Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1998 Sep 1;18(17):6713-22.
doi: 10.1523/JNEUROSCI.18-17-06713.1998.

Complement depletion reduces macrophage infiltration and activation during Wallerian degeneration and axonal regeneration

A T Dailey  1 , A M Avellino, L Benthem, J Silver, M Kliot
Affiliations

Complement depletion reduces macrophage infiltration and activation during Wallerian degeneration and axonal regeneration

A T Dailey et al. J Neurosci. .

Abstract

After peripheral nerve injury, macrophages infiltrate the degenerating nerve and participate in the removal of myelin and axonal debris, in Schwann cell proliferation, and in axonal regeneration. In vitro studies have demonstrated the role serum complement plays in both macrophage invasion and activation during Wallerian degeneration of peripheral nerve. To determine its role in vivo, we depleted serum complement for 1 week in adult Lewis rats, using intravenously administered cobra venom factor. At 1 d after complement depletion the right sciatic nerve was crushed, and the animals were sacrificed 4 and 7 d later. Macrophage identification with ED-1 and CD11a monoclonal antibodies revealed a significant reduction in their recruitment into distal degenerating nerve in complement-depleted animals. Complement depletion also decreased macrophage activation, as indicated by their failure to become large and multivacuolated and their reduced capacity to clear myelin, which was evident at both light and electron microscopic levels. Axonal regeneration was delayed in complement-depleted animals. These findings support a role for serum complement in both the recruitment and activation of macrophages during peripheral nerve degeneration as well as a role for macrophages in promoting axonal regeneration.

PubMed Disclaimer

Figures

Fig. 1.
Fig. 1.
Graphs depicting the macrophage response in control and complement-depleted animals. Counts represent the number of macrophages per 0.1 mm2 stained with either ED-1 (A) or CD11a (B) antibodies. A, In intact nerves there is no difference in macrophage counts between control and complement-depleted groups. At 4 d after crush there is a trend toward fewer macrophages in the complement-depleted animals (23.4 ± 5.3 vs 27.2 ± 2.3;p = 0.1). At 7 d after crush the difference in macrophage counts between the two groups has reached statistical significance (31.2 ± 2.1 vs 38.9 ± 2.1; *p < 0.05). B, In intact nerves there is no staining with the CD11a antibody. At both 4 d (1.3 ± 0.1 vs 3.8 ± 1.3; *p < 0.05) and 7 d (2.6 ± 0.3 vs 5.1 ± 0.5; *p < 0.05) after crush the complement-depleted group has a statistically significant reduction in the number of stained cells when compared with the control group.
Fig. 2.
Fig. 2.
Longitudinal sections of degenerating sciatic nerve stained with either ED-1 or CD11a antibodies at 7 d after crush injury. A–D, Staining with ED-1 antibody.E, F, Staining with CD11a antibody.A, C, E, Control animal.B, D, F, A complement-depleted animal. Note the reduced number of macrophages in the complement-depleted animal (B) in comparison to the control animal (A). C, Shown at higher power are large multivacuolated macrophages (arrows) in a control animal as compared with the much smaller macrophages in the complement-depleted animal (D, arrows). E,F, Shown are small CD11a antibody-staining cells only, presumably representing recently recruited macrophages. Many more CD11a-staining cells are seen in the control (E) than in the complement-depleted (F) animal. Scale bars: in A, B, 0.1 mm; inC–F, 0.05 mm.
Fig. 3.
Fig. 3.
Macrophages in different states of activation.A, Shown is a ramified resident macrophage from an intact nerve in a control animal. B, Shown is an example from a control animal of a large multivacuolated foamy macrophage in a degenerating nerve crushed 7 d previously. C, Shown are macrophages in a degenerating nerve crushed 7 d previously from a complement-depleted animal. These macrophages resemble the ramified endogenous macrophages seen in intact nerves. Scale bar, 0.02 mm.
Fig. 4.
Fig. 4.
Histogram depicting macrophage cell size, expressed in surface area, in control (n = 8) and complement-depleted (n = 8) degenerating nerves 7 d after crush. Note that the complement-depleted group has a greater proportion of macrophages that are <2 × 10−4 mm2, very few cells that are >3 × 10−4 mm2, and no cells that are >7 × 10−4mm2. The mean cell area was significantly smaller for the complement-depleted group (1.31 ± 0.04 × 10−4 mm2) than for the control group (2.50 ± 0.23 × 10−4mm2; p < 0.05).
Fig. 5.
Fig. 5.
Longitudinal sections of degenerating peripheral nerve stained with Erichrome Cyanine R to depict myelin profiles.A, Represented is an intact nerve from a control animal. Note the regular elongated tube-like myelin profiles. B, Shown is a degenerating nerve from a control animal 7 d after crush in which myelin ovoids (single arrows) and clear spaces (double arrows) have replaced the normal myelin sheaths. Persistent myelin sheaths have varying diameters, with some exhibiting markedly increased space between the basal laminae (arrowheads). C, A degenerating nerve from a complement-depleted animal shows greater preservation of myelin. Scale bar, 0.05 mm.
Fig. 6.
Fig. 6.
Representative electron micrographs from degenerating nerves 7 d after crush from control (A, B) and complement-depleted (C) animals. In A, an intratubal macrophage (black arrow) is associated with lipid vacuoles and myelin fragments (arrowhead) within a degenerating myelin sheath. Two adjacent structures (clear arrows) depict basement membrane containing lipid vacuoles and cellular remnants, but no intact myelin. B, Shown is a macrophage (arrow) with an irregular nucleus, dark heterochromatin, and pseudopodia engaging a myelin sheath (arrowhead). In a complement-depleted animal (C) the myelin remains visible within the sheath (arrowheads), although it may have collapsed and separated from the surrounding Schwann cell cytoplasm. There are some small macrophages (arrows) that have not yet engaged in the phagocytosis of myelin. In the bottom right corneris a blood vessel (v) containing monocytes that have not yet entered the degenerating nerve segment. All pictures are displayed at 800× original magnification.
Fig. 7.
Fig. 7.
Longitudinal sections of nerves stained for regenerating axons with a neurofilament antibody at 7 d after crush injury. These sections were taken 10 mm distal to the crush site.A and B are low-power whereasC and D are high-power photomicrographs. Sections from a control animal (A, C) show a greater number of regenerated axons than in a complement-depleted animal (B, D). In addition, the complement-depleted animal has a greater amount of residual neurofilament debris (arrowheads,D) as compared with the control animal (C). Scale bar, 0.05 mm.
Fig. 8.
Fig. 8.
Graph showing the counts of neurofilament-stained regenerating axons at different times and different points from the crush site. At both 4 and 7 d after crush, complement-depleted animals have fewer regenerating axons than control animals. At 4 d after crush, only the 3 mm point was examined (5.7 ± 0.7 vs 10.0 ± 1.0; *p< 0.05). At 7 d after crush, both 3 mm (15.0 ± 0.9 vs 21.8 ± 0.9; **p < 0.001) and 10 mm points (10.7 ± 0.6 vs 15.9 ± 0.5; ***p < 0.001) were examined.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Avellino AM, Hart D, Dailey AT, MacKinnon M, Ellegala D, Kliot M. Differential macrophage responses in the peripheral and central nervous system during Wallerian degeneration of axons. Exp Neurol. 1995;136:183–198. - PubMed
    1. Baichwal RR, Bigbee JW, DeVries GH. Macrophage-mediated myelin-related mitogenic factor for cultured Schwann cells. Proc Natl Acad Sci USA. 1988;85:1701–1705. - PMC - PubMed
    1. Bedi KS, Winter J, Berry M, Cohen J. Adult rat dorsal root ganglion neurons extend neurites on predegenerated but not on normal peripheral nerves in vitro. Eur J Neurosci. 1992;4:193–200. - PubMed
    1. Beuche W, Friede RL. The role of non-resident cells in Wallerian degeneration. J Neurocytol. 1984;13:767–796. - PubMed
    1. Beuche W, Friede RL. Myelin phagocytosis in Wallerian degeneration depends on silica-sensitive, bg/bg-negative and Fc-positive monocytes. Brain Res. 1986;378:97–106. - PubMed

Publication types

Substances

LinkOut - more resources