Fine structure of host-graft relationships between transplanted chromaffin cells and CNS

Characterization of a Propionibacterium acnes Surface Protein as a Fibrinogen-Binding Protein

Propionibacterium acnes (P. acnes) is a major skin-associated bacterium that was long considered commensal, until several studies revealed it to be an opportunistic pathogen. We investigated the ability of P. acnes surface proteins to recognize ECM proteins and showed that a 58 kDa P. acnes surface protein was specifically recognized by human fibrinogen (hFg). The 58 kDa protein was further characterized by two-dimensional (2-D) electrophoresis and MALDI-ToF as a P. acnes host cell-surface attachment protein, PA25957, recognizing dermatan sulfate (DsA1). This protein sequence contains 432 amino acids with the presence of three structurally different domains: an N-terminal signal peptide, a C-terminal LPXTG motif, and a PT repeat region. DsA1 is mostly produced during stationary phase. It appears to be highly glycosylated, containing GalNAc residues. Purified DsA1 strongly recognizes the Aα and Bβ subunits of hFg, and specific enzymatic deglycosylation of hFg demonstrated the involvement of the protein backbone in the recognition process. The Bβ subunit of hFg was cloned in four peptide fractions (Fg1-Fg4). The N-terminal Fg1 peptide of hFg was recognized by DsA1, and priming DsA1 with Fg1 inhibited DsA1/hFg recognition. We describe here for the first time, the characterization of a P. acnes surface glycoprotein recognizing human fibrinogen.

Evaluation of hyperalgesia in spared nerve injury model using mechanical, thermal, and chemical stimuli in the mouse

OBJECTIVE

Neuropathic pain results from multiple etiological factors and is a debilitating condition often resulting from partial injury to a peripheral nerve. However, the mechanism underlying this syndrome remains unclear. The aim of the present study is to investigate whether a spared nerve injury model with transection of both the common peroneal nerve (CPN) and tibial nerve (TN) branches of the sciatic nerve is associated with pain or hypersensitivity in the mouse.

METHODS

A skin and muscle incision was made, and we tightly ligated CPN+TN or the sural nerve (SN) alone as branches of the sciatic nerve. Mechanical and thermal allodynia were tested using von Frey filaments and radiant heat at -1, 1, 3, 5, and 7 days after surgery.

RESULTS

The thresholds of mechanical and thermal stimuli were increased and decreased in the CPN+TN-ligated and SN-ligated groups, respectively. Chemical hyperalgesia was estimated using two doses of intraplantar administration of formalin (0.1 and 1%) 1 week after surgery. Then behaviors were videotaped and playback was used to measure time of licking of the hind paws. The licking time induced by 0.1% formalin was significantly shortened in the CPN+TN-ligated group and significantly prolonged in the SN-ligated group. Number of c-Fos-immunoreactive cells in the spinal cord was not affected by CPN+TN ligation, but was significantly increased in the SN-ligated group.

DISCUSSION

These findings suggest that changing the combination of nerves in sciatic branch ligation produces different sensitivities to stimuli and SN ligation will be useful for inducing allodynia and hyperalgesia in the mouse.