Spatiotemporal quantification of tumor necrosis factor-alpha and interleukin-10 after crush injury in rat sciatic nerve utilizing immunohistochemistry

Abstract

The purpose of this study was to investigate quantitatively the longitudinal temporal, spatial changes of the tumor necrosis factor-alpha (TNF) and interleukin-10 (IL-10) immunopositive cells during Wallerian degeneration and the following regeneration after crush injury in rat sciatic nerve using immunohistochemistry and enzyme linked immunosorbent assay (ELISA). The number of TNF-immunopositive cells reached its peak and increased significantly in all the segments distal to the crush site 3 days after injury. On Day 7, TNF-immunopositive cells decreased in all the segments distal to the crush site, and a significant decrease was observed 14 days after injury. From Day 21 to Day 56, there were no significant differences in the numbers of TNF-immunopositive cells. The average size of TNF immunopositive cells became significantly larger with degeneration. The number of IL-10-immunopositive cells decreases significantly 1 day after crush injury. IL-10-immunopositive cells increased on Day 3, returning to control levels. Seven days after injury, a significant increase in the number of IL-10-immunopositive cells was observed. There was also no significant difference in the number of IL-10-immunopositive cells beyond Day 14 except for a part of distal segments. The number of IL-10-immunopositive cells showed no significant differences in all the segments on Day 56. The protein levels of IL-10 measured by ELISA were similar to the result of immunohistochemistry. These results suggest that the significant change in IL-10 occurred prior to the significant change in TNF and that IL-10 may be the key to the change in TNF.

Toll-Like Receptor Signaling Is Critical for Wallerian Degeneration and Functional Recovery after Peripheral Nerve Injury

“…These results do not rule out the possibility that more significant levels of TNF could have been detected at later time points after injury. In this regard, others have reported, using a similar lesion model, that TNF expression in the rodent sciatic nerve distal stump peaks at 3 d after injury (La Fleur et al, 1996;George et al, 2004;Sawada et al, 2007). The hybridization signal for the genes encoding IFN␤ and iNOS mRNA was comparable to background levels (data not shown).…”

Inflammatory Profiling of Schwann Cells in Contact with Growing Axons Distal to Nerve Injury

“…This early peak is followed by a second, later phase of increased cytokine expression [9, 10]. A second phase of IL-1 β , TNF α and IL-10 upregulation [12, 13] and period of axon growth [14] occur within 7 days after nerve crush injury. Our immunofluorescence staining results have shown that, in addition to invaded macrophages and other immune cells [15–17], Schwann cells constitute another robust source of both pro- and anti-inflammatory cytokines distal to nerve crush injury for 7 d. In addition, double immunostaining revealed that GAP43+ growing axons are in close contact with Schwann cells strongly decorated by immunofluorescence for IL-1 β , TNF α , IL-4, and IL-10 (Figures 1(d)–1(i), 2(d)–2(i), 3(d)–3(i), and 4(d)–4(i)).…”

“…Expression of IL-10 after nerve injury is an interesting subject, because it attenuates production of proinflammatory cytokines IL-1 β and TNF α . Significant increase of IL-10 and IL-10-immunopositive cells has been observed 7 d after nerve injury [13, 32]. Thus, IL-10 may promote axonal regeneration by inhibiting overproduction of proinflammatory cytokines.…”

The Glia Response after Peripheral Nerve Injury: A Comparison between Schwann Cells and Olfactory Ensheathing Cells and Their Uses for Neural Regenerative Therapies

“…SCs secrete many factors to recruit macrophages and modulate Wallerian degeneration, such as LIF, TNFα, IL-1α, and IL-1β [78,79]. LIF stimulates autocrine monocyte chemoattractant protein (MCP-1) expression in SCs [80] while TNFα and interleukin (IL-1β) have been linked to increased matrix metalloproteinase (MMP-9) [81,82], which are all involved in macrophage migration and recruitment.…”