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).

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.

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.

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 β-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.

Fexofenadine Suppresses Delayed-Type Hypersensitivity in the Murine Model of Palladium Allergy

Palladium is frequently used in dental materials, and sometimes causes metal allergy. It has been suggested that the immune response by palladium-specific T cells may be responsible for the pathogenesis of delayed-type hypersensitivity in study of palladium allergic model mice. In the clinical setting, glucocorticoids and antihistamine drugs are commonly used for treatment of contact dermatitis. However, the precise mechanism of immune suppression in palladium allergy remains unknown. We investigated inhibition of the immune response in palladium allergic mice by administration of prednisolone as a glucocorticoid and fexofenadine hydrochloride as an antihistamine. Compared with glucocorticoids, fexofenadine hydrochloride significantly suppressed the number of T cells by interfering with the development of antigen-presenting cells from the sensitization phase. Our results suggest that antihistamine has a beneficial effect on the treatment of palladium allergy compared to glucocorticoids.

Collagen scaffold microenvironments modulate cell lineage commitment for differentiation of bone marrow cells into regulatory dendritic cells

The microenvironment plays a pivotal role for cell survival and functional regulation, and directs the cell fate determination. The biological functions of DCs have been extensively investigated to date. However, the influences of the microenvironment on the differentiation of bone marrow cells (BMCs) into dendritic cells (DCs) are not well defined. Here, we established a 3D collagen scaffold microenvironment to investigate whether such 3D collagen scaffolds could provide a favourable niche for BMCs to differentiate into specialised DCs. We found that BMCs embedded in the 3D collagen scaffold differentiated into a distinct subset of DC, exhibiting high expression of CD11b and low expression of CD11c, co-stimulator (CD40, CD80, CD83, and CD86) and MHC-II molecules compared to those grown in 2D culture. DCs cultured in the 3D collagen scaffold possessed weak antigen uptake ability and inhibited T-cell proliferation in vitro; in addition, they exhibited potent immunoregulatory function to alleviate allo-delay type hypersensitivity when transferred in vivo. Thus, DCs differentiated in the 3D collagen scaffold were defined as regulatory DCs, indicating that collagen scaffold microenvironments probably play an important role in modulating the lineage commitment of DCs and therefore might be applied as a promising tool for generation of specialised DCs.

Phyllanthin from Phyllanthus amarus inhibits cellular and humoral immune responses in Balb/C mice

BACKGROUND

Phyllanthin found in many Phyllanthus species has various biochemical and pharmacological properties especially on its hepatoprotective effects. However, its effect on the immune system has not been well documented.

PURPOSE

In the present study, phyllanthin isolated from Phyllanthus amarus was investigated for its immunosuppressive effects on various cellular and humoral immune responses in Balb/C mice.

METHODS

Male mice were treated daily at 20, 40 and 100mg/kg of phyllanthin for 14 days by oral gavage. The effects of phyllanthin on cellular immune responses in treated /non treated mice were determined by measuring CD 11b/CD 18 integrin expression, phagocytosis, nitric oxide (NO) production, myeloperoxidase activity (MPO), T and B cells proliferation, lymphocyte phenotyping, serum cytokines production by activated T-cells and delayed type hypersensitivity (DTH). Its effects on humoral immune responses were evaluated by determining the serum levels of lysozyme and ceruloplasmin, and immunoglobulins (IgG and IgM).

RESULTS

Phyllanthin dose-dependently inhibited CD11b/CD18 adhesion, the engulfment of E. coli by peritoneal macrophages molecules, NO and MPO release in treated mice. Phyllanthin caused significant and dose-dependent inhibition of T and B lymphocytes proliferation and down-regulation of the Th1 (IL-2 and IFN-γ) and Th2 (IL-4) cytokines. Phyllanthin at 100mg/kg caused a significant reduction in the percentage expression of CD4⁺ and CD8⁺ in splenocytes and the inhibition was comparable to that of cyclosporin A at 50mg/kg. At 100mg/kg, phyllanthin also dose-dependently exhibited strong inhibition on the sheep red blood cell (sRBC)-induced swelling rate of mice paw in DTH. Significant inhibition of serum levels of ceruloplasmin and lysozyme were observed in mice fed with higher doses (40 and 100mg/kg) of phyllanthin. Anti-sRBC immunoglobulins (IgM and IgG) antibody titer was down-regulated in immunized and phyllanthin-treated mice in a dose-dependent manner with maximum inhibition being observed at 100mg/kg.

CONCLUSION

The strong inhibitory effects of phyllanthin on the cellular and humoral immune responses suggest that phyllanthin may be a good candidate for development into an effective immunosuppressive agent.

Generalized Bullous Fixed Drug Eruption due to Bromhexine

We describe a patient with a generalized bullous form of Fixed Drug Eruption (FDE) induced by bromhexine, a commonly used drug for respiratory symptoms. This is a rare association and generalized bullous FDE is also very rare. We emphasize the importance of patch tests in identifying the culprit drug.

Delayed Allergy to Aminopenicillins: Clinical and Immunological Findings

Aminopenicillins are the most used β-lactam antibiotics. Morbilliform or maculopapular rashes are rather frequent during therapy with aminopenicillins. The pathogenesis of these reactions is often due to a cell-mediated allergy. The aim of this work is to characterize patients with cell-mediated allergy to aminopenicillins and to identify alternative β-lactam drugs that can be safely administered to these patients. We studied 27 subjects affected by cell-mediated allergy to aminopenicillins. The diagnosis was made on the basis of positivity of patch tests with aminopenicillins. These patients then underwent an allergological evaluation (skin and patch tests, oral and/or intramuscular challenge tests) with a wide spectrum of β-lactam antibiotics. Our work highlights the following main characteristics of cell-mediated allergy to aminopenicillins: time elapsing between drug administration and onset of symptoms of about 2 days; the maculopapular rash and delayed appearance of urticaria/angioedema were the most typical symptoms (82.8% of cases); a cross-reactivity with aminocephalosporins is usually absent, or it is limited to cephalexin (in our study, in fact, just 3 out of 20 patients challenged with cephalexin showed a positive oral challenge test); all the β-lactams, other than aminopenicillins, are well tolerated. Patch tests represent a specific diagnostic tool with a good predictive value of identifying alternative drugs that can be safely administered to patients with β-lactam allergy. Our patients could tolerate other β-lactam drugs after a complete allergological evaluation. On the basis of our study, cell-mediated allergy to aminopenicillins should be considered a well-defined nosologic entity.

Antigen-Specific Mammary Inflammation Depends on the Production of IL-17A and IFN-γ by Bovine CD4+ T Lymphocytes

Intramammary infusion of the antigen used to sensitize cows by the systemic route induces a local inflammation associated with neutrophil recruitment. We hypothesize that this form of delayed type hypersensitivity, which may occur naturally during infections or could be induced intentionally by vaccination, can impact the outcome of mammary gland infections. We immunized cows with ovalbumin to identify immunological correlates of antigen-specific mammary inflammation. Intraluminal injection of ovalbumin induced a mastitis characterized by a prompt tissue reaction (increase in teat wall thickness) and an intense influx of leukocytes into milk of 10 responder cows out of 14 immunized animals. The magnitude of the local inflammatory reaction, assessed through milk leukocytosis, correlated with antibody titers, skin thickness test, and production of IL-17A and IFN-γ in a whole-blood antigen stimulation assay (WBA). The production of these two cytokines significantly correlated with the magnitude of the milk leukocytosis following the ovalbumin intramammary challenge. The IL-17A and IFN-γ production in the WBA was dependent on the presence of CD4+ cells in blood samples. In vitro stimulation of peripheral blood lymphocytes with ovalbumin followed by stimulation with PMA/ionomycin allowed the identification by flow cytometry of CD4+ T cells producing either IL-17A, IFN-γ, or both cytokines. The results indicate that the antigen-specific WBA, and specifically IL-17A and IFN-γ production by circulating CD4+ cells, can be used as a predictor of mammary hypersensitivity to protein antigens. This prompts further studies aiming at determining how Th17 and/or Th1 lymphocytes modulate the immune response of the mammary gland to infection.

[DRUG INDUCED EXANTHEMA AND SEVERE CUTANEOUS DRUG REACTIONS]

Cutaneous adverse drug reactions (CADR) are delayed hypersensivities. Their clinical presentation and severity are very diverse ranging from the frequent and benign exanthemas to the rare but severe CADR involving deep organs in the case of drug reaction with eosinophilia and systemic symptoms (DRESS) or leading to skin bulla and epidermal detachment in toxic epidermal necrolysis. The main differential diagnoses are infections, especially viral ones, which could give clinical symptoms identical to those occurring in CADR.

Diagnosis and treatment of leprosy type 1 (reversal) reaction

Leprosy is a chronic granulomatous infection caused by the organism Mycobacterium leprae that primarily affects the skin and peripheral nerves. Leprosy has several distinct clinical presentations ranging from moderate to severe, with the extent of disease generally depending on the host's immune response to the infection. Treatment typically involves antimicrobials (eg, clofazimine, dapsone, rifampin). Once treatment is started, an important aspect of patient care is the recognition of possible reversal reactions. We report the case of a 44-year-old man who repeatedly developed physical findings consistent with a type 1 (reversal) reaction after undergoing multiple treatments for leprosy. A discussion of leprosy along with its clinical manifestations, treatment methods, and management of reversal reactions also is provided.

Tattoo complaints and complications: diagnosis and clinical spectrum

Tattoos cause a broad range of clinical problems. Mild complaints, especially sensitivity to sun, are very common and seen in 1/5 of cases. Medical complications are dominated by allergy to tattoo pigment haptens or haptens generated in the skin, especially in red tattoos but also in blue and green tattoos. Symptoms are major and can be compared to cumbersome pruritic skin diseases. Tattoo allergies and local reactions show distinct clinical manifestations, with plaque-like, excessive hyperkeratotic, ulcero-necrotic, lymphopathic, neuro-sensory, and scar patterns. Reactions in black tattoos are papulo-nodular and non-allergic and associated with the agglomeration of nanoparticulate carbon black. Tattoo complications include effects on general health conditions and complications in the psycho-social sphere. Tattoo infections with bacteria, especially staphylococci, which may be resistant to multiple antibiotics, may be prominent and may progress into life-threatening sepsis. Contaminated tattoo ink is an open-window risk vector that can lead to epidemic tattoo infections across national borders due to contaminated bulk production. Hepatitis B and C and human immunodeficiency virus (HIV) transferred by tattooing remain a significant risk needing active prevention. It is noteworthy that cancer arising in tattoos, in regional lymph nodes, and in other organs due to tattoo pigments and ingredients has not been detected or noted as a significant clinical problem hitherto, despite millions of people being tattooed for decennia. Clinical observation and epidemiology disagree with register data, which indicate an increased risk of cancer due to chemical carcinogens present in some inks. Registers rely on chronic dosaging of cell lines and animals. However, tattooing in humans is essentially a single-dose exposure, which might explain the observed discrepancy.

Histopathological and immunohistochemical features of drug-induced exanthems

Exanthematic eruptions, together with urticaria-angioedema syndrome and fixed drug eruption, are the most frequent cutaneous adverse drug reactions. Among the drug-induced exanthems (DIEs), erythematous maculopapular eruptions are the most common. Their management, especially when retrospective, is often not easy, and it is based on the use of clinical criteria, history, results of some laboratory tests, drug elimination test, skin tests, and oral challenge test. The superficial perivascular and spongiotic dermatitis, which is the prevalent histopathological features of DIEs, is not very useful in the differential diagnosis with virus- and bacteria-induced exanthems (VBIEs). On the contrary, some immune-histochemical findings (interleukin-5 overexpression, concomitant enhancement of perforin, interleukin-5, and granzyme B production, positivity for fatty acid synthase-ligand-L in amoxicillin-induced exanthems) seem to be more important. These data justifie the inclusion of DIEs in the subtypes IVb and IVc of delayed hypersensitivity reactions.

The development of a murine model for Forcipomyia taiwana (biting midge) allergy

BACKGROUND

Forcipomyia taiwana (biting midge) allergy is the most prevalent biting insect allergy in Taiwan. An animal model corresponding to the human immuno-pathologic features of midge allergy is needed for investigating the mechanisms and therapies. This study successfully developed a murine model of Forcipomyia taiwana allergy.

METHODS

BALB/c mice were sensitized intra-peritoneally with midge extract on days 0, 7, 14, 21 then intra-dermally on days 28, 31 and 35. Serum midge-specific IgE, IgG1, and IgG2a were measured every 14 days by indirect ELISA. The mice were challenged intradermally with midge extract at day 40 and then sacrificed. Proliferation and cytokine production of splenocytes after stimulation with midge extract were determined by MTT assay and ELISA, respectively. The cytokine mRNA expression in response to midge stimulation was analyzed by RT-PCR.

RESULTS

Serum IgE, total IgG, and IgG1 antibody levels against midge extract were significantly higher in the midge-sensitized mice than in the control mice. After the two-step sensitization, all mice in the midge-sensitized group displayed immediate itch and plasma extravasation reactions in response to challenge with midge extract. Skin histology from midge-sensitized mice showed marked eosinophil and lymphocyte infiltrations similar to that observed in humans. Stimulation of murine splenocytes with midge extract elicited significant proliferation, IL-4, IL-10, IL-13 and IFN-γ protein production, and up-regulation of mRNA in a dose-dependent manner in the midge-sensitized group, but not in the control group.

CONCLUSIONS

A murine model of midge bite allergy has been successfully developed using a two-step sensitization protocol. The sensitized mice have very similar clinical and immunologic reactions to challenge with midge proteins as the reactions of human to midge bites. This murine model may be a useful platform for future research and the development of treatment strategies for insect bite allergy.

[Dual role of photosensibilizator merocyanine 540 as a bactericidal agent and immune reaction regulator]

AIM

Develop conditions for inactivation of staphylococcus by using photosensibilizator merocyanine 540 (MC540) for the production of antigenic preparation (AP). Study some of immune reactions to AP and the possibility of regulation of DTH reaction to AP under the effect of MC540.

MATERIALS AND METHODS

Merocyanine 540 (MC540, Sigma-Aldrich, Switzerland) is used in the study. MC540 and Staphylococcus aureus, strain 78 (Sa78) were irradiated by light of a mercury-quartz lamp DRSH-250 (Zelenograd). C56BL/6 line mice were immunized once by subcutaneous administration of AP. DTH reaction was tested 7 days after the immunization. Functional activity of peritoneal exudate macrophages was determined 1 and 9 days after the immunization. Immune modulating effect of MC540 in DTH was determined after its per os administration to mice 1 hour after AP sensibilization.

RESULTS

In order to obtain AP, S. aureus suspension at the concentration of 2.5 x 10(7) CFU/ml in 25 microM MC540 solution and 0.25 M NaCl solution were exposed to irradiation for 5 minutes. During DTH reaction induction its intensity dependence on AP dose was revealed. A persistent increase of a lysosomatic enzyme cathepsin D in macrophages of peritoneal exudate after a single administration of AP was noted. During MC540 irradiation an accumulation of photoproducts that have a pronounced immune suppression effect in DTH reaction had a dose-dependent character.

CONCLUSION

Use of saline allows to increase bactericidal potential of a photosensibilizator (PS). However during therapy of localized forms of infection a possible immune modulating effect of PS on macro organism should be considered. By varying PS dose and irradiation time not only maximum bactericidal effect can be achieved but also regulation of inflammatory reactions in the area of PS effect can be ensured.

18β-glycyrrhetinic acid induces immunological adjuvant activity of Th1 against Candida albicans surface mannan extract

The aim of this study was to determine the immunological adjuvant effect of 18β-glycyrrhetinic acid (GA) isolated from Glycyrrhizae radix. In the experiments, BALB/c mice were immunized on days 1 and 22 intraperitoneally (i.p.) with an emulsion form of Candida albicans surface mannan extract (SM) mixed with either Incomplete Freund's Adjuvant [SM/IFA], or Complete Freund's Adjuvant [SM/CFA] or GA mixed with IFA [SM/GA/IFA]. One week after the second immunization, polyclonal sera were collected from these animals in order to determine IgG isotypes and cytokine profiles in the sera. After the collection, the spleen samples were collected to determine the degree of T cell proliferation. Additionally, the DTH (delayed type hypersensitivity) response was examined by measuring the footpad swelling of immunized mice. Data resulting from the T cell proliferation test showed that SM/GA/IFA enhanced the proliferation the most. The enhancement was about 85% more compared to SM/IFA (p<0.05). IgG isotypes and cytokine profiles displayed that SM/GA/IFA induced the most abundant production of total IgG with the highest IgG2a/IgG1 ratio (1.31) and greatest IFN-γ secretion. In contrast, SM/CFA resulted in an IgG2a/IgG1 ratio less than 1 and SM/IFA produced a dominant induction of IL-4, but almost no IFN-γ secretion. Together, these observations revealed that GA developed a greater Th1 immune response than Th2 response. The DTH determination confirmed that GA-addition induced dominant Th1 immunity - displaying the highest footpad-swelling followed by SM/CFA and BSA/IFA, respectively. All of this data indicates that GA has a Th1-immunological adjuvant activity, which would be beneficial in the treatment of Th1-disordered disease due to C. albicans.

Immunotoxic effects of imidacloprid following 28 days of oral exposure in BALB/c mice

Imidacloprid, a neonicotinoid insecticide has been in use worldwide for several years in agriculture and veterinary medicine. It is possible that residue of this compound may be recycled in the food chain and thus information regarding effects from potential exposure to it is warranted. The objective of the present study was to evaluate immunotoxic effects of imidacloprid in female BALB/c mice. Imidacloprid was administered orally daily at 10, 5, or 2.5mg/kg over 28 days. Specific parameters of humoral and cellular immune response including hemagglutinating antibody (HA) titer to sheep red blood cells (SRBC; T-dependent antigen), delayed type hypersensitivity (DTH) response to SRBC, and T-lymphocyte proliferation in response to phytohemagglutinin (PHA) were evaluated. The results showed that imidacloprid at high dose, specifically suppressed cell-mediated immune response as was evident from decreased DTH response and decreased stimulation index of T-lymphocytes to PHA. At this dose, there were also prominent histopathological alterations in spleen and liver. Histopathological analysis of footpad sections of mice revealed dose-related suppression of DTH response. Imidacloprid at low dose of 2.5mg/kg/day did not produce any significant alterations in cellular and humoral immune response and it seemed to be an appropriate dose for assessment of 'no observable adverse effects level' for immunotoxicity in BALB/c mice. The results also indicated that imidacloprid has immunosuppressive effects at doses >5mg/kg, which could potentially be attributed to direct cytotoxic effects of IMD against T cells (particularly TH cells) and that long-term exposure could be detrimental to the immune system.

Partial deficiency of sphingosine-1-phosphate lyase confers protection in experimental autoimmune encephalomyelitis

Background

Sphingosine-1-phosphate (S1P) regulates the egress of T cells from lymphoid organs; levels of S1P in the tissues are controlled by S1P lyase (Sgpl1). Hence, Sgpl1 offers a target to block T cell-dependent inflammatory processes. However, the involvement of Sgpl1 in models of disease has not been fully elucidated yet, since Sgpl1 KO mice have a short life-span.

Methodology

We generated inducible Sgpl1 KO mice featuring partial reduction of Sgpl1 activity and analyzed them with respect to sphingolipid levels, T-cell distribution, and response in models of inflammation.

Principal Findings

The partially Sgpl1 deficient mice are viable but feature profound reduction of peripheral T cells, similar to the constitutive KO mice. While thymic T cell development in these mice appears normal, mature T cells are retained in thymus and lymph nodes, leading to reduced T cell numbers in spleen and blood, with a skewing towards increased proportions of memory T cells and T regulatory cells. The therapeutic relevance of Sgpl1 is demonstrated by the fact that the inducible KO mice are protected in experimental autoimmune encephalomyelitis (EAE). T cell immigration into the CNS was found to be profoundly reduced. Since S1P levels in the brain of the animals are unchanged, we conclude that protection in EAE is due to the peripheral effect on T cells, leading to reduced CNS immigration, rather than on local effects in the CNS.

Significance

The data suggest Sgpl1 as a novel therapeutic target for the treatment of multiple sclerosis.

BD750, a benzothiazole derivative, inhibits T cell proliferation by affecting the JAK3/STAT5 signalling pathway

BACKGROUND AND PURPOSE

A series of benzothiazole derivatives were screened for immunosuppressive activity; of these compounds BD750 was found to be the most effective immunosuppressant. The purpose of the current study was to determine the immunosuppressive activity of BD750 on T cell proliferation and its potential mode of action.

EXPERIMENTAL APPROACH

T cell proliferation, CD25 and CD69 expression and cell cycle distribution were measured in vitro by flow cytometry. Cell viability was determined by CCK-8 assay. Cytokine levels were measured by elisa. The activation of signal-regulated molecules was assessed by Western blot analysis. The effects of BD750 were evaluated in vivo in a mouse model of delayed-type hypersensitivity.

KEY RESULTS

BD750 significantly inhibited mouse and human T cell proliferation, stimulated either by anti-CD3/anti-CD28 monoclonal antibodies or by an alloantigen, in a dose-dependent manner in vitro. No obvious cytotoxic effects of BD750 were observed in our experimental conditions. Furthermore, BD750 did not inhibit CD25 and CD69 expression or IL-2 and IL-4 secretion, but induced cell cycle arrest at the G(0) /G(1) phase in activated T cells. In IL-2-stimulated CTLL-2 cells and primary activated T cells, BD750 inhibited cell proliferation and STAT5 phosphorylation, but not Akt or p70S6K phosphorylation. BD750 also reduced the T cell-mediated delayed-type hypersensitivity response in mice in a dose-dependent manner.

CONCLUSION AND IMPLICATIONS

These data indicate that BD750 inhibits IL-2-induced JAK3/STAT5-dependent T cell proliferation. BD750 has the potential to be used as a lead compound for the design and development of new immunosuppressants for preventing graft rejection and treating autoimmune diseases.

In vitro methods for diagnosing nonimmediate hypersensitivity reactions to drugs

Nonimmediate drug hypersensitivity reactions (DHRs) are difficult to manage in daily clinical practice, mainly owing to their heterogeneous clinical manifestations and the lack of selective biological markers. In vitro methods are necessaryto establish a diagnosis, especially given the low sensitivity of skin tests and the inherent risks of drug provocation testing. In vitro evaluation of nonimmediate DHRs must include approaches that can be applied during the different phases of the reaction. During the acute phase, monitoring markers in both skin and peripheral blood helps to discriminate between immediate and nonimmediate DHRs with cutaneous responses and to distinguish between reactions that, although they present similar clinical symptoms, are produced by different immunological mechanisms and therefore have a different treatment and prognosis. During the resolution phase, in vitro testing is used to detect the response of T cells to drug stimulation; however, this approach has certain limitations, such as the lack of validated studies assessing sensitivity. Moreover, in vitro tests indicate an immune response that is not always related to a DHR. In this review, members of the Immunology and Drug Allergy Committee of the Spanish Society of Allergy and Clinical Immunology (SEAIC) provide an overview of the most widely used in vitro tests for evaluating nonimmediate DHRs.

Acephate immunotoxicity in White Leghorn cockerel chicks upon experimental exposure

Immunotoxicity for subacute exposure to acephate (O,S-dimethyl-acetylphosphoramidothioate) was assessed in day old White Leghorn (WLH) cockerel chicks. The chicks were divided into five groups. Groups C1 and C2 served as plain control and vehicle control respectively. Chicks of groups T1, T2 and T3 were administered acephate suspended in groundnut oil at 21.3mg/kg, 28.4mg/kg and 42.6mg/kg respectively orally for 28 days. A non-significant reduction in total leukocyte count was observed. Although, anti-Newcastle Disease Virus (NDV) antibody titer, serum total protein (TP), serum globulin, serum albumin and organ:body weight ratios of immune organs were significantly suppressed. The delayed type hypersensitivity response to 2,4-dinitro-1-chlorobenzene (DNCB) was not significantly altered. Histopathologically, bursa and spleen showed mild depletion of lymphocytes. Furthermore, DNA fragmentation assay was performed and detected ladder pattern (180bp) in DNA. It was concluded that subacute acephate exposure at low concentrations may affect immune responses in avian species.

[Study on the immunocompetence of polysaccharide extracted from root of Salvia miltiorrhiza]

OBJECTIVE

To study the immune activity of polysaccharide extracted from root of Salvia miltiorrhiza.

METHODS

Investigated the effects of polysaccharide extracted from root of Salvia miltiorrhiza on lymphocyte proliferation response of mouse induced by LPS (the lipopolysaccharide LPS), phagocytosis of the peritoneal macrophage of mice to chick erythrocytes and the mouse models of delayed type hypersensitivity (DTH) response induced by DNFB.

RESULTS

Lymphocyte proliferation and phagocytosis of the peritoneal macrophage of mice could be promoted by the polysaccharide, which could inhibit ear edema and capillary permeability increase induced by DNFB and enlarged the thymus and splenic index in mice. The expression of iNOS, IFN-alpha and IL-1beta was inhibited significantly in the treatment group.

CONCLUSION

The polysaccharide extracted from Salvia miltiorrhiza can improve immune function.

Fully human antibodies against the Protease-Activated Receptor-2 (PAR-2) with anti-inflammatory activity

PAR-2 belongs to a family of G-protein coupled Protease-Activated Receptors (PAR) which are activated by specific proteolytic cleavage in the extracellular N-terminal region. PAR-2 is activated by proteases such as trypsin, tryptase, proteinase 3, factor VIIa, factor Xa and is thought to be a mediator of inflammation and tissue injury, where elevated levels of proteases are found. Utilizing the HuCAL GOLD® phage display library we generated fully human antibodies specifically blocking the protease cleavage site in the N-terminal domain. In vitro affinity optimization resulted in antibodies with up to 1000-fold improved affinities relative to the original parental antibodies with dissociation constants as low as 100 pM. Corresponding increases in potency were observed in a mechanistic protease cleavage assay. The antibodies effectively inhibited PAR-2 mediated intracellular calcium release and cytokine secretion in various cell types stimulated with trypsin. In addition, the antibodies demonstrated potent inhibition of trypsin induced relaxation of isolated rat aortic rings ex vivo. In a short term mouse model of inflammation, the trans vivo DTH model, anti-PAR-2 antibodies showed inhibition of the inflammatory swelling response. In summary, potent inhibitors of PAR-2 were generated which allow further assessment of the role of this receptor in inflammation and evaluation of their potential as therapeutic agents.

[Morphogenesis of the structural changes of the internal organs in superinvasive opisthorchiasis]

The study of the model of superinvasive opisthorchiasis (SO) in Syrian hamsters and autopsy material obtained from patients with SO, it was shown that during the early period of pulmonary disease, the lungs underwent changes developing on the basis of delayed-type hypersensitivity reactions. In the chronic phase of SO, exudative and predominant productive reactions were revealed leading to the interstitial lung disease, fibrosing alveolitis. In the heart in SO, eosinophilic cell myocarditis was found with subsequent diffuse cardiosclerosis. In the testes, sclerotic processes with atrophy of glandulocytes (Leydig cells) and sustentocytes (Sertoli cells) were detected. The structural changes in the lungs, heart and testes were induced by parasite metabolites, that are deposited in tissues in the form of granules and conglomerates.

Unusual presentation of cobalt hypersensitivity in a patient with a metal-on-metal bearing in total hip arthroplasty

Pain after hip arthroplasty is less likely to be attributed to dermal sensitivity from orthopedic implants. Unexplained persistent pain after hip arthroplasty typically leads to further investigation, occasionally revealing a metal sensitivity. Our case study presents an unusual finding of a delayed type IV cobalt hypersensitivity in a patient several years after use of cobalt in the contralateral hip. Recognition and a high index of suspicion are needed for timely treatment of metal allergy when it presents as persistent pain after hip arthroplasty.

Drug hypersensitivity reactions involving skin

Immune reactions to drugs can cause a variety of diseases involving the skin, liver, kidney, lungs, and other organs. Beside immediate, IgE-mediated reactions of varying degrees (urticaria to anaphylactic shock), many drug hypersensitivity reactions appear delayed, namely hours to days after starting drug treatment, showing a variety of clinical manifestations from solely skin involvement to fulminant systemic diseases which may be fatal. Immunohistochemical and functional studies of drug-specific T cells in patients with delayed reactions confirmed a predominant role for T cells in the onset and maintenance of immune-mediated delayed drug hypersensitivity reactions (type IV reactions). In these reactions, drug-specific CD4+ and CD8+ T cells are stimulated by drugs through their T cell receptors (TCR). Drugs can stimulate T cells in two ways: they can act as haptens and bind covalently to larger protein structures (hapten-carrier model), inducing a specific immune response. In addition, they may accidentally bind in a labile, noncovalent way to a particular TCR of the whole TCR repertoire and possibly also major histocompatibility complex (MHC)-molecules - similar to their pharmacologic action. This seems to be sufficient to reactivate certain, probably in vivo preactivated T cells, if an additional interaction of the drug-stimulated TCR with MHC molecules occurs. The mechanism was named pharmacological interaction of a drug with (immune) receptor and thus termed the p-i concept. This new concept may explain the frequent skin symptoms in drug hypersensitivity to oral or parenteral drugs. Furthermore, the various clinical manifestations of T cell-mediated drug hypersensitivity may be explained by distinct T cell functions leading to different clinical phenotypes. These data allowed a subclassification of the delayed hypersensitivity reactions (type IV) into T cell reactions which, by releasing certain cytokines and chemokines, preferentially activate and recruit monocytes (type IVa), eosinophils (type IVb), or neutrophils (type IVd).

Enhanced contact hypersensitivity by delayed T-helper 2 response in BALB/c mice

T-helper (Th) 1/Th2 balance determines the direction of contact hypersensitivity (CHS). To clarify the immunopathogenesis of contact dermatitis, 2,4-dinitrofluorobenzene (DNFB)-induced CHS reaction was compared between the BALB/c and C57BL/6 mice. The two strains were sensitized with DNFB systemically and challenged with DNFB locally. The CHS reaction in BALB/c mice was intense compared with that in C57BL/6 mice at 24 and 48 hours post-DNFB challenge. The dermal lesions were characterized by infiltration of lymphocytes, eosinophils, neutrophils, and macrophages including CD4+ and CD8+ T cells, and interleukin (IL)-4-producing(+) and interferon (IFN)-gamma+ cells in BALB/c mice. In C57BL/6 mice, the composition of inflammatory cells was same as those in BALB/c mice except for eosinophils, CD4+ T cells, and IL-4+ cells. There was no increase in the number of mast cells in the two strains. Local and systemic productions of IL-4 and IFN-gamma in BALB/c mice were higher than those in C57BL/6 mice. Although blood IgE values increased in BALB/c mice, but not in C57BL/6 mice, at 48 hours postchallenge, its value was low. The delayed Th2-like response together with Th1-like response in BALB/c mice may induce strong CHS reaction compared with C57BL/6 mice, which may dominantly develop Th1-like reaction. Moreover, mast cell and IgE do not appear to be involved in delayed CHS.

Sex-specific effects of glucose deprivation on cell-mediated immunity and reproduction in Siberian hamsters (Phodopus sungorus)

In most species, sexes differ in levels of parasitism. These differences have traditionally been believed to be static, but a capacity for adjusting anti-parasite investments would allow sexes to allocate resources adaptively contingent on environmental conditions. During stressful periods, such as a food shortage, allocation decisions would be mandated in males and females, but the biasing of resources may differ depending on the value of various physiological alternatives to the fitness of each sex. To determine whether sexes sacrifice immune or reproductive capacity when stressed, male and female Siberian hamsters (Phodopus sungorus) were pharmacologically deprived of glucose. Glucose deprivation was expected to compromise immune activity (delayed-type hypersensitivity) more than reproductive capacity in males because male fitness is limited by reproductive opportunities. The opposite was predicted for females because of the greater value of surviving to breed in favorable conditions. Contrary to expectations, glucoprivation compromised immune activity in female, but not male, hamsters. Conversely, glucoprivation reduced male, but not female, reproductive organ masses. These results may reflect the adjustments made by wild hamsters during food shortages, or they may be influenced by the study design; neither sex was permitted to incur other behavioral and physiological costs, such as lactation and parental care. Regardless, our results indicate that sex differences in parasitism are likely to be plastic in many circumstances, but further work in free-living animals is critical to ascertain whether results of the present study are naturally representative.

Vaccine adjuvant systems containing monophosphoryl lipid A and QS21 induce strong and persistent humoral and T cell responses against hepatitis B surface antigen in healthy adult volunteers

A randomised, double-blind study assessing the potential of four adjuvants in combination with recombinant hepatitis B surface antigen has been conducted to evaluate humoral and cell-mediated immune responses in healthy adults after three vaccine doses at months 0, 1 and 10. Three Adjuvant Systems (AS) contained 3-O-desacyl-4'-monophosphoryl lipid A (MPL) and QS21, formulated either with an oil-in-water emulsion (AS02B and AS02V) or with liposomes (AS01B). The fourth adjuvant was CpG oligonucleotide. High levels of antibodies were induced by all adjuvants, whereas cell-mediated immune responses, including cytolytic T cells and strong and persistent CD4(+) T cell response were mainly observed with the three MPL/QS21-containing Adjuvant Systems. The CD4(+) T cell response was characterised in vitro by vigorous lymphoproliferation, high IFN-gamma and moderate IL-5 production. Antigen-specific T cell immune response was further confirmed ex vivo by detection of IL-2- and IFN-gamma-producing CD4(+) T cells, and in vivo by measuring increased levels of IFN-gamma in the serum and delayed-type hypersensitivity (DTH) responses. The CpG adjuvanted vaccine induced consistently lower immune responses for all parameters. All vaccine adjuvants were shown to be safe with acceptable reactogenicity profiles. The majority of subjects reported local reactions at the injection site after vaccination while general reactions were recorded less frequently. No vaccine-related serious adverse event was reported. Importantly, no increase in markers of auto-immunity and allergy was detected over the whole study course. In conclusion, the Adjuvant Systems containing MPL/QS21, in combination with hepatitis B surface antigen, induced very strong humoral and cellular immune responses in healthy adults. The AS01B-adjuvanted vaccine induced the strongest and most durable specific cellular immune responses after two doses. These Adjuvant Systems, when added to recombinant protein antigens, can be fundamental to develop effective prophylactic vaccines against complex pathogens, e.g. malaria, HIV infection and tuberculosis, and for special target populations such as subjects with an impaired immune response, due to age or medical conditions.

The importance of myeloid-derived suppressor cells in the regulation of autoimmune effector cells by a chronic contact eczema

Induction of a chronic eczema is a most efficient therapy for alopecia areata (AA). We had noted a reduction in regulatory T cells during AA induction and wondered whether regulatory T cells may become recruited or expanded during repeated skin sensitization or whether additional regulatory cells account for hair regrowth. AA could not be cured by the transfer of CD4(+)CD25(high) lymph node cells from mice repeatedly treated with a contact sensitizer. This obviously is a consequence of a dominance of freshly activated cells as compared with regulatory CD4(+)CD25(+) T cells. Instead, a population of Gr-1(+)CD11b(+) cells was significantly increased in skin and spleen of AA mice repeatedly treated with a contact sensitizer. Gr-1(+)CD11b(+) spleen cells mostly expressed CD31. Expression of several proinflammatory cytokines as well as of the IFN-gamma receptor and the TNF receptor I were increased. Particularly in the skin, Gr-1(+) cells expressed several chemokines and CCR8 at high levels. Gr-1(+)CD11b(+) cells most potently suppressed AA effector cell proliferation in vitro and promoted partial hair regrowth in vivo. When cocultured with CD4(+) or CD8(+) cells from AA mice, the Gr-1(+)CD11b(+) cells secreted high levels of NO. However, possibly due to high level Bcl-2 protein expression in AA T cells, apoptosis induction remained unaltered. Instead, zeta-chain expression was strongly down-regulated, which was accompanied by a decrease in ZAP70 and ERK1/2 phosphorylation. Thus, a chronic eczema supports the expansion and activation of myeloid suppressor cells that, via zeta-chain down-regulation, contribute to autoreactive T cell silencing in vitro and in vivo.

Management and preparedness for infusion and hypersensitivity reactions

BACKGROUND

Like nearly all systemic cancer therapies, monoclonal antibodies are associated with hypersensitivity reactions. This article reviews the characteristics and management of hypersensitivity reactions to monoclonal antibodies and commonly used chemotherapy agents.

METHODS

MEDLINE was searched for recent studies and reviews pertaining to hypersensitivity reactions with monoclonal antibodies (cetuximab, rituximab, trastuzumab, panitumumab, bevacizumab), platinum compounds (carboplatin, oxaliplatin), and taxanes (paclitaxel, docetaxel). Emphasis was placed on articles that provided practical information on hypersensitivity reaction management. Data found in the literature were supplemented with information from the package insert for each agent.

RESULTS

Severe hypersensitivity reactions are rare, with an incidence of < or =5%, provided patients receive proper premedication, close monitoring, and prompt intervention when symptoms occur. Hypersensitivity reactions to platinum compounds are generally consistent with type 1 hypersensitivity, occurring after multiple cycles of therapy. Reactions to taxanes and monoclonal antibodies produce similar symptoms, but are generally immediate, occurring during the first few minutes of the first or second infusion. However, 10%-30% of reactions to monoclonal antibodies are delayed, and may occur in later infusions, indicating the importance of close observation of the patient following administration. Mild-to-moderate reactions can be managed by temporary infusion interruption, reduction of the infusion rate, and symptom management. Rechallenge should be considered after complete resolution of all symptoms. Severe reactions may require treatment discontinuation.

CONCLUSION

Hypersensitivity or infusion reactions to platinum compounds are acquired; reactions to taxanes and monoclonal antibodies are immediate and typically occur during the first few minutes of the first infusion. The different time of onset should be considered when developing strategies for preventing and managing hypersensitivity reactions. The decision to rechallenge or discontinue treatment after a reaction occurs depends on the severity of the reaction and other clinical factors.

In situ detection of antigen-specific T cells in cryo-sections using MHC class I tetramers after dendritic cell vaccination of melanoma patients

Application of tetrameric MHC class I-peptide complexes has significantly improved the monitoring of antigen-specific T cell immune responses in mouse models as well as in clinical studies. Especially MHC class I tetramer analysis of tumor-specific T cells in suspension or on thick vibratome sections from viable tissue has been proven extremely useful. Using the well-characterized mouse tyrosinase-related-protein-2 specific cytotoxic T cell (CTL) clone LP9, we now developed a method that allows for specific identification of T cells with MHC class I tetramers in 8 mum thick, chemically fixed cryosections. The protocol was validated in a murine influenza virus-infection model. Moreover, analysis of delayed type hypersensitivity (DTH) skin biopsies from melanoma patients vaccinated with peptide-loaded mature dendritic cells, revealed the presence and location of anti-tumor CTLs. The specificity of the CTLs detected in situ correlated with both the DTH challenge specificity and reactivity of cell suspensions derived from the same biopsies. Collectively, our data demonstrate that in situ MHC class I tetramer staining provides a valuable tool to reveal the presence and anatomical location of specific CTLs in frozen tissue following immune-based treatment strategies in cancer patients.

Dependency of the trans vivo delayed type hypersensitivity response on the action of regulatory T cells: implications for monitoring transplant tolerance

BACKGROUND

The trans vivo delayed-type hypersensitivity (DTH) assay has been used for monitoring the immune status of clinical transplant recipients. Here we tested the hypothesis that the assay can reveal control of allograft rejection by CD25CD4 regulatory T cells (Treg).

METHODS

CBA.Ca (H2) recipients of heterotopic C57BL/10 (H2, B10) heart transplants were untreated or pretreated with anti-CD4 antibody and donor-specific blood. This protocol has been shown previously to induce operational tolerance to alloantigens that is dependent on CD25CD4 Treg. Four weeks after transplantation leukocytes were harvested and used for the trans vivo DTH assay. Cells were stimulated with irradiated B10 leukocytes or subcellular antigen and injected into ear pinnae of immune deficient CB17.SCID.beige hosts.

RESULTS

Stimulation of leukocytes from recipients rejecting B10 cardiac allografts with recall alloantigen caused a "strong" swelling response, whereas similar stimulation of leukocytes from operationally tolerant mice resulted in significantly less swelling (n=17; P=0.003). When CD25 T cells were depleted from "tolerant" leukocytes, the swelling response triggered was similar to that obtained using cells from rejecting animals (P<0.001), while coinjection of purified CD25CD4 cells from tolerant recipients with rejecting cells suppressed the swelling response (P=0.007) to the level observed with cells from tolerant mice. Both the effector and the regulatory response were triggered by indirect allorecognition and blocking experiments showed that the regulation observed was dependent on cytoxic T lymphocyte antigen (CTLA) 4.

CONCLUSION

The trans vivo DTH assay can be used to reveal regulation mediated by CD25CD4 T cells and is CTLA4 dependent.

Persistent delayed-type hypersensitivity reaction to injectable non-animal-stabilized hyaluronic acid

OBJECTIVE

Injectable hyaluronic acid is a glycosaminoglycan used for soft-tissue augmentation. A number of products that are not Food and Drug Administration (FDA) approved for use in the United States are used commonly in Europe. We report a case of persistent delayed-type hypersensitivity to injected non-animal-stabilized hyaluronic acid. The patient was initially injected in Europe with a non-FDA-approved filler but traveled to the United States for evaluation of this adverse reaction.

METHODS

A case of adverse reaction to non-animal-stabilized hyaluronic acid is described. An overview of selected hyaluronic acid filler products is provided.

RESULTS

The patient developed persistent facial edema after injection of hyaluronic acid filler to the melolabial folds, glabella, lips, and perioral rhytids.

CONCLUSION

Injectable hyaluronic acid can be associated with a variety of complications including immediate and delayed-type hypersensitivity reactions. Physicians should be familiar with products used in other countries, as patients may present for evaluation following adverse reaction to fillers obtained abroad or from American physicians using non-FDA-approved products.

Delayed allergic reaction to natalizumab associated with early formation of neutralizing antibodies

BACKGROUND

Natalizumab is a new therapeutic option for relapsing-remitting multiple sclerosis. As with other antibody therapies, hypersensitivity reactions have been observed. In the Natalizumab Safety and Efficacy in Relapsing-Remitting Multiple Sclerosis (AFFIRM) trial, infusion-related hypersensitivity reactions developed in 4% of patients, usually within 2 hours after starting the infusion.

OBJECTIVE

To report a significant, delayed, serum sickness-like, type III systemic allergic reaction to natalizumab.

DESIGN

Case report describing clinical follow-up and the serial measurement of antinatalizumab antibodies.

PATIENT

A 23-year-old man with relapsing-remitting multiple sclerosis developed a fever, arthralgias, urticarial exanthema, and a swollen lower lip during several days after his second infusion of natalizumab.

RESULTS

The patient developed a delayed, serum sickness-like, type III systemic allergic reaction to natalizumab. Five weeks after initiation of this therapy, he tested positive for antinatalizumab antibodies and exhibited persistent antibody titers 8 and 12 weeks later. His symptoms completely resolved with a short course of oral glucocorticosteroids.

CONCLUSION

Clinicians and patients should be alert not only to immediate but also to significantly delayed substantial allergic reactions to natalizumab.

Immunomodulatory and apoptotic effects of Stachys obtusicrena on proliferative lymphocytes

BACKGROUND

Several medicinal plants have shown anti-proliferative and apoptotic effects on human lymphocytes. In the present study the immunomodulatory properties of Stachys obtusicrena, a native plant to Iran, was examined and its possible effects on the induction of apoptosis were determined.

MATERIAL/METHODS

The in vivo effect of the methanolic extract of S. obtusicrena on delayed type hypersensitivity (DTH) and antibody production was investigated in mice immunized with the antigen. The proliferation of human lymphocytes stimulated with mitogen in the presence of the extract was determined by [3H]-thymidine incorporation assay. Mitogen-treated lymphocytes were exposed to the extract and analyzed for induction of apoptosis using flow cytometry and gel electrophoresis.

RESULTS

Data obtained from the DTH and antibody responses indicated a dose-related decrease in both parameters in the extract-treated mice compared with the untreated control group. In the in vitro study performed on the lymphocytes, the extract caused a dose-dependent decline in [3H]-thymidine uptake. The stimulation index of all cultures treated with different concentrations of the extract was less than 1. IL-2 levels in the culture supernatants of the activated lymphocytes showed a dose-related decrease as well. Results of flow cytometry indicated a dose-dependent accumulation of cells in the sub-G1 phase. The internucleosomal DNA fragmentation study showed typical DNA laddering in agarose gels.

CONCLUSIONS

The present study showed inhibitory effects of S. obtusicrena on both cellular and humoral immune responses and suggests that this effect may in part be due to the induction of apoptosis in proliferative lymphocytes.

IL-17-mediated regulation of innate and acquired immune response against pulmonary Mycobacterium bovis bacille Calmette-Guerin infection

IL-17 is a cytokine that induces neutrophil-mediated inflammation, but its role in protective immunity against intracellular bacterial infection remains unclear. In the present study, we demonstrate that IL-17 is an important cytokine not only in the early neutrophil-mediated inflammatory response, but also in T cell-mediated IFN-gamma production and granuloma formation in response to pulmonary infection by Mycobacterium bovis bacille Calmette-Guérin (BCG). IL-17 expression in the BCG-infected lung was detected from the first day after infection and the expression depended on IL-23. Our observations indicated that gammadelta T cells are a primary source of IL-17. Lung-infiltrating T cells of IL-17-deficient mice produced less IFN-gamma in comparison to those from wild-type mice 4 wk after BCG infection. Impaired granuloma formation was also observed in the infected lungs of IL-17-deficient mice, which is consistent with the decreased delayed-type hypersensitivity response of the infected mice against mycobacterial Ag. These data suggest that IL-17 is an important cytokine in the induction of optimal Th1 response and protective immunity against mycobacterial infection.

Fitness of cell-mediated immunity independent of repertoire diversity

Fitness of cell-mediated immunity is thought to depend on TCR diversity; however, this concept has not been tested formally. We tested the concept using JH(-/-) mice that lack B cells and have TCR Vbeta diversity <1% that of wild-type mice and quasimonoclonal (QM) mice with oligoclonal B cells and TCR Vbeta diversity 7% that of wild-type mice. Despite having a TCR repertoire contracted >99% and defective lymphoid organogenesis, JH(-/-) mice rejected H-Y-incompatible skin grafts as rapidly as wild-type mice. JH(-/-) mice exhibited T cell priming by peptide and delayed-type hypersensitivity, although these responses were less than normal owing either to TCR repertoire contraction or defective lymphoid organogenesis. QM mice with TCR diversity contracted >90%, and normal lymphoid organs rejected H-Y incompatible skin grafts as rapidly as wild type mice and exhibited normal T cell priming and normal delayed-type hypersensitivity reactions. QM mice also resisted Pneumocystis murina like wild-type mice. Thus, cell-mediated immunity can function normally despite contractions of TCR diversity >90% and possibly >99%.

Administration of anti-type II collagen antibody sustains footpad swelling of mice caused by a delayed-type hypersensitivity reaction and induces severe arthritis

Delayed-type hypersensitivity (DTH) is an immune reaction induced by antigen. In the mice footpads at which DTH is elicited, transient swellings which usually peaks at 24-48 h after the antigen challenge are observed. We found that the footpad swellings of mice are sustained for at least 7 days after the antigen challenge if the mice were injected with anti-type II collagen monoclonal antibody (anti-CII MoAb) before the antigen challenge. A histological section of the swelled hindpaw revealed that severe joint inflammation and bone destruction was induced. These features were not observed in the footpads of the DTH-induced mice. Analysis of the inflammatory reaction induced by both the DTH and the anti-CII MoAb injection, here named as DTH arthritis, revealed the following: (1) DTH arthritis is elicited in an antigen-specific manner; and (2) the development of DTH arthritis is mediated by antigen-specific T cells, especially CD4+ T cells.

Methodologies for developmental immunotoxicity (DIT) testing

Developmental immunotoxicity has gained increasing recognition as a significant factor influencing the risk of later life disease. Based on the data collected thus far on different chemicals and drugs, the developing immune system can be significantly more sensitive than the adult immune system to xenobiotic-induced insult. There are distinct differences between the immune system surrounding birth and that in the mature adult as well as differences in the nature of immunotoxic changes based on age. Immunosuppresssion is not the only concern. Immunotoxic changes that increase the risk for allergic or autoimmune responses should also be considered. Therefore, one should not assume that immunotoxicity assays validated for adult exposure assessment are inherently the most predictive for developmental immunotoxicology (DIT) evaluation. Many of those adult-based protocols were developed solely to detect immunosuppression, whereas DIT concerns include shifts in immune balance. For this reason, it is useful to examine the various immune endpoints that have been employed in recent perinatal immunotoxicity studies, compare those against routine adult immunotoxicity evaluation protocols, and consider the options that are available for effective DIT testing. The results published on several chemicals and drugs in recent years suggest that functional tests are a front-line priority for perinatal immunotoxicity detection and that a combination of at least two functional tests (such as a multi-isotype T-dependent antibody response (TDARs), and a cell-mediated immune response assay such as the delayed-type hypersensitivity assay and/or T cell or NK cytotoxicity assays) should be paired with immune cell populations and histopathological analysis. Cytokine production measurements offer outstanding promise and may eventually be able to be substituted for other more laborious procedures. However, multi-cytokine analysis needs to be standardized in terms of optimum source for analysis and protocol.