Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder characterized by reduced circulating levels and/or impaired function of alpha-1 antitrypsin (AAT), a key serine protease inhibitor, in which loss of effective antiprotease protection results in unchecked neutrophil elastase activity and progressive lung tissue destruction. Although AATD accounts for approximately 1% of chronic obstructive pulmonary disease (COPD) cases and up to 2% of emphysema, AATD-related COPD remains largely underdiagnosed, despite guideline recommendations for systematic evaluation in patients with COPD, particularly in high-risk clinical settings. Pathologically, AATD-related COPD is not limited to the typical early-onset, lower-lobe-predominant emphysema, also including upper-lobe or mixed emphysema patterns, airway-predominant disease, small airways dysfunction, and bronchiectasis. Clinically, AATD-related COPD is distinguished from smoking-related COPD by its earlier onset, physiological impairment that is often disproportionate to smoking exposure, and its potential presence of certain extrapulmonary manifestations. Diagnosis and monitoring are also challenged by the frequent discordance between airflow limitation and gas transfer impairment, as well as the early involvement of small airways, limiting reliance on spirometry alone. A multimodal assessment incorporating more sensitive functional techniques and CT densitometry may provide a more precise evaluation of disease burden, progression, and prognosis. Management generally follows standard COPD principles, with intravenous AAT augmentation therapy remaining currently the only established disease-modifying therapy for selected patients with severe deficiency. The advent of new pharmacological and gene-based therapies emphasizes the importance of developing personalized management strategies that integrate genotype and longitudinal disease behavior. This narrative review summarizes current evidence on AATD-associated COPD, focusing on its genetic basis and pathophysiological features, clinical and functional heterogeneity, current and emerging diagnostic and monitoring approaches, and disease-specific management considerations.

Background/Objectives: Determining the cardiovascular cause of death, particularly distinguishing ischemic from congestive mechanisms, remains challenging in forensic practice, especially in early ischemia without definitive histological findings. Proteomic techniques and molecular profiling may provide complementary diagnostic information beyond conventional autopsy. Methods: We applied an untargeted high-resolution proteomic approach to postmortem cardiac tissue samples from cardiovascular (ischemic and congestive) and non-cardiovascular deaths. Identified proteins were analyzed using bioinformatic and differential expression workflows. Selected candidates were evaluated in peripheral blood samples for translational validation using statistical modeling, including regression analyses and receiver operating characteristic (ROC) curve assessment. Results: A total of 572 proteins were identified. Although no proteins fulfilled strict exclusivity criteria for a single cause-of-death group, differential expression analysis revealed distinct molecular patterns distinguishing ischemic, congestive, and non-cardiovascular deaths. Thirty-one proteins were differentially expressed between ischemic and congestive cases, including α-1 antitrypsin (AAT), plasma levels did not demonstrate statistically significant discrimination. In contrast, plasma Apolipoprotein A-IV (ApoA-IV) levels were significantly associated with ischemic death in regression models, and ROC analysis yielded a cutoff point with complete separation between ischemic and selected non-cardiovascular cases. However, the limited sample size warrants cautious interpretation due to potential overfitting. Conclusions: Postmortem cardiac proteomic profiling reveals biologically coherent molecular signatures associated with different cardiovascular causes of death. Although further validation in larger independent cohorts is required, ApoA-IV emerges as a promising candidate biomarker for ischemic cardiac death. Multimarker proteomic strategies may complement traditional autopsy to enhance diagnostic accuracy in forensic investigations, particularly in cases with equivocal morphological findings.

Alpha-1 antitrypsin deficiency (AATD) is an inherited disorder characterized by intracellular retention of mutant Z (Pi*Z) alpha-1 antitrypsin (AAT) within hepatocytes, resulting in progressive liver disease. Currently, no approved pharmacological therapies exist for AATD-associated hepatic injury. Emerging preclinical evidence indicates that inhibition of mammalian target of rapamycin (mTOR) ameliorates liver pathology in AATD; however, the status of mTOR activity and its regulatory mechanisms under Pi*Z AAT-induced cellular stress remains incompletely understood. In this study, we investigated alterations in mTOR signaling and its upstream regulatory pathways using a gene-edited human hepatocyte model harboring the Pi*Z mutation (Huh7.5Z cells) and a Pi*Z AAT transgenic mouse model. Attenuation of mTORC1 activity was observed in both cellular and murine Pi*Z models. In vitro analyses demonstrated activation of AMP-activated protein kinase (AMPKα), a key inhibitory regulator of mTORC1, accompanied by paradoxical activation of Akt and the unfolded protein response (UPR) branch ATF6α. Pharmacological inhibition of mTOR significantly reduced intracellular Pi*Z AAT accumulation, alleviated ER stress, and suppressed apoptotic signaling through enhancement of autophagy. These findings reveal that hepatocytes adapt to Pi*Z AAT-induced stress through coordinated regulation of mTOR by AMPK, Akt, and ATF6α pathways. This study provides mechanistic insight into metabolic and stress-response signaling in AATD and identifies mTOR modulation as a promising therapeutic strategy for AATD-associated liver disease.

In previous studies we have shown that accumulation of the polymerogenic variant ATZ that causes α1-antitrypsin deficiency (ATD) activates NFκB DNA binding. Here we discovered that this response, which we are naming the polymerized protein response (PPR), is characterized by NFκB p50 homodimers, distinct from the p50/p65 heterodimers in the canonical NFκB inflammatory response and the unfolded protein response (UPR). The PPR is also activated by other disease associated variants that polymerize in the ER whereas disease-associated variants that do not form polymers activate p50/p65 heterodimers and UPR. The PPR elicits a unique gene expression profile, including changes that stabilize p50 homodimers in cytoplasm and nucleus. The PPR is blocked by specific genetic substitutions within the luminal and cytosolic domains of Derlin-2 providing evidence that the ERAD retrotranslocation complex is a proximal transducer of this signaling mechanism. We hypothesize that the PPR is a proteostasis response pathway complementary to the UPR, designed to protect the cell from the specific proteotoxic effects of polymers that form aberrantly in the ER.

Impaired wound healing is a major cause of morbidity among patients with diabetes. Human α1-antitrypsin (hAAT) promotes the resolution of injured tissues. In hyperglycemic conditions, circulating hAAT is likely to undergo glycation, yet it is unknown whether its reparative properties are preserved. We hypothesized that clinical-grade hAAT treatment, but not deliberately glycated hAAT (gly-hAAT), would promote wound repair under hyperglycemic conditions. Mice were rendered hyperglycemic, excisional wounding was performed, and wounds were treated with topical albumin or hAAT every three days. The wound area was assessed, and samples were collected for histology and gene expression analysis. Gly-hAAT was generated from clinical-grade hAAT, after which in vitro RAW 264.7 macrophage responses and re-epithelialization of A549 cells were assessed. Gap closure was further assessed using sera from a human cohort (prospective samples from 10 patients with poorly controlled diabetes at Soroka University Medical Center, Beer-Sheva, Israel, 2018). Group comparisons were performed using one-way ANOVA with Tukey's post hoc test. hAAT accelerated in vivo wound closure and in vitro A549 cell gap closure, accompanied by an anti-inflammatory IL-1Ra/IL-1β gene expression profile. In contrast, gly-hAAT inhibited normoglycemic mouse wound closure, evoked an inflammatory response in macrophages, and interfered with A549 cell gap closure; concomitant hAAT treatment improved gap closure. Similarly, patient serum inhibited A549 gap closure, and concomitant hAAT treatment improved gap closure. Importantly, inferential statistical analysis was not performed on this outcome due to the small and heterogeneous human cohort. In conclusion, hAAT accelerated wound closure in hyperglycemic mice and in A549 cells, whereas gly-hAAT promoted inflammatory responses and impaired wound closure, a trend reversed by native hAAT. These findings support the concept that glycation undermines the beneficial functions of circulating hAAT and provides a mechanistic insight into the pathophysiology of diabetic wound healing. Further studies are warranted to evaluate clinical-grade hAAT as a potential therapeutic for hyperglycemia-associated impaired wound healing.

Ferroptosis is a critical contributor to various cardiomyopathies; however, broad-spectrum endogenous inhibitors remain largely undefined. Although human alpha-1-antitrypsin (hAAT) exhibits cytoprotective properties, its involvement in cardiac ferroptosis remains unexplored. To directly assess endogenous hAAT function in vivo, we generated CRISPR/Cas9-mediated humanized knock-in mouse models expressing either functional (SERPINA1[WT]) or loss-of-function (SERPINA1[Q129⁎]) hAAT, and subjected them to doxorubicin-induced cardiomyopathy and myocardial infarction. SERPINA1[WT] mice exhibited robust protection against cardiac dysfunction, fibrosis, and remodeling, whereas SERPINA1[Q129⁎] mice conferred no benefit, establishing that protection is strictly dependent on functional protein integrity. This protective effect was mediated through potent suppression of ferroptosis, as evidenced by reduced lipid peroxidation and iron accumulation. Mechanistically, endogenous hAAT activated the Nrf2 signaling pathway, upregulating key anti-ferroptotic effectors including GPX4, HO-1, and xCT; this protection was abolished by the Nrf2 inhibitor ML385. Our findings identify functional hAAT as a novel, broad-spectrum ferroptosis inhibitor operating through the Nrf2/GPX4 axis, highlighting its potential as a therapeutic target for diverse ferroptosis-driven cardiomyopathies.

Human induced pluripotent stem cells (hiPSCs) possess broad differentiation potential; however, efficient maturation into functional hepatocytes remains challenging, in part because conventional differentiation strategies rely on 2D culture or partially defined 3D systems that fail to recapitulate key developmental microenvironmental cues. Although 3D culture has been shown to promote hepatic specification and maturation, a fully defined platform that supports the entire differentiation process from hiPSCs in 3D has not been established. Here, we report a scalable synthetic peptide hydrogel (PepGel) platform that enables hiPSCs to self-organize into long-term, proliferative luminal cavity (LC) architectures within 3D colonies (LC-hiPSCs). These LC-hiPSCs exhibited markedly enhanced differentiation efficiency compared to hiPSC aggregates generated via scaffold-free suspension methods. Using a shear-thinning, self-healing hydrogel configuration optimized for suspension culture, we produced large quantities of LC-hiPSCs and directed their differentiation into PepGel-derived hiPSC-derived hepatocyte-like cells (PG-hiHs). PG-hiHs formed polarized, multi-luminal organoid-like structures and exhibited robust expression of hepatocyte-specific genes and proteins, high cytochrome P450 activity, and in vitro metabolic functions comparable to primary human hepatocytes (PHHs). Following live shipment and transplantation into immunocompromised mouse livers, PG-hiHs engrafted efficiently and maintained human-specific albumin and alpha-1 antitrypsin secretion at PHH-equivalent levels. Furthermore, both LC-hiPSCs and PG-hiHs retained viability, structural organization, and phenotype in complex 3D bioprinted constructs for at least 14 days. Together, this work establishes a fully defined, reproducible, and scalable 3D platform that supports the entire differentiation process, overcoming limitations in hiPSC-derived hepatic maturation and enables physiologically relevant hepatocyte-like tissues for disease modeling, regenerative medicine, and biofabrication.

Individuals homozygous for the SERPINA1 "Z" mutation with alpha-1 antitrypsin deficiency (AATD) are highly susceptible to emphysema. This predisposition has classically been attributed to a relative deficiency of circulating alpha-1 antitrypsin (AAT) reaching the lungs and associated protease-antiprotease imbalance. Accumulating evidence suggests that the presence of misfolded Z-AAT protein either in the circulation, the lung interstitium, or within resident lung cells could contribute to emphysema pathogenesis. We have shown that type 2 alveolar epithelial cells (AT2s), progenitor cells of the lung alveolus, heterogeneously retain Z-AAT and exhibit a transcriptional disease signature in AATD patient samples. However, a lack of model systems that faithfully recapitulate AT2 biology and associated Z-AAT expression has limited our ability to study this phenomenon. Here, we apply syngeneic induced pluripotent stem cell-derived AT2s (iAT2s) and a novel mouse model featuring AT2-specific inducible human SERPINA1 expression to interrogate the cell-instrinsic consequences of Z-AAT expression, validating findings in an independent dataset of human COPD lung tissue comparing ZZ to MM SERPINA1 genotypes. We find further evidence of Z-AAT retention within AT2s and identify shared AT2 transcriptomic disease signatures conserved across model systems, characterized by innate immune and inflammatory signaling, NF-κB activation, and endoplasmic reticulum stress. Mice with AT2-specific Z-AAT expression additionally demonstrate increased susceptibility to elastase-induced emphysema, providing functional evidence for AT2-intrinsic contributions to AATD-associated lung disease. Within iAT2s, a subpopulation of Z-AAT expressing cells exhibits activation of the PERK-eIF2α signaling axis and markers of an alveolar basal intermediate (ABI) state, emerging cell-autonomously in the absence of mesenchymal co-culture. Together, these data provide evidence that Z-AAT expression in AT2s induces heterogenous cell-intrinsic stress responses including proteotoxic stress, inflammatory signaling, and aberrant cell fate adoption, and is sufficient to result in predisposition to injury, supporting a potential contribution of AT2-intrinsic Z-AAT toxicity to human AATD-associated emphysema pathogenesis.