Kidney cancer poses unique clinical challenges because of its resistance to conventional treatments and its tendency to metastasize. The kidney is particularly susceptible to dysfunction of the complement system, an immune network that tumors often exploit. Recent discoveries have highlighted that the complement system not only plays a crucial role in immune surveillance and defense in the circulatory system, but also functions intracellularly and autonomously. This concept has shifted the focus of investigation toward understanding how complement proteins influence cancer progression by regulating the tumor microenvironment (TME), cell signaling, proliferation, metabolism, and the immune response. With the complement system and its inhibitors emerging as a promising new class of immunotherapeutics and potential complement-targeted treatments advancing through development pipelines and clinical trials, this Review provides a timely examination of how harnessing the complement system could lead to effective tumor treatments and how to strategically combine complement inhibitors with other cancer treatments, offering renewed hope in the fight against kidney cancer.
Ravikumar Aalinkeel, Richard J. Quigg, Jessy Alexander
Type 2 (Th2) allergic diseases are chronic conditions characterized by a Th2-polarized immune response to allergens. These diseases can be categorized by affected barrier sites: skin (atopic dermatitis, allergic contact dermatitis), gut (food allergy), and respiratory tract (e.g., asthma, chronic rhinosinusitis). The global prevalence of Th2 allergic diseases has increased the need for a deeper understanding of their pathophysiology. Several associations have been identified between genetic variants in the genes encoding components of the complement system and allergic disease. Moreover, levels of several complement proteins are elevated in patients with allergy. Experimental evidence demonstrates that the complement system plays a critical role in the development of these diseases across barrier sites. While site-specific differences exist in the complement components involved, key pathways, particularly C3 and C5, are prominent across the skin, gut, and lung.
Sarah A. Thomas, Stephane Lajoie
Reduced kidney function is associated with increased risk of cardiovascular disease in addition to kidney disease progression. Kidney disease is considered an inflammatory state, based on elevated levels of C-reactive protein and inflammatory cytokines. A key mediator of cardiovascular and kidney disease progression in the setting of reduced kidney function is systemic and vascular inflammation. However, the exact pathways that link chronic kidney disease (CKD) with inflammation remain incompletely understood. For decades it has been known that factor D, the main activator of the alternative complement pathway, is increased in the plasma of patients with reduced kidney function. Recent biomarker evidence suggests alternative pathway activation in this setting. CKD, therefore, seems to alter the balance of alternative pathway proteins, promoting inflammation and potentially exacerbating complement-mediated diseases and CKD-associated complications. In this manuscript, we review the impact of reduced kidney function on biomarkers of the alternative complement pathway and the implications of alternative pathway activation on cardiovascular disease and kidney disease progression. Importantly, we highlight the need for ongoing research efforts that may lead to opportunities to target the alternative pathway of complement withx the goal of improving kidney and cardiovascular outcomes in persons with reduced kidney function.
Diana I. Jalal, Joshua M. Thurman, Richard J.H. Smith
Initially identified as a regulator of complement activation on host cells, the known roles of CD46 (membrane cofactor protein [MCP]) have expanded. We now know that this ancient molecule is expressed on almost all nucleated cells as a family of four predominant isoforms. It also is involved in human reproduction, modulation of T cell activation and immunoinflammatory effector functions, autophagy, and the newly identified intracellular complement system (complosome). CD46 is also known as a “pathogen” magnet, being a port of entry for at least seven bacteria and five viruses. Moreover, CD46 has recently emerged as a key player in cancer biology. Numerous studies provide evidence of the association among elevated CD46 expression, malignant transformation, and metastasizing potential. These features, along with its roles as pathogen receptor, have made CD46 a target for cancer therapeutics. Thus, modified viral vectors (such as strains of adenovirus and measles virus) targeting CD46 currently are being exploited against a wide range of cancers. Another oncologic treatment utilizes a CD46-targeting human mAb as an antibody-drug conjugate. Herein, we review CD46 and its “multiverse” of cancer interactions.
M. Kathryn Liszewski, John P. Atkinson
HNSCC remains a substantial health issue, with treatment options including surgery, radiation, and platinum-based chemotherapy. Unfortunately, despite progress in research, only modest gains have been made in disease control, with existing treatments resulting in significant functional and quality-of-life issues. The introduction of immunotherapy in the treatment of HNSCC has resulted in some improvements in outlook for patients and is now standard of care for populations with both recurrent and metastatic disease. However, despite the early successes, responses to immune checkpoint inhibition (ICI) remain modest to low, approaching 14%–22% objective response rates. Challenges to the effectiveness of ICI and other immunotherapies are complex, including the diverse and dynamic molecular plasticity and heterogeneity of HNSCCs; lack of immunogenic antigens; accumulated suppressive immune populations such as myeloid cells and dysfunctional T cells; nutrient depletion; and metabolic dysregulation in the HNSCC tumor microenvironment. In this Review, we explore the mechanisms responsible for immunotherapy resistance, dissect these challenges, and discuss potential opportunities for overcoming hurdles to the development of successful immunotherapy for HNSCC.
Xia Liu, R. Alex Harbison, Mark A. Varvares, Sidharth V. Puram, Guangyong Peng
Metabolic dysfunction–associated steatotic liver disease (MASLD) is characterized by increased hepatic steatosis with cardiometabolic disease and is a leading cause of advanced liver disease. We review here the genetic basis of MASLD. The genetic variants most consistently associated with hepatic steatosis implicate genes involved in lipoprotein input or output, glucose metabolism, adiposity/fat distribution, insulin resistance, or mitochondrial/ER biology. The distinct mechanisms by which these variants promote hepatic steatosis result in distinct effects on cardiometabolic disease that may be best suited to precision medicine. Recent work on gene-environment interactions has shown that genetic risk is not fixed and may be exacerbated or attenuated by modifiable (diet, exercise, alcohol intake) and nonmodifiable environmental risk factors. Some steatosis-associated variants, notably those in patatin-like phospholipase domain-containing 3 (PNPLA3) and transmembrane 6 superfamily member 2 (TM6SF2), are associated with risk of developing adverse liver-related outcomes and provide information beyond clinical risk stratification tools, especially in individuals at intermediate to high risk for disease. Future work to better characterize disease heterogeneity by combining genetics with clinical risk factors to holistically predict risk and develop therapies based on genetic risk is required.
Vincent L. Chen, Annapurna Kuppa, Antonino Oliveri, Yanhua Chen, Prabhu Ponnandy, Puja B. Patel, Nicholette D. Palmer, Elizabeth K. Speliotes
Metabolic dysfunction–associated steatotic liver disease (MASLD) is a major cause of liver disease worldwide, and our understanding of its pathogenesis continues to evolve. MASLD progresses from steatosis to steatohepatitis, fibrosis, and cirrhosis, and this Review explores how the gut microbiome and their metabolites contribute to MASLD pathogenesis. We explore the complexity and importance of the intestinal barrier function and how disruptions of the intestinal barrier and dysbiosis work in concert to promote the onset and progression of MASLD. The Review focuses on specific bacterial, viral, and fungal communities that impact the trajectory of MASLD and how specific metabolites (including ethanol, bile acids, short chain fatty acids, and other metabolites) contribute to disease pathogenesis. Finally, we underscore how knowledge of the interaction between gut microbes and the intestinal barrier may be leveraged for MASLD microbial-based therapeutics. Here, we include a discussion of the therapeutic potential of prebiotics, probiotics, postbiotics, and microbial-derived metabolites.
Bernd Schnabl, Christopher J. Damman, Rotonya M. Carr
Anomalies during angiogenesis can initiate the formation of arteriovenous malformations (AVMs), characterized by aberrant connections between arteries and veins and fast lesional blood flow. These anomalies can manifest anywhere in the body, including the brain, and they typically appear at birth and evolve alongside growth of the individual. Depending on their location and size, AVMs can induce progressive deformation, chronic pain, functional impairment, and ulceration and pose life-threatening risks such as hemorrhage and organ dysfunction. The primary treatment modalities entail surgical intervention or embolization followed by surgery. However, these approaches are often challenging and seldom offer definitive resolution. In addition, inadequately performed surgery may trigger angiogenic rebound, fostering AVM recurrence. Advancements in comprehending the molecular pathways underlying AVMs have sparked interest in repurposing targeted therapies initially devised for cancer treatment. The first results are promising, giving new hope to the patients affected with these often devastating and debilitating lesions, the management of which presents major clinical challenges.
Julien Coulie, Emmanuel Seront, Miikka Vikkula, Laurence M. Boon
Acute kidney injury (AKI) encompasses pathophysiology ranging from glomerular hypofiltration to tubular cell injury and outflow obstruction. This Review will focus on the tubulointerstitial processes that underlie most cases of AKI. Tubular epithelial cell (TEC) injury can occur via distinct insults, including ischemia, nephrotoxins, sepsis, and primary immune-mediated processes. Following these initial insults, tubular cells can activate survival and repair responses or they can develop mitochondrial dysfunction and metabolic reprogramming, cell-cycle arrest, and programmed cell death. Developing evidence suggests that the fate of individual tubular cells to survive and proliferate or undergo cell death or senescence is frequently determined by a biphasic immune response with initial proinflammatory macrophage, neutrophil, and lymphocyte infiltration exacerbating injury and activating programmed cell death, while alternatively activated macrophages and specific lymphocyte subsets subsequently modulate inflammation and promote repair. Functional recovery requires that this reparative phase supports proteolytic degradation of tubular casts, proliferation of surviving TECs, and restoration of TEC differentiation. Incomplete resolution or persistence of inflammation can lead to failed tubular repair, fibrosis, and chronic kidney disease. Despite extensive research in animal models, translating preclinical findings to therapies remains challenging, emphasizing the need for integrated multiomic approaches to advance AKI understanding and treatment.
Megan L. Baker, Lloyd G. Cantley
In mammalian cells cholesterol can be synthesized endogenously or obtained exogenously through lipoprotein uptake. Plasma membrane (PM) is the primary intracellular destination for both sources of cholesterol, and maintaining appropriate membrane cholesterol levels is critical for cellular viability. The endoplasmic reticulum (ER) acts as a cellular cholesterol sensor, regulating synthesis in response to cellular needs and determining the metabolic fates of cholesterol. Upon reaching the ER, cholesterol can be esterified to facilitate its incorporation into lipoproteins and lipid droplets or converted into other molecules such as bile acids and oxysterols. In recent years, it has become clear that the intracellular redistribution of lipids, including cholesterol, is critical for the regulation of various biological processes. This Review highlights physiology and mechanisms of nonvesicular (protein-mediated) intracellular cholesterol trafficking, with a focus on the role of Aster proteins in PM to ER cholesterol transport.
Alessandra Ferrari, Peter Tontonoz
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