Pharmacokinetic Study of a Novel Recombinant Human Granulocyte Colony-stimulating Factor in Rats

Objective To study the pharmacokinetics of a novel recombinant human granulocyte colonystimulating factor (rhG-CSFa) in rats and to determine the proteolytic rates of rhG-CSFa in the whole blood and serum of rats in vitro. Methods The pharmacokinetics of rhG-CSFa and conventional (wild type,WT) granulocyte colonystimulating factor (G-CSF) were investigated in Sprague-Dawley rats which received either intravenous or subcutaneous injection of rhG-CSFa or WT G-CSF at three different doses (20,50,or 100 μg/kg). The blood samples of rats were collected at multiple time points (from 0.08 to 12 h) and the concentrations of rhG-CSFa and WT G-CSF in serum were determined with a sandwich enzyme-linked immunosorbent assay (ELISA). For the study of proteolytic rates in vitro,the concentrations of rhG-CSFa or WT G-CSF were determined at 3-minute intervals after addition of the respective drug to rat’s whole blood or serum. Results Pharmacokinetic analysis of serum rhG-CSFa or WT G-CSF levels indicated that,at each dose tested,for either route of drug administration,the area under concentration-time curve values and the maximum serum concentration of rhG-CSFa were higher than those of WT G-CSF,and the serum half life of rhG-CSFa was longer than that of WT G-CSF. Subsequent in vitro whole blood and serum stability study showed that the rates of drug degradation in WT G-CSF were 1.8 folds and 1.5 folds higher than those in rhG-CSFa,respectively. Conclusion rhG-CSFa has better serum and whole blood stability in vitro and higher bioavailability in vivo as compared to WT G-CSF.

Anti-apoptotic effects of recombinant human granulocyte colony-stimulating factor in focal cerebral ischemic rats

The neuroprotective effects of granulocyte colony-stimulating factor in cerebral ischemia/reperfusion injury are currently contentious. The present study examined the effects of subcutaneous injection of recombinant human granulocyte colony-stimulating factor （50 pg/kg） over 5 days in a model of cerebral ischemia/reperfusion with intraluminal filament occlusion in rats. The results indicated that recombinant human granulocyte colony-stimulating factor reduced brain infarct volume following cerebral ischemia/reperfusion injury in rats, down-regulated the expression of caspase-3 mRNA （a key protease for apoptosis in the cerebral ischemia zone）, lowered the rate of neuronal apoptosis in the cerebral ischemia zone, and notably ameliorated neurological function. These results indicate that recombinant human granulocyte colony-stimulating factor has anti-apoptotic effects on neurons following focal cerebral ischemia/reperfusion injury, and exerts neuroprotective effects.

Refolding with Simultaneous Purification of Recombinant Human Granulocyte Colony-stimulating Factor from Escherichia coli Using Strong Anion Exchange Chromatography

The urea denatured recombinant human granulocyte colony-stimulating factor (rhG- CSF) which was expressed in Escheriachia coli (E. coli) was refolded with simultaneous purification by strong anion exchange chromatography (SAX) in the presence of low concentration- of urea. The effect of urea concentration on this refolding process was investigated. The obtained refolded rhG-CSF has a high specific activity of 2.3×108 U/mg, demonstrating that the proteins were completely refolded during the chromatographic process. With only one step by SAX in 40 min, purity and mass recovery of the refolded and purified rhG-CSF were 97% and 43%, respectively.

A New Protocol for Solubilization, Refolding and Purification of Recombinant Human Granulocyte Colony-stimulating Factor in Inclusion Bodies

Recombinant human granulocyte colony-stimulating factor （rhG-CSF） in inclusion bodies was solubilized by 8 mol/L urea solution and subsequently precipitated by acetone to improve its purity. After that, the precipitates were solubilized by sodium hydroxide solution containing 2 mol/L urea. Then the solubilized rhG-CSF was passed through a size exclusion chromatography for refolding and extensive purification, and further purified by a weak anion exchange chromatography. The purity and mass recovery of refolded rhG-CSF were 96.5% and 75.6%, respectively. The bioactivity was 8.4x10^7 IU/mg.

Aetiology of Tick-Borne Infections in an Adult Swedish Population—Are Co-Infections with Multiple Agents Common?

In Scandinavia, tick-borne infections affecting humans include Lyme borreliosis (LB), tick-borne encephalitis (TBE) and human granulocytic anaplasmosis (HGA). Each of these infections can present with unspecific symptoms. In this prospective clinical study, we recruited patients based on two independent inclusion criteria;1) patients with unspecific symptoms, i.e. fever (≥38.0℃) or a history of feverishness and/or any combination of headache, myalgia or arthralgia and 2) patients with erythema migrans (EM), following an observed tick bite or tick exposure within one month prior to onset of symptoms. A total of 206 patients fulfilled the study. Among these, we could identify 186 cases of LB (174 with EM), 18 confirmed and two probable cases of HGA and two cases of TBE. Thirteen of the HGA cases presented without fever. Furthermore, 22 of the EM patients had a sub-clinical co-infection with Anaplasma phagocytophilum, based on serology. Both TBE cases had co-infections, one with Borrelia burgdorferi and one with Anaplasma phagocytophilum. We conclude that it is important to consider several causative agents and possible co-infections in the clinical management of infectious diseases where ticks may be suspected as vectors.

A retrospective study of pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) in preventing neutropenia during definitive concurrent chemoradiotherapy in patients with esophageal squamous carcinoma

Objective:To compare the efficacy and safety of pegylated recombinant human granulocyte colony-stimulating factor(PEG-rhG-CSF)for preventive or delayed treatment in neutropenia,completion rate of concurrent chemoradiotherapy and hospitalization rate in patients with esophageal squamous carcinoma during definitive concurrent chemoradiotherapy.Methods:A total of 70 patients with esophageal squamous carcinoma in Peking University Cancer Hospital from January 2019 to December 2020,who received PEG-rhG-CSF during concurrent chemoradiotherapy,were enrolled in this retrospective analysis.There were 32 patients in the preventive group,and 38 patients in the delayed group.The incidence of neutropenia,completion rate of concurrent chemoradiotherapy and neutropeniarelated hospitalization rate were compared between PEG-rhG-CSF preventive group and delayed group.Results:The incidence of severe neutropenia(Grades 3–4)in all patients was 31.4%.Comparison between preventive group and delayed group showed that the incidence of severe neutropenia was 6.3%and 39.4%(χ^(2)=10.428,P=0.001),respectively.In preventive group,the incidence of severe neutropenia was 3.7%and 20.0%,respectively,for primary prevention and secondary prevention of PEG-rhG-CSF(χ^(2)=12.321,P=0.001).The completion rate of concurrent chemoradiotherapy was 93.8%in the preventive group and 63.2%in the delayed group(χ^(2)=9.220,P=0.002).The incidence of treatment interruption was 25.7%in the whole group,12.5%in the preventive group and 36.8%in the delayed group(χ^(2)=5.389,P=0.020).Seven patients(7/70,10.0%)were hospitalized and treated with intravenous antibiotics for neutropenia,including 1 in the preventive group and 6 in the delayed group(P=0.078).Conclusions:Prophylactic use of PEG-rhG-CSF during concurrent chemoradiotherapy for patients with esophageal squamous carcinoma can effectively reduce the incidence of neutropenia,ensure the safety of treatment,and improve the completion rate of concurrent chemoradiotherapy.

APPLICATION OF RECOMBINANT HUMAN GRANULOCYTE COLONY-STIMULATING FACTOR (FILGRASTIM) FOLLOWING ALLOGENEIC BONE MARROW TRANSPLANTATION

The effect of rhG-CSF (Filgrastim by Amgen Co.as Neupogen and Kirin Co.as Gran) was evaluated in 20 patients with leukemia after allogeneic