Giant cell arteritis & polymyalgia rheumatica (GCA + PMR)
Giant cell arteritis (GCA) is a granulomatous large-vessel vasculitis of the aorta and its branches — classically the temporal artery — presenting with new headache, jaw claudication, scalp tenderness, polymyalgic symptoms, and most dangerously vision loss from anterior ischemic optic neuropathy. GCA vision symptoms are a minutes-to-hours emergency: untreated, the affected eye can blind permanently, and the contralateral eye follows in 25-50% of cases within days. Acute management is high-dose prednisone (40-60 mg, or 60-80 mg with visual involvement) started on clinical suspicion before biopsy confirmation, with IV methylprednisolone pulses for vision-threat. Polymyalgia rheumatica (PMR) shares the spectrum — bilateral shoulder + hip stiffness, age >50, elevated ESR + CRP, often morning-predominant; 15-20% of PMR patients develop GCA. The steroid-sparing landscape has been transformed: tocilizumab (Actemra) FDA 2017 for GCA via GiACTA — the first non-steroid agent with replicated efficacy in vasculitis. Sarilumab (Kevzara) FDA February 2023 for PMR via SAPHYR — the first FDA-approved DMT for PMR after sixty years of prednisone-only management. Upadacitinib (Rinvoq) JAK1 inhibitor SELECT-GCA Phase 3 positive readout 2024-2025, FDA submission expected. Methotrexate older steroid-sparing alternative. ACR/EULAR 2022 GCA criteria + ACR/EULAR 2012 PMR criteria + EULAR 2015 + ACR 2024 vasculitis guidelines + Vasculitis Foundation. No peptide in the Juno library has GCA or PMR evidence. Twenty-fourth deliberate non-elevation.
What changes during this transition
GCA and PMR are the load-bearing safety axis of the substrate expansion. GCA is the only entry where delayed treatment means permanent blindness in minutes to hours — anterior ischemic optic neuropathy from posterior ciliary artery occlusion is irreversible once it happens, and the contralateral eye follows within days in 25-50% of untreated cases. Every substrate entry on this page anchors that safety thread: peptides are not the conversation, and the community framing that BPC-157, TB-500, thymosin alpha-1, or any peptide can substitute for prednisone in active GCA needs to be disrupted, not engaged with neutrally. The diagnostic and therapeutic landscape is unusually rich. Diagnosis is anchored by ACR/EULAR 2022 GCA criteria, with temporal artery biopsy as gold standard, temporal artery ultrasound (halo sign) increasingly used, and PET-CT for large-vessel involvement. PMR diagnosis uses ACR/EULAR 2012 criteria with the broader EULAR 2015 + ACR 2024 vasculitis-spectrum guidelines. Treatment landscape has been transformed in eight years: tocilizumab (Actemra) anti-IL-6R FDA-approved 2017 for GCA via the GiACTA Phase 3 trial — paradigm-shifting because it was the first non-steroid agent with replicated steroid-sparing efficacy. Sarilumab (Kevzara) anti-IL-6R FDA-approved February 2023 for PMR via SAPHYR — first FDA-approved DMT for PMR specifically; before this, PMR was prednisone-only for sixty years. Upadacitinib (Rinvoq) JAK1 inhibitor — SELECT-GCA Phase 3 positive readout 2024-2025, FDA submission expected, opening an oral steroid-sparing option. Methotrexate as the older steroid-sparing alternative; sarilumab, secukinumab, and abatacept explored across the spectrum. Where Juno's library fits is deliberate non-elevation. No peptide has GCA or PMR evidence. Every peptide considered for this axis (BPC-157, TB-500, thymosin alpha-1, Selank, NMN, plus the LL-37 autoimmune-contraindication and SS-31 mitochondrial-extrapolation cases) fails on the same core grounds: no human evidence in GCA or PMR from any jurisdiction, mechanistic logic that doesn't predict benefit (or actively predicts the wrong direction of effect, as with TA-1's T-cell-maturation register sitting opposite to T-cell-driven vasculitis), and a standard-of-care backdrop where the evidence-based steroid-sparing agents (tocilizumab, sarilumab, upadacitinib in trials, methotrexate) are doing the actual disease-modifying work. The substrate entries exist for honest /ask answers when users probe — usually because they've read community claims about BPC-157 for 'any inflammation' or TB-500 for 'vascular healing' or thymosin alpha-1 for 'immune modulation' — and the honest answer in every case is no, with specifics about why each peptide is wrong for this context. Rule 6 is sharpest on TA-1: hepatitis B Tier 1 evidence does not propagate to vasculitis, and the immune-activation direction of effect sits opposite to the immune-suppressive therapeutic goal.
Important caveat
GCA and PMR are rheumatology-managed conditions — your rheumatologist anchors diagnosis (ACR/EULAR 2022 GCA criteria + temporal artery biopsy gold standard + temporal artery ultrasound + PET-CT for large-vessel involvement; ACR/EULAR 2012 PMR criteria), acute management (high-dose prednisone 40-60 mg standard, 60-80 mg with visual symptoms, IV methylprednisolone pulses for vision-threat), and the steroid-sparing decision (tocilizumab FDA 2017 GCA via GiACTA; sarilumab FDA Feb 2023 PMR via SAPHYR; upadacitinib SELECT-GCA Phase 3 positive readout 2024-2025 with FDA submission expected; methotrexate older alternative). VISION SYMPTOMS IN SUSPECTED GCA ARE A MINUTES-TO-HOURS EMERGENCY — anterior ischemic optic neuropathy is permanent once it happens and the contralateral eye follows in 25-50% of untreated cases within days. Do not message a peptide source for new headache + jaw claudication + scalp tenderness + visual symptoms; go to the emergency department. No peptide in the Juno library has GCA or PMR evidence — none should be considered as an alternative to or substitute for the evidence-based steroid-sparing landscape. Community framing of BPC-157 for 'any inflammation' conflates local tissue repair with disease-modifying immunosuppression; they are not the same thing. TB-500's 'vascular healing' framing inverts the therapeutic goal in active vasculitis (suppress inflammation, not stimulate angiogenesis). Thymosin alpha-1's documented direction of effect is toward T-cell maturation — the wrong direction for T-cell-driven granulomatous vasculitis, with Rule 6 sharpest here (hepatitis B Tier 1 evidence does NOT propagate to vasculitis, and may actively work against the therapeutic goal). Selank's anxiolytic case is real in source-jurisdiction context but doesn't address disease — anxiety after GCA diagnosis or during high-dose prednisone is real and deserves first-line management (mental health referral, taper adjustment, sleep support) before any peptide overlay. NMN's general-aging case doesn't map to pathway-specific IL-6 / IFN-γ / IL-17 vasculitis mechanisms — and the elderly polypharmacy safety profile (prednisone + IL-6R blockers + antihypertensives + statins + aspirin if used) hasn't been characterized rigorously. ESR and CRP are the disease-activity markers your rheumatology team is following. Vasculitis Foundation is the patient-side anchor. EULAR 2015 + ACR 2024 vasculitis guidelines + ACR/EULAR 2022 GCA criteria + ACR/EULAR 2012 PMR criteria are the guideline references. WADA athletes: BPC-157 (S0) and TB-500 (S2) prohibited at all times — neither has a GCA or PMR use case anyway. Pregnancy: GCA and PMR pregnancies are rare given the >50 age criterion but require rheumatology + maternal-fetal medicine coordination if they occur; high-dose prednisone is generally continued through pregnancy when GCA dictates, with attention to gestational diabetes risk; tocilizumab and sarilumab pregnancy data are limited and require specialist guidance.
Want this list to grow? The library is editorial — if there’s a peptide you think belongs on this page with documented or mechanistically-clear evidence, send us a note with the citation and we’ll review it under the same evidence-tier discipline as every other entry.