Heart muscle protein
This one protein sits at the center of every route into this illness. It is unique to heart muscle. Injecting it is how the laboratory model of autoimmune heart inflammation is created; a virus can expose it by damaging the cells that hold it; and releasing the immune brakes can let the body notice it. Three different roads, one destination.
In depth
A contractile protein found only in heart muscle — and the target the immune system mistakes for an enemy.
What drives it
Immunotherapy heart inflammation increases it.
The same self-antigen, reached by a completely different road. 'Mechanistic studies further implicate autoreactive T cells targeting cardiac α-MYOSIN heavy chain (α-MyHC), a contractile protein uniquely expressed in cardiac muscle, as central mediators... In preclinical models, immunization with α-MyHC peptides induces autoimmune myocarditis' (pmc12698404 · doi 10.3389/fimmu.2025.1677984 — Overview of immune checkpoint inhibitor associated myocarditis mechanisms diagnostics and treatment). ⇒ this is the exact protein used to create the laboratory autoimmune model. A virus can expose it, a cancer drug can unmask it, and a syringe can inject it — and the heart suffers the same way in all three cases. The downstream is shared too: 'dual blockade of PD-1 and CTLA-4 induces a pro-inflammatory phenotype in cardiac tissues through upregulation of NF-κB, NLRP3 inflammasome components, and MyD88'. doi 10.3389/fimmu.2025.1677984
Autoimmune spread increases it.
How an infection becomes an autoimmune disease — the step has a name. A Japanese cardiology source states the three-phase structure directly and names the bridge: '第二期 (phase II)では、心筋組織の崩壊が心筋抗原の流出につながり自己免疫を誘導（epitope spreading）' — in phase ii, the breakdown of heart muscle tissue leads to the release of cardiac antigens, inducing autoimmunity by epitope spreading (近畿大学医学部 微生物学教室 — 心筋炎 Myocarditis (Kindai University School of Medicine, Department of Microbiology)). ⇒ the dying muscle cell spills proteins the immune system has never properly met. It learns to attack them, and then keeps attacking after the virus is gone. And the prognosis is stark: '未治療の場合、約半数の患者さんが、診断後２年以内に死亡するという統計もあります' — untreated, about half of patients die within two years of diagnosis.
What it drives
It increases Immune balance.
The same self-antigen, reached by a completely different road. 'Mechanistic studies further implicate autoreactive T cells targeting cardiac α-MYOSIN heavy chain (α-MyHC), a contractile protein uniquely expressed in cardiac muscle, as central mediators... In preclinical models, immunization with α-MyHC peptides induces autoimmune myocarditis' (pmc12698404 · doi 10.3389/fimmu.2025.1677984 — Overview of immune checkpoint inhibitor associated myocarditis mechanisms diagnostics and treatment). ⇒ this is the exact protein used to create the laboratory autoimmune model. A virus can expose it, a cancer drug can unmask it, and a syringe can inject it — and the heart suffers the same way in all three cases. The downstream is shared too: 'dual blockade of PD-1 and CTLA-4 induces a pro-inflammatory phenotype in cardiac tissues through upregulation of NF-κB, NLRP3 inflammasome components, and MyD88'. doi 10.3389/fimmu.2025.1677984
It reduces Heart muscle cell.
The same self-antigen, reached by a completely different road. 'Mechanistic studies further implicate autoreactive T cells targeting cardiac α-MYOSIN heavy chain (α-MyHC), a contractile protein uniquely expressed in cardiac muscle, as central mediators... In preclinical models, immunization with α-MyHC peptides induces autoimmune myocarditis' (pmc12698404 · doi 10.3389/fimmu.2025.1677984 — Overview of immune checkpoint inhibitor associated myocarditis mechanisms diagnostics and treatment). ⇒ this is the exact protein used to create the laboratory autoimmune model. A virus can expose it, a cancer drug can unmask it, and a syringe can inject it — and the heart suffers the same way in all three cases. The downstream is shared too: 'dual blockade of PD-1 and CTLA-4 induces a pro-inflammatory phenotype in cardiac tissues through upregulation of NF-κB, NLRP3 inflammasome components, and MyD88'. doi 10.3389/fimmu.2025.1677984
It increases Viral entry receptor.
10679478 — the virus's doorway has a second job, and it works without any virus at all. Japanese work on the autoimmune model found: '心筋ミオシン免疫のみで心筋細胞および血管内皮においてCXADR発現が誘発されその後持続する' — cardiac myosin immunization alone induces cxadr expression in cardiomyocytes and vascular endothelium, and it persists. And: 'CXADR過剰発現マウスでは、コクサッキーウイルスが感染していなくても心筋組織への炎症細胞浸潤が認められた' — in mice overexpressing it, inflammatory cells infiltrated the heart even without any coxsackievirus infection (上原記念生命科学財団研究報告集 33 (2019) — EAMにおけるCXADR発現の解析 (Uehara Memorial Foundation Research Report Vol.33, Yokohama City University)). ⇒ the mechanism is adhesion: the endothelial cxadr domain 'JAMLと異種間分子結合を形成することで、循環免疫細胞の血管内皮への遊走・接着' — it binds jaml on circulating immune cells and pulls them into the vessel wall. the same protein that lets the virus in also lets the immune system in. It is a doorway in both directions, and the source calls it '劇症型心筋炎および心筋症に対する有力な治療標的の一つ' — a promising therapeutic target for fulminant myocarditis and cardiomyopathy.
Blends that modulate it
Each blend page names this pathway and carries the study behind its claim.
See it on the map
Open the causal map to follow this pathway upstream and downstream, arrow by arrow, each with its study.