Thermal Injury Causes DNA Damage and Lethality in Unheated Surrounding Cells: Active Thermal Bystander Effect

Direct heat exposure to cells causes protein degradation and DNA damage, which can lead to genetic alteration and cell death, but little is known about heat-induced effects on the surrounding tissue. After burns or laser surgery, loss of viability in the surrounding tissue has been explained by a temperature gradient due to heat diffusion. This study shows that, in the absence of any direct heating, heat diffusion, or cell-to-cell contact, “bystander” cells that share the medium with heat-exposed cells exhibit DNA damage, apoptosis, and loss of viability. We coin this phenomenon “active thermal bystander effect” (ATBE). Significant ATBE was induced by fibroblasts exposed for 10minutes to a temperature range of 44–50°C (all P<0.011). The ATBE was not induced by cells heated to lethality above 54°C and immediate medium exchange did not suppress the effect. Therefore, the thermal bystander effect appears to be an active process in which viable, heat-injured cells induce a signal cascade and/or mediator that damages or kills surrounding bystander cells. The ATBE may have clinical relevance for acute burn trauma, hyperthermic treatments, and distant tissue damage after localized heat stress

Fractional laser exposure induces neutrophil infiltration (N1 phenotype) into the tumor and stimulates systemic anti-tumor immune response

Background: Ablative fractional photothermolysis (aFP) using a CO2 laser generates multiple small diameter tissue lesions within the irradiation field. aFP is commonly used for a wide variety of dermatological indications, including treatment of photodamaged skin and dyschromia, drug delivery and modification of scars due to acne, surgical procedures and burns. In this study we explore the utility of aFP for treating oncological indications, including induction of local tumor regression and inducing anti-tumor immunity, which is in marked contrast to current indications of aFP. Methodology/Principal findings We used a fractional CO2 laser to treat a tumor established by BALB/c colon carcinoma cell line (CT26.CL25), which expressed a tumor antigen, beta-galactosidase (beta-gal). aFP treated tumors grew significantly slower as compared to untreated controls. Complete remission after a single aFP treatment was observed in 47% of the mice. All survival mice from the tumor inoculation rejected re-inoculation of the CT26.CL25 colon carcinoma cells and moreover 80% of the survival mice rejected CT26 wild type colon carcinoma cells, which are parental cells of CT26.CL25 cells. Histologic section of the FP-treated tumors showed infiltrating neutrophil in the tumor early after aFP treatment. Flow cytometric analysis of tumor-infiltrating lymphocytes showed aFP treatment abrogated the increase in regulatory T lymphocyte (Treg), which suppresses anti-tumor immunity and elicited the expansion of epitope-specific CD8+ T lymphocytes, which were required to mediate the tumor-suppressing effect of aFP. Conclusion: We have demonstrated that aFP is able to induce a systemic anti-tumor adaptive immunity preventing tumor recurrence in a murine colon carcinoma in a mouse model. This study demonstrates a potential role of aFP treatments in oncology and further studies should be performed

Measuring Temperature Induced Phase Change Kinetics in Subcutaneous Adipose Tissues Using Near Infrared Spectroscopy, MR Imaging and Spectroscopy and OCT

Monitoring phase transition in adipose tissue and formation of lipid crystals is important in Cryo-procedures such as Selective Cryolipolysis (SC). We exploited a Near-Infrared Spectroscopy (NIRS) method to monitor the onset of fat phase transition (freezing/melting) in human abdominal adipose tissue. The changes in optical scattering were compared to Differential Scanning Calorimetry (DSC) measurements as the gold standard method for measuring phase transition. For some samples, concurrent in vitro measurements of optical scattering using NIRS and the MR signal parameters (T2*) as well as spectral parameters using MR Spectroscopy were performed in a 3 T MR scanner during a cooling/heating cycle. To further investigate phase-transition in adipose tissue in microscopic level, an identical cooling/heating procedure was replicated on a small piece of fat harvested from the same tissue while being imaged under Optical Coherence Tomography (OCT). For all methods, their relationship with temperature shows inflexions in a narrow range, characteristic of lipid phase transition. In particular, the good agreement between DSC and Optical measurements suggests that such NIRS methods can be used to improve dosimetry and to minimize variations of clinical outcome for cryo-procedures

Health Economic Consequences Associated With COVID-19–Related Delay in Melanoma Diagnosis in Europe

Importance: The COVID-19 pandemic resulted in delayed access to medical care. Restrictions to health care specialists, staff shortages, and fear of SARS-CoV-2 infection led to interruptions in routine care, such as early melanoma detection; however, premature mortality and economic burden associated with this postponement have not been studied yet. Objective: To determine the premature mortality and economic costs associated with suspended melanoma screenings during COVID-19 pandemic lockdowns by estimating the total burden of delayed melanoma diagnoses for Europe. Design, Setting, and Participants: This multicenter economic evaluation used population-based data from patients aged at least 18 years with invasive primary cutaneous melanomas stages I to IV according to the American Joint Committee on Cancer (AJCC) seventh and eighth editions, including melanomas of unknown primary (T0). Data were collected from January 2017 to December 2021 in Switzerland and from January 2019 to December 2021 in Hungary. Data were used to develop an estimation of melanoma upstaging rates in AJCC stages, which was verified with peripandemic data. Years of life lost (YLL) were calculated and were, together with cost data, used for financial estimations. The total financial burden was assessed through direct and indirect treatment costs. Models were building using data from 50 072 patients aged 18 years and older with invasive primary cutaneous melanomas stages I to IV according to the AJCC seventh and eighth edition, including melanomas of unknown primary (T0) from 2 European tertiary centers. Data from European cancer registries included patient-based direct and indirect cost data, country-level economic indicators, melanoma incidence, and population rates per country. Data were analyzed from July 2021 to September 2022. Exposure: COVID-19 lockdown-related delay of melanoma detection and consecutive public health and economic burden. As lockdown restrictions varied by country, lockdown scenario was defined as elimination of routine medical examinations and severely restricted access to follow-up examinations for at least 4 weeks. Main Outcomes and Measures: Primary outcomes were the total burden of a delay in melanoma diagnosis during COVID-19 lockdown periods, measured using the direct (in US$) and indirect (calculated as YLL plus years lost due to disability [YLD] and disability-adjusted life-years [DALYs]) costs for Europe. Secondary outcomes included estimation of upstaging rate, estimated YLD, YLL, and DALY for each European country, absolute direct and indirect treatment costs per European country, proportion of the relative direct and indirect treatment costs for the countries, and European health expenditure. Results: There were an estimated 111 464 (range, 52 454-295 051) YLL due to pandemic-associated delay in melanoma diagnosis in Europe, and estimated total additional costs were$7.65 (range, $3.60 to$20.25) billion. Indirect treatment costs were the main cost driver, accounting for 94.5% of total costs. Estimates for YLD in Europe resulted in 15 360 years for the 17% upstaging model, ranging from 7228 years (8% upstaging model) to 40 660 years (45% upstaging model). Together, YLL and YLD constitute the overall disease burden, ranging from 59 682 DALYs (8% upstaging model) to 335 711 DALYs (45% upstaging model), with 126 824 DALYs for the real-world 17% scenario. Conclusions and Relevance: This economic analysis emphasizes the importance of continuing secondary skin cancer prevention measures during pandemics. Beyond the personal outcomes of a delayed melanoma diagnosis, the additional economic and public health consequences are underscored, emphasizing the need to include indirect economic costs in future decision-making processes. These estimates on DALYs and the associated financial losses complement previous studies highlighting the cost-effectiveness of screening for melanoma

Fractional Laser Releases Tumor-Associated Antigens in Poorly Immunogenic Tumor and Induces Systemic Immunity

Currently ablative fractional photothermolysis (aFP) with CO2 laser is used for a wide variety of dermatological indications. This study presents and discusses the utility of aFP for treating oncological indications. We used a fractional CO2 laser and anti-PD-1 inhibitor to treat a tumor established unilaterally by the CT26 wild type (CT26WT) colon carcinoma cell line. Inoculated tumors grew significantly slower in aFP-treated groups (aFP and aFP + anti-PD-1 groups) and complete remission was observed in the aFP-treated groups. Flow cytometric analysis showed aFP treatment elicited an increase of CD3+, CD4+, CD8+ vand epitope specific CD8+ T cells. Moreover, the ratio of CD8+ T cells to Treg increased in the aFP-treated groups. Additionally, we established a bilateral CT26WT-inoculated mouse model, treating tumors on one-side and observing both tumors. Interestingly, tumors grew significantly slower in the aFP + anti-PD-1 groups and complete remission was observed for tumors on both aFP-treated and untreated sides. This study has demonstrated a potential role of aFP treatments in oncology

Immunochemical staining and flow cytometric analysis for tumor infiltrating neutrophils.

<p>(A) proportion of neutrophil compared with CD45⁺CD3^- leukocytes in the tumor of flow cytometric analysis. (B and C) representative images of flow cytometry for neutrophil on day 1 after aFP in the control group and aFP group respectively. The number in the figures represents proportion of neutrophil compared with CD45⁺CD3^- leukocytes. (D and E) immunohistochemical staining for neutrophil in the tumor 1 days after aFP in the control group and aFP group respectively. Cells stained as red color are neutrophils. Inset shows multi nucleated neutrophils as the dominant immune infiltrate seen in H&E-stained aFP-treated tumor. (F) magnified image of neutrophil in figure (4D, G and H) immunohistochemical staining for CD206-expressing neutrophil in the tumor 1 days after aFP in the control group and aFP group respectively. Cells stained as yellow color are neutrophils expressing CD206.</p

Tumor volume and survival curves after aFP treatment.

<p>(A) tumor volume curves of mice in the control group and aFP group after tumor inoculation. *** <i>P</i> < 0.0001. The bars represent SD. (B) tumor volume curve of mice in the control group, and tumor volume curves of cured mice and non-cured mice which are split from original curve in aFP group. * <i>P</i> < 0.01, ** <i>P</i> < 0.005 comparing control to aFP-non cured group. The bars represent SD. (C) Kaplan-Meier survival curves of mice receiving tumor inoculation. The significance values for the difference between the survival curves are: control vs. FP (<i>p</i> < 0.05).</p

Ablative fractional photothermolysis.

<p>(A) photo of skin surface appearance immediately after ablative fractional photothermolysis (100 mJ pulse energy). Black arrow indicates one of the laser-generated holes formed by tissue vaporization/ablation. There is an absence of graying or blistering immediately after laser exposure, which also suggests an absence of major thermal injury. (B) H&E-stained CT26.CL25 tumor immediately after the ablative fractional photothermolysis (aFP) laser treatment with a pulse energy of 100mJ. White arrows indicate an ablated hole which is characteristic of aFP procedures. The ablated hole appeared to be collapsed and distorted within the tumor tissue. (C) CT26.CL25 tumor immediately after aFP, stained by NBTC staining that shows vital cells as a blue color. White arrows indicate dead cells caused by physical effects of the laser treatment. Most of the tissue within the aFP volumes exhibited a blue staining, indicating an absence of widespread thermal injury or tissue bulk heating.</p

Immunohistochemical staining for apoptotic tumor cells.

<p>(A and B) Immunohistochemical staining for apoptotic cells in the tumor 1 day after aFP in the control group and aFP group respectively. Representative images are shown. Cells stained as red color, which are indicated by white arrow heads are apoptotic cells.</p