Tissue Pathology - An Overview

Introduction:

Cell proliferation could be due to both intrinsic and extrinsic factors. This further stimulates or inhibits cell growth. Cell growth can be marked by growth factors, injury, or deformation of tissues. Hence, cell inhibitors and the deficiency of these factors cause cell growth. Invasion of pathogens directly or indirectly into the system causes illness. The primary responsibility of these pathogens is inflammation in host cells.

What Are the Extrinsic Factors Influencing Pathogens for Infection?

External factors influencing the normal biology of internal cells are:

• Atmospheric Gas Constitution: Certain gasses aid the proliferation or retardation of pathogens. For example, carbon dioxide regulates the activity of certain microbes as well as controls the growth of specific microbes.

• Hygiene Factors: Proper disinfected environment stops pathogenic activity.

• Cross-contamination: If proper sterilization is not maintained, the chances of cross-infection are high.

• Temperature: Every rise in temperature raises the catalytic activity of pathogens.

• Humidity: High water content in the atmospheric gas promotes pathogens.

Other microbes in the atmosphere retards the growth of pathogens by producing their proteins which act as an antibiotic and bacteriocin in nature.

What Are the Intrinsic Factors Promoting Pathogenic Activity in the Body?

Intrinsic factors of pathogenic activity are:

• pH.

• Food microbiology.

• Nutritive value.

• Water activity.

• Temperature.

• Chemicals.

• Toxicity or infection.

What Are the Pathogenic Factors Affecting Tissue Repair?

Pathogenic toxins can alter wound healing. It could be both extrinsic and intrinsic factors.

• Extrinsic Factors: This is primarily caused by infection and further delays the reparative process.

• Intrinsic Factors: Like the anti-inflammatory response of host cells.

• Nutritional Factors: Delayed wound healing occurs due to a deficiency of vitamins and proteins. For example, vitamin C deficiency inhibits collagen synthesis, delaying wound healing.

• Mechanical Factors: Foreign objects and mechanical pressure delay healing.

• Extent of Injury: It determines the span of the healing process. Followed by scar formation (fibrosis).

• Site of Injury: This determines the tissue regeneration process.

• Production of Collagen: Excessive production of collagen or raised granulation tissue above the repaired scar. For example, keloid.

• Underlying Conditions: Underlying chronic inflammatory disease, which develops other illnesses. For example, rheumatoid arthritis.

What Are the Pathological Conditions Caused by Unknown Factors?

Illness of undefined etiology is seen in both acute and chronic conditions.

Acute Conditions:

• Rheumatoid Arthritis: It causes inflammation in the joints. This condition is caused by viruses such as Epstein- Barr virus, Rubella, and Parvovirus B19.

• Alzheimer's Disease: Alzheimer's disease is caused by the degeneration of neurons in the brain. It causes dementia and is more prevalent in senile patients.

Chronic Conditions:

• Cervical or Penile Cancer: Seen in patients with multiple sexual partners.

• Basal Cell Carcinoma of the Skin: Ultraviolet radiation seems to be a potent carcinogen.

Do All Pathogens Cause Tissue Damage?

No, not all pathogens cause tissue damage. Pathogens can be symptomatic or asymptomatic in nature. Different pathogens show different characteristics. Microbes replicating themselves in host cells are found to be less toxic.

Pathogens of Viral Origin: There are viruses that merely cause diseases, like enterovirus and reovirus. Cell death or programmed cell death or apoptosis can be observed in Human immunodeficiency virus (HIV), Adenovirus, Herpes virus, Influenza, and Picornavirus. Rickettsiae and Chlamydia also damage the cells. Viruses like Chlamydia, Mycoplasma, Mycobacteria, Rickettsiae, and Brucella do not form toxins, hence causing any tissue damage.

Pathogens of Bacterial Origin: Infections like poliomyelitis and influenza show mild symptoms during antibody response. The human body is made up of many bacterias, especially in the mouth, gut, and intestines. The interference of these bacteria has been of beneficiary use and less toxicity. Bacterias in the nasopharynx region, namely Meningococci and Pneumococci, have proven to be harmless. But there are pathogens that do cause toxicity, like Mycobacterium lepra, leprosy, and tubercle bacilli. These bacterias in the bloodstream cause damage and kill the macrophages and replicate. Certain bacteria like Staphylococci and Streptococci show phagocytosis. Staphylococcus causes food infection. Plaque formation in teeth is caused by Streptococcus mutans. Certain strains of Staphylococcus aureus cause multi-system diseases like toxic shock syndrome (TSS). Shigella dysenteriae, which causes watery diarrhea, can replicate further to cause multi-system disorders, like renal failure, thrombocytopenia, microangiopathic hemolytic anemia, hemorrhagic colitis (HC), and hemolytic urea syndrome (HUS).

It is observed that the toxins released from bacteria have high molecular weight and are antigenic, whereas the fungal toxins released are of low molecular weight and are not antigenic. The presence of protein toxins (enzymes) released from Gram-positive and Gram-negative bacteria shows phagocytosis.

What Are the Pathogens Causing Infection Through External Mediums?

Bacillus anthracis found in bovine animals. This is ingested through spores of Anthrax toxin. This infection can cause edema and septicemia and eventually lead to death. Though the infection is predominant in animals, cross-infection through wool and hair, bovine bones of infected animals passed through transplantation of bone during the surgical procedure, and fertilizer cannot be discarded.

Clostridium tetani spores can germinate in the infected wound of humans. Spores can be found in soil, feces, necrotized tissue, septical abortion, or the umbilical stump of newborns.

C.botulinum is found in soil and vegetables; consumption can cause neurological toxicity like vertigo, cranial nerve palsies, and respiratory failure leading to death. Toxins produced in some food particles like mushrooms cause hallucinations. Glandular fever causing enlargement of the spleen is seen in the pathogenicity of the immune system (swelling of lymph nodes).

What Are the Symptoms of Tissue Pathology?

• Edema.

• Stress.

• Hemorrhage.

• Shock.

• Placental inflammation or fetal death.

• Cross-infection.

• Toxicity.

• Multi-organ dysfunction.

• Scars.

• Tumors.

• Immunosuppression.

• Hormonal imbalance.

• Cancer (for example, Papillomavirus, Herpes virus, Leukemia virus).

• Electrolyte imbalance.

• Morbidity and mortality.

What Are the Tests for Diagnosis of Pathogens?

• Genomic Sequencing: These tests are used to study genetic changes. There are various methods to carry out this study. Due to their structural complexity, only small stretches of DNA strands can be studied at a time. One such method is the ‘clone-by-clone’ approach. Other methods, like breaking the genomic sequence into tiny pieces called the ‘whole genome shotgun’ method, are also practiced. This method is tiring as it takes longer to decode the DNA.

Modern PCR, multiplex PCR (mPCR), quantitative PCR(qPCR) or RT-PCR, and droplet PCR: These tests evaluate bacterial and viral cultures.

• Magnetic Resonance Imaging (MRI): Magnetic resonance imaging is used to detect developmental anomalies, trauma, tumors, stroke, multiple sclerosis, dementia, and other infections.

• Culture of the Samples: Samples like blood, sputum, urine, and cerebrospinal fluid are used to detect the presence of pathogens.

• Colorimetric Sensors: It is used to detect nanoparticles.

What Are the Treatment Option for Tissue Pathogenicity?

Administration of drugs, vaccines, gene editing, stem cell therapy, transplant, and radiation therapy in debilitating illnesses is the cure.

Antibacterial Treatments Are:

• Erythromycin: Treated against Staphylococci, Streptococci, and Pneumococci.

• Clarithromycin: Used against Mycobacterium avium complex(AVM).

• Roxithromycin: Treated against Legionella.

Antiviral Treatments Are:

• Idoxuridine: Used for herpes encephalitis and herpetic ulcerations of the cornea.

• Acyclovir: Treated against the Herpes virus.

Antimalarial Treatments Are:

• Chloroquine: Treated against malaria.

Antiprotozoal Treatments Are:

• Metronidazole: Treated for Giardia lamblia.

• Furazolidone: Used against Trichomoniasis.

• Suramin Sodium: Treated for African trypanosomiasis (sleeping sickness).

Antimicrobial Treatments Are:

• Trimethoprim: For treating Streptococci, Staphylococcus aureus, Salmonella Shigella, and Proteus.

• Nitrofurantoin, Furazolidone, Nitrofurazone and Nifuroxime: Used against Gram-positive and Gram-negative bacteria, Candida albicans and Trichomonas vaginalis.

Antifungal Treatments Are:

• Clotrimazole: Used for fungal infections like ringworm and athlete’s foot which causes persistent itching.

• Amphotericin B: Used against infections of Blastomycosis, Histoplasmosis, and Cryptococcosis.

Conclusion:

Pathogenicity of tissues could be trauma-induced, from external sources like soil, vegetables, animals, and air, and from internal primary or secondary infections. Advancement in the field of bio-nano engineering and clinical research and trial of new drugs has contributed to the curability of such pathogenicity.