Cytokines in Febrile Diseases

Inflammation in the Peripheral Nervous System after Injury

Nerve injury is a common condition that occurs as a result of trauma, iatrogenic injury, or long-lasting stimulation. Unlike the central nervous system (CNS), the peripheral nervous system (PNS) has a strong capacity for self-repair and regeneration. Peripheral nerve injury results in the degeneration of distal axons and myelin sheaths. Macrophages and Schwann cells (SCs) can phagocytose damaged cells. Wallerian degeneration (WD) makes the whole axon structure degenerate, creating a favorable regenerative environment for new axons. After nerve injury, macrophages, neutrophils and other cells are mobilized and recruited to the injury site to phagocytose necrotic cells and myelin debris. Pro-inflammatory and anti-inflammatory factors involved in the inflammatory response provide a favorable microenvironment for peripheral nerve regeneration and regulate the effects of inflammation on the body through relevant signaling pathways. Previously, inflammation was thought to be detrimental to the body, but further research has shown that appropriate inflammation promotes nerve regeneration, axon regeneration, and myelin formation. On the contrary, excessive inflammation can cause nerve tissue damage and pathological changes, and even lead to neurological diseases. Therefore, after nerve injury, various cells in the body interact with cytokines and chemokines to promote peripheral nerve repair and regeneration by inhibiting the negative effects of inflammation and harnessing the positive effects of inflammation in specific ways and at specific times. Understanding the interaction between neuroinflammation and nerve regeneration provides several therapeutic ideas to improve the inflammatory microenvironment and promote nerve regeneration.

Infection of domestic pigs with a genotype II potent strain of ASFV causes cytokine storm and lymphocyte mass reduction

The whole-genome sequence of an African swine fever virus (ASFV) strain (HuB/HH/2019) isolated from Hubei, China, was highly similar to that of the Georgia 2007/1 strain ASFV. After infection with strong strains, domestic pigs show typical symptoms of infection, including fever, depression, reddening of the skin, hemorrhagic swelling of various tissues, and dysfunction. The earliest detoxification occurred in pharyngeal swabs at 4 days post-infection. The viral load in the blood was extremely high, and ASFV was detected in multiple tissues, with the highest viral loads in the spleen and lungs. An imbalance between pro- and anti-inflammatory factors in the serum leads to an excessive inflammatory response in the body. Immune factor expression is suppressed without effectively eliciting an immune defense. Antibodies against p30 were not detected in acutely dead domestic pigs. Sequencing of the peripheral blood mononuclear cell transcriptome revealed elevated transcription of genes associated with immunity, defense, and stress. The massive reduction in lymphocyte counts in the blood collapses the body's immune system. An excessive inflammatory response with a massive reduction in the lymphocyte count may be an important cause of mortality in domestic pigs. These two reasons have inspired researchers to reduce excessive inflammatory responses and stimulate effective immune responses for future vaccine development.

Antipyretic effect of inhaled Tetrastigma hemsleyanum polysaccharide on substance and energy metabolism in yeast-induced pyrexia mice via TLR4/NF-κb signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Tetrastigma hemsleyanum Diels et Gilg, is one of the perennial evergreen plants with grass vine, which has obvious curative effect on severe infectious diseases. Although Tetrastigma hemleyanum has long been recognized for its capacity of antipyretic and antitoxic, its specific mechanism is unknown.

AIM OF THE STUDY

To evaluate the antipyretic effect of Tetrastigma hemleyanum polysaccharide (THP) on mice with dry yeast-induced fever, and to explore its specific antipyretic mechanism.

METHODS

In this study, THP was administered by aerosol in febrile mice. The rectal temperatures of treated animals were monitored at different time points. Histopathological evaluation and various inflammatory indexes were used to assess inflammatory damage. The concentration variations of the central neurotransmitter, endocrine system, substance and energy metabolism indicators were measured to explore the physiological mechanism. Quantitative real-time PCR, Western bolt and Immunohistochemistry were performed to identify the correlation between antipyretic and TLR4/NF-κB signaling pathway.

RESULTS

THP reduced the body temperature of febrile mice induced by dry yeast, as well as the levels of thermogenic cytokines and downregulated the contents of thermoregulatory mediators. THP alleviated the pathological damage of liver and hypothalamus caused by fever. In addition, THP decreased the secretion of thyroid hormone, substance and energy metabolism related indicators. Furthermore, THP significantly suppressed TLR4/NF-κB signaling pathway-related indicators.

CONCLUSIONS

In conclusion, our results suggest that inhaled THP exerts antipyretic effect by mediating the thermoregulatory mediator, decreasing the content of pyrogenic factors to lower the body temperature, and eventually restoring the high metabolic level in the body to normal via inhibiting TLR4/NF-κB signaling pathway. The study provides a reasonable pharmacodynamic basis for the treatment of polysaccharide in febrile-related diseases.

Fever of unknown origin associated with immune checkpoint inhibitors

Since the approval for the treatment of melanoma in 2014, immune checkpoint inhibitors (ICIs) have revolutionized the therapy pattern across various malignancies. Coinciding with their frequent usage, their adverse effects, including fever, cannot be neglected. In the context of cancer diseases and cancer treatments, fever of unknown origin (FUO), which has long posed a challenge for clinicians in terms of diagnosis and management, brings forth new connotation and significance. In this paper review, we present the concept of ICIs-associated FUO, consider activated immune system and elevated cytokines as common mechanisms by which ICIs induce fever and various immune-related adverse events (irAEs), summarize and compare the primary etiologies of ICI-associated FUO, and compare it with conventional types of FUO.

Contamination of bacterial extracellular vesicles (bEVs) in human urinary extracellular vesicles (uEVs) samples and their effects on uEVs study

Bacterial overgrowth is common for improperly stored urine. However, its effects on human urinary extracellular vesicles (uEVs) study had not been previously examined nor documented. This study investigated the presence of bacterial EVs (bEVs) contaminated in uEVs samples and their effects on uEVs study. Nanoscale uEVs were isolated from normal human urine immediately after collection (0-h) or after 25°C-storage with/without preservative (10 mM NaN3) for up to 24-h. Turbidity, bacterial count and total uEVs proteins abnormally increased in the 8-h and 24-h-stored urine without NaN3. NanoLC-ESI-LTQ-Orbitrap MS/MS identified 6-13 bacterial proteins in these contaminated uEVs samples. PCR also detected bacterial DNAs in these contaminated uEVs samples. Besides, uEVs derived from 8-h and 24-h urine without NaN3 induced macrophage activation (CD11b and phagocytosis) and secretion of cytokines (IFN-α, IL-8, and TGF-β) from macrophages and renal cells (HEK-293, HK-2, and MDCK). All of these effects induced by bacterial contamination were partially/completely prevented by NaN3. Interestingly, macrophage activation and cytokine secretion were also induced by bEVs purified from Escherichia coli. This study clearly shows evidence of bEVs contamination and their effects on human uEVs study when the urine samples were inappropriately stored, whereas NaN3 can partially/completely prevent such effects from the contaminated bEVs.