Comprehensive evaluation of recombinant lactate dehydrogenase production from inclusion bodies

The dual effects of propofol down-regulating PD-L1 expression and inhibiting autophagy to reduce cerebral ischemia reperfusion injury

Propofol, an anesthetic, has shown neuroprotective effects in animal and cellular models of cerebral ischemia-reperfusion (I/R) injury, likely by suppressing I/R-induced excessive autophagy. PD-L1 and immune escape are implicated in experimental stroke outcomes, but their mechanisms remain unclear. Here, we demonstrate that oxygen-glucose deprivation/reoxygenation (OGD/R) in astrocytes upregulates PD-L1 expression and autophagy, effects that are attenuated by propofol treatment via the NF-κB pathway. In vivo, propofol protects mice from I/R injury by downregulating PD-L1, inflammatory factors, and autophagy. Clinically, craniotomy patients receiving propofol exhibited higher CD3+ and CD4+ T lymphocyte percentages and lower PD-L1 and inflammatory factor levels. Our findings elucidate propofol's dual role in downregulating PD-L1 and inhibiting autophagy in cerebral I/R injury, suggesting its potential as a novel therapeutic strategy to mitigate inflammation and immune dysregulation.

Online monitoring of protein refolding in inclusion body processing using intrinsic fluorescence

Inclusion bodies (IBs) are protein aggregates formed as a result of overexpression of recombinant protein in E. coli. The formation of IBs is a valuable strategy of recombinant protein production despite the need for additional processing steps, i.e., isolation, solubilization and refolding. Industrial process development of protein refolding is a labor-intensive task based largely on empirical approaches rather than knowledge-driven strategies. A prerequisite for knowledge-driven process development is a reliable monitoring strategy. This work explores the potential of intrinsic tryptophan and tyrosine fluorescence for real-time and in situ monitoring of protein refolding. In contrast to commonly established process analytical technology (PAT), this technique showed high sensitivity with reproducible measurements for protein concentrations down to 0.01 g L- 1 . The change of protein conformation during refolding is reflected as a shift in the position of the maxima of the tryptophan and tyrosine fluorescence spectra as well as change in the signal intensity. The shift in the peak position, expressed as average emission wavelength of a spectrum, was correlated to the amount of folding intermediates whereas the intensity integral correlates to the extent of aggregation. These correlations were implemented as an observation function into a mechanistic model. The versatility and transferability of the technique were demonstrated on the refolding of three different proteins with varying structural complexity. The technique was also successfully applied to detect the effect of additives and process mode on the refolding process efficiency. Thus, the methodology presented poses a generic and reliable PAT tool enabling real-time process monitoring of protein refolding.