Quantitative assessment of burst suppression as a predictor of seizure recurrence in refractory status epilepticus.

OBJECTIVE: To determine whether quantitative EEG analysis of burst suppression can predict seizure recurrence in patients with refractory status epilepticus (RSE) being treated with anesthetic doses of continuous IV antiseizure medications (cIVASM). METHODS: Quantitative assessment of burst suppression (including epileptiform discharges [EDs] and evolution) in 31 occasions (from 27 patients), and correlation with seizure recurrence up to 48 hours post sedative wean. RESULTS: Occasions resulting in seizure recurrence (vs. no seizure recurrence) had lower burst (8.4 vs. 10.6 µV) and interburst interval (IBI) (4.2 vs. 4.8 µV) average amplitude, duration (bursts 2.8 vs. 3.6 s: IBIs 3.6 vs. 4.4 s); and burst total power (0.4 vs. 0.7 µV2). Bursts (0.86 vs. 0.60) and IBIs (0.28 vs. 0.07) with EDs, higher number of EDs within bursts (mean 2.1 vs. 1.4) and IBIs (0.6 vs. 0.2), and positive evolution measures all predicted seizure recurrence, although EDs had the greatest adjusted odds ratio on multivariate analysis. CONCLUSIONS: For patients in burst suppression, successful wean of cIVASM was not determined by classical burst suppression measures, but instead how "epileptiform" bursts and IBIs were, as determined by EDs in both bursts and IBIs and surrogates for evolution within bursts. SIGNIFICANCE: If confirmed, these objective measures could be used during clinical care to help determine when to wean cIVASM in patients with RSE.

Chemokines expressed by engineered bacteria recruit and orchestrate antitumor immunity.

Tumors use multiple mechanisms to actively exclude immune cells involved in antitumor immunity. Strategies to overcome these exclusion signals remain limited due to an inability to target therapeutics specifically to the tumor. Synthetic biology enables engineering of cells and microbes for tumor-localized delivery of therapeutic candidates previously unavailable using conventional systemic administration techniques. Here, we engineer bacteria to intratumorally release chemokines to attract adaptive immune cells into the tumor environment. Bacteria expressing an activating mutant of the human chemokine CXCL16 (hCXCL16K42A) offer therapeutic benefit in multiple mouse tumor models, an effect mediated via recruitment of CD8+ T cells. Furthermore, we target the presentation of tumor-derived antigens by dendritic cells, using a second engineered bacterial strain expressing CCL20. This led to type 1 conventional dendritic cell recruitment and synergized with hCXCL16K42A-induced T cell recruitment to provide additional therapeutic benefit. In summary, we engineer bacteria to recruit and activate innate and adaptive antitumor immune responses, offering a new cancer immunotherapy strategy.

A programmable encapsulation system improves delivery of therapeutic bacteria in mice.

Living bacteria therapies have been proposed as an alternative approach to treating a broad array of cancers. In this study, we developed a genetically encoded microbial encapsulation system with tunable and dynamic expression of surface capsular polysaccharides that enhances systemic delivery. Based on a small RNA screen of capsular biosynthesis pathways, we constructed inducible synthetic gene circuits that regulate bacterial encapsulation in Escherichia coli Nissle 1917. These bacteria are capable of temporarily evading immune attack, whereas subsequent loss of encapsulation results in effective clearance in vivo. This dynamic delivery strategy enabled a ten-fold increase in maximum tolerated dose of bacteria and improved anti-tumor efficacy in murine models of cancer. Furthermore, in situ encapsulation increased the fraction of microbial translocation among mouse tumors, leading to efficacy in distal tumors. The programmable encapsulation system promises to enhance the therapeutic utility of living engineered bacteria for cancer.

Enhancing the tropism of bacteria via genetically programmed biosensors.

Engineered bacteria for therapeutic applications would benefit from control mechanisms that confine the growth of the bacteria within specific tissues or regions in the body. Here we show that the tropism of engineered bacteria can be enhanced by coupling bacterial growth with genetic circuits that sense oxygen, pH or lactate through the control of the expression of essential genes. Bacteria that were engineered with pH or oxygen sensors showed preferential growth in physiologically relevant acidic or oxygen conditions, and reduced growth outside the permissive environments when orally delivered to mice. In syngeneic mice bearing subcutaneous tumours, bacteria engineered with both hypoxia and lactate biosensors coupled through an AND gate showed increased tumour specificity. The multiplexing of genetic circuits may be more broadly applicable for enhancing the localization of bacteria to specified niches.