Stroke is one of the leading causes of death and disability. Despite the high prevalence of stroke, characterizing the acute neural recovery patterns that follow stroke and predicting long-term recovery remains challenging. Objective methods to quantify and characterize neural injury are still lacking. Since neuroimaging methods have a poor temporal resolution, EEG has been used as a method for characterizing post-stroke recovery mechanisms for various deficits including motor, language, and cognition as well as predicting treatment response to experimental therapies. In addition, transcranial magnetic stimulation (TMS), a form of non-invasive brain stimulation, has been used in conjunction with EEG (TMS-EEG) to evaluate neurophysiology for a variety of indications. TMS-EEG has significant potential for exploring brain connectivity using focal TMS-evoked potentials and oscillations, which may allow for the system-specific delineation of recovery patterns after stroke. In this review, we summarize the use of EEG alone or in combination with TMS in post-stroke motor, language, cognition, and functional/global recovery. Overall, stroke leads to a reduction in higher frequency activity (≥8 Hz) and intra-hemispheric connectivity in the lesioned hemisphere, which creates an activity imbalance between non-lesioned and lesioned hemispheres. Compensatory activity in the non-lesioned hemisphere leads mostly to unfavorable outcomes and further aggravated interhemispheric imbalance. Balanced interhemispheric activity with increased intrahemispheric coherence in the lesioned networks correlates with improved post-stroke recovery. TMS-EEG studies reveal the clinical importance of cortical reactivity and functional connectivity within the sensorimotor cortex for motor recovery after stroke. Although post-stroke motor studies support the prognostic value of TMS-EEG, more studies are needed to determine its utility as a biomarker for recovery across domains including language, cognition, and hemispatial neglect. As a complement to MRI-based technologies, EEG-based technologies are accessible and valuable non-invasive clinical tools in stroke neurology.

Background/Aims: Liver injury and the Unfolded Protein Response (UPR) are tightly linked, but their relationship differs with cell-type and injurious stimuli. UPR initiation promotes hepatic stellate cell (HSC) activation and fibrogenesis, but the underlying mechanisms are unclear. Despite the complexity and overlap downstream of UPR transducers IRE1α, ATF6α, and PERK, previous research in HSCs primarily focused on IRE1α. Here, we interrogated the fibrogenic role of ATF6α or PERK in vitro and HSC-specific UPR signaling in vivo. Methods/Results: Overexpression of ATF6α, but not the PERK effector ATF4, promoted HSC activation and fibrogenic gene transcription in immortalized HSCs. Furthermore, ATF6α inhibition through Ceapin-A7, or Atf6a deletion, disrupted TGFβ-mediated activation of primary hHSCs or mHSCs respectively. We interrogated the fibrogenic role of ATF6α in vivo through conditional HSC-specific Atf6a deletion. Atf6aHSCΔ/Δ mice displayed reduced fibrosis and HSC activation following bile-duct ligation (BDL) or CCl4-induced injury. The Atf6aHSCΔ/Δ phenotype differed from HSC-specific Ire1a deletion, as Ire1aHSCΔ/Δ mice showed reduced fibrogenic gene transcription no changes in fibrosis compared to Ire1afl/fl mice following BDL. Interestingly, ATF6α signaling increased in Ire1aΔ/Δ HSCs, while IRE1α signaling was upregulated in Atf6aΔ/Δ HSCs. Finally, we asked whether co-deletion of Arf6a and Ire1a additively limits fibrosis. Unexpectedly, fibrosis worsened in Atf6aHSCΔ/ΔIre1aHSCΔ/Δ mice following BDL, and Atf6aΔ/ΔIre1aΔ/Δ mHSCs showed increased fibrogenic gene transcription. Conclusions: ATF6α and IRE1α individually promote fibrogenic transcription in HSCs and ATF6α drives fibrogenesis in vivo. Unexpectedly, disruption of both pathways sensitizes the liver to fibrogenesis, suggesting that fine-tuned UPR signaling is critical for regulating HSC activation and fibrogenesis.

Hepatic fibrosis is driven by deposition of matrix proteins following liver injury. Hepatic stellate cells (HSCs) drive fibrogenesis, producing matrix proteins, including procollagen I, which matures into collagen I following secretion. Disrupting intracellular procollagen processing and trafficking causes endoplasmic reticulum stress and stress-induced HSC apoptosis and thus is an attractive antifibrotic strategy. We designed an immunofluorescence-based small interfering RNA (siRNA) screen to identify procollagen I trafficking regulators, hypothesizing that these proteins could serve as antifibrotic targets. A targeted siRNA screen was performed using immunofluorescence to detect changes in intracellular procollagen I. Tumor necrosis factor receptor associated factor 2 and noncatalytic region of tyrosine kinase-interacting kinase (TNIK) was identified and interrogated in vitro and in vivo using the TNIK kinase inhibitor NCB-0846 or RNA interference-mediated knockdown. Our siRNA screen identified nine genes whose knockdown promoted procollagen I retention, including the serine/threonine kinase TNIK. Genetic deletion or pharmacologic inhibition of TNIK through the small molecule inhibitor NCB-0846 disrupted procollagen I trafficking and secretion without impacting procollagen I expression. To investigate the role of TNIK in liver fibrogenesis, we analyzed human and murine livers, finding elevated TNIK expression in human cirrhotic livers and increased TNIK expression and kinase activity in both fibrotic mouse livers and activated primary human HSCs. Finally, we tested whether inhibition of TNIK kinase activity could limit fibrogenesis in vivo. Mice receiving NCB-0846 displayed reduced CCl 4 -induced fibrogenesis compared to CCl 4 alone, although α-smooth muscle actin levels were unaltered. Conclusions: Our siRNA screen effectively identified TNIK as a key kinase involved in procollagen I trafficking in vitro and hepatic fibrogenesis in vivo. (Hepatology Communications 2022;6:593-609).

The EXPLORE cohort is a multinational, prospective cohort of acute hepatic porphyria used to examine disease activity and clinical management in patients who experience recurrent attacks. Gouya et al. report on 112 patients enrolled over 2 years who were followed for at least 6 months, of whom 98 (88%) experienced a total of 483 attacks, 86 of which required treatment and/or hemin administration. By month 12 of the study, it was found that enrolled subjects spent an average of 5 nights in the hospital along with an average of 3.6 visits to the emergency department, had diminished quality of life, and 68% had decreased full-time employment. These findings indicate the need for improved therapies that can both reduce and lessen the severity of acute attacks. (Hepat ology 2020;71:1546-1558).