[Characteristics of grassland degradation and its relationship with climate factors on Qinghai-Tibetan Plateau, China]

Understanding the distribution, characteristics, and changing trend and persistence of grassland degradation and revealing its mechanism on the Qinghai-Tibetan Plateau can provide scientific basis for effective grassland management and conservation. We selected grassland coverage as the remote sensing monitoring index to establish the remote sensing monitoring and evaluation index system of grassland degradation and evaluate grassland degradation during 2016 to 2020 on the Qinghai-Tibet Plateau. The changing trend and persistence of grassland coverage were analyzed using linear regression and Hurst index analysis on a long time series scale (1982-2020). The partial correlation analysis was used to examine the influence of climate on grassland degradation. The results showed that grassland degradation reached 24.3% during 2016 to 2020, which was mainly light and moderate degradation, and largely distributed in low altitude and high fractional vegetation cover areas. From 1982 to 2020, grassland coverage tended to increase in the north, west and southwest, and decreased in the east and center of the Qinghai-Tibetan Plateau. The Hurst index of grassland coverage was less than 0.5 in 98.1% of the total grassland, indicating grassland coverage showed negatively persistent. The partial correlation coefficient between grassland coverage and precipitation (0.096) was higher than that of temperature (-0.033). About 16.0% area was dominated by temperature, which was mainly distributed in the central and southeast. About 12.2% area was dominated by precipitation, which was distributed in the northeast and west of the Qinghai-Tibetan Plateau.

Exosome-mediated delivery of SCD-1 siRNA promoted the death of anaplastic thyroid carcinoma cells via regulating ROS level

PURPOSE

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive cancers in the world. Stearoyl-CoA desaturase-1 (SCD-1) is one of major enzymes in the de novo synthesis of fatty acids and is related to cancer aggressiveness and poor patient prognosis. The study aimed to construct exosomes loaded SCD-1 interference, investigate its effects and mechanisms on the cell proliferation and apoptosis of ATC cells.

METHODS

The expressions of SCD-1 in normal thyroid cell line and ATC cell lines were determined by qRT-PCR and western blotting, respectively. Exosomes were prepared and purification then loaded with SCD-1 siRNA by electroporation and observed by transmission electron microscopy. Higher SCD-1 mRNA and protein levels were found in ATC cell lines compared than normal thyroid cell line (P < 0.05), and both Hth-7 and FRO cells could uptake PKH67-labeled exosomes. The effects of exosomes loaded SCD-1 siRNA on ATC cells were measured by CCK8 assay and apoptosis detection kit.

RESULTS

When compared with control group, the cell viability significantly decreased in both two ATC cell lines taken up exosomes loaded SCD-1 siRNA (P < 0.001), and apoptotic and necrotic cells obviously increased (P < 0.05). In order to explore the mechanism of exosomes loaded SCD-1 on ATC, the ROS level was detected by fluorescence reagent. It was found that exosomes loaded SCD-1 siRNA significantly increased intracellular ROS level of ATC cells (P < 0.05).

CONCLUSIONS

Exosomes loaded SCD-1 siRNA inhibited ATC cellular proliferation and promoted cellular apoptosis, and the mechanisms involved maybe the regulation of fatty acids metabolism and ROS level. Our study provides a promising therapeutic strategy for ATC.

Platelet-rich plasma regulating the repair of ultraviolet B-induced acute tissue inflammation: adjusting macrophage polarization through the activin receptor-follistatin system

Ultraviolet B (UVB) is one of the most common exogenous factors in skin aging, especially photoaging. Once a large amount of UVB accumulates within a short period of time, skin tissue can become inflamed. It has also been found in clinics that platelet-rich plasma (PRP) can promote wound repair; therefore, the aim of this study was to identify the mechanism by which PRP repairs UVB-induced skin photodamage. We used PRP of Sprague-Dawley rats with the two-spin technique in the established acute UVB radiation photodamage model and harvested the corresponding skin after 1, 7, and 28 d. Hematoxylin and eosin staining was used to observe tissue inflammation. We found that PRP reduces inflammation in the early stages of UVB-induced acute skin damage, and then promotes the proliferation of collagen in the middle and late stages. Moreover, PRP can stimulate Act A and M1 polarization in the early stage, while inhibiting activin A (Act A) and inducing M2 polarization in the middle and late stages. In conclusion, this study demonstrates that PRP plays an important regulatory role in helping reduce UVB-induced acute skin tissue inflammation by adjusting macrophage polarization, which alleviates skin inflammation and stimulates collagen regeneration.

Acute myeloid leukemia with adult atopic dermatitis as first manifestation: A case report

RATIONALE

Atopic dermatitis (AD) is a chronic recurrent dermatitis with profound itching, which could be the first manifestation of acute myeloid leukemia (AML).

PATIENT CONCERNS

A 53-year-old Chinese man suffered a 6-month history of systemic symmetrical dermatitis, accompanied with profound itching. The patient was diagnosed as "eczema" in several hospitals, and the effects of antihistamine and topical steroid creams were poor. Nocturnal sleep was seriously affected by aggravating pruritus. Laboratorial examination was compatible with AML-M4.

DIAGNOSES

AML-M4 with AD as first manifestation.

INTERVENTIONS

IA regimen (ayninen and cytarabine) were used in induction chemotherapy. However, the patient did not achieve complete remission, and although his rash had improved, he still experienced severely general body itching. On the seventh day of chemotherapy, the patient entered the period of granulocyte deficiency with infection.

OUTCOMES

The patient died due to septic shock after chemotherapy.

LESSONS

The case strengthens the awareness of AML with AD as first manifestation and raises oncological vigilance in patients with AD refractory.

Case series of neck accessory tragus

We report three cases of neck accessory tragus, which is the largest number of cases with dermatologists reported in China. Neck accessory tragus belongs to special accessory auricular anomaly. Case 1: A 5-year-old girl presented with a skin-colored mass above her right clavicle since birth. Physical examination revealed a pea-sized mass positioned above the right clavicle. Case 2 and case 3 were a 3-month-old female infant and a 4-month-old male infant, respectively. Both of their parents complained that the masses gradually increased in front of the neck. Histopathologically, all of the three cases showed cartilage beneath the subcutaneous tissue. All cases were diagnosed as cervical auricles.

MG-132 treatment promotes TRAIL-mediated apoptosis in SEB-1 sebocytes

AIMS

This study aimed to identify the mechanism of how MG-132 stimulates cell death in SEB-1 sebocytes.

MATERIALS AND METHODS

TUNEL staining and annexin-FITC/PI flow cytometry were utilized to examine the apoptotic cell number of SEB-1 sebocytes and HaCaT keratinocytes upon MG-132 and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) treatment. MTT assay and CCK-8 assay monitored the proliferative rate and viability of both cell lines with different treatment. Western blotting (WB) and qPCR were performed to detect the expression of TRAIL and members of Bcl-2 family at protein and gene level. Additionally, RNA interfering was used to knockdown the mRNA transcription of TRAIL and BIK gene.

KEY FINDINGS

MG-132 treatment enhanced cell death in SEB-1 sebocytes but not in HaCaT keratinocytes. Meanwhile, TRAIL concentrations in SEB-1 sebocytes treated with MG-132 were markedly elevated. Furthermore, treatment with TRAIL or the TRAIL receptor-specific monoclonal antibody AY4 at various doses stimulated cell death in SEB-1 sebocytes in a time- and dose-dependent manner. Silencing of TRAIL restored the cell viability of SEB-1 cells to a normal level after MG-132 treatment. Combined treatment of SEB-1 sebocytes with TRAIL and MG-132 synergistically triggered cell death, suppressed cell proliferation and survival, and promoted BIK expression. Furthermore, BCL2 Interacting Killer (BIK) knockdown via RNA interference participated in the recovery of cell survival reduced by treatment with TRAIL and MG-132.

SIGNIFICANCE

These findings suggest that treatment with the selective proteasome suppressor MG-132 and TRAIL induces cell death in sebocytes through upregulation of BIK, a member of the Bcl-2 family.

A case report of toxic epidermal necrolysis associated with AZD-9291

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are a strain of small molecule inhibitors mainly used to treat the metastatic non-small cell lung cancer. Their predominant adverse effect is skin toxicity, usually manifested as acneiform rash, skin fissure, xerosis, and paronychia. Severe epidermal necrosis and exfoliation rarely occur. As one of the new generation of epidermal growth factor receptor-tyrosine kinase inhibitors, AZD-9291 is claimed to have better efficacy and fewer side effects, particularly appropriate for patients with EGFR T790M mutation. Herein we report a 51-year-old man who developed a large area of skin necrosis and was diagnosed with toxic epidermal necrolysis after AZD-9291 ingestion.

MiR-23a-depressed autophagy is a participant in PUVA- and UVB-induced premature senescence

Autophagy is a cellular catabolic mechanism that is activated in response to stress conditions, including ultraviolet (UV) irradiation, starvation, and misfolded protein accumulation. Abnormalities in autophagy are associated with several pathologies, including aging and cancer. Furthermore, recent studies have demonstrated that microRNAs (miRNAs) are potent modulators of the autophagy pathway. As a result, the current study aims to elucidate the role of the autophagy-related miRNA miR-23ain the process of photoaging. Experiments demonstrated that the antagomir-mediated inactivation of miR-23a resulted in the stimulation of PUVA- and UVB-depressed autophagy flux and protected human fibroblasts from premature senescence. Furthermore, AMBRA1 was identified as a miR-23a target. AMBRA1 cellular levels increased following the introduction of miR-23a antagomirs. And a bioinformatics analysis revealed that the AMBRA1 3' UTR contains functional miR-23a responsive sequences. Finally, it was also demonstrated that both AMBRA1 overexpression and Rapamycin treatment were both able to rescue fibroblasts from PUVA and UVB irradiation-induced autophagy inhibition, but that these effects could also be mitigated by miR-23a overexpression. Therefore, this study concludes that miR-23a-regulated autophagy is a novel and important regulator of ultraviolet-induced premature senescence and AMBRA1 is a rate-limiting miRNA target in this pathway.

Chemical leukoderma induced by dimethyl sulfate

Chemical leukoderma occurs due to the toxic effect of a variety of chemical agents. Mechanisms include either destruction or inhibition of melanocytes. We report two male patients (36 and 51 years old) who presented with multiple hypopigmented macules and patches on the neck, wrist, and legs after exposure to dimethyl sulfate in a chemical industry. Physical examination revealed irregular depigmentation macules with sharp edges and clear hyperpigmentation around the lesions. History of repeated exposure to a chemical agent can help the clinical diagnosis of chemical leukoderma. This diagnosis is very important for prognosis and therapeutic management of the disease.

Combined effects of long-pulsed neodymium-yttrium-aluminum-garnet laser, diprospan and 5-fluorouracil in the treatment of keloid scars

Keloids are benign tumors that originate from scar tissues, but they usually overgrow beyond the original wounds. In a three-month single-center clinical trial, 69 patients were randomly divided into three groups. Patients in group 1 were treated with intralesional injection of diprospan (2 mg betamethasone disodium phosphate and 5 mg betamethasone dipropionate in 1 ml) with one-month intervals for three months. Patients in groups 2 and 3 were injected with a combination of 0.5 ml 5-fluorouracil (5-FU; 25 mg/ml) and diprospan as above for three months also. Prior to each injection, the keloids of patients in group 3 were additionally irradiated by a 1,064-nm neodymium-yttrium-aluminum-garnet (Nd:YAG) laser with a single pulse at an energy density of 90-100 J/cm² and a pulse width of 12 msec. Clinical responses were evaluated by patient self-assessment and overall assessment by an observer according to the clinical signs of erythema, pruritus and pliability. A total of sixty-two patients completed the tests of the present study. At 2 and 3 months, the patients in all treatment groups showed an acceptable improvement in nearly all measurements. At the end of the study, the erythema and toughness score was significantly reduced and itch reduction was significantly greater in the diprospan + 5-FU + Nd:YAG group when compared to those in the other groups (P<0.05 for all indexes). The acceptable responses (good to excellent improvements) reported by blinded observers were as follows: 12% in the diprospan group, 48% in the diprospan + 5-FU group and 69% in the diprospan + 5-FU + Nd:YAG group. All of the results indicated that the combination of diprospan + 5-FU + Nd:YAG was the most efficacious therapy for keloid scars.

[Reducing maternal parenting stress of children with autism spectrum disorder: father's involvement]

Objective: To explore the relationship between fathers' nursing time and maternal parenting stress of children with autism spectrum disorder(ASD). Method: Mothers of 98 ASD children who were first diagnosed in the department of Child Health Care, Children's Hospital of Fudan University during June 2015 to January 2016 were included in the ASD group, with mothers of 92 typical children from a Community Maternal and Child Health Hospital and a kindergarten in the control group. The evaluation of parenting stress, parents' nursing time and other related factors were cross-sectionally analyzed. Interview was conducted with the following tools: Parental Stress Index-Short Form(PSI-SF)for maternal parenting stress, and self-made General Parenting Information Questionnaire for nursing time of both parents and other related factors. The relationships were analyzed by Multiple Linear Regression analysis and Wilcoxon Rank-Sum test. Result: Maternal parenting stress of ASD children had a significant negative correlation with father's nursing time in total score of parenting stress, PCDI domain and PD domain (t=-2.76, -2.98, -2.79; P=0.007, 0.004, 0.006), within which PD domain also included family annual income and mothers' nursing time (R(2)=0.22, 0.24, 0.25); while no such correlation was found in control group in terms of father's nursing time(P=0.22, 0.42, 0.06). Wilcoxon Rank-Sum test showed that in 62 (63.3%) double-income ASD families and 72(78.3%) double-income typical families, there were significant differences between ASD fathers' and ASD mothers'and typical fathers'nursing time(2.0(0.5, 2.1)vs. 3.5(2.4, 6.0)vs. 3.0(2.0, 4.7)h, t=-86.32、-49.65, all P<0.01). Conclusion: Lack of fathers' involvements was common in ASD children's families. Increasing these fathers' nursing time, as well as their enthusiasm and initiative in the family intervention could relieve maternal parenting stress and improve the intervention pattern of ASD children.

Photodynamic therapy inhibit Fibroblast Growth Factor-10 induced keratinocyte differentiation and proliferation through ROS in Fibroblast Growth Factor Receptor-2b pathway

5-aminolevulinic acid-photodynamic therapy (ALA-PDT) is known to be effective in several skin diseases such as acne, actinic keratoses, condyloma acuminata. However, some detailed mechanisms of ALA-PDT to treat these skin diseases still remain elusive. In this study, we aimed to investigate mechanism of ALA-PDT in in-vitro and in-vivo models. For in vitro, we use human keratinocyte cell line (HaCaT) cells. CCK-8 was used to detect cell proliferation activity, immunofluorescence and western blotting method to detect the content of keratin (K)1, K6, K16, protein kinase C (PKC), fibroblast growth factor receptor-2b (FGFR2b) protein, ELISA and RT-PCR to detect expression of interleukin (IL) 1α in the cell supernatant, and detect reactive oxygen species (ROS). For in vivo, we use 20 rabbits to induce hyperkeratosis acne model in their ear. Dermatoscope was used to see follicle hyperkeratosis and skin biopsy to analyze histology and immunohistochemical of PKC, FGFR2b, K1, K6 and K16. Results from this study suggest that ROS stimulated by ALA-PDT lead to inhibition of FGFR2b pathway in PKC downstream to cause reduction of IL1α expression, and eventually, keratinocytes differentiation and proliferation. Our data thus reveal a treatment mechanism of ALA-PDT underlying hyperkeratosis related dermatoses.

The efficacy of conditioned media of adipose-derived stem cells combined with ablative carbon dioxide fractional resurfacing for atrophic acne scars and skin rejuvenation

OBJECTIVE

To evaluate the effects of conditioned medium of adipose-derived stem cells (ADSC-CM) on efficacy and side effects after fractional carbon dioxide laser resurfacing (FxCR) when treating subjects with facial atrophic acne scars or with skin rejuvenation needs.

MATERIALS AND METHODS

Twenty-two subjects were enrolled in the study and divided into two groups. Nine subjects were included in skin rejuvenation group and thirteen subjects were included in acne scar group, and all subjects underwent three sessions of FxCR. ADSC-CM was applied on FxCR site of one randomly selected face side. Evaluations were done at baseline, 1 week after first treatment, and 1 month after each treatment. The outcome assessments included subjective satisfaction scale; blinded clinical assessment; and the biophysical parameters of roughness, elasticity, skin hydration, transepidermal water loss (TEWL), and the erythema and melanin index. Biopsies taken from one subject in skin rejuvenation group were analyzed using hematoxylin and eosin, Masson's Trichrome, and Gomori's aldehyde fuchsin staining.

RESULTS

ADSC-CM combined with FxCR increased subject satisfaction, elasticity, skin hydration, and skin elasticity and decreased TEWL, roughness, and the melanin index in both acne scars and skin rejuvenation groups. Histologic analysis showed that ADSC-CM increased dermal collagen density, elastin density, and arranged them in order.

CONCLUSION

ADSC-CM with FxCR is a good combination therapy for treating atrophic acne scars and skin rejuvenation.

TRIAL REGISTRATION

JSPH2012-082 - Registered 14 Feb 2012.

Pyogenic granuloma in a patient with psoriasis successfully treated by 5-aminolevulinic acid photodynamic therapy: A case report

Pyogenic granuloma (PG) is an acquired benign vascular tumor of unknown etiology. In the present case report, PG was detected in a 49-year-old Chinese male patient with chronic plaque psoriasis. The psoriasis lesions on the finger where the granuloma had developed had been scratched excessively, as declared by the patient. No retinoid therapeutic agents were used during treatment. The patient responded poorly to cryotherapy and surgical curettage. However, following one session of 5-aminolevulinic acid photodynamic therapy (ALA-PDT), signs of improvement were demonstrated 1 week after the treatment, and 1 month following treatment, there were no signs of reoccurrence. Although a report demonstrating treatment success in one patient may be inadequate to estimate the true efficiency of ALA-PDT, dermatologists may consider ALA-PDT as an alternative therapy for stubborn PG.

Update on treatment of photodermatosis

Photodermatoses are a group of skin conditions associated with an abnormal reaction to ultraviolet (UV) radiation. There are several of the photosensitive rashes which mainly affect the UV exposed areas of the skin. It can be classified into four groups: immunology mediated photodermatoses, chemical and drug induced photosensitivity, photoaggravated dermatoses, and genetic disorders. A systematic approach including history, physical examination, phototesting, photopatch testing, and laboratory tests are important in diagnosis of a photodermatosis patient. In order to optimally treat a disease of photodermatoses, we need to consider which treatment offers the most appropriate result in each disease, such as sunscreens, systemic medication, topical medication, phototherapy, and others. For all groups of photodermatoses, photoprotection is one of the essential parts of management. Photoprotection, which includes sunscreening and wearing photoprotective clothing, a wide brimmed hat, and sunglasses, is important. There are also promising emerging photoprotective agents.

Generalized lentiginosis in an 11 year old boy

Generalized lentiginosis refers to generalized lentigines without systemic abnormalities, characterized by multiple brown or black macules owing to increased proliferation of melanocytes. There are also lentiginosis syndromes associated with systemic abnormalities such as Peutz-Jeghers syndrome, Leopard syndrome, and Carney complex. Generalized lentiginosis can be diagnosis by patient's history, physical and laboratory examination, and histopathology. We report an 11-year-old boy who presented with multiple dark brown macules, varying in size, but less than 0.5 cm, with no abnormalities of other systemic organs.

Topical pimecrolimus inhibits high-dose UVB irradiation-induced epidermal Langerhans cell migration, via regulation of TNF-α and E-cadherin

Background

Topical pimecrolimus has been shown to reverse epidermal CD1a⁺ Langerhans cell reduction induced by high-dose ultraviolet (UV)B irradiation, but the mechanism is still unclear. This study aimed to investigate the possible mechanism of the effect of pimecrolimus on high-dose UVB-irradiated epidermal Langerhans cells.

Methods

Forty human foreskin tissues were divided into four groups: control; pimecrolimus-only; UVB-only; and UVB + pimecrolimus. All tissues were cultured, and each tissue was cut into four pieces, corresponding to four time points (0 hours, 18 hours, 24 hours, and 48 hours). We collected the tissues and culture medium at each time point. The percentage of CD1a⁺ cells in medium was detected by flow cytometry. The tissues were detected for messenger (m)RNA and protein expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and E-cadherin, by reverse-transcription polymerase chain reaction (PCR) and Western blot.

Results

At 18 hours, 24 hours, and 48 hours, the CD1a⁺ cells in the culture medium of the UVB-only group and the UVB + pimecrolimus group were significantly more than in the control group, while the CD1a⁺ cells of the UVB + pimecrolimus group was less than of the UVB-only group. For both the UVB-only group and UVB + pimecrolimus group, TNF-α expression (by both reverse-transcription PCR and Western blot) of the tissues was clearly higher and E-cadherin expression was significantly lower compared with the control group, at 18 hours, 24 hours, and 48 hours. For the UVB + pimecrolimus group, TNF-α was clearly lower and E-cadherin was significantly higher compared with the UVB-only group.

Conclusion

Topical pimecrolimus inhibited epidermal Langerhans cell migration induced by high-dose UVB irradiation, via regulation of TNF-α and E-cadherin.

A comparative study of the efficacy and safety of radiofrequency ablation and botulinum toxin A in treating masseteric hypertrophy

The aim of the present study was to evaluate the effects of two treatments for masseteric hypertrophy. In total, 24 patients with masseteric hypertrophy were enrolled in this study. Patients were randomly divided into two groups: 12 individuals were treated with radiofrequency (RF) ablation and 12 patients received an injection of botulinum toxin A. The thickness of the masseter muscle under tension was measured using ultrasound and clinical photographs were captured prior to treatment and at 6 and 12 months following treatment. Complications were observed during 12-month follow-up. In the group injected with botulinum toxin A, masseteric muscle thickness decreased to the lowest point 6 months after the injections but increased until 12 months after injection. However, in the group treated with RF ablation, muscle thickness decreased steadily over the 12 months following surgery. Therefore, the results of the present study indicated that the effect of RF ablation on the thickness of the masseter muscle may be much larger than that obtained following injection with botulinum toxin A.

Effect of UVB irradiation on microRNA expression in mouse epidermis

The aim of this study was to assess the effects of UVB irradiation on miRNA expression in the mouse epidermis. We determined miRNA expression profiles in the epidermis of UVB irradiated mice and untreated mice, and conducted TargetScan and Gene Ontology analyses to predict miRNA targets. Three miRNAs were downregulated and three were upregulated in the epidermis of UVB irradiated mice compared with untreated mice, and were predicted to be associated with photocarcinogenesis, hypomethylation and apoptosis. miRNAs are potentially involved in the pathogenesis of photodamage, and may aid in the treatment and prevention of UVB-induced dermatoses.

Mitigation of acute ultraviolet B radiation-mediated damages by baicalin in mouse skin

BACKGROUND

Solar ultraviolet (UV) irradiation, in particular UVB with a wavelength range between 290 and 320 nm, induces different hazardous effects on the skin, including sunburn, photoaging and cancer. Protection against sun-induced damage is therefore a highly desirable goal. Chemoprevention is being investigated as a potential approach for the management of UV damages including skin cancer.

AIM

In this study, to determine the relevance of our in vitro findings to in vivo situations, we assessed the effects of baicalin on UVB-mediated damages in mice skin.

METHODS

Balb/C hairless mice were topically pretreated (24 h before UVB) or post-treated (5 min after UVB) with baicalin (1 mg/cm(2) skin area/mouse/100 microl acetone) and were exposed to UVB 24 h later (180 mJ/cm(2)). The animals were sacrificed 1 and 24 h after the UVB exposure. Skin edema, histopathology changes, hydrogen peroxide (H2O2) and cyclobutane pyrimidine dimers (CPDs)-positive cells were assessed to determine the UVB-induced photodamage.

RESULTS

Our data demonstrated that a topical application of baicalin, either as a pretreatment or as a post-treatment, resulted in a significant decrease in UVB mediated increases in skin edema, skin hyperplasia and infiltration of leukocytes. Further, baicalin treatments (pre and post) also resulted in a significant decrease in UVB mediated (1) generation of H2O2 and (2) formation of DNA photolesions: CPDs.

CONCLUSION

Based on these data, we suggest that baicalin could be developed as an agent for the management of conditions elicited by UV exposure including skin cancer.

Lethal effect and apoptotic DNA fragmentation in response of D-GalN-treated mice to bacterial LPS can be suppressed by pre-exposure to minute amount of bacterial LPS: Dual role of TNF receptor 1

AIM: To investigate whether induction of tolerance of mice to lipopolysaccharide (LPS) was able to inhibit apoptotic reaction in terms of characteristic DNA fragmentation and protect mice from lethal effect.

METHODS: Experimental groups of mice were pretreated with non-lethal amount of LPS (0.05 μg). Both control and experimental groups simultaneously were challenged with LPS plus D-GalN for 6-7 h. The evaluations of both DNA fragmentations from the livers and the protection efficacy against lethality to mice through induction of tolerance to LPS were conducted.

RESULTS: In the naive mice challenge with LPS plus D-GalN resulted in complete death in 24 h, whereas a characteristic apoptotic DNA fragmentation was exclusively seen in the livers of mice receiving LPS in combination with D-GalN. The mortality in the affected mice was closely correlated to the onset of DNA fragmentation. By contrast, in the mice pre-exposed to LPS, both lethal effect and apoptotic DNA fragmentation were suppressed when challenged with LPS/D-GalN. In addition to LPS, the induction of mouse tolerance to TNF also enabled mice to cross-react against death and apoptotic DNA fragmentation when challenged with TNF and/or LPS in the presence of D-GalN. Moreover, this protection effect by LPS could last up to 24 h. TNFR1 rather than TNFR2 played a dual role in signaling pathway of either induction of tolerance to LPS for the protection of mice from mortality or inducing morbidity leading to the death of mice.

CONCLUSION: The mortality of D-GalN-treated mice in response to LPS was exceedingly correlated to the onset of apoptosis in the liver, which can be effectively suppressed by brief exposure of mice to a minute amount of LPS. The induced tolerance status was mediated not only by LPS but also by TNF. The developed tolerance to either LPS or TNF can be reciprocally cross-reacted between LPS and TNF challenges, whereas the signaling of induction of tolerance and promotion of apoptosis was through TNFR1, rather than TNFR2.

A striking correlation between lethal activity and apoptotic DNA fragmentation of liver in response of D-galactosamine-sensitized mice to a non-lethal amount of lipopolysaccharide

AIM

To observe whether challenge of bacterial lipopolysaccharide (LPS) with D-galactosamine (D-GalN) in mice will result in apoptotic characteristic of vital organs.

METHODS

The experimental group of mice was challenged directly with bacterial LPS (0.05 microg) in the presence of D-GalN (20 mg), and the control group of mice was challenged either with bacterial LPS or with D-GalN alone. The organs including brain, kidney, heart, spleen, lung, and liver were removed at an indicated time point under ether anesthesia, and immediately homogenized, from which DNA was extracted. The DNA obtained from these organs was analyzed by agarose gel electrophoresis to determine whether the DNA laddering phenomenon existed. The amount of plasma LDH and GOT was detected in mice challenged with bacterial LPS in the presence of D-GalN, and either bacterial LPS or D-GalN alone.

RESULTS

Apoptotic DNA fragmentation was initially seen at 4 h after challenge only in the livers of mice challenged with bacterial LPS and D-GalN, all mice in this group challenged with bacterial LPS and D-GalN died at 7 h after challenge; in contrast, the animals in the control group were all alive and the DNA was integral.

CONCLUSION

The liver is the only specific target organ where apoptotic DNA fragmentation was present in mice treated with D-GalN and challenged with bacterial LPS and the liver impairment might be the critical cause of the lethality of mice elicited by bacterial LPS.