The trypsin-like serine protease domain of Paralichthys olivaceus complement factor I regulates complement activation and inhibits bacterial growth.

In mammals, complement factor I (CFI) is a serine protease in serum and plays a pivotal role in the regulation of complement activation. In the presence of cofactor, CFI cleaves C3b to iC3b, and further degrades iC3b to C3c and C3d. In teleost, the function of CFI is poorly understood. In this study, we examined the immunological property of CFI from Japanese flounder (Paralichthys olivaceus) (PoCFI), a teleost species with important economic value. PoCFI is composed of 597 amino acid residues and possesses a trypsin-like serine protease (Tryp) domain. We found that PoCFI expressions occurred in nine different tissues and were upregulated by bacterial challenge. Recombinant PoCFI-Tryp (rPoCFI-Tryp) inhibited complement activation and degraded C3b in serum. rPoCFI-Tryp exhibited apparent binding capacities to a board-spectrum of bacteria and inhibited bacterial growth. These results provide the first evidence to indicate that CFI in teleost negatively regulates complement activation via degradation C3b, and probably plays a role in host immune defense against bacterial infection.

[Testicular mixed nonseminomatous germ cell cancer: a case report and review of the literature].

OBJECTIVE: Testicular mixed nonseminomatous germ cell cancer (TMNGCC) is rarely reported. This study aimed to explore the clinical symptoms, pathological characteristics and treatment methods of TMNGCC. METHODS: We analyzed the clinical data of 1 case of TMNGCC, observed its pathological characteristics under the light microscope by histology, cytochemistry, immunohistochemistry and immune marking, and investigated the clinical features of such tumors by reviewing the relevant literature. RESULTS: The patient presented with a chief complaint of painless testicular swelling for 3 years. Histopathological examinations revealed a tumor of papillary, fissural or adenoid structure, with large polygonal or columnar cells with one or more irregular vesicular nuclei, the nuclear membrane clear, the cytoplasm eosinophilic or basophilic, and the interstitium infiltrated by a few lymphocytes. Here are the immunohistochemical results: CD117 -, CK8-18 + +, CD30 + +, CK + + +, vimentin -, PLAP +/-, P53 +, AFP + and EMA + +. The tumor was pathologically diagnosed as teratogenic embryonic testicular cancer, and treated by radical surgery, followed by adjuvant chemotherapy according to the treatment of TMNGCC. One-year follow-up found the patient to be alive. CONCLUSION: TMNGCC is a rare malignant tumor, mostly with unobvious clinical symptoms. Its diagnosis primarily depends on physical examination, ultrasonography, CT, and measurement of serum tumor markers; its confirmation necessitates pathological examination, and its first-choice treatment is surgical resection.