, thymus extract) with saline and spleen polypeptide controls, with naloxone challenge

  In Wistar rats, thymulin raised the pain threshold in unstressed animals and blunted the further rise in threshold caused by 3 h and 12 h immobilization stress (p=0.022 and p=0.027), with a smaller opioid component of the stress analgesia.

  Key resultStress-induced rise in pain threshold was smaller with thymulin than in controls (3 h immobilization p=0.022; 12 h p=0.027)

  Study details

  Studied

  Male Wistar rats

  Compared with

  Saline and spleen polypeptide controls

  Main outcome

  Pain sensitivity (tail-flick test) and opioid component of stress-induced analgesia

  Authors' conclusion

  The authors concluded that pre-activation of the opioid system by thymic polypeptides raises the non-opioid share of stress analgesia and prevents opioid system exhaustion.

  Limitations

  Rat study; group sizes not stated in the abstract.

  CyberLeninka (Russian)

Reported side effects

No human safety data in the published literature; rodent studies found that low doses can increase pain sensitivity.

✓ positive · ✗ negative · ~ mixed · ? inconclusive, judged on each paper's own main outcome. Grades: A strong human evidence → D little or none. Papers and verdicts are drawn from PubMed, Europe PMC and Russian journals (CyberLeninka); not medical advice.