Melittin as a safe compound to BALB/c mice immune system; a tiered approach immunotoxicity screening.

BACKGROUND: Maintenance of immune system integrity is a vital requirement to protect human body against pathogens/cancers. Natural compounds have long been used due to their benefits for the immune system. One of which is bee venom that contains a peptide called melittin having antimicrobial and anticancer effects. Since a limited number of studies regarding the effects of melittin on the immune system have been carried out, we aimed to evaluate the effects of melittin on BALB/c mice immune system parameters. METHODS: Female BALB /c mice were treated intraperitoneally (i.p) with 0.75 and 1.5 mg/kg doses of melittin for 14 days (5 doses per week). The negative control group received i.p normal saline whereas the positive controls received i.p 20 mg/kg cyclophosphamide (CYP). Immunological parameters such as hematological parameters, delayed-type hypersensitivity (DTH), hemagglutination titer (HA), spleen cellularity, splenocytes proliferation, as well as spleen and bone marrow histopathological assessment were evaluated. RESULTS: Our findings showed that melittin has no gross pathological effect on the spleen and bone marrow. It was also demonstrated that melittin has no any significant effect on hematological parameters. Melittin did not cause any significant changes to proliferation response of splenocytes to PHA and LPS, spleen cellularity, DTH response, as well as the production of anti-SRBC antibodies. According to our results, melittin at 0.75 and 1.5 mg/kg doses could not induce significant changes on immune parameters and as a result, melittin was found to be safe for the mice immune system.

A Histologic Timeline of a Delayed Hypersensitivity Reaction after the COVID-19 Pfizer Booster.

A 54-year-old man presented with worsening bilateral rashes on legs and arms 7 days after receiving his BNT162b2 mRNA COVID-19 (Pfizer) vaccine booster. He developed burning on his palms about 5 days after receiving the booster. On day 6, he observed significant edema on his fingers and palms in addition to thin erythematous papules on his forearms. On day 7, he developed edema on his bilateral dorsal feet, and thin erythematous plaques on his shins. He stated that the rashes were pruritic. He had no rashes following the first two doses of the Pfizer vaccine. He denied having any history of skin disease, autoimmune disease, or allergies. Physical examination revealed multiple thin erythematous papules coalescing into thin plaques on his flexor forearms, and thin erythematous plaques on his dorsal feet (Figure 1). Three 4-mm punch biopsies were performed on his left flexor forearm. The biopsies were carried out at papules present for different lengths of time. Papules at biopsy sites "A," "B," and "C" were present for approximately 24-36 hours, 12-18 hours, and 3-6 hours, respectively (Figure 1).

Delayed localized hypersensitivity reactions to COVID-19 mRNA vaccines: a 6-month retrospective study.

Several individuals have developed delayed localized cutaneous vaccine reactions to the two novel mRNA Covid-19 vaccines. Clinical and histopathologic results of this case series study confirm that the localized injection-site reactions to the mRNA COVID-19 vaccines are delayed hypersensitivity reactions that, unlike immediate hypersensitivity reactions, are not a contraindication to vaccination.

Clinical and histopathological spectrum of delayed adverse cutaneous reactions following COVID-19 vaccination.

BACKGROUND: As more people become vaccinated against the SARS-CoV-2 virus, reports of delayed cutaneous hypersensitivity reactions are beginning to emerge. METHODS: In this IRB-approved retrospective case series, biopsy specimens of potential cutaneous adverse reactions from the Pfizer-BioNTech or Moderna mRNA vaccine were identified and reviewed. Clinical information was obtained through the requisition form, referring clinician, or medical chart review. RESULTS: Twelve cases were included. Histopathological features from two injection-site reactions showed a mixed-cell infiltrate with eosinophils and a spongiotic dermatitis with eosinophils. Three biopsy specimens came from generalized eruptions that showed interface changes consistent with an exanthematous drug reaction. Three biopsy specimens revealed a predominantly spongiotic pattern, consistent with eczematous dermatitis. Small-vessel vascular injury was seen in two specimens, which were diagnosed as urticarial vasculitis and leukocytoclastic vasculitis, respectively. There were two cases of new-onset bullous pemphigoid supported by histopathological examination and direct immunofluorescence studies. Eosinophils were seen in 10 cases. CONCLUSIONS: Dermatopathologists should be aware of potential cutaneous adverse reactions to mRNA-based COVID-19 vaccines. Histopathological patterns include mixed-cell infiltrates, epidermal spongiosis, and interface changes. Eosinophils are a common finding but are not always present. Direct immunofluorescence studies may be helpful for immune-mediated cutaneous presentations such as vasculitis or bullous pemphigoid.

Lactoferrin as an Adjuvant for the Generation of Delayed Type Hypersensitivity to Orally Administered Antigen.

OBJECTIVE: The aim of this investigation was to evaluate the property of bovine lactoferrin (LF) in the generation of delayed type hypersensitivity (DTH) as an oral adjuvant during immunization with ovalbumin (OVA) and BCG. METHODS: LF admixed with OVA or BCG was used for immunization of CBA or C57BL/6 mice when given via oral or subcutaneous routes. Elicited DTH response was measured post immunization. Inhibition studies using mannose or galactose were accomplished by gavage prior to oral administration of antigens. LF was also examined for effects on BCG uptake by bone marrow derived macrophages (BMM). RESULTS: LF at doses of 1.0 mg and 10.0 mg, admixed with OVA (10.0 mg), significantly enhanced the antigen-specific DTH reaction. The stimulatory effects of LF were inhibited by the oral pretreatment of mice with 50.0 mg of mannose but not galactose. LF also enhanced the DTH reaction to orally administered BCG. LF enhanced uptake of BCG by BMM in a dose-dependent manner. CONCLUSION: LF was able to augment development of DTH when orally administered with OVA or BCG antigens. Inhibition studies suggest the involvement of the receptor with an affinity to mannose in mediation of the adjuvant effect. LF augmentation of the DTH response was partially effective when given in advance of oral delivery of the antigen; this effect could also be saturated by mannose. BCG studies provide preliminary evidence for LF in the potential augmentation of oral vaccination to prevent mycobacterial infection. In vitro experiments provide evidence that LF plays a role in modulation of antigen presenting cell activation.

Immunomodulatory role of reactive oxygen species and nitrogen species during T cell-driven neutrophil-enriched acute and chronic cutaneous delayed-type hypersensitivity reactions.

Rationale: Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are important regulators of inflammation. The exact impact of ROS/RNS on cutaneous delayed-type hypersensitivity reaction (DTHR) is controversial. The aim of our study was to identify the dominant sources of ROS/RNS during acute and chronic trinitrochlorobenzene (TNCB)-induced cutaneous DTHR in mice with differently impaired ROS/RNS production. Methods: TNCB-sensitized wild-type, NADPH oxidase 2 (NOX2)- deficient (gp91phox-/-), myeloperoxidase-deficient (MPO-/-), and inducible nitric oxide synthase-deficient (iNOS-/-) mice were challenged with TNCB on the right ear once to elicit acute DTHR and repetitively up to five times to induce chronic DTHR. We measured ear swelling responses and noninvasively assessed ROS/RNS production in vivo by employing the chemiluminescence optical imaging (OI) probe L-012. Additionally, we conducted extensive ex vivo analyses of inflamed ears focusing on ROS/RNS production and the biochemical and morphological consequences. Results: The in vivo L-012 OI of acute and chronic DTHR revealed completely abrogated ROS/RNS production in the ears of gp91phox-/- mice, up to 90 % decreased ROS/RNS production in the ears of MPO-/- mice and unaffected ROS/RNS production in the ears of iNOS-/- mice. The DHR flow cytometry analysis of leukocytes derived from the ears with acute DTHR confirmed our in vivo L-012 OI results. Nevertheless, we observed no significant differences in the ear swelling responses among all the experimental groups. The histopathological analysis of the ears of gp91phox-/- mice with acute DTHRs revealed slightly enhanced inflammation. In contrast, we observed a moderately reduced inflammatory immune response in the ears of gp91phox-/- mice with chronic DTHR, while the inflamed ears of MPO-/- mice exhibited the strongest inflammation. Analyses of lipid peroxidation, 8-hydroxy-2'deoxyguanosine levels, redox related metabolites and genomic expression of antioxidant proteins revealed similar oxidative stress in all experimental groups. Furthermore, inflamed ears of wild-type and gp91phox-/- mice displayed neutrophil extracellular trap (NET) formation exclusively in acute but not chronic DTHR. Conclusions: MPO and NOX2 are the dominant sources of ROS/RNS in acute and chronic DTHR. Nevertheless, depletion of one primary source of ROS/RNS exhibited only marginal but conflicting impact on acute and chronic cutaneous DTHR. Thus, ROS/RNS are not a single entity, and each species has different properties at certain stages of the disease, resulting in different outcomes.

Lesiones costrosas a estudio / Scabby injuries

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Sabra dermatitis: combined features of delayed hypersensitivity and foreign body reaction to implanted glochidia.

A striking dermatitis referred to by its colloquial designation of sabra dermatitis is associated with glochidia inoculation from the Opuntia cactus commonly known as the prickly pear. We report a 45-year-old woman who had an unexpected encounter with a cactus plant during a trip to Texas. She brushed up against the plant and was aware that she had been inoculated with several spines of the plant. Five days later she developed erythematous papules on the digits accompanied by swelling. The biopsy showed a very striking granulomatous reaction pattern within the dermis. There was a linear pattern of necrobiosis, likely representing a tract of inoculation injury palisaded by histiocytes including multinucleated forms. This necrobiotic tract demonstrated retained glochidia, each measuring roughly 40 to 70 microns in diameter. The nature of the inflammatory response is one that combines features of classic delayed hypersensitivity and an innate foreign body response. The glochidia are capable of eliciting a T cell mediated immune response; it is reasonable to assume that a Th1 cytokine signal is responsible for the unique pattern of inflammation including the secondary influx of neutrophils and relative lack of tissue eosinophilia.

Lichenoid granulomatous dermatitis as a tuberculid in association with spondylitis due to Mycobacterium tuberculosis.

Lichenoid granulomatous dermatitis (LGD) is a histopathologic pattern with a band-like lymphocytic infiltrate, typical of lichenoid dermatitis, combined with dermal histiocytes and granulomatous inflammation. Prior reports have described cases of LGD caused by non-tuberculous mycobacteria, with evidence of intralesional acid-fast bacilli or mycobacterial DNA. Herein, we report a patient with pulmonary and extrapulmonary Mycobacterium tuberculosis infection who developed LGD. No evidence of M. tuberculosis was detected within the cutaneous lesions, suggesting a potential delayed-type hypersensitivity reaction to tuberculosis.

The effect of cytoplasmic crude extracts of Trichophyton verrucosum on cell mediated immunity.

OBJECTIVE: Trichophyton verrucosum is a slow growing dermatophyte responsible for a number of skin diseases such as ringworm, and is characterized by patches of hair loss and thick crusts on the host skin in domestic animals. In this study, we examined the immunomodulatory effects of crude extract of Trichophyton verrucosum (TV)cytoplasm in a mouse model. METHODS: The TV variate was cultured on Sabouraud dextrose agar and the mycelium was grinded by mechanical force. The purified protein was obtained from crude extract of the fungus, and protein concentration was measured by BradFord assay. Six to eight week-female BALB/c mice were divided into three groups: test group, receiving cytoplasmic crude extract plus defibrinated sheep blood; control group, receiving defibrinated sheep blood; and normal group, receiving normal saline. Injections were performed on days 0, 3, 5, 7 and 9 and the mice were sacrificed four days after the last injection. T lymphocyte metabolic activity was examined by methyl thiazol tetrazolium (MTT) assay, and also interleukin-4 (IL-4) and interferon-γ (IFNγ) levels were evaluated by enzyme-linked immunosorbent assay (ELISA). RESULTS: MTT assay showed that the TV extract stimulated lymphocyte metabolic activity. ELISA results showed that despite increase in the level of IFNγ, no changes were observed in IL-4 level. CONCLUSIONS: Results indicated that crude extract of TV cytoplasm may probably act as an immune modulator, which affects Th1 responses. The TV crude extract may be an appropriate agent to induce cellular immunity for combating dermatophytosis infection in animals; and therefore, TV extract may have some potential applications in vaccine/adjuvant technology.

Thimerosal induces skin pseudo-allergic reaction via Mas-related G-protein coupled receptor B2.

BACKGROUND: Thimerosal has been used as a preservative in many products which may cause contact dermatitis. It is the second most common allergen in positive patch test reactions, though being a clinical irrelevant allergen. Thimerosal-induced contact dermatitis is generally considered to be a delayed-type hypersensitivity reaction, but it is difficult to explain the fact that most patients develop an allergic reaction upon first encounter with thimerosal. Recent studies have demonstrated the association between Mas-related G protein coupled receptor X2 (MRGPRX2) and pseudo-allergic reactions which occur at the first contact with stimulation. This suggests the possibility that thimerosal may cause contact dermatitis via MRGPRX2 mediated mechanism. OBJECTIVES: To investigate the role of Mas-related G-protein coupled receptor B2 (MrgprB2)/MRGPRX2 in contact dermatitis induced by thimerosal. METHODS: Thimerosal induced pseudo-allergic reactions via MrgprB2/ MRGPRX2 were investigated using a novel skin pseudo-allergic reaction mouse model, footpad swelling and extravasation assays in vivo and mast cell degranulation assay in vitro. RESULTS: Thimerosal induced contact dermatitis in dorsal skin and footpad swelling in wild-type mice, but had no significant effect in MrgprB2-knockout mice. Thimerosal-induced dermatitis is characterized by infiltration of inflammatory cells and elevation of serum histamine and inflammatory cytokines, rather than elevation of serum IgE level. Thimerosal increased the intracellular Ca2+ concentration in HEK293 cells overexpressing MrgprB2/MRGPRX2. Downregulation of MRGPRX2 resulted in the reduced degranulation of LAD2 human mast cells. CONCLUSIONS: MrgprB2 mediates thimerosal-induced mast cell degranulation and pseudo-allergic reaction in mice. MRGPRX2 may be a key contributor to human contact dermatitis.

Advances in drug allergy, urticaria, angioedema, and anaphylaxis in 2018.

Many notable advances in drug allergy, urticaria, angioedema, and anaphylaxis were reported in 2018. Broad-spectrum antibiotic use and, consequently, antibiotic resistance are widespread, and algorithms to clarify ß-lactam allergy and optimize antibiotic use were described. Meaningful data emerged on the pathogenesis of delayed drug hypersensitivity reactions. Progress not only in defining biomarkers but also in understanding the effect on quality of life and developing better treatments has been made for patients with chronic idiopathic urticaria. Patients with hereditary angioedema (HAE) have gained additional access to highly efficacious therapies, with associated improvements in quality of life, and some progress was made in our understanding of recurrent angioedema in patients with normal laboratory results. Guidelines have defined clear goals to help providers optimize therapies in patients with HAE. The epidemiology and triggers of anaphylaxis and the mechanisms underlying anaphylaxis were elucidated further. In summary, these disorders (and labels) cause substantial burdens for individual persons and even society. Fortunately, publications in 2018 have informed on advancements in diagnosis and management and have provided better understanding of mechanisms that potentially could yield new therapies. This progress should lead to better health outcomes and paths forward in patients with drug allergy, urticaria, HAE, and anaphylaxis.

Invariant natural killer T cells stimulated with cholesteryl glycosides modulate immune responses in allergy and delayed-type hypersensitivity.

Invariant NKT cells were stimulated with cholesteryl O-acyl α-glycosides in the context of CD1d. The activated NKT cells have potential to sustain the homeostasis in the body exposed to excess in either Th1- or Th2-immunity.

Immunological In Vivo and In Vitro Investigations of Aqueous Extract of Stem Bark of Pterocarpus erinaceus Poir (Fabaceae).

BACKGROUND: Macrophages are the first cells to recognize invading foreign bodies and are central to cell mediated and humoral immunity. Therefore, the activation of macrophages is a key event for effective innate and adaptive immunity. Pterocarpus erinaceus has been reported to control infectious diseases, but the mechanism remains to be elucidated. In this study, we demonstrated the immune-modulatory effect of aqueous extract of P. erinaceus using human macrophages and lymphocytes, as well as mice. METHODS: Hot water was used to extract P. erinaceus from the stem bark. Its effect on lymphocytes was measured by evaluating proliferative response and delayed hypersensitivity. Phagocytic activity of macrophages were measured based on neutral red uptake assay, nitric oxide production and myeloperoxidase and phosphatase acid activity. Hematopoietic and infectious activities were analyzed using the effect on infectious stress and chloramphenicol-induced leucopenic mice model. RESULTS: Aqueous extract showed stronger stimulatory effects on the neutral red uptake, production of nitric oxide and phosphatase acid activity in lipopolysaccharide-activated macrophages. In addition, aqueous extract significantly stimulated the proliferation of phytohemagglutinin-activated lymphocytes, enhanced delayed hypersensitivity response to erythrocytes and attenuated infection-induced fever. Furthermore, aqueous extract also significantly increased the rate of recovery of white blood cell levels in chloramphenicol-induced leucopenia mice. CONCLUSIONS: The results suggest that aqueous extract of P. erinaceus stem bark is able to modulate the immune system and has potential effects in clinical conditions when an immune-enhancing and anti-infectious effect is desired.