Immune and repair responses in joint tissues and lymph nodes after knee arthroplasty surgery in mice

Abstract

The importance of a local tissue immune response in healing injured tissues such as skin and lung is well established. Little is known about whether sterile wounds elicit lymph node (LN) responses and inflammatory responses after injury of musculoskeletal tissues that are mechanically loaded during the repair response. We investigated LN and tissue immune responses in a tibial implant model of joint replacement surgery where wounded tissue is subjected to movement and mechanical loading postoperatively. Draining inguinal and iliac LNs expanded postoperatively, including increases in regulatory T cells and activation of a subset of T cells. Thus, tissue injury was actively sensed in secondary lymphoid organs, with the potential to activate adaptive immunity. Joint tissues exhibited three temporally distinct immune response components, including a novel interferon (IFN) response with activation of signal transducer and activator of transcription (STAT) and interferon regulatory factor (IRF) pathways. Fibrovascular tissue formation was not associated with a macrophage type 2 (M2) reparative immune response, but instead with delayed induction of interleukin-1 family (IL-1β, IL-33, IL-36), IL-17, and prostaglandin pathway genes concomitant with transforming growth factor (TGF)-β and growth factor signaling, fibroblast activation, and tissue formation. Tissue remodeling was associated with activity of the HOX antisense intergenic RNA (HOTAIR) pathway. These results provide insights into immune responses and regulation of tissue healing after knee arthroplasty that potentially can be used to develop therapeutic strategies to improve healing, prevent arthrofibrosis, and improve surgical outcomes.

Immune Response to Persistent Staphyloccocus Aureus Periprosthetic Joint Infection in a Mouse Tibial Implant Model

“…S5 in Appendix S1). In line with our recent report, (45) surgery alone transiently expanded draining LNs at day 7, with a return to near baseline at day 35. Substantial LN expansion was only observed on the infected R side, consistent with a unilateral infection.…”

“…Lymph nodes (bilateral iliac and inguinal) were harvested, minced, and digested with type II collagenase (Worthington, Lakewood, NJ, USA) as described. (45) Single-cell suspensions were counted and then incubated with purified rat anti-mouse CD16/CD32 (mouse Fc block; BD Biosciences, San Jose, CA, USA; #553141 used at 1:50 dilution) before proceeding to surface marker staining. The following fluorophore-conjugated antibodies were used: anti-CD3, CD4, CD8, CD25, CD69, NK1.1, TCRγδ, CXCR5, ICOS, CD11b, F4/80, Ly6C, Ly6G, CD11c, I-Ab, CCR2, and CD9 (additional information provided in Supplemental Table S2).…”

“…H&E-stained histological sections of operated limbs of noninfected mice revealed a mild inflammatory reaction at days 3 and 7, subsequently resolving over time in accord with our recent report. (45) In contrast, the tissues from infected animals had much more severe infiltration of inflammatory cells, mainly polymorphonuclear neutrophils (PMNs), as early as 3 dpi. At day 7, there was heavy acute inflammation involving intraarticular soft tissues, articular capsule, and surrounding soft tissues (Fig.…”

“…S1A, B). We compared day 7, corresponding to activation of adaptive immunity, (47) to day 35, corresponding to a more chronic phase of immune The images for control non-infected mice in (C) were derived from the same mice used in the study of Xia and colleagues, (45) and the scoring for control noninfected mice in (D) was performed on the same mice and samples as in the study of Xia and colleagues. (45) The control and infected mice were analyzed together as part of the same experiment.…”

“…Immune cell activation and cytokine gene expression are maintained 35 dpi in infected joint tissues, cancellous bone, and peri-implant tissue. (A) qPCR analysis of the expression of Il6, Cxcl10, Tnf, and Il17a mRNA in joint soft tissues of non-infected and infected mice (RNA samples from the noninfected day 7 group in (A) and (C) are the same samples that were used in gene expression analysis in the study of Xia and colleagues (45). (B) Heatmap of cytokine, chemokine, and immune effector molecule gene expression in joint soft tissues of infected mice at 7 and 35 dpi.…”