Misplaced Pages

#803196

53-560: Emerging genetic, molecular, and biochemical studies have identified extensive crosstalk among the molecular components across various cell death pathways in response to a variety of pathogens and innate immune triggers. Historically, inflammatory caspase -mediated pyroptosis   and RIPK-driven necroptosis were described as two major inflammatory cell death pathways. While the PANoptosis pathway has some molecular components in common with pyroptosis and necroptosis , as well as with

106-496: A germ . The term pathogen came into use in the 1880s. Typically, the term pathogen is used to describe an infectious microorganism or agent, such as a virus, bacterium, protozoan , prion , viroid , or fungus . Small animals, such as helminths and insects, can also cause or transmit disease. However, these animals are usually referred to as parasites rather than pathogens. The scientific study of microscopic organisms, including microscopic pathogenic organisms,

159-425: A monotherapy , the likelihood of remission was 22% higher if probiotics were used in combination with 5-aminosalicylic acid therapy. Whereas in people who are already in remission, it is unclear whether probiotics help to prevent future relapse, either as a monotherapy or combination therapy . One study reported successfully treating experimental colitis in mice with mesenchymal stem cells . Additional research

212-477: A camera inserted into the rectum ( sigmoidoscopy , colonoscopy ). An important investigation in the assessment of colitis is biopsy for histopathology . A very small piece of tissue (usually about 2mm) is removed from the bowel mucosa during endoscopy and examined under the microscope by a histopathologist. A biopsy report generally does not state the diagnosis, but should state any presence of chronic colitis, give an indication of disease activity, as well as state

265-546: A murine model of HS and infection reduces mortality; furthermore, deleting essential PANoptosis effectors upstream completely rescues the mice from mortality, thereby identifying NINJ1 and PANoptosis effectors as potential therapeutic targets. The regulation of PANoptosis involves numerous PANoptosomes, which include multiple sensor molecules such as NLRP3 , ZBP1 , AIM2 , NLRC5 , and NLRP12 , along with complex-forming molecules such as caspases and RIPKs. These components activate various downstream cell death executioners and play

318-509: A process involving meiosis and fertilization . Meiosis involves the intimate pairing of homologous chromosomes and recombination between them. Examples of eukaryotic pathogens capable of sex include the protozoan parasites Plasmodium falciparum , Toxoplasma gondii , Trypanosoma brucei , Giardia intestinalis , and the fungi Aspergillus fumigatus , Candida albicans and Cryptococcus neoformans . Viruses may also undergo sexual interaction when two or more viral genomes enter

371-480: A role in disease. Therefore, modulating the components of this pathway has potential for therapy. However, excessive activation of PANoptosis can lead to inflammation , inflammatory disease, and cytokine storm syndromes. Treatments that block TNF and IFN-γ to prevent PANoptosis have provided therapeutic benefit in preclinical models of cytokine storm syndromes, including cytokine shock, SARS-CoV-2 infection, sepsis , and hemophagocytic lymphohistiocytosis , suggesting

424-437: A theorized equilibrium between a pathogen spreading to additional hosts to parasitize resources, while lowering their virulence to keep hosts living for vertical transmission to their offspring. Algae are single-celled eukaryotes that are generally non-pathogenic. Green algae from the genus Prototheca lack chlorophyll and are known to cause the disease protothecosis in humans, dogs, cats, and cattle, typically involving

477-519: A therapeutic target. Similarly, the NLRC5-PANoptosome, which also contains NLRP12, was identified as a response to NAD + depletion downstream of heme-containing triggers. Deletion of NLRC5 protects against not only hemolytic disease models, but also colitis and HLH models. Additionally, PANoptosis can be induced by heat stress (HS), such as fever, during infection, and NINJ1 is a key executioner in this context. Deletion of NINJ1 in

530-423: A variety of bacterial, viral, fungal, and parasitic pathogens, cholera is only caused by some strains of Vibrio cholerae . Additionally, some pathogens may only cause disease in hosts with an immunodeficiency . These opportunistic infections often involve hospital-acquired infections among patients already combating another condition. Infectivity involves pathogen transmission through direct contact with

583-413: A variety of immunodeficiency disorders caused by viruses related to human immunodeficiency virus (HIV), such as BIV and FIV . Humans can be infected with many types of pathogens, including prions, viruses, bacteria, and fungi, causing symptoms like sneezing, coughing, fever, vomiting, and potentially lethal organ failure . While some symptoms are caused by the pathogenic infection, others are caused by

SECTION 10

#1732794152804

636-545: A variety of infections, incluiding influenza A virus , herpes simplex virus 1 (HSV1), and coronavirus . For example, PANoptosis is important for host defense during influenza infection through the ZBP1-PANoptosome and during HSV1 infections through the AIM2-PANoptosome. Studies with beta-coronaviruses have shown that IFN can induce ZBP1 -mediated PANoptosis during SARS-CoV-2 infection, thereby limiting

689-758: A wide array of pathogens and it has been estimated that only 3% of the disease caused by plant pathogens can be managed. Animals often get infected with many of the same or similar pathogens as humans including prions, viruses, bacteria, and fungi. While wild animals often get illnesses, the larger danger is for livestock animals. It is estimated that in rural settings, 90% or more of livestock deaths can be attributed to pathogens. Animal transmissible spongiform encephalopathy (TSEs) involving prions include bovine spongiform encephalopathy (mad cow disease), chronic wasting disease , scrapie , transmissible mink encephalopathy , feline spongiform encephalopathy , and ungulate spongiform encephalopathy. Other animal diseases include

742-414: A wide variety of issues such as shorter plant height, growths or pits on tree trunks, root or seed rot, and leaf spots. Common and serious plant fungi include the rice blast fungus , Dutch elm disease , chestnut blight and the black knot and brown rot diseases of cherries, plums, and peaches. It is estimated that pathogenic fungi alone cause up to a 65% reduction in crop yield. Overall, plants have

795-646: Is Clostridioides difficile colitis , which is informally abbreviated as "C-diff colitis". It classically forms pseudomembranes and is often referred to as pseudomembranous colitis, which is its (nonspecific) histomorphologic description. Enterohemorrhagic colitis may be caused by Shiga toxin in Shigella dysenteriae or Shigatoxigenic group of Escherichia coli (STEC), which includes serotype O157:H7 and other enterohemorrhagic E. coli . Parasitic infections, like those caused by Entamoeba histolytica , can also cause colitis. Indeterminate colitis

848-510: Is called microbiology , while parasitology refers to the scientific study of parasites and the organisms that host them. There are several pathways through which pathogens can invade a host. The principal pathways have different episodic time frames, but soil has the longest or most persistent potential for harboring a pathogen. Diseases in humans that are caused by infectious agents are known as pathogenic diseases. Not all diseases are caused by pathogens, such as black lung from exposure to

901-769: Is downstream of caspase-8 inhibition. On the other hand, PANoptosis is [TDK1] driven by caspases and RIPKs and is executed by gasdermins, MLKL, NINJ1 , and potentially other yet to be identified molecules cleaved by caspases. Moreover, caspase-8 is essential for cell death in PANoptosis but needs to be inactivated or inhibited to induce necroptosis. Summary of the different morphologies, mechanisms and outcomes of apoptosis, pyroptosis, necroptosis, and PANoptosis PANoptosis has also been implicated in inflammatory diseases, neurological diseases, and cancer. Additionally, activation of PANoptosis can clear infected cells for host defense, and it has shown preclinical promise as an anti-cancer strategy. PANoptosis has now been identified in

954-485: Is low-certainty evidence that probiotic supplements may increase the probability of clinical remission. People receiving probiotics were 73% more likely to experience disease remission and over 2x as likely to report improvement in symptoms compared to those receiving a placebo, with no clear difference in minor or serious adverse effects. Although there was no clear evidence of greater remission when probiotic supplements were compared with 5‐aminosalicylic acid treatment as

1007-663: Is resistant to the commonly prescribed beta-lactam antibiotics . A 2013 report from the Centers for Disease Control and Prevention (CDC) estimated that in the United States, at least 2 million people get an antibiotic-resistant bacterial infection annually, with at least 23,000 of those patients dying from the infection. Due to their indispensability in combating bacteria, new antibiotics are required for medical care. One target for new antimicrobial medications involves inhibiting DNA methyltransferases , as these proteins control

1060-522: Is swelling or inflammation of the large intestine ( colon ). Colitis may be acute and self-limited or long-term . It broadly fits into the category of digestive diseases . In a medical context, the label colitis (without qualification) is used if: The signs and symptoms of colitis are quite variable and dependent on the cause of the given colitis and factors that modify its course and severity. Common symptoms of colitis may include: mild to severe abdominal pains and tenderness (depending on

1113-642: Is the classification for colitis that has features of both Crohn's disease and ulcerative colitis . Indeterminate colitis' behaviour is usually closer to ulcerative colitis than Crohn's disease. Treatment for this condition can include medications such as steroids and dietary changes.  In some instances, hospitalization and surgery may be required. Moreover, several studies recently have found significant relationship between colitis and dairy allergy (including: cow milk, cow milk UHT and casein), suggesting some patients may benefit from an elimination diet . The use of oral probiotic supplements to modify

SECTION 20

#1732794152804

1166-574: Is the most common cause of thrush , and Cryptococcus neoformans , which can cause a severe form of meningitis . Typical fungal spores are 4.7 μm long or smaller. Prions are misfolded proteins that transmit their abnormal folding pattern to other copies of the protein without using nucleic acids . Besides obtaining prions from others, these misfolded proteins arise from genetic differences, either due to family history or sporadic mutations. Plants uptake prions from contaminated soil and transport them into their stem and leaves, potentially transmitting

1219-637: The Baltimore classification separates viruses by seven classes of mRNA production: Protozoans are single-celled eukaryotes that feed on microorganisms and organic tissues. Many protozoans act as pathogenic parasites to cause diseases like malaria , amoebiasis , giardiasis , toxoplasmosis , cryptosporidiosis , trichomoniasis , Chagas disease , leishmaniasis , African trypanosomiasis (sleeping sickness), Acanthamoeba keratitis , and primary amoebic meningoencephalitis (naegleriasis). Parasitic worms (helminths) are macroparasites that can be seen by

1272-439: The anthrax vaccine and pneumococcal vaccine . Many other bacterial pathogens lack vaccines as a preventive measure, but infection by these bacteria can often be treated or prevented with antibiotics . Common antibiotics include amoxicillin , ciprofloxacin , and doxycycline . Each antibiotic has different bacteria that it is effective against and has different mechanisms to kill that bacteria. For example, doxycycline inhibits

1325-405: The echinocandin family of drugs and fluconazole . While algae are commonly not thought of as pathogens, the genus Prototheca causes disease in humans . Treatment for protothecosis is currently under investigation, and there is no consistency in clinical treatment. Many pathogens are capable of sexual interaction. Among pathogenic bacteria , sexual interaction occurs between cells of

1378-449: The tobacco mosaic virus which caused scientist Martinus Beijerinck to coin the term "virus" in 1898. Bacterial plant pathogens cause leaf spots, blight, and rot in many plant species. The most common bacterial pathogens for plants are Pseudomonas syringae and Ralstonia solanacearum , which cause leaf browning and other issues in potatoes, tomatoes, and bananas. Fungi are another major pathogen type for plants. They can cause

1431-676: The Clustered Regularly Interspaced Short Palindromic Repeats ( CRISPR ) associated with bacteriophages, removing the viral genes to avoid infection. This mechanism has been modified for artificial CRISPR gene editing . Plants can play host to a wide range of pathogen types, including viruses, bacteria, fungi, nematodes, and even other plants. Notable plant viruses include the papaya ringspot virus , which has caused millions of dollars of damage to farmers in Hawaii and Southeast Asia, and

1484-683: The PANoptosis-inducing agents TNF and IFN-γ can reduce tumor size in preclinical models. The combination of the nuclear export inhibitor selinexor and IFN can also cause PANoptosis and regress tumors in preclinical models. More recent evidence suggests that NLRC5 - NLRP12 -mediated PANoptosis is activated by heme , which can be released by red blood cell lysis during infection or inflammatory disease, in combination with specific components of infection or cellular damage. Deletion of NLRP12 protects against pathology in animal models of hemolytic disease, suggesting this could also act as

1537-508: The bodily fluids or airborne droplets of infected hosts, indirect contact involving contaminated areas/items, or transfer by living vectors like mosquitos and ticks . The basic reproduction number of an infection is the expected number of subsequent cases it is likely to cause through transmission. Virulence involves pathogens extracting host nutrients for their survival, evading host immune systems by producing microbial toxins and causing immunosuppression . Optimal virulence describes

1590-407: The colon's inner surface), ulcerations and hemorrhage . Symptoms suggestive of colitis are worked-up by obtaining the medical history , a physical examination and laboratory tests ( CBC , electrolytes , stool culture and sensitivity, stool ova and parasites et cetera). Additional tests may include medical imaging (e.g. abdominal computed tomography , abdominal X-rays ) and an examination with

1643-401: The composition and behavior of the microbiome has been considered as a possible therapy for both induction and maintenance of remission in people with Crohn's disease and ulcerative colitis. A Cochrane review in 2020 did not find clear evidence of improved remission likelihood, nor lower adverse events, in people with Crohn's disease, following probiotic treatment. For ulcerative colitis, there

PANoptosis - Misplaced Pages Continue

1696-561: The deletion of caspase-8 and RIPK3 prevents cell death. During Francisella novicida infection, PANoptosis occurs through the AIM2-PANoptosome. PANoptosis has also been observed in Salmonella enterica and Listeria monocytogenes infections, where the combined loss of caspases and RIPK3 significantly protects cells from death. PANoptosis also occurs in fungal infections, including those caused by Candida albicans and Aspergillus fumigatus . Treatment of cancer cells with

1749-473: The efficacy of IFN treatment during infection and resulting in morbidity and mortality. This suggests that inhibiting ZBP1 may improve the therapeutic efficacy of IFN therapy during SARS-CoV-2 infection and possibly other inflammatory conditions where IFN-mediated cell death and pathology occur. In Yersinia pseudotuberculosis infections, PANoptosis is induced through the RIPK1-PANoptosome, and

1802-772: The highest disease burdens , killing 1.6 million people in 2021, mostly in Africa and Southeast Asia. Bacterial pneumonia is primarily caused by Streptococcus pneumoniae , Staphylococcus aureus , Klebsiella pneumoniae , and Haemophilus influenzae . Foodborne illnesses typically involve Campylobacter , Clostridium perfringens , Escherichia coli , Listeria monocytogenes , and Salmonella . Other infectious diseases caused by pathogenic bacteria include tetanus , typhoid fever , diphtheria , and leprosy . Fungi are eukaryotic organisms that can function as pathogens. There are approximately 300 known fungi that are pathogenic to humans, including Candida albicans , which

1855-515: The host genome, and hijack the host's machinery to produce hundreds of new viruses until the cell bursts open to release them for additional infections. The lytic cycle describes this active state of rapidly killing hosts, while the lysogenic cycle describes potentially hundreds of years of dormancy while integrated in the host genome. Alongside the taxonomy organized by the International Committee on Taxonomy of Viruses (ICTV),

1908-458: The immune system of the host, so that when the potential host encounters the virus in the wild, the immune system can defend against infection quickly. Vaccines designed against viruses include annual influenza vaccines and the two-dose MMR vaccine against measles , mumps , and rubella . Vaccines are not available against the viruses responsible for HIV/AIDS , dengue , and chikungunya . Treatment of viral infections often involves treating

1961-420: The immune system's efforts to kill the pathogen, such as feverishly high body temperatures meant to denature pathogenic cells. Despite many attempts, no therapy has been shown to halt the progression of prion diseases . A variety of prevention and treatment options exist for some viral pathogens. Vaccines are one common and effective preventive measure against a variety of viral pathogens. Vaccines prime

2014-572: The levels of expression for other genes, such as those encoding virulence factors. Infection by fungal pathogens is treated with anti-fungal medication. Athlete's foot , jock itch , and ringworm are fungal skin infections that are treated with topical anti-fungal medications like clotrimazole . Infections involving the yeast species Candida albicans cause oral thrush and vaginal yeast infections . These internal infections can either be treated with anti-fungal creams or with oral medication. Common anti-fungal drugs for internal infections include

2067-583: The naked eye. Worms live and feed in their living host, acquiring nutrients and shelter in the digestive tract or bloodstream of their host. They also manipulate the host's immune system by secreting immunomodulatory products which allows them to live in their host for years. Helminthiasis is the generalized term for parasitic worm infections, which typically involve roundworms , tapeworms , and flatworms . While bacteria are typically viewed as pathogens, they serve as hosts to bacteriophage viruses (commonly known as phages). The bacteriophage life cycle involves

2120-433: The non-lytic apoptosis pathway, these mechanisms are separate processes that are associated with distinct triggers, protein complexes, and execution pathways. Inflammasome -dependent pyroptosis involves inflammatory caspases, including caspase-1 and caspase-11 in mice, and caspases-1, - 4 , and - 5 in humans, and is executed by gasdermin D . In contrast, necroptosis occurs via RIPK1/3-mediated MLKL activation, which

2173-453: The pollutant coal dust , genetic disorders like sickle cell disease , and autoimmune diseases like lupus . Pathogenicity is the potential disease-causing capacity of pathogens, involving a combination of infectivity (pathogen's ability to infect hosts) and virulence (severity of host disease). Koch's postulates are used to establish causal relationships between microbial pathogens and diseases. Whereas meningitis can be caused by

PANoptosis - Misplaced Pages Continue

2226-428: The presence of any epithelial damage (erosions and ulcerations). Histopathology findings generally associated with chronic colitis include: Other findings include basal plasmacytosis and mucin depletion. Histopathology findings generally associated with active colitis include: There are many types of colitis. They are usually classified by the cause. Types of colitis include: A subtype of infectious colitis

2279-822: The prions to herbivorous animals . Additionally, wood, rocks, plastic, glass, cement, stainless steel, and aluminum have been shown binding, retaining, and releasing prions, showcasing that the proteins resist environmental degradation. Prions are best known for causing transmissible spongiform encephalopathy (TSE) diseases like Creutzfeldt–Jakob disease (CJD), variant Creutzfeldt–Jakob disease (vCJD), Gerstmann–Sträussler–Scheinker syndrome (GSS), fatal familial insomnia (FFI), and kuru in humans. While prions are typically viewed as pathogens that cause protein amyloid fibers to accumulate into neurodegenerative plaques, Susan Lindquist led research showing that yeast use prions to pass on evolutionarily beneficial traits. Not to be confused with virusoids or viruses, viroids are

2332-477: The same host cell. This process involves pairing of homologous genomes and recombination between them by a process referred to as multiplicity reactivation. The herpes simplex virus , human immunodeficiency virus , and vaccinia virus undergo this form of sexual interaction. These processes of sexual recombination between homologous genomes supports repairs to genetic damage caused by environmental stressors and host immune systems. Colitis Colitis

2385-589: The same species by the process of genetic transformation . Transformation involves the transfer of DNA from a donor cell to a recipient cell and the integration of the donor DNA into the recipient genome through genetic recombination . The bacterial pathogens Helicobacter pylori , Haemophilus influenzae , Legionella pneumophila , Neisseria gonorrhoeae , and Streptococcus pneumoniae frequently undergo transformation to modify their genome for additional traits and evasion of host immune cells. Eukaryotic pathogens are often capable of sexual interaction by

2438-530: The smallest known infectious pathogens. Viroids are small single-stranded, circular RNA that are only known to cause plant diseases, such as the potato spindle tuber viroid that affects various agricultural crops. Viroid RNA is not protected by a protein coat, and it does not encode any proteins, only acting as a ribozyme to catalyze other biochemical reactions. Viruses are generally between 20–200 nm in diameter. For survival and replication, viruses inject their genome into host cells, insert those genes into

2491-688: The soil-associated species Prototheca wickerhami . Bacteria are single-celled prokaryotes that range in size from 0.15 and 700 μM. While the vast majority are either harmless or beneficial to their hosts, such as members of the human gut microbiome that support digestion, a small percentage are pathogenic and cause infectious diseases. Bacterial virulence factors include adherence factors to attach to host cells, invasion factors supporting entry into host cells, capsules to prevent opsonization and phagocytosis , toxins, and siderophores to acquire iron. The bacterial disease tuberculosis , primarily caused by Mycobacterium tuberculosis , has one of

2544-575: The stage of the disease), persistent hemorrhagic diarrhea with pus either present or absent in the stools , fecal incontinence , flatulence , fatigue , loss of appetite and unexplained weight loss . More severe symptoms may include: shortness of breath , a fast or irregular heartbeat and fever . Other less common or rare non-specific symptoms that may accompany colitis include: arthritis , mouth ulcers , painful, red and swollen skin and irritated, bloodshot eyes . Signs seen on colonoscopy include: colonic mucosal erythema (redness of

2597-537: The symptoms of the infection, rather than providing medication to combat the viral pathogen itself. Treating the symptoms of a viral infection gives the host immune system time to develop antibodies against the viral pathogen. However, for HIV, highly active antiretroviral therapy (HAART) is conducted to prevent the viral disease from progressing into AIDS as immune cells are lost. Much like viral pathogens, infection by certain bacterial pathogens can be prevented via vaccines. Vaccines against bacterial pathogens include

2650-461: The synthesis of new proteins in both gram-negative and gram-positive bacteria , which makes it a broad-spectrum antibiotic capable of killing most bacterial species. Due to misuse of antibiotics, such as prematurely ended prescriptions exposing bacteria to evolutionary pressure under sublethal doses, some bacterial pathogens have developed antibiotic resistance . For example, a genetically distinct strain of Staphylococcus aureus called MRSA

2703-400: The therapeutic potential of modulating this pathway. Pathogen This is an accepted version of this page In biology , a pathogen ( Greek : πάθος , pathos "suffering", "passion" and -γενής , -genēs "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent , or simply

SECTION 50

#1732794152804

2756-420: The viruses injecting their genome into bacterial cells, inserting those genes into the bacterial genome, and hijacking the bacteria's machinery to produce hundreds of new phages until the cell bursts open to release them for additional infections. Typically, bacteriophages are only capable of infecting a specific species or strain. Streptococcus pyogenes uses a Cas9 nuclease to cleave foreign DNA matching

2809-444: Was conducted by Huang et al. that analyzed specific genes and biological markers that are associated with the risk of colon cancer development in patients with colitis. The results showed a correlation between certain biomarkers and the development of disease. Colitis is common in parts of the world where helminthic colonisation is rare, and uncommon in those areas where most people carry worms. Infections with helminths may alter

#803196