Animals in the penicillin-sensitive group (Group I) showed severe dyspnoea (4/4), urticaria (2/4), oedema (3/4), lacrimation (4/4). Oedema was noticed in the eyelids (Fig 1a), lips, brisket region (Fig 1b), face, perianal and anal region (Fig 1c and 1d) in group I. Rectal body temperature of animals in the penicillin-sensitive group (102.50±0.64
oF) was significantly elevated compared to animals in Penicillin Tolerant (98±0.36
oF) and control group (98.4±0.40
oF), while the non-significant difference in rectal body temperature of animals in group II and group III were observed (Table 1). A similar trend was also observed in the case of heart rate (131.75±2.95 beats in group I, 90.33±3.07 beats in group II and 87.50±2.72 beats in group III) and respiration rate (35.00 ±3.48 breaths per minute (bpm) in group I, 26.33±1.87 bpm in group II and 24.77±1.31 bpm in group III). These clinical manifestations of penicillin hypersensitivity observed in the present study are in concurrence with findings of earlier studies
(Radostits et al., 2007, Omidi 2009,
Boonk et al., 1982). Elevated body temperature and urticaria have been attributed to muscle tremors and are mediated by IgE directed against allergic determinants generated from oxidative damage (
Omidi 2009) and oxidative metabolites
Boonk et al., (1982) of the culprit drug. An interesting clinical finding of the current study was three animals out of four in the penicillin hypersensitivity group (2 female and 1 male) showed odema in the brisket region. These findings are supported by the study of (
Omidi 2009), who proposed increased vascular permeability and leakage of albumin in chlorogenic acid hypersensitivity in rats.
Our results indicated that erythrocytes lysate from penicillin-hypersensitive animals were having higher ROS (Reactive oxygen species) as compared to the other two groups. Animal in groups I (30.72±2.05 nmol/g Hb) treated with penicillin was having significantly (P<0.05) increased levels of MDA (Malondialdehyde) in comparison to groups III (21.45±1.37 nmol/g Hb). While as MDA levels in groups II (27.35±2.38 nmol/g Hb) were comparable with values in groups III and groups II (Table 1). SOD (20.66±2.49 IU/mg Hb in group I and 28.41±1.74 IU/mg Hb in group II) and GPx (28.19±3.57 IU/mg Hb in group I and 59.24±5.01 IU/mg Hb in group II) content in the penicillin-hypersensitive group was significantly (P<0.05) depleted compared to group III. Penicillin administration in group I resulted in significantly (P<0.05) increased levels of NO production (59.72±7.79 μmol/L) as compared with the group II (38.61±4.44 Μmol/L) and group III (33.78±4.12 μmol/L). We observed that there was no appreciable significant difference in NO levels in groups II and III (P<0.05) (Fig 2a). The concentration of XO (Xanthine Oxidase) was significantly elevated (P<0.05) in group I (0.38±0.02 mU/mL) compared to group III (0.16±0.01 mU/mL) so it can be postulated that Penicillin treatment significantly increased the activity of XO in group I (P<0.05) (Table 1). In the present study significantly reduced levels of G6PD (16.22±1.42 IU/gHb) were found in the penicillin hypersensitivity group compared to the penicillin tolerant and control group (Fig 2b). The results of current study indicate significant positive correlation between G6PD with GPx (r=0.547, P<0.01) and SOD (r=0.34, P<0.05). While a significant negative correlation was found between G6PD with XO (r=0.39,
P<0.05). Furthermore, XO and SOD (r= -0.32, P<0.01) exhibited a significant negative correlation. Catalase (r=-0.43, P<0.01) and GPx (r=-0.43, P<0.01) and values of XO showed significantly positive correlation with NO (r=0.40, P<0.05) (Table 1).
Excessive generation of ROS leads to depletion of antioxidant enzymes
Nabi et al., (2021) therefore it may be proposed that injection of culprit drugs in penicillin-sensitive patients results in oxidative stress because of excessive generation of ROS and depletion of the antioxidant defense system.
Radostits et al., (2007) has earlier proposed the “reactive metabolite hypothesis” according to their study reactive oxidative species generated in adverse drug reactions activate the immune system in drug-induced hypersensitivity. In the current study, SOD activity was observed to be significantly decreased in the penicillin-sensitive group. Analysis of peripheral mononuclear cell resistance to adverse drug reaction was found to have elevated levels of SOD in erythrocyte homogenate
Cornejo-Garcia et al., (2016). Human Immunodeficiency Virus (HIV) infected individuals sensitive to adverse drug reactions were found to have significantly lower levels of antioxidant enzymes
Buhl et al., (1989). Increased levels of nitric oxide in the penicillin-sensitive group (59.09±13.89) are supported by experimental study of
Radostits et al., 2007 (2014) on induced cardiac anaphylaxis in the rat model and the study concluded that elevated levels of nitric oxide (NO) play a pivotal role in immune dysregulation via ROS acting as a stimulus for the clonal proliferation of mast cells. In the present study, we could not observe any significant difference in values of reduced glutathione, catalase and glutathione reductase across different experimental groups.
Pro-inflammatory cytokines particularly TNF-alpha and IL-6 have important roles pathology of drug-induced hypersensitivity. Penicillin injection in the penicillin-sensitive group caused significant (p<0.05) elevation in the serum levels of TNF-alpha, (757.75±52.80 pg/ml) and IL-6 (3389.75 ±283.73 pg/ml) as compared to the healthy control group and the penicillin-resistant group (Fig 2c and 2d). The levels of pro-inflammatory markers (TNF-α and IL-6) were significantly elevated in the penicillin-sensitive group compared to the penicillin-resistant group and control group. It may be proposed from the present study that the generation of ROS may activate the inflammatory cascade which sensitizes the host cells to an allergen in drug-induced hypersensitivity. To support these speculations, the results of the present study observed significantly increased levels of pro-inflammatory cytokines (TNF-α and IL-6) in penicillin-sensitive patients. There are various indirect pieces of evidence for the role of oxidative stress in hypersensitivity reactions
(Rieder et al., (1989); Cribb and Spielberg (1992) proposed that in the initial stage of hypersensitivity oxidative metabolite of the culprit drug form covalent bonding with endogenous host macromolecules and resulting (oxidative metabolite-endogenous macromolecule) addict functions as an allergic determinant to initiate hypersensitivity reaction.
Adeyanju et al., (2018) has postulated oxidation of sulfhydryl and disulphide bond in endogenous proteins by free radical generated in drug-sensitive subjects’ results in the generation of allergens. Furthermore,
Rieder et al., (1989) proposed that lowered oxidative defense/redox imbalance inhibits various enzymatic pathways involved in cellular defense and hence causes immune sensitization of host cells. These assumptions are further validated by the use of anti-oxidants which ameliorate the drug-induced hypersensitivity reaction and concurrently lowered allergic adduct in blood
Samitas et al., (2018). These propositions are further supported by
Yanagawa et al., (2017) who proposed that mast cell degranulation can be triggered by ROS generated during oxidative stress. The role of oxidative stress markers like NO and XO have been studied in allergic and anaphylactic conditions
Frijhoff et al., (2015) and effective inhibition of these markers has shown pronounced clinical improvement in these conditions
Bayer et al., (2013). As reported by previous studies numbers
Samitas et al., (2013) of oxidative stress markers have been found to play an important role in anaphylaxis so for effective treatment of anaphylaxis there is an urgent need to understand pathogenetic hotspots activated by oxidative stress markers.
G6PD functions as an indirect antioxidant as the enzyme is involved in the activation of NADPH + H+-SOD and GSH-Px
Beutler (2002). Results of our study showed a significantly positive correlation between G6PD activity and major antioxidants (SOD and GSH-Px) and its negative correlation with ROS suggests a contributory role of G6PD in oxidative damage and henceforth hypersensitivity. G6PD has a sparing effect on SOD activity and supplies NADPH to the cellular microenvironment which keeps GSH-Px and other enzymes in a reduced state
Rezaei and Naghadeh (2006). Decreased G6PD activity has been proposed to cause oxidative damage to reticuloendothelial cells and the release of endogenous factors results in immune dysregulation
Roth et al., (1988). However, there were some limitations of the present study which includes a sample size.
In the present study, the sample was less, so there is a need to study the role of ROS in a large sample size and hypersensitivity induced by vehicles used in common medicinal preparations.