Distinct severity of HLH in both human and murine mutants with complete loss of cytotoxic effector PRF1, RAB27A, and STX11

Abstract

Key Points• Syntaxin-11-deficient (Stx11 Ϫ/Ϫ ) murine model faithfully reproduced the manifestations of HLH after LCMV infection.• HLH severity differed significantly with a severity gradient from perforin (early onset) Rab27a syntaxin-11 (late onset).Inherited defects of granule-dependent cytotoxicity led to the life-threatening immune disorder hemophagocytic lymphohistiocytosis (HLH), characterized by uncontrolled CD8 T-cell and macrophage activation. In a cohort of HLH patients with genetic abnormalities expected to result in the complete absence of perforin, Rab27a, or syntaxin-11, we found that disease severity as determined by age at HLH onset differed significantly, with a severity gradient from perforin (early onset) > Rab27a > syntaxin-11 (late onset). In parallel, we have generated a syntaxin-11-deficient (Stx11 ؊ /

SM protein Munc18-2 facilitates transition of Syntaxin 11-mediated lipid mixing to complete fusion for T-lymphocyte cytotoxicity

“…CTLs from STX11 knockout mice (47,48) and of patients with F-HLH-4 and -5, which have mutations in STX11 and Munc18-2, respectively (7, 17, 49), display reduced cytotoxic activity toward sensitive target cells. In particular, the defective cytotoxic activity associated with F-HLH-associated missense mutations STX11-L58P (50), Munc18-2-E132A (34) and Munc18-2-R65Q (33), which interfere with the STX11/Munc18-2 association, reflect a direct role of this interaction for mediating lytic granule content release.…”

A novel immunoregulatory role for NK-cell cytotoxicity in protection from HLH-like immunopathology in mice

“…As mice harboring a conditional perforin allele are not yet available, we created mice with a NK-cell-specific ablation of Stx11, a protein that is required for the release of perforin-containing cytotoxic granules. 16,17,29 We crossed loxP-flanked Stx11 mice 16 with a transgenic mouse line expressing Cre recombinase under the promoter of NKp46 (Ncr1) 25 expected, NK cells from T 1 NK Stx112 mice failed to degranulate in vitro, whereas CD8 T cells degranulated normally on CD3/ CD28 activation as assessed by CD107 expression (supplemental Figure 3).…”

“…LCMV viral load was assessed by quantitative polymerase chain reaction as described previously. 16 Briefly, cDNA was isolated from tissue samples and analyzed with primers for LCMV (forward: 59-TCTCATCCCAAC CATTTGCA-39 and reverse: 59-GGGAAATTTGACAGCACAACAA-39) and b-actin (forward: 59-CCAGCAGATGTGGATCAGCA-39 and reverse: 59-CTTGCGGTGCACGATGG-39) using SYBR Green PCR Master Mix (Applied Biosystems).…”

“…Cytotoxic-deficient mice (such as Prf1, Rab27a, Unc13d, Stx11, and Lyst mice) develop a severe HLH-like syndrome after infection with lymphocytic choriomeningitis virus (LCMV). [13][14][15][16][17][18] In the absence of cytotoxic activity of CD8 T cells, an accumulation of the antigen-presenting cells that continuously activate CTLs was reported in Prf1 2/2 mice. 19 The hyperactivated CTLs secrete high levels of interferon (IFN)-g, which appears critical for the development of HLH-like symptoms.…”

IL-2 consumption by highly activated CD8 T cells induces regulatory T-cell dysfunction in patients with hemophagocytic lymphohistiocytosis

“…3 Preclinical models for studying FHL have been developed using lymphocytic choriomeningitis virus (LCMV)-triggering inflammation in perforin-deficient mice. 4,5 These murine models recapitulate the key components of human disease, including life-threatening inflammation, cytopenia, cytokine storm, and immune cell infiltration in different organs, including the liver and central nervous system. Specifically, these studies helped to uncover the pathophysiology of FHL, demonstrating that both CD8 1 T cells and IFN-g are the principal terminal effectors of the disease.…”