Imatinib inhibits pericyte-fibroblast transition and inflammation and promotes axon regeneration by blocking the PDGF-BB/PDGFRß pathway in spinal cord injury.

BACKGROUND: Fibrotic scar formation and inflammation are characteristic pathologies of spinal cord injury (SCI) in the injured core, which has been widely regarded as the main barrier to axonal regeneration resulting in permanent functional recovery failure. Pericytes were shown to be the main source of fibroblasts that form fibrotic scar. However, the mechanism of pericyte-fibroblast transition after SCI remains elusive. METHODS: Fibrotic scarring and microvessels were assessed using immunofluorescence staining after establishing a crush SCI model. To study the process of pericyte-fibroblast transition, we analyzed pericyte marker and fibroblast marker expression using immunofluorescence. The distribution and cellular origin of platelet-derived growth factor (PDGF)-BB were examined with immunofluorescence. Pericyte-fibroblast transition was detected with immunohistochemistry and Western blot assays after PDGF-BB knockdown and blocking PDGF-BB/PDGFRß signaling in vitro. Intrathecal injection of imatinib was used to selectively inhibit PDGF-BB/PDGFRß signaling. The Basso mouse scale score and footprint analysis were performed to assess functional recovery. Subsequently, axonal regeneration, fibrotic scarring, fibroblast population, proliferation and apoptosis of PDGFRß+ cells, microvessel leakage, and the inflammatory response were assessed with immunofluorescence. RESULTS: PDGFRß+ pericytes detached from the blood vessel wall and transitioned into fibroblasts to form fibrotic scar after SCI. PDGF-BB was mainly distributed in the periphery of the injured core, and microvascular endothelial cells were one of the sources of PDGF-BB in the acute phase. Microvascular endothelial cells induced pericyte-fibroblast transition through the PDGF-BB/PDGFRß signaling pathway in vitro. Pharmacologically blocking the PDGF-BB/PDGFRß pathway promoted motor function recovery and axonal regeneration and inhibited fibrotic scar formation. After fibrotic scar formation, blocking the PDGFRß receptor inhibited proliferation and promoted apoptosis of PDGFRß+ cells. Imatinib did not alter pericyte coverage on microvessels, while microvessel leakage and inflammation were significantly decreased after imatinib treatment. CONCLUSIONS: We reveal that the crosstalk between microvascular endothelial cells and pericytes promotes pericyte-fibroblast transition through the PDGF-BB/PDGFRß signaling pathway. Our finding suggests that blocking the PDGF-BB/PDGFRß signaling pathway with imatinib contributes to functional recovery, fibrotic scarring, and inflammatory attenuation after SCI and provides a potential target for the treatment of SCI.

Brevinin-2PN, an antimicrobial peptide identified from dark-spotted frog (Pelophylax nigromaculatus), exhibits wound-healing activity.

Brevinins exhibit a wide range of structural features and strong biological activities. Brevinin-2, derived from several amphibians, has shown antimicrobial activities. However, little is known about the wound-healing activity of brevinin-2. In this study, brevinin-2 cDNA was identified from the skin transcriptome of the dark-spotted frog (Pelophylax nigromaculatus) and it comprises a signal peptide, a propeptide, and a mature peptide. Sequence alignment with brevinin-2 derived from other amphibians showed variability of the mature peptide, and the presence of a C-terminal cyclic heptapeptide domain (Cys-Lys-Xaa4-Cys) in the mature peptide. Dark-spotted frog brevinin-2 belonged to the brevinin-2 cluster and was closely related to brevinin-2HB1 from Pelophylax hubeiensis. Synthetic dark-spotted frog brevinin-2 mature peptide (brevinin-2PN) exhibited antibacterial activity against several pathogens by destroying cell membrane integrity and hydrolysis of genomic DNA. Brevinin-2PN exhibited significant wound-healing activity by accelerating the healing of human skin fibroblast cell scratches, influencing cell migration, and stimulating gene expression of growth factors.

Complex proximal femoral fracture in a young patient followed up for 3 years: A case report.

BACKGROUND: Ipsilateral femoral neck and intertrochanteric fractures in young patients are extremely rare, and there is no reference for fracture classification and treatment options. CASE SUMMARY: We report a 27-year-old male patient who sustained ipsilateral femoral neck and intertrochanteric fractures and was treated with a proximal femoral locking compression plate (PFLCP). The literature on these fractures was also reviewed. At the last follow-up three years after surgery, the patient had no obvious pain in the hip, and the range of motion in the hip joint was slightly limited, but met the normal life and work needs. There were no complications such as necrosis of the femoral head. CONCLUSION: The PFLCP can be used to treat these complex proximal femoral fractures, and selection should be based on the patient's specific fractures.

Antimicrobial and immunomodulatory activity of beta-defensin from the Chinese spiny frog (Quasipaa spinosa).

The ß-defensins are important components of the vertebrate innate immune system. While mammalian ß-defensins have wide-ranging antibacterial and immunomodulatory activities, those of amphibians remain largely uncharacterised. In this study, ß-defensin cDNA was identified from the skin transcriptome of the Chinese spiny frog Quasipaa spinosa. This ß-defensin (QS-BD) consists of a signal and a mature peptide. Sequence alignments with other amphibian ß-defensins showed conservation of the functional mature peptide and that its closest relative is ß-defensin from Zhangixalus puerensis. Synthetic QS-BD showed antibacterial activity against Vibrio vulnificus, Vibrio harveyi, Streptococcus iniae, and Aeromonas hydrophila. QS-BD showed bactericidal activity by destroying the cell membrane integrity, but did not hydrolyse genomic DNA. QS-BD treatment promoted respiratory bursts and upregulated the expression of interleukin-1ß and tumour necrosis factor-α in the murine leukemic monocyte/macrophage cell line RAW264.7. This is the first demonstration of immunomodulatory activity by an amphibian ß-defensin.

M1-type microglia can induce astrocytes to deposit chondroitin sulfate proteoglycan after spinal cord injury.

After spinal cord injury (SCI), astrocytes gradually migrate to and surround the lesion, depositing chondroitin sulfate proteoglycan-rich extracellular matrix and forming astrocytic scar, which limits the spread of inflammation but hinders axon regeneration. Meanwhile, microglia gradually accumulate at the lesion border to form microglial scar and can polarize to generate a pro-inflammatory M1 phenotype or an anti-inflammatory M2 phenotype. However, the effect of microglia polarization on astrocytes is unclear. Here, we found that both microglia (CX3CR1+) and astrocytes (GFAP+) gathered at the lesion border at 14 days post-injury (dpi). The microglia accumulated along the inner border of and in direct contact with the astrocytes. M1-type microglia (iNOS+CX3CR1+) were primarily observed at 3 and 7 dpi, while M2-type microglia (Arg1+CX3CR1+) were present at larger numbers at 7 and 14 dpi. Transforming growth factor-ß1 (TGFß1) was highly expressed in M1 microglia in vitro, consistent with strong expression of TGFß1 by microglia in vivo at 3 and 7 dpi, when they primarily exhibited an M1 phenotype. Furthermore, conditioned media from M1-type microglia induced astrocytes to secrete chondroitin sulfate proteoglycan in vitro. This effect was eliminated by knocking down sex-determining region Y-box 9 (SOX9) in astrocytes and could not be reversed by treatment with TGFß1. Taken together, our results suggest that microglia undergo M1 polarization and express high levels of TGFß1 at 3 and 7 dpi, and that M1-type microglia induce astrocytes to deposit chondroitin sulfate proteoglycan via the TGFß1/SOX9 pathway. The study was approved by the Institutional Animal Care and Use Committee of Anhui Medical University, China (approval No. LLSC20160052) on March 1, 2016.

Characterization of the complete mitochondrial genome of the Chong'an Moustache Toad, Leptobrachium liui (Pope, 1947) with a phylogenetic analysis of Megophryidae.

The Chong'an Mustache Toad, Leptobrachium liui (Pope, 1947) is a Chinese endemic species, inhabiting the mountain streams with rich vegetation in southeastern China. The first complete mitochondrial genome (mitogenome) of L. liui was assembled using the data of whole-genome sequencing. The size of the complete mitogenome for L. liui was 17,190 bp, which included 13 PCGs, 23 tRNAs with two concatenated tRNAMet genes, 2 rRNAs, a non-coding region, and a D-loop. The Bayesian tree shows that L. liui was positioned near L. leishanense within the genus Leptobrachium.

Full genomic sequence analysis of swine genotype 3 hepatitis E virus isolated from Shanghai.

The full genomic nucleotide sequence of a previously identified genotype 3 hepatitis E virus (HEV), strain SAAS-JDY5, was obtained using RT-PCR and rapid amplification of cDNA ends (RACE). The genome consisted of 7225 nucleotides, excluding a poly-A tail at the 3' terminus, and contained three open reading frames (ORFs), ORF-1, ORF-2 and ORF-3, encoding 1702, 660 and 113 amino acids, respectively. Phylogenetic analysis confirmed that SAAS-JDY5 belonged to genotype 3 HEV and was most closely related to the Japanese isolate wbJYG1 (AB222184). SAAS-JDY5 shared approximately 87% nucleotide similarity to human and swine strains from the United States, compared with 74-75% similarity to Asian (genotype 4) and Mexican strains (genotype 2). Alignment of the SAAS-JDY5 genomic sequence with reference sequences of the same genotype revealed one nucleotide substitution and one deletion at positions 5145 and 7189 (3' UTR), respectively. Moreover, SAAS-JDY5 contained two additional nucleotides (AC) at the very end of the 3'-terminus preceding the poly-A tail of the genome. Comparison of the putative amino acid sequence encoded by the SAAS-JDY5 genome with sequences of other genotype 3 isolates revealed 15 unique amino acid substitutions and one deletion in ORF-1, and three substitutions in ORF-2.