Jianpi Gushen Huayu decoction ameliorated diabetic nephropathy through modulating metabolites in kidney, and inhibiting TLR4/NF-κB/NLRP3 and JNK/P38 pathways.

BACKGROUND: Jianpi Gushen Huayu Decoction (JPGS) has been used to clinically treat diabetic nephropathy (DN) for many years. However, the protective mechanism of JPGS in treating DN remains unclear. AIM: To evaluate the therapeutic effects and the possible mechanism of JPGS on DN. METHODS: We first evaluated the therapeutic potential of JPGS on a DN mouse model. We then investigated the effect of JPGS on the renal metabolite levels of DN mice using non-targeted metabolomics. Furthermore, we examined the effects of JPGS on c-Jun N-terminal kinase (JNK)/P38-mediated apoptosis and the inflammatory responses mediated by toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB)/NOD-like receptor family pyrin domain containing 3 (NLRP3). RESULTS: The ameliorative effects of JPGS on DN mice included the alleviation of renal injury and the control of inflammation and oxidative stress. Untargeted metabolomic analysis revealed that JPGS altered the metabolites of the kidneys in DN mice. A total of 51 differential metabolites were screened. Pathway analysis results indicated that nine pathways significantly changed between the control and model groups, while six pathways significantly altered between the model and JPGS groups. Pathways related to cysteine and methionine metabolism; alanine, tryptophan metabolism; aspartate and glutamate metabolism; and riboflavin metabolism were identified as the key pathways through which JPGS affects DN. Further experimental validation showed that JPGS treatment reduced the expression of TLR4/NF-κB/NLRP3 pathways and JNK/P38 pathway-mediated apoptosis related factors. CONCLUSION: JPGS could markedly treat mice with streptozotocin (STZ)-induced DN, which is possibly related to the regulation of several metabolic pathways found in kidneys. Furthermore, JPGS could improve kidney inflammatory responses and ameliorate kidney injuries in DN mice via the TLR4/NF-κB/NLRP3 pathway and inhibit JNK/P38 pathway-mediated apoptosis in DN mice.

Jian-Pi-Gu-Shen-Hua-Yu Decoction Alleviated Diabetic Nephropathy in Mice through Reducing Ferroptosis.

Background: Diabetic nephropathy (DN), one of the most frequent complications of diabetes mellitus, is a leading cause of end-stage renal disease. However, the current treatment methods still cannot effectively halt the progression of DN. Jian-Pi-Gu-Shen-Hua-Yu (JPGS) decoction can be used for the treatment of chronic kidney diseases such as DN, but the specific mechanism of action has not been fully elucidated yet. Purpose: The aim of this study is to clarify whether JPGS alleviates the progression of diabetic nephropathy by inhibiting ferroptosis. Materials and Methods: We established a DN mouse model to investigate the therapeutic effect of JPGS in a DN mouse model. Subsequently, we examined the effects of JPGS on ferroptosis- and glutathione peroxidase 4 (GPX4) pathway-related indices. Finally, we validated whether JPGS inhibited ferroptosis in DN mice via the GPX4 pathway using GPX4 inhibitor and ferroptosis inhibitors. Results: The results indicate that JPGS has a therapeutic effect on DN mice by improving kidney function and reducing inflammation. Additionally, JPGS treatment decreased iron overload and oxidative stress levels while upregulating the expression of GPX4 pathway-related proteins. Moreover, JPGS demonstrated a similar therapeutic effect as Fer-1 in the context of DN treatment, and RSL3 was able to counteract the therapeutic effect of JPGS and antiferroptotic effect. Conclusion: JPGS has significant therapeutic and anti-inflammatory effects on DN mice, and its mechanism is mainly achieved by upregulating the expression of GPX4 pathway-related proteins, thereby alleviating iron overload and ultimately reducing ferroptosis.

Mechanical study of alisol B 23-acetate on methionine and choline deficient diet-induced nonalcoholic steatohepatitis based on untargeted metabolomics.

Alisol B 23-acetate (AB23A) has been demonstrated to have beneficial effects on nonalcoholic steatohepatitis (NASH). However, the mechanisms of AB23A on NASH remain unclear. This study aimed to investigate the mechanisms underlying the metabolic regulatory effects of AB23A on NASH. We used AB23A to treat mice with NASH, which was induced by a methionine and choline deficient (MCD) diet. We initially investigated therapeutic effect and resistance to oxidation and inflammation of AB23A on NASH. Subsequently, we performed untargeted metabolomic analyses and relative validation assessments to evaluate the metabolic regulatory effects of AB23A. AB23A reduced lipid accumulation, ameliorated oxidative stress and decreased pro-inflammatory cytokines in the liver. Untargeted metabolomic analysis found that AB23A altered the metabolites of liver. A total of 55 differential metabolites and three common changed pathways were screened among the control, model and AB23A treatment groups. Further tests validated the effects of AB23A on modulating common changed pathway-involved factors. AB23A treatment can ameliorate NASH by inhibiting oxidative stress and inflammation. The mechanism of AB23A on NASH may be related to the regulation of alanine, aspartate and glutamate metabolism, d-glutamine and d-glutamate metabolism, and arginine biosynthesis pathways.

Crocin Ameliorates Diabetic Nephropathy through Regulating Metabolism, CYP4A11/PPARγ, and TGF-ß/Smad Pathways in Mice.

INTRODUCTION: Crocin is one of the main components of Crocus sativus L. and can alleviate oxidative stress and inflammation in diabetic nephropathy (DN). However, the specific mechanism by which crocin treats DN still needs to be further elucidated. METHOD: In the present study, a mouse model of DN was first established to investigate the therapeutic effect of crocin on DN mice. Subsequently, non-targeted metabolomics techniques were used to analyze the mechanisms of action of crocin in the treatment of DN. The effects of crocin on CYP4A11/PPARγ and TGF-ß/Smad pathway were also investigated. RESULT: Results showed that crocin exhibited significant therapeutic and anti-inflammatory, and anti-oxidative effects on DN mice. In addition, the non-targeted metabolomics results indicated that crocin treatment affected several metabolites in kidney. These metabolites were mainly associated with biotin metabolism, riboflavin metabolism, and arachidonic acid metabolism. Furthermore, crocin treatment upregulated the decreased levels of CYP4A11 and phosphorylated PPARγ, and reduced the increased levels of TGF-ß1 and phosphorylated Smad2/3 in the kidneys of DN mice. CONCLUSION: In conclusion, our study validated the considerable therapeutic, anti-inflammatory, and antioxidative impacts of crocin on DN mice. The mechanism of crocin treatment may be related to the regulation of biotin riboflavin and arachidonic acid metabolism, the activation of CYP4A11/PPARγ pathway, and the inhibition of TGF-ß/Smad pathway in the kidney.

Rosa laevigata Michx. Polysaccharide Ameliorates Diabetic Nephropathy in Mice through Inhibiting Ferroptosis and PI3K/AKT Pathway-Mediated Apoptosis and Modulating Tryptophan Metabolism.

Diabetic nephropathy (DN) is a metabolic disease wherein chronic hyperglycemia triggers various renal cell dysfunctions, eventually leading to progressive kidney failure. Rosa laevigata Michx. is a traditional Chinese herbal medicine. Many studies have confirmed its antioxidative, anti-inflammatory, and renoprotective effects. However, the effects and mechanisms of Rosa laevigata Michx. polysaccharide (RLP) in DN remain unclear. In this study, a DN mouse model was established to investigate the therapeutic effect of RLP on DN mice. Then, nontargeted metabolomics was used to analyze the potential mechanism of RLP in the treatment of DN. Finally, the effects of RLP on ferroptosis and the PI3K/AKT pathway were investigated. The results demonstrated that RLP effectively alleviated renal injury and reduced inflammation and oxidative stress in the kidney. In addition, nontargeted metabolomic analysis indicated that RLP could modulate riboflavin metabolism and tryptophan metabolism in DN mice. Notably, ferroptosis and PI3K/AKT pathway-mediated apoptosis in the kidney were also ameliorated following RLP treatment. In conclusion, this study confirmed that RLP had a significant therapeutic effect on DN mice. Furthermore, RLP treatment modulated tryptophan metabolism and inhibited ferroptosis and PI3K/AKT pathway-mediated apoptosis in the kidney.

Integrated 16S rRNA sequencing and nontargeted metabolomics analysis to reveal the mechanisms of Yu-Ye Tang on type 2 diabetes mellitus rats.

Introduction: Yu-Ye Tang (YYT) is a classical formula widely used in treatment of type 2 diabetes mellitus (T2DM). However, the specific mechanism of YYT in treating T2DM is not clear. Methods: The aim of this study was to investigate the therapeutic effect of YYT on T2DM by establishing a rat model of T2DM. The mechanism of action of YYT was also explored through investigating gut microbiota and serum metabolites. Results: The results indicated YYT had significant therapeutic effects on T2DM. Moreover, YYT could increase the abundance of Lactobacillus, Candidatus_Saccharimonas, UCG-005, Bacteroides and Blautia while decrease the abundance of and Allobaculum and Desulfovibrio in gut microbiota of T2DM rats. Nontargeted metabolomics analysis showed YYT treatment could regulate arachidonic acid metabolism, alanine, aspartate and glutamate metabolism, arginine and proline metabolism, glycerophospholipid metabolism, pentose and glucuronate interconversions, phenylalanine metabolism, steroid hormone biosynthesis, terpenoid backbone biosynthesis, tryptophan metabolism, and tyrosine metabolism in T2DM rats. Discussion: In conclusion, our research showed that YYT has a wide range of therapeutic effects on T2DM rats, including antioxidative and anti-inflammatory effects. Furthermore, YYT corrected the altered gut microbiota and serum metabolites in T2DM rats. This study suggests that YYT may have a therapeutic impact on T2DM by regulating gut microbiota and modulating tryptophan and glycerophospholipid metabolism, which are potential key pathways in treating T2DM.

San-Huang-Yi-Shen capsule ameliorates diabetic nephropathy in mice through inhibiting ferroptosis.

Diabetic nephropathy (DN) is one of the main complications of diabetes. However, effective therapy to block or slow down the progression of DN is still lacking. San-Huang-Yi-Shen capsule (SHYS) has been shown to significantly improve renal function and delay the progression of DN. However, the mechanism of SHYS on DN is still unclear. In this study, we established a mouse model of DN. Then, we investigated the anti-ferroptotic effects of SHYS including the reduction of iron overload and the activation of cystine/GSH/GPX4 axis. Finally, we used a GPX4 inhibitor (RSL3) and ferroptosis inhibitor (ferrostatin-1) to determine whether SHYS ameliorates DN through inhibiting ferroptosis. The results showed that SHYS treatment was effective for mice with DN in terms of improving renal function, and reducing inflammation and oxidative stress. Besides, SHYS treatment reduced iron overload and upregulated the expression of cystine/GSH/GPX4 axis-related factors in kidney. Moreover, SHYS exhibited similar therapeutic effect on DN as ferrostatin-1, RSL3 could abolish the therapeutic and anti- ferroptotic effects of SHYS on DN. In conclusion, SHYS can be used to treat mice with DN. Furthermore, SHYS could inhibit ferroptosis in DN through reducing iron overload and upregulating the expression of cystine/GSH/GPX4 axis.

Ethyl-acetate fraction from a cinnamon-cortex extract protects pancreatic ß-cells from oxidative stress damage.

Background: The pathogenesis of diabetes mellitus is mediated mainly by oxidative stress produced by damaged pancreatic ß-cells. We identified that an ethyl-acetate fraction (EA) from a cinnamon-cortex extract (CCE) is rich in flavonoid, and showed no toxicity to ß cells. Objective: In this study, we evaluated the pharmacologic activities of EA on pancreatic ß cells using a model of oxidative stress induced by H2O2 or alloxan. Results: The results showed that EA could significantly reduce reactive oxygen (ROS) accumulation to improve the survival of cells. Western blot showed that EA treatment upregulated expression of nuclear factor erythroid 2 related factor 2, heme oxygenase-1, and gamma glutamylcysteine synthetase. The same model study found that EA also can protect ß cells against the apoptosis induced by oxidative stress. Furthermore, EA can enhance insulin secretion in rat and mouse ß cell lines treated or not with alloxan or H2O2. The expression of the insulin transcription factor PDX-1 increased in an EA concentration-dependent manner. At last, the major functional compounds of EA analysis showed that three compounds, cinnamyl alcohol, coumarin, and cinnamic acid, had similar effects as EA. Conclusions: In sum, our data suggested that EA fraction from CCE can protect ß cells from oxidative stress, and increase insulin secretion to improve the function of ß cells. This function might be due to these three compounds found in EA. Our findings provide a theoretical basis and functional molecules for the use of CCE against diabetes mellitus.

Two Resveratrol Oligomers Inhibit Cathepsin L Activity to Suppress SARS-CoV-2 Entry.

Cell entry of severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) depends on specific host cell proteases, which are the key targets for preventing and treating viral infections. Herein, we describe miyabenol C and trans-ε-viniferin, two resveratrol oligomers that specifically inhibit SARS-CoV-2 entry by targeting host protease cathepsin L. Several cell-based assays were used to demonstrate the effect of resveratrol oligomers, and their target was identified via screening of antiviral targets. Molecular docking analysis suggested that the oligomers could occupy the active cavity of cathepsin L. The surface plasmon resonance assay showed that the equilibrium dissociation constant (KD) values of miyabenol C-cathepsin L and trans-ε-viniferin-cathepsin L were 5.54 and 8.54 µM, respectively, indicating their excellent binding ability for cathepsin L. Our study demonstrated the potential application of resveratrol oligomers as lead compounds in controlling SARS-CoV-2 infection by targeting cathepsin L.

Baihu renshen decoction ameliorates type 2 diabetes mellitus in rats through affecting gut microbiota enhancing gut permeability and inhibiting TLR4/NF-κB-mediated inflammatory response.

Baihu Rensheng decoction (BHRS) can effectively improve insulin resistance (IR) and decrease blood glucose in diabetic patients. However, its specific mechanism of action remains unclear. In this study, a type 2 diabetes mellitus (T2DM) rat model was established using a high-fat diet combined with streptozotocin (STZ) injection and treated with BHRS. Firstly, the therapeutic and anti-inflammatory effects of BHRS on T2DM were evaluated. Secondly, the effects of BHRS on gut permeability were evaluated and western blot was used to detect the changes of TLR4/NF-κB pathway-related protein expressions in liver. Finally, 16S rRNA sequencing was used to detect alteration of gut microbiota diversity and abundance in rats after BHRS treatment. Our results showed that BHRS could alleviate the hyperglycemia, hyperlipidemia, IR, and pathological changes of liver, pancreas, and kidney in T2DM rats. BHRS could also decrease the levels of pro-inflammatory cytokines and inhibit the oxidative stress. Immunohistochemistry showed BHRS could increase the expression tight junction-related proteins (ZO-1 and occludin) in colon. Besides, the level of LPS in serum was decreased after BHRS treatment. Western blot results showed that the protein expression of TLR4, MyD88 and the phosphorylation IκB, and NF-κBp65 were lowered after BHRS treatment. 16S rRNA sequencing showed that BHRS treatment altered the diversity of gut microbiotra and decreases the Firmicutes/Bacteroidetes (F to B) ratio at the phylum level. At the genus level, BHRS could increase the relative abundances of Lactobacillus, Blautia, and Anaerostipes and decrease the relative abundances of Allobaculum, Candidatus Saccharimonas, and Ruminococcus. In conclusion, our study revealed the various ameliorative effects of BHRS on T2DM, including improving the liver and kidney functions and alleviating the hyperglycemia, hyperlipidemia, pathological changes, oxidative stress and inflammatory response. The mechanisms of BHRS on T2DM are likely linked to the repair of gut barrier and the inhibition of TLR4/NF-κB-mediated inflammatory response and the improvement in the dysbiosis of gut microbiota.

San-Huang-Yi-Shen Capsule Ameliorates Diabetic Kidney Disease through Inducing PINK1/Parkin-Mediated Mitophagy and Inhibiting the Activation of NLRP3 Signaling Pathway.

San-Huang-Yi-Shen capsule (SHYS) has been used in the treatment of diabetic kidney disease (DKD) in clinics. However, the mechanism of SHYS on DKD remains unclear. In this study, we used a high-fat diet combined with streptozocin (STZ) injection to establish a rat model of DKD, and different doses of SHYS were given by oral gavage to determine the therapeutic effects of SHYS on DKD. Then, we studied the effects of SHYS on PINK1/Parkin-mediated mitophagy and the activation of NLRP3 inflammasome to study the possible mechanisms of SHYS on DKD. Our result showed that SHYS could alleviate DKD through reducing the body weight loss, decreasing the levels of fasting blood glucose (FBG), and improving the renal function, insulin resistance (IR), and inhibiting inflammatory response and oxidative stress in the kidney. Moreover, transmission electron microscopy showed SHYS treatment improved the morphology of mitochondria in the kidney. In addition, western blot and immunoflourescence staining showed that SHYS treatment induced the PINK1/Parkin-mediated mitophagy and inhibited the activation of NLRP3 signaling pathway. In conclusion, our study demonstrated the therapeutic effects of SHYS on DKD. Additionally, our results indicated that SHYS promoted PINK1/Parkin-mediated mitophagy and inhibited NLRP3 inflammasome activation to improve mitochondrial injury and inflammatory responses.

Qingrequzhuo capsule alleviated methionine and choline deficient diet-induced nonalcoholic steatohepatitis in mice through regulating gut microbiota, enhancing gut tight junction and inhibiting the activation of TLR4/NF-κB signaling pathway.

Qingrequzhuo capsule (QRQZ), composed of Morus alba L., Coptis chinensis Franch., Anemarrhena asphodeloides Bunge, Alisma plantago-aquatica subsp. orientale (Sam.) Sam., Citrus × aurantium L., Carthamus tinctorius L., Rheum palmatum L., Smilax glabra Roxb., Dioscorea oppositifolia L., Cyathula officinalis K.C.Kuan, has been used to treat nonalcoholic steatohepatitis (NASH) in clinic. However, the mechanism of QRQZ on NASH remains unclear. Recent studies have found that the dysfunction of gut microbiota could impair the gut barrier and induce the activation of TLR4/NF-kB signaling pathway, and further contribute to the inflammatory response in NASH. Modulating the gut microbiota to reduce inflammation could prevent the progression of NASH. In this study, a mouse model of NASH was generated by methionine and choline deficient diet (MCD) and treated with QRQZ. First, we evaluated the therapeutic effects of QRQZ on liver injury and inflammation in the NASH mice. Second, the changes in the gut microbiota diversity and abundance in each group of mice were measured through 16S rRNA sequencing. Finally, the effects of QRQZ on gut mucosal permeability, endotoxemia, and liver TLR4/NF-kB signaling pathway levels were examined. Our results showed that QRQZ significantly reduced the lipid accumulation in liver and the liver injury in NASH mice. In addition, QRQZ treatment decreased the levels of inflammatory cytokines in liver. 16S rRNA sequencing showed that QRQZ affected the diversity of gut microbiota and a f f e c t e d t h e r e l a t i v e a b u n d a n c e s o f D u b o s i e l l a , Lachnospiraceae_NK4A136_group, and Blautiain NASH mice. Besides, QRQZ could increase the expression of tight junction proteins (zonula occludens-1 and occludin) in gut and decrease the lipopolysaccharide (LPS) level in serum. Western blot results also showed that QRQZ treatment decreased the protein expression ofTLR4, MyD88 and the phosphorylation of IkB and NF-kBp65 and qPCR results showed that QRQZ treatment down-regulated the gene expression of interleukin (IL)-1b, IL-6, and tumor necrosis factor (TNF)-a in liver. In conclusion, our study demonstrated that QRQZ could reduce the lipid accumulation and inflammatory response in NASH model mice. The mechanisms of QRQZ on NASH were associated with modulating gut microbiota, thereby inducing the tight junction of gut barrier, reducing the endotoxemia and inhibiting the activation of TLR4/NFkB signaling pathway in liver.

Main Risk Factors of Type 2 Diabetes Mellitus with Nonalcoholic Fatty Liver Disease and Hepatocellular Carcinoma.

Type 2 diabetes mellitus (T2DM) with nonalcoholic fatty liver disease (NAFLD) is a pathological metabolic disease characterized by high ketone lipid based on abnormal lipid metabolism. Compared with patients with single T2DM or NAFLD, T2DM complicated with NAFLD has more complicated pathogenic factors and pathological processes. Hepatocellular carcinoma (HCC), the leading malignancy arising from cirrhosis, is the second most lethal cancer globally. The purpose of this study was to clarify the main risk factors of T2DM with NAFLD and HCC. There are many challenges in the diagnosis and treatment of T2DM patients with NAFLD and HCC. The current gold standard is to adjust treatment strategy, optimize metabolic control, and improve liver phenotype. It is necessary to identify further the risk factors driving the progression of T2DM with NAFLD and HCC and evaluate new therapeutic targets, in addition to exploring the syndromic forms of T2DM combined with NAFLD and providing a theoretical basis for early prevention, diagnosis, and treatment of the disease using traditional Chinese medicine (TCM).

Efficacy and Clinical Value of Liraglutide for Treatment of Diabetes Mellitus Complicated by Non-Alcoholic Fatty Liver Disease.

BACKGROUND The aim of this study was to investigate the efficacy and clinical value of liraglutide for the treatment of patients with diabetes mellitus (DM) complicated by non-alcoholic fatty liver disease (NAFLD). MATERIAL AND METHODS Patients with DM complicated by NAFLD (n=835) were enrolled. Patients were divided into 2 groups: 424 patients were included in the liraglutide group and 411 patients were included in the conventional drug group. Venous blood was collected to test blood glucose levels, blood lipid levels, and liver function. After discharge, patients were followed up for between 6 months and 1 year and assigned a quality-of-life score. RESULTS The blood glucose levels of patients in both groups were improved after treatment (P<0.05). The blood lipid levels of patients in both groups improved after treatment (P<0.05). Various blood lipid parameters of patients in the liraglutide group were significantly better than in the conventional drug group (P<0.05). The liver function of patients in the conventional drug group was not significantly different before or after treatment (P>0.05), while in the liraglutide group it improved significantly after treatment (P<0.05). The average quality-of-life score at follow-up in the liraglutide group was 81.00±9.33 points, which was significantly higher than the 68.53±8.44 points in the conventional drug group (P<0.05). CONCLUSIONS Liraglutide for the treatment of DM complicated by NAFLD can effectively improve the blood glucose and lipid levels as well as liver function of patients.

[Protective mechanism on the vascular pathological process in diabetes mellitus rats by Rheum officeinale].

OBJECTIVE: To explore the protective mechanism of officeihale on the vascular pathological process in diabetes mellitus (DM) rats. METHOD: After the DM rat model was established, 24 DM rats were randomly divided into model group (12 DM rats) and Rheum officeinale group (12 DM rats). Rheum officeinale was orally given in 10 g kg(-1) per day, and the other two groups were given equal pure water. 8 weeks later, blood samples were collected to determine the level of nitric oxide (NO) and endothelin-1 (ET-1). Thoracic aortic rings was prepared to observe the inhibiting effect of Ach with different concentration on contraction caused by NE. Another part of aorta was made to observe the expression of ICAM-1 and VCAM-1 by method of SP immunohistochemistry staining, RESULT: Rheum officeinale group obviously decreased the level of ET-1 and increased the NO compared with model group (P <0.05). The expression of ICAM-1 and VCAM-1 could be obviously inhibited in Rheum officeinale group compared with model group. (P <0.05). CONCLUSION: Rheum officeinale could decrease the level of ET-1 with increased the NO in diabetes rats, and inhibit the expression of ICAM-1 and VCAM-1, which may be mechanisms of protecting the endothelium of vessel in diabetes rats.

[Observation on the ultrastructure of Pneumocystis carinii].

OBJECTIVE: To study the life cycle and morphology of Pneumocystis carinii by ultrastructural observation. METHODS: Wistar rat model of P. carinii infection was established by subcutaneous injection with dexamethasone. Lung tissue of the infected rats was used for the transmission electron microscopical study. RESULTS: The organisms were mainly present in the lung alveolar cavity, and also in the alveolar septum, pulmonary macrophages and neutrophils. More trophozoites of P. carinii attached to the type I alveolar epithelial cells, and rarely to the type II alveolar epithelial cells. Most of these trophozoites showed pseudopodial evaginations on their pellicles. The nucleus-associated organelle and spindle microtubules were observed in some trophozoites. The precyst phase was in three forms: early, intermediate and late form. Synaptonemal complexes indicating meiotic nuclear divisions and a clump of mitochondria were also observed in the precyst. The pellicle of the cyst has a thickened portion with a pore. There were nucleus with nucleolus, mitochondrion, vesicles, endoplasmic reticulum and numerous ribosomes in the organisms, and tubular expansions on its surface. CONCLUSION: The life cycle of P. carinii consists of trophozoite, precyst and cyst stages. The presence of a single pore in the cyst wall reveals that pore formation may be a mode of excystation for intracystic bodies of P. carinii.