Zhiyi Liu

The "hotness" or "coldness" of the tumors are determined by the information of the cancer cells themselves, tumor immune characteristics, tumor microenvironment, and signaling mechanisms, which are key factors affecting cancer patients' clinical efficacy. The switch mechanism of "hotness" and "coldness" and its corresponding pathological characteristics and treatment strategies are the frontier and hot spot of tumor treatment. How to distinguish the "hotness" or "coldness" effectively and clarify the causes, microenvironment state, and characteristics are very important for the tumor response and efficacy treatments. Starting from the concept of hot and cold tumor, this review systematically summarized the molecular characteristics, influencing factors, and therapeutic strategies of "hot and cold tumors," and analyzed the immunophenotypes, the tumor microenvironment, the signaling pathways, and the molecular markers that contribute to "hot and cold tumors" in details. Different therapeutic strategies for "cold and hot tumors" based on clinical efficacy were analyzed with drug targets and proteins for "cold and hot tumors." Furthermore, this review combines the therapeutic strategies of different "hot and cold tumors" with traditional medicine and modern medicine, to provide a basis and guidance for clinical decision-making of cancer treatment.

Monitoring subcellular functional and structural changes associated with metabolism is essential for understanding healthy tissue development and the progression of numerous diseases, including cancer, diabetes, and cardiovascular and neurodegenerative disorders. Unfortunately, established methods for this purpose either are destructive or require the use of exogenous agents. Recent work has highlighted the potential of endogenous two-photon excited fluorescence (TPEF) as a method to monitor subtle metabolic changes; however, mechanistic understanding of the connections between the detected optical signal and the underlying metabolic pathways has been lacking. We present a quantitative approach to detecting both functional and structural metabolic biomarkers noninvasively, relying on endogenous TPEF from two coenzymes, NADH (reduced form of nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide). We perform multiparametric analysis of three optical biomarkers within intact, living cells and three-dimensional tissues: cellular redox state, NADH fluorescence lifetime, and mitochondrial clustering. We monitor the biomarkers in cells and tissues subjected to metabolic perturbations that trigger changes in distinct metabolic processes, including glycolysis and glutaminolysis, extrinsic and intrinsic mitochondrial uncoupling, and fatty acid oxidation and synthesis. We demonstrate that these optical biomarkers provide complementary insights into the underlying biological mechanisms. Thus, when used in combination, these biomarkers can serve as a valuable tool for sensitive, label-free identification of changes in specific metabolic pathways and characterization of the heterogeneity of the elicited responses with single-cell resolution.

Active changes in mitochondrial structure and organization facilitate cellular homeostasis. Because aberrant mitochondrial dynamics are implicated in a variety of human diseases, their assessment is potentially useful for diagnosis, therapy, and disease monitoring. Because current techniques for evaluating mitochondrial morphology are invasive or necessitate mitochondria-specific dyes, their clinical translation is limited. We report that mitochondrial dynamics can be monitored in vivo, within intact human skin by relying entirely on endogenous two-photon-excited fluorescence from the reduced metabolic coenzyme nicotinamide adenine dinucleotide (NADH). We established the sensitivity of this approach with in vivo, fast temporal studies of arterial occlusion-reperfusion, which revealed acute changes in the mitochondrial metabolism and dynamics of the lower human epidermal layers. In vitro hypoxic-reperfusion studies validated that the in vivo outcomes were a result of NADH fluorescence changes. To demonstrate the diagnostic potential of this approach, we evaluated healthy and cancerous human skin epithelia. Healthy tissues displayed consistent, depth-dependent morphological and mitochondrial organization patterns that varied with histological stratification and intraepithelial mitochondrial protein expression. In contrast, these consistent patterns were absent in cancerous skin lesions. We exploited these differences to successfully differentiate healthy from cancerous tissues using a predictive classification approach. Collectively, these results demonstrate that our label-free, automated, near real-time assessments of mitochondrial organization-relying solely on endogenous contrast-could be useful for accurate, noninvasive in vivo diagnosis.

Mitochondrial DNA (MT-DNA) are intrinsically inflammatory nucleic acids released by damaged solid organs. Whether the appearance of cell-free MT-DNA is linked to poor COVID-19 outcomes remains undetermined. Here, we quantified circulating MT-DNA in prospectively collected, cell-free plasma samples from 97 subjects with COVID-19 at the time of hospital presentation. Circulating MT-DNA were sharply elevated in patients who eventually died, required ICU admission or intubation. Multivariate regression analysis revealed that high circulating MT-DNA levels is an independent risk factor for all of these outcomes after adjusting for age, sex and comorbidities. Additionally, we found that circulating MT-DNA has a similar or superior area-under-the curve when compared to clinically established measures of systemic inflammation, as well as emerging markers currently of interest as investigational targets for COVID-19 therapy. These results show that high circulating MT-DNA levels is a potential indicator for poor COVID-19 outcomes.