Single-cell transcriptomics reveals granzyme K-expressing cytotoxic Tfh cells in tertiary lymphoid structures in IgG4-RD.

BACKGROUND: Germinal center (GC) responses controlled by T follicular helper (Tfh) and T follicular regulatory (Tfr) cells are crucial for the generation of high-affinity antibodies. Acquired immune responses to tissue-released antigens might be mainly induced in tertiary lymphoid organs (TLOs) with GCs in affected tissues. IgG4-related disease (IgG4-RD) demonstrates polarized isotype switching and TLOs in affected tissues. We performed single-cell transcriptomics of tissue-infiltrating T cells from these TLOs to obtain a comprehensive, unbiased view of tissue-infiltrating GC-Tfh cells. OBJECTIVE: To identify GC-Tfh-cell subsets in TLOs in patients with IgG4-RD using single-cell transcriptomics. METHODS: Single-cell RNA sequencing of sorted CD3+ T cells and multicolor immunofluorescence analysis were used to investigate CD4+CXCR5+Bcl6+ GC-Tfh cells in affected lesions from patients with IgG4-RD. RESULTS: Infiltrating CD4+CXCR5+Bcl6+ Tfh cells were divided into 5 main clusters. We detected HLA+ granzyme K+ (GZMK+) Tfh cells with cytotoxicity-associated features in patients with IgG4-RD. We also observed abundant infiltrating Tfr cells with suppressor-associated features in patients with IgG4-RD. These GZMK+ Tfh cells and Tfr cells clustered together in affected tissues from patients with IgG4-RD. CONCLUSIONS: This single-cell data set revealed a novel subset of HLA+GZMK+ cytotoxic Tfh cells infiltrating affected organs in patients with IgG4-RD, suggesting that infiltrating Tfr cells might suppress cytotoxic Tfh cells.

Effect of a computer-assisted navigation system on the lag screw placement accuracy of less experienced surgeons.

BACKGROUND: Femoral trochanteric fracture is treated by osteosynthesis using an angle-fixed implant. Lag screw cut-out is a postoperative complication, and a tip-apex distance (TAD) of 20 mm or shorter is recommended to prevent it. The use of a navigation system for lag screw placement has been reported, but the use and non-use of navigation systems by less experienced surgeons has not been assessed. The objective of this study was to retrospectively investigate the usefulness of a navigation system for short femoral nailing. METHODS: The subjects were 101 patients with femoral trochanteric fracture treated by osteosynthesis at our hospital between May 2017 and December 2018 (male, 14; female, 87; mean age, 84.7 years; navigation use group, 55; non-navigation use group, 46). The patients were divided into four groups: groups treated by less experienced surgeons with (Navigation-Young surgeon [NY] group, n = 35) and without (Manual-Young surgeon [MY] group, n = 23) the use of a navigation system; and groups treated by experienced surgeons with (Navigation-Aged surgeon [NA] group, n = 20) and without (Manual-Aged surgeon [MA] group, n = 23) the use of a navigation system. TAD (mm) and operative time (min) were compared. RESULTS: The TAD was significantly longer in the MY group than in the NY group. The percentages of patients with 10-20 mm TAD were as follows: NY group, 94.3%; MY group, 65.2%; NA group, 100%; MA group, 100%. The mean operative time was significantly longer in the NY group than in the MA group, but no significant difference in mean operative time was noted between the NY and MY groups or between the NA and MA groups. CONCLUSIONS: A computer-assisted navigation system improves the accuracy of lag screw placement performed by less experienced operators without increasing the operative time.

Histological analysis of the ligamentum flavum of patients with dialysis-related spondyloarthropathy.

Dialysis-related spondyloarthropathy (DRS) is a severe complication of long-term hemodialysis that ultimately leads to functional disability of the upper and lower extremities. Although the cause of this disease is still unknown, it is thought that amyloid deposits are involved. beta2-Microglobulin (beta2M) is a major component of amyloid fibrils, some of which are modified with the advanced glycation end-product (AGE). To clarify the pathophysiology of DRS we histologically examined the ligamentum flavum of the cervical spine in 15 patients with DRS. The mean duration of hemodialysis was 20 years (12-27 years). In addition to the congo red stain for amyloid, beta2M and AGE were detected by immunohistochemical methods. Macrophages were stained with CD68 antibody. Amyloid deposits were found in tissues, although the extent of the stained area differed among the patients. Part of the amyloid deposit area was positively immunostained for beta2M and AGE. In 10 cases macrophages positive for CD68 infiltrated around the amyloid deposits. Comparing these histological findings with the dialysis duration, more positive staining areas for beta2M and AGE were found in the tissue from patients with long-term dialysis. These findings suggest that both beta2M and AGE play roles in the pathogenesis of DRS.